Download Lipid Formulations of Amphotericin B: Recent Progress and Future

S133
Lipid Formulations of Amphotericin B: Recent Progress and Future Directions
John W. Hiemenz and Thomas J. Walsh
From the H Lee Moffitt Cancer Center and Research Institute,
Divisions of Bone Marrow Transplantation, Infectious Diseases, and
Tropical Medicine, University of South Florida, Tampa, Florida; and
the Infectious Diseases Section, National Cancer Institute, National
Institutes of Health, Bethesda, Maryland
Three lipid formulations of amphotericin B are now either marketed for clinical use or undergoing
further study before they can be approved in various countries worldwide. Amphotericin B lipid
complex (ABLC; Abelcet, Liposome Company, Princeton, NJ) is a concentration of ribbonlike
structures of a bilayered membrane formed by combining a 7:3 molar ratio of dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylglycerol with amphotericin B. Amphotericin B colloidal
dispersion (ABCD; Amphocil, Sequus Pharmaceuticals, Menlo Park, CA) is composed of disklike
structures of cholesteryl sulfate complexed with amphotericin B. AmBisome (Nexstar, San Dimas,
CA), the only true liposomal amphotericin B, consists of small unilamellar vesicles made up of
a bilayer membrane of hydrogenated soy phosphatidylcholine and distearoylphosphatidylglycerol
stabilized with cholesterol in a 2:0.8:1 ratio combined with amphotericin B. All of the preparations
appear to be preferentially accumulated in organs of the reticuloendothelial system, as opposed to
the kidney. In vivo animal models as well as current clinical experience suggest that use of these
formulations results in overall improvement in the therapeutic index. Patients with life-threatening
mycosis for whom therapy has failed or who are intolerant to therapy with amphotericin B deoxycholate have been successfully treated with these formulations. However, further study is warranted to
help clarify the usefulness of each of the lipid formulations as first-line therapy for documented or
suspected invasive fungal infections.
Lipid Formulations of Amphotericin B: Recent Progress
and Future Directions
Invasive fungal infections have been increasingly recognized
as a major cause ofmorbidity and mortality in the immunocompromised host [1,2]. Patients infected with HIV, recipients of
solid organ transplants, and those who are receiving therapy
for underlying malignancy are particularly susceptible to these
infections [3 - 7]. The use of high-dose ablative therapy and
either bone-marrow or peripheral-blood stem cell transplantation for a variety of malignant and nonmalignant disorders has
also contributed to the increasing incidence of invasive fungal
infections [8-10].
Candida albicans and Aspergillus species have predominated as the most common fungal pathogens in patients with
profound and prolonged neutropenia and in those who have
undergone allogeneic bone marrow transplantation [7-12].
Cryptococcal meningitis was recognized as one of the first
AIDS-defining illnesses and remains the most common invasive fungal infection in this patient population [3]. However,
Reprints or correspondence: Dr. John W. Hiemenz, Divisions of Bone Marrow Transplantation, Infectious Diseases, and Tropical Medicine, H. Lee Moffitt Cancer Center, University of South Florida, 12902 Magnolia Drive, Tampa,
Florida 33612.
CUnical Infectious Diseases 1996;22(SuppI2):S133-44
© 1996 by The University of Chicago. All rights reserved.
1058-4838/96/2205-0009$02.00
along with the increasing frequency of fungal infections over
the last decade, there has also been an increase in the number
of pathogens recognized as causing invasive disease in the immunocompromised host. Non-albicans Candida species, Torulopsis glabrata, Fusarium species, and Trichosporon beigelii
lead the growing list of newer fungal pathogens [13-14].
Amphotericin B has remained the drug of choice for lifethreatening invasive fungal infections over the last 30 years,
primarily due to its broad spectrum of activity [15-19]. The
usefulness of this polyene has been limited by its narrow therapeutic index. Amphotericin B therapy is associated with a number of adverse events. Although infusion-related side effects
such as fever, rigors, and chills are common in patients who
receive therapy with amphotericin B, medical management of
these symptoms usually suffices to allow continuation of the
drug. However, renal insufficiency in association with azotemia, renal tubular acidosis, and impaired urinary concentrating
ability resulting in electrolyte imbalance may be severe enough
to lead to dose reduction or premature discontinuation of the
drug. Moreover, even when full-dose amphotericin B is continued regardless of the development of severe renal insufficiency,
therapy for immunocompromised patients with invasive fungal
infections often fails. The mortality rates for patients with invasive aspergillosis remain high, and most neutropenic patients
die of this infection despite prolonged full-dose therapy with
amphotericin B [18, 19].
Liposomes
Alec D. Bangham, while investigating the properties of cell
membranes at the Institute ofAnimal Physiology in Cambridge,
Sl34
Hiemenz and Walsh
Water
cm
1996;22 (SuppI2)
The pharmacokinetics and pharmacodynamics of drugs incorporated into liposomes may differ greatly from those of the
free counterpart. This new drug-delivery system may help to
better target certain pharmaceuticals, thus improving their therapeutic index [21]. Studies suggest that drugs incorporated into
liposomes or lipid formulations are selectively taken up into
the reticuloendothelial system and concentrated in the liver,
spleen, lungs, lymph nodes, and, to a lesser extent, bone marrow. Lipid-rich particles are also believed to be ingested by
phagocytic cell monocytes, which may help to target sites of
infection or inflammation [20,21].
Liposomal Amphotericin B
_
Water-soluble agent
•
Fat-soluble agent
Figure 1. Diagram of fat and water-soluble agents encapsulated
in a liposome. Reproduced with permission from Hospital Practice
(1992;30:53). © 1992, the McGraw-Hill Companies.
England, was the first to demonstrate that, at high concentrations, phospholipids dispersed in water spontaneously form
microscopic closed vesicles. These vesicles consisted of water
surrounded by bilayered phospholipid membranes. Bangham
called these tiny fat bubbles "smectic mesophases." They were
later named "Iiposomes" by his colleague Gerald Weissman
[20,21]. Liposomes are composed of biodegradable phospholipid molecules that are made up of a hydrophilic head attached
to a hydrophobic tail. When placed in water, the molecules
spontaneously arrange themselves into bilayered membranes,
which coalesce to form vesicles. The hydrophilic heads face
outward, shielding the hydrophobic tails. Spherical vesicles
form to protect the hydrophobic ends (figure 1). Since
Bangham's description ofliposomes over 30 years ago, numerous methods of creating these molecules have been outlined in
several publications. Biochemists, biophysicists, and physiologists have been able to alter the size, charge, permeability, and
even number of bilayered membranes in a liposome. Physiologists have used liposomes in the study of cell membrane interactions.
Numerous studies over the last two decades have investigated the practical use of liposomes. Water-soluble substances
such as drugs, enzymes, and even genes have been entrapped
in the aqueous phase of the bilayer. Fat-soluble substances such
as polyene antibiotics can be incorporated into the lipid bilayer.
Amphotericin B, which is higWy lipophilic, was first incorporated into liposomes over 10 years ago in an attempt to
increase its therapeutic index. In 1981, New et al. reported
reduced amphotericin B-related toxicity associated with the
use of liposomal-associated drug in an animal model of leishmaniasis [22]. The following year, Graybill et al. and Taylor
et aI. reported an improved therapeutic index for liposomalassociated amphotericin B in animal models of cryptococcosis
and histoplasmosis [23, 24]. These articles suggested that lipid
formulations of amphotericin B could significantly reduce the
toxicities associated with free drug without compromising efficacy.
Lopez-Berestein et al. extended the in vivo studies with a
novel form ofliposomal amphotericin B, which they compared
to conventional amphotericin B in the treatment of disseminated candidiasis in neutropenic mice. They observed a significant reduction of toxicity with liposomal amphotericin B
without loss of efficacy [25] (figure 2). Liposomes created
by Lopez-Berestein and Juliano were multilamellar vesicles
consisting of a mixture of the two phospholipids dimyristoyl
phosphatidyIcholine (DMPC) and dimyristoyl phosphatidylglycerol (DMPG) in a 7:3 molar ratio containing 5%-10%
mole ratio of amphotericin to lipid. Preliminary compassionateuse experience with this product in severely immunocompromised cancer patients with progressive fungal infections at the
M. D. Anderson Hospital and Tumor Institute (Houston) suggested that invasive disease could be controlled even in patients
for whom conventional amphotericin B therapy had previously
failed. Moreover, the liposomal product had significantly less
nephrotoxicity than conventional amphotericin B even at much
higher doses [26, 27].
This experience led to further development oflipid formulations of amphotericin B by the pharmaceutical industry over
the last decade. There are three products that currently are
undergoing clinical trials in the United States. All three have
been licensed for clinical use and are currently available commercially in a number of countries in Western Europe. One
lipid formulation of amphotericin B, amphotericin B lipid complex (ABLC; Abelcet Liposome Company, Princeton, NJ) has
recently been approved by the U.S. Food and Drug Administra-
em 1996; 22
(Suppl 2)
Lipid Formulations of Amphotericin B
100
Sl35
~3t-----"--------BB-+----~-B-+-----E~
80
Figure 2. Percent of mice that
survived C. albicans infection.
Mice were treated with a single
dose of liposomal amphotericin B
of 0.8 mg/kg (£), 2 mg/kg (0), 3
mg/kg ( • ), or 4 mg/kg (D). • =
untreated controls. Reprinted with
permission from [25].
60
40
20
o
o
5
10
15
20
25
Days after infection
tion for use in patients with invasive aspergillosis who are
refractory to or intolerant of treatment with conventional amphotericin B.
Amphotericin B Lipid Complex
In attempting to explain why the product developed by Berestein and Juliano could be significantly less toxic than conventional amphotericin B while maintaining its efficacy, Janoff
and colleagues began a series of experiments to study this form
of lipid-associated amphotericin B in their laboratory located
in Princeton, New Jersey. They found that the original formulation of lipid-associated amphotericin B contained a variety of
liposomal and nonliposomal structures of lipid bilayers. It appeared that the nonliposomal structures in the formation that
they called "ribbons" were responsible for the reduction in
toxicity [28, 29]. They subsequently performed a series of
experiments combining the lipid formulation of DMPC and
DMPG in a 7:3 molar ratio with varying concentrations of
amphotericin B.
Freeze-etch electron microscopy of formulations made with
0, 5, 25, and 50 mol% of amphotericin B showed significant
differences in the structures formed. The formulation made up
of 5%mole concentration of amphotericin B, which was similar
to the BeresteiniJuliano product, consisted of lipid vesicles
smaller than the large vesicles that formed in the absence of
amphotericin B. It also contained the ribbonlike structures seen
in the original product. When the concentration of amphotericin
B was increased to 25 mol%, "liposomal" vesicles essentially
disappeared and were replaced by tightly packed ribbon structures. At concentrations of > 50 mol% amphotericin B, the
formulation continued to appear as ribbon structures; however,
the amphotericin B and lipid were no longer closely complexed
(figures 3 and 4). The ribbon structures formed by complexing
DMPC and DMPG with amphotericin B were called "amphotericin B lipid complex" or "ABLC."
In vitro studies suggested that the hemolytic activity of this
lipid formulation at low concentrations (<3 mol% ofamphotericin B to lipid) was similar to that of conventional amphotericin
B, but as the mole ratio of amphotericin B increased and the
ribbon structures began to form, there was a marked reduction
of overall toxicity. As amphotericin B is increasingly complexed with the lipid, the amount of free amphotericin B in
solution is reduced, presumably accounting for the decreased
toxicity. The efficacy of ABLC has also been attributed to the
ability of lipases from either fungi or inflammatory cells at the
site of infection to release the complexed amphotericin B from
the lipid formulation. However, the improvement in the therapeutic index may also be related to binding to high density
lipoproteins as well as to selective interaction with fungal cell
membranes [30].
Animal models. ABLC has been compared with conventional amphotericin B in a number of animal models including mice, rats, rabbits, and dogs. Concentrations of amphotericin B in the liver, spleen, and lungs of mice and rats
appear to be much higher after a single dose of ABLC than
after a single dose of amphotericin B deoxycholate. The
level of amphotericin B found in the kidney tissue of mice
appeared similar to the level of amphotericin B after injection of ABLC at the 1 mg/kg dose. However, plasma levels
of amphotericin B were consistently lower after injection of
the lipid complex ABLC than were levels obtained after
injection of amphotericin B deoxycholate. When increasing
the dose of the lipid complex, the levels of drug in the liver,
spleen, and lung tissue rise dramatically; however, this rise
is associated with little change in the levels of drug in the
kidney and essentially no rise in plasma levels [29, 31, 32].
Studies in mice showed that after a single iv dose the LD so
for the lipid complex of amphotericin B was 40 mg/kg
whereas that for conventional amphotericin B was 3 mg/
kg. Multiple-dose studies of ABLC continued to show a
significant reduction in toxicity even at 10 times the standard
SI36
Hiemenz and Walsh
em 1996;22 (Suppl 2)
Figure 3. Freeze-etch micrographs of various DMPC:DMPG/amphotericin B dispersions quenched from 20°C. All systems contained
DMPC:DMPG in a molar ratio of 7:3 and an amphotericin B molar percentage (with respect to the bulk lipid) of 0, (a), 5% (b), 25% (c), and
50% (d) (original magnification, x25,000). Reprinted with permission from [29].
dose of conventional amphotericin B in mice [31] and four
times the standard dose in rabbits [33].
The efficacy of ABLC has also been evaluated in a number
of animal models of fungal infection and was found to be
comparable to that of conventional amphotericin B. Moreover,
in a number of cases the lipid formulation was effective when
conventional amphotericin B was ineffective at controlling the
fungal infection at the maximum tolerated dose [31, 34, 35].
ABLC (10 mglkg) also demonstrated rapid fungicidal activity
in the treatment of experimental cryptococcal meningitis [36].
The ability to deliver much higher doses of amphotericin B in
the form of a lipid complex without reaching the maximum
tolerated dose was thought to account for the improved therapeutic index [29].
Human studies. The pharmacokinetics of ABLC in humans
resembles those in animals. Circulating blood levels of ampho-
tericin B were much lower in male volunteers after singledose infusion of ABLC than after infusion of conventional
amphotericin B deoxycholate [37]. The lipid complex is believed to be rapidly taken up by the reticuloendothelial system
and concentrated in the liver, spleen, lungs, and other tissues
of the body. Tissue levels of amphotericin B were measured
at autopsy of a heart transplant patient after 3 days of treatment
with ABLC. Relatively high concentrations of amphotericin B
were detected in the spleen (290 JLg/g), liver (196 JLg/g), and
lungs (222 JLg/g). Lower concentrations were detected in the
kidney (6.9 JLg/g), lymph nodes (7.6 JLg/g), brain (1.6 JLg/g),
and heart (4.9 JLg/g) (1. A. Boyle, unpublished data).
ABLC has been compared with conventional amphotericin
B in a number of small phase II and phase III clinical trials of
patients with leishmaniasis, coccidioidomycosis, and cryptococcosis. A dose-escalation trial of ABLC vs. conventional
crD 1996;22 (Suppl 2)
Lipid Formulations of Amphotericin B
Top view
of single complex
Side view
Gih1IIftIJ
Membrane of associated complexes
Figure 4. The putative structure of amphotericin B lipid complex
(ABLC). Amphotericin B and lipid are arranged in a 1: 1 interdigitated
complex. Reprinted with permission from [29].
amphotericin B in patients with leishmaniasis showed that the
lipid formulation was effective and that it was less nephrotoxic
than the standard drug [38]. Preliminary results of two other
trials of patients with coccidioidomycosis or cryptococcosis
suggest that the lipid complex form of amphotericin B was
also effective but that it was less nephrotoxic than conventional
amphotericin B [39,40]. A randomized controlled trial comparing ABLC with conventional amphotericin B in the treatment
of candidiasis has been completed and found no significant
difference in efficacy between the two treatments. This study
randomized 231 patients to receive ABLC (5 mg/[kg' d)) or
amphotericin B (0.6-1 mg/[kg' d)) in a 2: 1 randomization for
the treatment of hematogenous and invasive candidiasis. Response rates (63% for ABLC vs. 68% for amphotericin B)
were not statistically different (P > .5). Nephrotoxicity was
significantly lower in the group of patients who were treated
with ABLC (P = .007). The frequency of other adverse reactions was similar for both drugs [41].
Approximately 1,000 patients have been treated with ABLC
according to an open-label emergency-use protocol. To be eligible to receive this drug, previous treatment with amphotericin
B (total dose at least 15 mg/kg or 1,000 mg) or other antifungals, including fluconazole and itraconazole, had to have failed
to control documented or presumed invasive fungal infection.
The patients could also receive the drug if they were considered
to be intolerant of or unable to receive amphotericin B because
of renal insufficiency.
The initial patient population of 228 cases was analyzed in
detail and included failures of amphotericin B (doses of;;;. 1,000
mg over ;;;.10 days; n = 116); failures of other antifungal
agents, including fluconazole and itraconazole (n = 18); amphotericin B- induced nephrotoxicity (serum creatinine level,
;;;'2.5 mg/dL in adults or ;;;.1.5 mg/dL in children; n = 73);
S137
and preexisting renal dysfunction (serum creatinine level, ;;;.3.0
mg/dL; n = 8).
ABLC was administered for a median duration of 25 days
at a mean maximum dose of 5 mg/(kg' d). Clinical response
rates, as assessed by the patient's primary physician, were 78%
(52/67) for candidiasis and 60% (43/72) for aspergillosis. Use
of ABLC was associated with a decrease in the serum creatinine
level during therapy. The mean serum creatinine level declined
significantly (P = .0001) from baseline in the entire population
and in the subgroup whose initial serum creatinine level was
> 2.5 mg/dL (n = 62). ABLC was effective in patients with
invasive mycoses who were unresponsive to or intolerant of
previous antifungal therapy and was infrequently associated
with dose-limiting nephrotoxicity [42].
Therapy with amphotericin B deoxycholate is frequently
started empirically long before invasive aspergillosis is documented, making it difficult to compare the lipid formulation to
its parent drug in a prospective randomized trial. Data from
151 patients with definite or probable invasive aspergillosis
who had been treated with ABLC according to emergency-use
protocols were therefore compared to data from medical charts
of 122 control patients with aspergillosis who had been treated
with conventional amphotericin B. Patients treated with ABLC
showed higher overall response rates (40% vs. 23%; P = .002)
than patients who were treated with amphotericin B. Moreover,
patients whose serum creatinine level was ;;;.2.5 mg/dL at the
initiation of treatment with ABLC had a significant decrease
in their serum creatinine levels between weeks 2 and 5 (P <
.004) despite continued therapy with 5 mg/(kg' d) of this drug.
Although trials with historical controls have major limitations,
ABLC appeared to be less nephrotoxic and at least as effective
for treating invasive aspergillosis, even in cases where therapy
with at least 500 mg of amphotericin B deoxycholate had failed
to control infection [43].
Figure 5. Scanning electron micrograph of amphotericin B colloidal dispersion (ABCD, Amphocil). Reprinted with pennission from
M. Gurwith (Sequus Phannaceuticals, Inc., Menlo Park, California).
Hiemenz and Walsh
SI38
Cholesteryl
Sulfate
Amphotericin B
- - - 1 2 2 : : 48 n m - - -
Figure 6. The putative structure of amphotericin B colloidal dispersion (ABCD, Amphocil). Reprinted with pennission from L. Pietrelli
(Sequus Phannaceuticals, Inc., Menlo Park, California).
Amphotericin B Colloidal Dispersion
Amphotericin B colloidal dispersion (ABCD;Amphocil,
Sequus Pharmaceuticals, Menlo Park, CA) is a complex of
amphotericin Band cholesteryl sulfate in a 1: 1 ratio. This lipid
formulation of amphotericin B forms disklike structures - 115
nm in diameter when combined with the cholesteryl sulfate,
leaving no free drug (figures 5 and 6) [44]. Hanson and Stevens
documented in vitro activity of ABCD against 41 isolates of
15 pathogenic species of fungi [45]. MICs and mean fungicidal
concentrations of ABCD appeared similar to those of the deoxycholate suspension of amphotericin B. There were, however,
some differences: the lipid formulation of amphotericin B was
more active against some species offungi, and the deoxycholate
suspension was more active against other species.
Animal models. The pharmacokinetics ofABCD have been
extensively studied in animal models. Plasma levels of amphotericin B after single iv bolus injection in the rat are significantly less at 1 hour when ABCD is compared with amphotericin B deoxycholate. The half-life of the lipid formulation,
however, is much longer and its volume of distribution much
greater. Concentrations of amphotericin B in liver tissue are
2-3 times higher after injection of ABCD than after injection
of amphotericin B deoxycholate. At the same time, concentrations of amphotericin B in the kidney are significantly reduced
even after 5 mg/kg of the colloidal dispersion is injected [46].
Similar findings oflower plasma concentrations, increased liver
deposition, and decreased kidney concentration of amphotericin B have been reported in the dog model [47]. Studies comparing ABCD with amphotericin B deoxycholate in mice, rats,
and dogs have shown that this lipid formulation is significantly
less toxic than equivalent doses of amphotericin B deoxycholate [48]. Up to 5 mg/(kg . d) of ABCD could be given to dogs
before this drug produced side effects that were similar to those
produced by 0.6 mg/(kg' d) of amphotericin B deoxycholate
[47].
cm
1996;22 (Suppl 2)
Animal models of systemic coccidioidomycosis, cryptococcosis, and aspergillosis have been used to study the relative
efficacy ofABCD compared with amphotericin B deoxycholate
[49-53]. Although the doses of amphotericin B deoxycholate
(1.3 mg/kg) required to clear the organs of fungi in a mouse
model of coccidioidomycosis were lower than those required
for ABCD (5 mg/kg), the lipid formulation had a significantly
better therapeutic index, as amphotericin B deoxycholate was
found to be 5-8 times more toxic than ABCD [49]. Unlike
the murine model of coccidioidomycosis, a murine model of
cryptococcosis showed that ABCD had equal efficacy when it
was compared with amphotericin B on a mg/kg basis. ABCD
was again found to be less toxic, suggesting an improvement
in the therapeutic index for the lipid formulation [50].
Rabbit models of invasive aspergillosis suggest that amphotericin B deoxycholate is superior to ABCD in tissue clearance
of fungi at equal doses of I mg/kg [51, 52]. However, increased
duration of survival was observed in persistently granulocytopenic rabbits with pulmonary aspergillosis when 5 mg/(kg' d)
of ABCD were compared with I mg/(kg' d) of amphotericin
B deoxycholate [52]. The investigators attributed the improved
therapeutic index to an enhanced rate of tissue clearance, decreased pulmonary injury, and reduced nephrotoxicity in the
rabbits treated with 5 mg/(kg' d) of ABCD. These findings
were further confirmed in a study of the evolution ofpulmonary
infiltrates in experimental pulmonary aspergillosis. With use
of ultrafast CT scanning and an image-analysis algorithm, a
dose-dependent clearance of pulmonary infiltrates in rabbits
treated with ABCD was documented [53]. Higher doses of
ABCD (5 and 10 mg/[kg' d]) exerted a rapid clearing effect
on the development of pulmonary lesions in comparison with
the response rates of amphotericin B at I mg/(kg' d).
Human studies. Hostetler et al. studied relatively low doses
of ABCD (up to 1 mg/[kg' d] or 2 mg/kg three times weekly
up to 10 weeks) for a group ofpatients with coccidioidomycosis
whose therapy had failed or who were intolerant to prior antifungal therapy. Although fever and rigors were common (75%
and 83% ofpatients, respectively), adverse events rarely limited
therapy. Most patients (71 %) had at least a minor response to
ABCD therapy, and a few (13%) had a major response with
use ofthe clinical scoring system adapted for coccidioidomycosis [54]. A preliminary report by Bowden and Cays of a phase
I clinical trial of ABCD suggested that doses of up to 7 mg/
(kg' d) may be well tolerated and effective in the setting of
opportunistic fungal infection [55].
The results of an open-labeled compassionate-use trial of
168 patients with documented or presumed invasive mycosis
who were treated with ABCD were recently reported. Patients
were eligible for enrollment in the study if their fungal infection had failed to adequately respond to a minimum of 7 days
of treatment with conventional amphotericin B deoxycholate
or if they had renal insufficiency that was preexisting or
secondary to acute drug-related nephrotoxicity (usually due
to therapy with conventional amphotericin B deoxycholate).
em 1996;22 (Suppl 2)
Lipid Formulations of Amphotericin B
8139
The initial dose of ABCD was variable (0.5, 1,2,3, or 4 mg/
[kg'dD and was dependent on the individual investigator's
judgement. A daily dose of 3 mg/(kg' d) was recommended
for candidiasis and other yeastIike fungi, whereas 4 mg/
(kg' d) was recommended for infections due to Aspergillus
species or other filamentous fungi. The dose of ABCD was
increased to as high as 6 mg/(kg . d) in some patients. ABCD
was administered for a median duration of 12.5 days, with a
mean cumulative dosage of 3,962 mg.
In 48 (49%) of97 cases in which the patients were clinically
evaluable, the fungal infection was believed to have partially
cleared or resolved after treatment with ABCD. Nineteen (58%)
of 33 patients with candidiasis and 11 (34%) of 32 with aspergillosis responded to therapy with ABCD. All 168 patients in
the trial were included in the safety analysis. Despite a mean
cumulative dose of 4 g of ABCD and daily doses as high as
6 mg/kg, the mean change in the serum creatinine level from
baseline until completion of therapy with ABCD was -0.02
mg/dL. This preliminary report suggests that the colloidal dispersion of amphotericin B, like the lipid complex, is active and
less nephrotoxic than the parent drug [56].
AmBisome
AmBisome (Nexstar, San Dimas, CA) is the only true "liposomal" preparation of the three lipid formulations of amphotericin B undergoing clinical trials. It differs from ABLC and
ABCD in that it is made up of small unilamellar lipid vesicles
that are uniform and spherical in size and that average 6070 om. The lipid bilayer is made up of hydrogenated soy
phosphatidylcholine and distearoylphosphatidylglycerol stabilized by cholesterol and combined with lipophilic amphotericin
B in a 2:0.8: 1:0.4 molar ratio (figure 7) [57]. The in vitro
antifungal activity of AmBisome was found to be comparable
to that of amphotericin B when a number of clinical isolates
from a large cancer center were tested [58].
A recent report, however, suggested that the small unilamellar liposomal form of amphotericin B may be as much as
4-8 times less active than the deoxycholate form against several isolates of C. albicans [59]. It is unclear what the significance of in vitro susceptibility testing is for lipid formulations
of amphotericin B. Unlike in vitro antibacterial drug susceptibility testing, in vitro antifungal drug susceptibility tests have
been hard to duplicate from laboratory to laboratory. Moreover,
lipid formulations ofamphotericin B were specifically designed
to complex or bind the antifungal for targeted drug delivery.
There may be a need for the drug to be taken up by the reticuloendothelial system or to be delivered to points of infection to
realize a therapeutic advantage.
Animal models. The pharmacokinetics, toxicity, and efficacy of AmBisome have been studied in the mouse, rat, and
rabbit [60, 61]. Peak plasma levels that can be obtained with
the liposomal form of amphotericin B were similar in mice,
rats, and rabbits. Liposomal amphotericin B is similar to the
Figure 7. Schematic structure of small unilamellar vesicle (AmBisome). Reprinted with permission from Buell et al. (Fujisawa USA,
Deerfield, IL).
other lipid formulations of amphotericin B as it appears to be
preferentially concentrated in the liver and spleen of animals;
however, the rate of uptake by the reticuloendothelial system
appears to be much slower than that by ABLC or ABCD. It is
hypothesized that the larger lipid complexes and dispersions
may be more readily phagocytized by the macrophages of the
reticuloendothelial system than the smaller unilamellar vesicles. The negative charge on the AmBisome particle also may
delay uptake by the reticuloendothelial system. These mechanisms may account for the fact that the liposomal form of
amphotericin B has much higher peak plasma levels and a
prolonged circulation time compared with its larger counterparts.
AmBisome has been found to be less nephrotoxic than conventional amphotericin B in the mouse, rat, and rabbit models.
There does, however, appear to be a slight rise in the levels
of liver transaminases with repeated infusions of liposomal
amphotericin B. The LO so after a single injection of liposomal
amphotericin B was> 175 mg/kg in mice and >50 mg/kg in
rats. This was 30-60 times greater than the LD so after a single
injection of conventional amphotericin B [60].
The efficacy of AmBisome has been studied in murine models of systemic candidiasis, cryptococcosis, and blastomycosis.
Gondal et al. showed that mice infected with C. albieans who
received any of the doses of liposomal amphotericin B studied
8140
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Hiemenz and Walsh
1996; 22 (Suppl 2)
Table 1. Phannacokinetics of lipid fonnulations of amphotericin B.
Compound
Amphotericin B
Brand name
Lipid
configuration
Mean Cmax in
Size (om)
Lipids
NA
NA
Deoxycholate
L-AMB
Fungizone (BristolMyers Squibb, Princeton,
NJ)
AmBisome
Small unilamellar
vesicle
(liposome)
80
Hydrogenated soy phosphatidylcholine,
distearoylphosphatidylglycerol
ABCD
Amphocil
Disklike
120-140
Cholesteryl sulfate
ABLC
Abelcet
Ribbonlike
1,600-11,000
Dimyristoyl phosphatidylcholine,
dimyristoyl phosphatidylglycerol
JLg/mL (dose)
0.98 (0.25 mglkg)
2.9 (0.68 mglkg)
7.3 (1.0 mglkg)
17.2 (2.5 mglkg)
57.6 (5.0 mglkg)
Increased
0.84 (0.5 mglkg)
2.19 (1.0 mglkg)
2.53 (1.5 mglkg)
Decreased
0.27 (0.5 mglkg)
1.1 (2.5 mglkg)
Decreased
NOTE. "Decreased," "increased," and "similar" are in reference to values for amphotericin B. ABCD = amphotericin B colloidal dispersion; ABLC =
amphotericin B lipid complex; AUC = area under the curve; C = pharmacokinetics in children; Cmax = maximum drug concentration; CI = clearance; L-AMB
= liposomal amphotericin B; NA = not applicable; Vd.. = volume of distribution.
* Model dependent.
(except for 1 mg/kg) lived longer as long as they were treated
early [62]. If treatment was delayed until 3 days after inoculation, the drug dose to achieve optimal benefit appeared to be
5 mg/kg. The maximum dose of conventional amphotericin B
given to mice by single injection was 2 mg/kg, and 1.5 mg!
(kg· d) was the maximum tolerated dose with multiple injections. Although Pahls and Schaffner recently found that AmBisome was significantly less toxic than conventional amphotericin B in their mouse model of candidiasis, they suggested it
was 4-8 times less active in clearing the infection [59]. The
dosing regimen in this model, however, may not have been
optimal to assess maximum antifungal effect.
Francis et al. reported the results of a comparison of amphotericin B deoxycholate with the small unilamellar liposomal
form of amphotericin B in persistently neutropenic rabbits with
pulmonary aspergillosis [63]. Rabbits were evaluated for duration of survival, lung tissue infection, and hemorrhagic pulmonary lesions by rapid CT scanning. Treatment with the liposomal form of amphotericin was studied at I, 5, and 10 mg/kg,
whereas therapy with amphotericin B deoxycholate was studied
at I mg/kg. Although rabbits who received any dose of AmBisome lived longer than those who received amphotericin B,
the rate of reduction of pulmonary hemorrhage was greatest at
a dose of 5 mg!(kg· d) while the dose of 10 mg/(kg· d) was
more nephrotoxic. Thus, 5 mg!(kg· d) was proposed as an optimal dose of AmBisome.
Human studies. Peak and trough plasma levels of amphotericin B were measured in 49 patients who received doses of
AmBisome of2, 3, or 4 mg/kg [64]. Mean peak concentrations
of up to 46 t-tg!mL with a corresponding mean trough level of
4 t-tg!mL were detected in the seven patients who received 4
mg/kg of the liposomal form of amphote~cinB. Tissue concentrations of amphotericin B were determined at autopsy in three
patients who had received therapy with AmBisome [65]. The
highest concentrations of drug were found in the liver and
spleen.
The pharmacokinetics of AmBisome in humans appear quite
similar to those determined in the animal model. Although the
peak plasma level and circulation time are greater for the small
unilamellar liposomal form of amphotericin B than for the lipid
complex and colloidal dispersion fonns, the liposomal form is
preferentially concentrated in the liver and spleen. The toxicity
profile of AmBisome also appears to parallel that of the other
lipid formulations of amphotericin B. Increases in serum creatinine level have occurred with use of liposomal amphotericin
B; however, liposomal amphotericin B also appears to be less
nephrotoxic than the deoxycholate form of the drug. Renal function improved in a number of patients when their regimen was
changed from conventional amphotericin B to AmBisome [66].
The serum phamiacokinetics of liposomal amphotericin B
were recently described in a prospective study of24 persistently
febrile neutropenic patients who received this small unilamellar
vesicle formulation of amphotericin B as empirical antifungal
therapy. Liposomal amphotericin B administered as a I-hour
infusion dose to this population was well tolerated and seldom
associated with infusion-related toxicity. Liposomal amphotericin B in serum samples was measured as amphotericin B by
high-pressure liquid chromatography. Using model-independent methods, the investigators found that the mean (±SD)
area under the serum concentration vs. time curve (AUCo-oo),
which was determined on the last day of infusion for 3 dose
cohorts (l, 2.5, and 5 mg/[kg· dD, reflected a nonlinear dose
em
Mean Vd•• in l/kg
(dosage)*
Mean Cl
in mL/[min' kg]
(dosage)
Amphotericin B
4 (1.0 mg/kg)
0.76 (0.68 mg/kg)
0.43 (1.0 mg/kg)
0.76 (0.68 mg/kg)
L-AMB
0.58 (1.0 mglkg)
0.69 (2.5 mglkg)
0.22 (5.0 mglkg)
Decreased
5.7 (0.5 mg/kg)
7.2 (1.0 mg/kg)
7.9 (1.5 mg/kg)
Increased
3.9 (0.5 mg/kg)
Not determined
Similar
0.27 (1.0 mg/kg)
0.33 (2.5 mg/kg)
0.17 (5.0 mg/kg)
Decreased
0.42 (0.5 mg/kg)
0.36 (1.0 mg/kg)
0.47 (1.5 mg/kg)
Similar
1.3 (0.5 mg/kg)
3.6 (2.5 mg/kg)
Increased
Compound
ABCD
ABLC
S141
Lipid Fonnu1ations of Amphotericin B
1996; 22 (Supp1 2)
relationship that was consistent with reticuloendothelial uptake
and redistribution [67] (table 1).
Phase II experience with the use of AmBisome in immunocompromised hosts with documented or presumed invasive
fungal infections has been reported from a number of centers in
Europe [65, 72, 73]. Patients were eligible to receive liposomal
amphotericin B if they failed to respond to amphotericin B
deoxycholate or were intolerant to this therapy. They could
also receive the lipid formulation if they had significant underlying renal insufficiency before antifungal therapy was started.
The most common reasons for immunodeficiency in these hosts
were underlying malignancy, solid organ or bone marrow transplantation, and AIDS. Documented invasive fungal infections
were most commonly due to Candida or Aspergillus species.
Clinical responses were seen in a number of patients with
documented invasive fungal infections even after therapy with
amphotericin B deoxycholate had failed. Patients who were
neutropenic at the time of therapy appeared to respond, although recovery of neutrophil counts, remission from underlying malignancy, and continued therapy with the liposomal form
of amphotericin B appeared to be necessary for resolution of
the fungal infection.
A phase II/III trial of AmBisome as prophylaxis against invasive fungal infections in bone marrow transplant patients was
conducted in Sweden. Liposomal amphotericin B at 1 mg/(kg· d)
was compared to placebo in a double-blind, randomized study.
There were fewer fungal infections in allogeneic transplant patients who received liposomal amphotericin B than in those who
received placebo, and no fungal infections were documented in
autologous transplant patients in either arm of the study. Although
the study drug was well tolerated, the overall duration of survival
Mean AVC in J.lg' hlmL
(dosage)
Human plasma
pharmacokinetics
[reference]
8.6 (0.25 mglkg)
69 (1.0 mg/kg)
206 (2.5 mg/kg)
713 (5.0 mg/kg)
Increased
21 (0.5 mg/kg)
46 (1.0 mg/kg)
57 (1.5 mg/kg)
Decreased
2.8 (0.5 mg/kg)
8.9 (2.5 mg/kg)
Decreased
[68,70]
[69] C
[67]
[70]
[37]
[71] C
for patients who were treated with placebo was similar to that
for patients who were treated prophylactically with liposomal
amphotericin B [74]. A number of reports of the compassionate
use of AmBisome in immunocompromised children with invasive
fungal infections have suggested that this liposomal form of amphotericin B is safe and effective when used in pediatric patients
[75-77]. Further studies designed to better define the safety, tolerance, and efficacy of AmBisome are currently under way in the
United States.
Lipid Emulsion Plus Amphotericin B Deoxycholate
Anecdotal reports of the use of amphotericin B mixed with
fat emulsions used for parenteral nutrition are increasing in
both Europe and the United States. Kirsh et al. reported reduced
toxicity without loss of antifungal activity when they treated
systemic murine candidiasis with a lipid-emulsion formulation
of amphotericin B [78]. Clinical experience with this approach
in neutropenic hosts and HIV-infected patients with candidiasis
has recently been published [79, 80]. French investigators have
reported the results of a prospective randomized trial comparing
the use of standard amphotericin B mixed in 5% dextrose vs.
amphotericin B mixed with 20% intralipid in a group ofpatients
requiring empirical treatment for persistent fever and neutropenia. Patients treated with the amphotericin B/fat emulsion
mixture appeared to have a significant reduction in infusionrelated toxicity and renal dysfunction. However, the study was
too small to show any difference in antifungal efficacy [81].
Unfortunately, amphotericin B does not appear to mix well
with the fat emulsion. When analyzing the combination of 0.6
mg/mL of amphotericin B in 10% or 20% fat emulsion, Trissel
S142
Hiemenz and Walsh
Table 2.
Ongoing clinical trials of lipid fonnulations of amphotericin B:
•
•
•
•
Empirical therapy for fever and neutropenia
First-line therapy for documented aspergillosis
First-line therapy for candidiasis in neutropenic patients
Dose-escalation trials in patients with other documented
fungal infection
found that the amount and size of undissolved particles were
substantially increased in comparison with amphotericin B in
5% dextrose [82]. These particles could be removed by an inline filter; however, this would markedly reduce the antifungal
efficacy of this compound. The amphotericin B/fat emulsion
mixture does not take into account current models of lipid
drug delivery, suggesting that a significant improvement in
therapeutic index may not have been seen with use of this
mixture.
Methods of preparing this drug have not been standardized,
and drug admixture in the pharmacy has not been approved by
the U. S. Food and Drug Administration. Lipid emulsions used
for parenteral nutrition are known to cause hepatic dysfunction,
platelet dysfunction, and increased risk of infection. Mixing
lipid emulsions with amphotericin B should be considered investigational, and the use of this compound should be limited to
clinical research protocols approved by an institutional review
board.
Future Directions for Research
Lipid formulations of amphotericin B have been undergoing
clinical investigation for over a decade. Many questions, however, remain to be elucidated. For example, little is known
about the comparative efficacy and pharmacodynamics of these
compounds. More work is clearly required in clarifying their
mechanism of action, the basis of the improved therapeutic
index, and the selective cytotoxicity. Drug interactions as well
as the possibility of any long-term toxic effects need to be
studied, particularly in patients who receive many months of
therapy for chronic invasive mycosis. An understanding of
the interaction of lipid formulations of amphotericin B with
immunomodulators such as cytokines and interleukins is also
necessary, when the use of such combinations is considered.
Further definition of the clinical usefulness ofthe lipid formulations of amphotericin B in specific target populations (e.g.,
newborn infants, children, diabetics, organ transplant recipients, surgical intensive care patients, HIV-infected patients,
and neutropenic patients) and for specific fungal infections is
needed. Only through the use of thoughtfully designed, carefully conducted, well-controlled clinical trials will we increase
our understanding of the appropriate use of these compounds
(table 2)
em
1996; 22 (Suppl 2)
Summary
The lipid formulations of amphotericin B represent an important contribution to the management of invasive fungal infections, particularly in immunocompromised patients who require higher doses of amphotericin B but who often do not
tolerate them well. Three products (ABLC, ABCD, and AmBisome) are commercially available and have been licensed for
clinical use in a number of countries in Western Europe. ABLC
has recently been approved for clinical use in the United States
for patients with aspergillosis who are refractory to or intolerant
of conventional treatment with amphotericin B deoxycholate.
The lipid formulations of amphotericin B should be considered in the management of invasive fungal infections in patients
with dose-limiting renal insufficiency, in patients who are intolerant of amphotericin B, and in patients with specific fungal
infections that are progressive despite treatment with amphotericin B deoxycholate (e.g., invasive aspergillosis). Future studies
are needed to define their role for first-line therapy, especially
in the setting of cost containment. The pharmacoeconomics of
the lipid formulations of amphotericin B warrant careful analysis in specific clinical settings; the potential of an improved
therapeutic index should be weighed against the increased cost
of these drugs in comparison with that of conventional amphotericin B deoxycholate [83].
References
1. Bodey GP. The emergence of fungi as major hospital pathogens. J Hosp
Infect 1988; ll(suppl A):411-26.
2. Walsh TJ, Pizzo PA. Nosocomial fungal infections: a classification for
hospital-acquired fungal infections and mycoses arising from endogenous flora or reactivation. Annu Rev Microbio11988;42:517-45.
3. Dismukes WE. Cryptococcal meningitis in patients with AIDS. J Infect
Dis 1988; 157:624-8.
4. Beck Sague C, Jarvis WR. Secular trends in the epidemiology of nosocomial fungal infections in the United States, 1980-1990. J Infect Dis
1993; 167:1247-51.
5. Weiland D, Ferguson RM, Peterson PK, Snover DC, Simmons RL, Najarian JS. Aspergillosis in 25 renal transplant patients: epidemiology,
clinical presentation, diagnosis, and management. Ann Surg 1983;
198:622-9.
6. Tollemar J, Ericzon BG, Holmberg K, Andersson 1. The incidence and
diagnosis of invasive fungal infections in liver transplant recipients.
Transplant Proc 1990;22:242-4.
7. Anaissie E. Opportunistic mycoses in the immunocompromised host: experience at a cancer center and review. Clin Infect Dis 1992; 14(suppl
1):S43-53.
8. Meyers JD. Fungal infections in bone marrow transplant patients. Semin
OncoI1990; 17(suppl 6):10-3.
9. DeBock R. Epidemiology of invasive fungal infections in bone marrow
transplantation. Bone Marrow Transplant 1994; 14(suppl 5):Sl-2.
10. Wingard JR, Beals SU, Santos GW, Merz WG, Sara1 R. Aspergillus infections in bone marrow transplant recipients. Bone Marrow Transplant
1987; 2: 175-81.
II. Komshian SV, Uwaydah AK, Sobel JD, Crane LR. Fungemia caused by
Candida species and Torulopsis glabrata in the hospitalized patient:
frequency, characteristics, and evaluation of factors influencing outcome. Rev Infect Dis 1989; II :379-90.
cm
1996; 22 (8uppl 2)
Lipid Formulations of Amphotericin B
12. Walsh TJ, Dixon DM. Nosocomial aspergillosis: environmental microbiology, hospital epidemiology, diagnosis, and treatment. Eur J Epidemiol
1989; 5: 131-42.
13. Anaissie E, Bodey GP, Kantarjian H, et al. New spectrum of fungal infections in patients with cancer. Rev Infect Dis 1989; 11 :369- 78.
14. Anaissie E, Kantarjian H, Ro J, et al. The emerging role of Fusarium
infections in patients with cancer. Medicine (Baltimore) 1988; 67:
77-83.
15. Walsh TJ. Management of immunocompromised patients with evidence
of an invasive mycosis. Hematol Oncol Clin North Am 1993;7:
1003-26.
16. Sarosi GA. Amphotericin B: still the 'gold standard' for antifungal therapy.
Postgrad Med 1990;88:151-2, 155-61, 165-6.
17. Gallis HA, Drew RH, Pickard WW. Amphotericin B: 30 years of clinical
experience. Rev Infect Dis 1990; 12:308-29.
18. Walsh TJ, Pizzo PA. Treatment of systemic fungal infections: recent progress and current problems. Eur J Clin Microbiol Infect Dis 1988; 7:
460-75.
19. Denning DW, Stevens DA. Antifungal and surgical treatment of invasive
fungal aspergillosis: review of 2,121 published cases. Rev Infect Dis
1990; 12: 1147-201.
20. Bangham AD. Liposomes: realizing their promise. Hosp Pract Off Ed
1992;27:51-6,61-2.
21. Ostro MJ, Cullis PRo Use ofliposomes as injectable-drug delivery systems.
Am J Hosp Pharm 1989;46:1576-87.
22. New RR, Chance ML, Heath S. Antileishmanial activity of amphotericin
and other antifungal agents entrapped in liposomes. J Antimicrob Chemother 1981;8:371-81.
23. Graybill JR, Craven PC, Taylor RL, Williams DM, Magee WE. Treatment
of murine cryptococcosis with liposome-associated amphotericin B. J
Infect Dis 1982; 145:748-52.
24. Taylor RL, Williams DM, Craven PC, Graybill JR, Drutz DJ, Magee WE.
Amphotericin B in liposomes: a novel therapy for histoplasmosis. Am
Rev Respir Dis 1982;125:610-1.
25. Lopez-Berestein G, Hopfer RL, Mehta R, Mehta K, Hersh EM, Juliano RL.
Liposome-encapsulated amphotericin B for treatment of disseminated
candidiasis in neutropenic mice. J Infect Dis 1984; 150:278-83.
26. Lopez-Berestein G, Fainstein V, Hopfer R, Mehta K, Sullivan MP, Keating
M. Liposomal amphotericin B for the treatment of systemic fungal
infections in patients with cancer: a preliminary study. J Infect Dis
1985; 151:704-10.
27. Lopez-Berestein G, Bodey GP, Frankel LS, Mehta K. Treatment ofhepatosplenic candidiasis with liposomal-amphotericin B. J Clin Oncol
1987;5:310-7.
28. JanoffAS, Boni LT, Popescu MC, et al. Unusual lipid structures selectively
reduce the toxicity of amphotericin B. Proc Nat! Acad Sci USA
1988; 85:6122-6.
29. Janoff AS, Perkins WR, Saleton SL, Swenson CEo Amphotericin B lipid
complex (ABLC™): a molecular rationale for the attenuation of amphotericin B-related toxicities. Journal of Liposome Research 1993; 3:
451-72.
30. Wasan KM, Lopez-Berestein G. The interaction ofliposomal amphotericin
B and serum lipoproteins within the biological milieu. Journal of Drug
Targeting 1994;2:373-80.
31. Clark JM, Whitney RR, Olsen SJ, et al. Amphotericin B lipid complex
therapy of experimental fungal infections in mice. Antimicrob Agents
Chemother 1991;35:615-21.
32. Olsen SJ, Swerdel MR, Blue B, Clark JM, Bonner DP. Tissue distribution
of amphotericin B lipid complex in laboratory animals. J Pharm Pharmacol 1991;43:831-5.
33. Lee J, Allende M, Dollenberg H, et al. Reticuloendothelial loading with
amphotericin B lipid complex (ABLC)-a novel pharmacodynamic
approach to treatment of experimental hepatosplenic candidiasis (HSC).
[abstract no 172]. In: Progra~ and abstracts of the 32nd Interscience
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
8143
Conference on Antimicrobial Agents and Chemotherapy (Anaheim).
Washington, DC: American Society for Microbiology, 1992: 139.
Whitney RR, Kunselman L, Clark JM, Bonner DP. Efficacy of amphotericin B lipid complex (ABLC) in cryptococcal meningitis in normal or
immunocompromised mice [abstract no 166]. In: Program and abstracts
of the 29th Interscience Conference on Antimicrobial Agents and Chemotherapy (Houston). Washington, DC: American Society for Microbiology. 1989: 128.
Clemons KV, Stevens DA. Comparative efficacies of amphotericin B lipid
complex and amphotericin B deoxycholate suspension against murine
blastomycosis. Antimicrob Agents Chemother 1991;35:2144-6.
Perfect JR, Wright KA. Amphotericin B lipid complex in the treatment
of experimental cryptococcal meningitis and disseminated candidosis.
J Antimicrob Chemother 1994;33:73-81.
Kan VL, Bennett JE, Amantea MA, et al. Comparative safety, tolerance,
and pharmacokinetics of amphotericin B lipid complex and amphotericin B desoxycholate in healthy male volunteers. J Infect Dis
1991; 164:418-21.
Llanos-Cuentas A, Cieza J, Echevarria J, et al. The safety and tolerance
of amphotericin B lipid complex (ABLC) vs. amphotericin B desoxycholate (Fungizone, [ABD in patients with mucocutaneous leishmaniasis
(MCL) [abstract no 234]. In: Program and abstracts of the 32nd Interscience Conference on Antimicrobial Agents and Chemotherapy (Anaheim). Washington, DC: American Society for Microbiology, 1992: 149.
Sharkey PK, Lipke R, Renteria A, et al. Amphotericin B lipid complex
(ABLC) in treatment (Rx) of coccidioidomycosis (C) [abstract no 742]
In: Program and abstracts of the 31 st Interscience Conference on Antimicrobial Agents and Chemotherapy (Chicago). Washington, DC:
American Society for Microbiology, 1991:222.
Graybill JR, Sharkey PK, Vincent D, et al. Amphotericin B lipid complex
(ABLC) in treatment (Rx) of cryptococcal meningitis (CM) in patients
with AIDS [abstract no 289]. In: Program and abstracts of the 31st
Interscience Conference on Antimicrobial Agents and Chemotherapy
(Chicago). Washington, DC: American Society for Microbiology,
1991:147.
Anaissie EJ, White M, Uzun 0, et al. Amphotericin B lipid complex
(ABLC®) versus amphotericin B (AMB) for treatment of hematogenous
and invasive candidiasis: a prospective, randomized, multicenter trial
[abstract no. LM 21]. In: Program and abstracts of the 35th Interscience
Conference on Antimicrobial Agents and Chemotherapy (San Francisco). Washington, DC: American Society for Microbiology, 1995:330.
Walsh TJ, Hiemenz JW, Seibel N, Anassie EJ. Amphotericin B lipid
complex in the treatment of 228 cases of invasive mycosis [abstract no
M69]. In: Program and abstracts of the 34th Interscience Conference
on Antimicrobial Agents and Chemotherapy (Orlando). Washington,
DC: American Society for Microbiology, 1994:247.
Hiemenz JW, Lister J, Anaissie EJ, et al. Emergency-use amphotericin B
lipid complex (ABLC) in the treatment of patients with aspergillosis:
historical control comparison with amphotericin B [abstract no 3383].
Blood 1995; 86(suppl 1):849a.
Guo LSS, Fielding RM, Lasic DD, et al. Novel antifungal drug delivery:
stable amphotericin B-cholesteryl sulfate discs. International Journal
of Pharmaceutics 1991;75:45-54.
Hanson LH, Stevens DA. Comparison of antifungal activity of amphotericin B desoxycholate with that of amphotericin B cholesteryl sulfate
colloidal dispersion. Antimicrob Agents Chemother 1992; 36:486-8.
Fielding RM, Smith PC, Wang LH, Porter J, Guo LS. Comparative pharmacokinetics of amphotericin B after administration of a novel colloidal
delivery system, ABCD, and a conventional formulation to rats. Antimicrob Agents Chemother 1991;35:1208-13.
Fielding RM, Singer AW, Wang LH, Babbar S, Guo LS. Relationship of
pharmacokinetics and drug distribution in tissue to increased safety of
amphotericin B colloidal dispersion in dogs. Antimicrob Agents Chemother 1992; 36:299- 307.
Sl44
Hiemenz and Walsh
48. Fielding RM, Porter J, Jekot J, Guo LSS. Altered tissue distribution results
in the reduced toxicity of amphotericin B colloidal dispersion [abstract
no A77]. In: Proceedings of the 91 st annual meeting of the American
Society for Microbiology (Dallas). Washington, DC: American Society
for Microbiology, 1991:13.
49. Clemons KV, Stevens DA. Comparative efficacy of amphotericin B colloidal dispersion and amphotericin B deoxycholate suspension in treatment
of murine coccidioidomycosis. Antimicrob Agents Chemother
1991;35:1829-33.
50. Hostetler JS, Clemons KV, Hanson LH, Stevens DA. Efficacy and safety
of amphotericin B colloidal dispersion compared with those of amphotericin B desoxycholate suspension for treatment of disseminated murine
cryptococcosis. Antimicrob Agents Chemother 1992;36:2656-60.
51. Patterson TF, Miniter P, Dijkstra J, Szoka FC Jr, Ryan 11, Andriole VT.
Treatment of experimental invasive aspergillosis with novel amphotericin B/cholesterol-sulfate complexes. J Infect Dis 1989;159:717-24.
52. Allende MC, Lee JW, Francis P, et al. Dose-dependent antifungal activity
and nephrotoxicity of amphotericin B colloidal dispersion in experimental pulmonary aspergillosis. Antimicrob Agents Chemother 1994;
38:518-22.
53. Walsh TJ, Garrett K, Feverstein E, et al. Therapeutic monitoring of experimental invasive pulmonary aspergillosis by ultrafast computerized tomography: a novel, noninvasive method for measuring responses to
antifungal therapy. Antimicrob Agents Chemother 1995;39:1065-9.
54. Hostetler JS, Caldwell JW, Johnson RH, et al. Coccidioidal infections
treated with amphotericin B colloidal dispersion (Amphocil or ABCD)
[abstract no 628]. In: Program and abstracts of the 32nd Interscience
Conference on Antimicrobial Agents and Chemotherapy (Anaheim).
Washington, DC: American Society for Microbiology, 1992:215.
55. Bowden RA, Cays M. Phase I study of amphotericin B colloidal dispersion
(ABCD: Amphocil) for the treatment of invasive fungal infection after
marrow transplant [abstract no 1685]. Blood 1993;82(suppll):425a.
56. Oppenheim BA, Herbrecht R, Kusne S. The safety and efficacy of amphotericin B colloidal dispersion in the treatment of invasive mycoses. Clin
Infect Dis 1995;21:1145-53.
57. Adler-Moore JP, Proffitt RT. Development, characterization, efficacy and
mode of action of AmBisome, a unilamellar liposomal formulation of
amphotericin B. Journal of Liposome Research 1993;3:429-50.
58. Anaissie E, Paetznick V, Proffitt R, Adler-Moore J, Bodey GP. Comparison
of the in vitro antifungal activity of free and liposomal-encapsulated
amphotericin B. Eur J Clin Microbiol Infect Dis 1991; 10:665-8.
59. Pahls S, Schaffner A. Comparison of the activity of free and liposomal
amphotericin B in vitro and in a model of systemic and localized murine
candidiasis. J Infect Dis 1994; 169:1057-61.
60. Proffitt RT, Satorius A, Chiang SM, Sullivan L, Adler-Moore JP. Pharmacology and toxicology of a liposomal formulation of amphotericin B
(AmBisome) in rodents. J Antimicrob Chemother 1991;28(suppl B):
49-61.
61. Lee JW, Amantea MA, Francis PA, et al. Pharmacokinetics and safety of
a unilamellar liposomal formulation of amphotericin B (AmBisome) in
rabbits. Antimicrob Agents Chemother 1994;38:713-8.
62. Gondal JA, Swartz RP, Rahman A. Therapeutic evaluation of free and
liposome-encapsulated amphotericin B in the treatment of systemic candidiasis in mice. Antimicrob Agents Chemother 1989;33:1544-8.
63. Francis P, Lee JW, Hoffman A, et al. Efficacy of unilamellar liposomal
amphotericin B in treatment of pulmonary aspergillosis in persistently
granulocytopenic rabbits: the potential role ofbronchoalveolar o-mannitol and serum galactomannan as markers of infection. J Infect Dis
1994; 169:356-68.
64. Tollemar J, Ringden 0. Early pharmacokinetic and clinical results from a
noncomparative multicenter trial of amphotericin B encapsulated in a
small unilamellar liposome (AmBisome) in rodents. Drug Investigation
1992;4:232-8.
cm
1996;22 (Suppl 2)
65. Ringden 0, Meunier F, Tollemar J, et al. Efficacy of amphotericin B
encapsulated in liposomes (AmBisome) in the treatment of invasive
fungal infections in immunocompromised patients. J Antimicrob Chemother 1991;28(suppl B):73-82.
66. Meunier F, Prentice HG, Ringden 0. Liposomal amphotericin B (AmBisome):safety data from a phase IIIIII clinical trial. J Antimicrob Chemother 1991;28(suppl B):83-91.
67. Walsh TJ, Bekersky I, Yeldandi V, et al. Pharmacokinetics of AmBisome
in persistently febrile neutropenic patients receiving empirical antifungal
therapy [abstract no All]. In: Program and abstracts ofthe 35th Interscience Conference on Antimicrobial Agents and Chemotherapy (San
Francisco). Washington, DC: American Society for Microbiology,
1995:13.
68. Atkinson AJ Jr, Bennett JE. Amphotericin B pharmocokinetics in humans.
Antimicrob Agents Chemother 1978; 13:271-6.
69. Benson IM, Nahata MC. Pharmacokinetics of amphotericin B in children.
Antimicrob Agents Chemother 1989;33:1989-93.
70. Sanders SW, Buchi KN, Goddard MS, Lang JK, Tolman KG. Single-dose
pharmacokinetics and tolerance of a cholesteryl sulfate complex of
amphotericin B administered to healthy volunteers. Antimicrob Agents
Chemother 1991;35:1029-34.
71. Walsh TJ, Whitcomb T, Hill S, Pizzo PA. Safety, tolerance, pharmacokinetics, and efficacy of amphotericin lipid complex (ABLe) in the treatment of hepatosplenic candidiasis in children. In: Proceedings of the
Conference on Candida and Candidiasis: Biology, Pathogenesis, and
Management. Washington, DC: American Society for Microbiology,
1996 (in press).
72. Mills W, Chopra R, Linch DC, Goldstone AH. Liposomal amphotericin
B in the treatment of fungal infections in neutropenic patients: a singlecentre experience of 133 episodes in 116 patients. Br J Haematol
1994; 86:754-60.
73. Ng TTC, Denning DW. Liposomal amphotericin B (AmBisome) therapy
in invasive fungal infections: evaluation of United Kingdom compassionate use data. Arch Intern Med 1995; 155:1093-8.
74. Tollemar J, Ringden 0, Andersson S, Sundberg B, Ljungman P, Tyden
G. Randomized double-blind study ofliposomal amphotericin B (AmBisome) prophylaxis of invasive fungal infections in bone marrow transplant recipients. Bone Marrow Transplant 1993; 12:577-82.
75. Ringden 0. Clinical experience with AmBisome with special emphasis
on experience with children. Bone Marrow Transplant 1993; 12(supp1
4):S149-50.
76. Tollemar J, Duraj F, Ericzon BG. Liposomal amphotericin B treatment in
a 9-month-old liver recipient. Mycoses 1990; 33:251-2.
77. Lackner H, Schwinger W, Urban C, et al. Liposomal amphotericin-B
(AmBisome) for treatment of disseminated fungal infections in two
infants of very low birth weight. Pediatrics 1992; 89: 1259-61.
78. Kirsh R, Goldstein R, Tarloff J, et al. An emulsion formulation of amphotericin B improves the therapeutic index when treating systemic murine
candidiasis. J Infect Dis 1988; 158:1065-70.
79. Chavanet PY, Garry I, Charlier N, et al. Trial of glucose versus fat emulsion in preparation of amphotericin for use in HIV infected patients
with candidiasis. BMJ 1992; 305:921- 5.
80. Caillot D, Casasnovas 0, Solary E, et al. Efficacy and tolerance of an
amphotericin B lipid (Intralipid) emulsion in the treatment of candidaemia in neutropenic patients. J Antimicrob Chemother 1993;31:161-9.
81. Moreau P, Milpied N, Fayette N, Ramee JF, Harousseau 11. Reduced
renal toxicity and improved clinical tolerance of amphotericin B mixed
with intralipid compared with conventional amphotericin B in neutropenic patients. J Antimicrob Chemother 1992;30:535-41.
82. Trissel LA. Amphotericin B does not mix with fat emulsion [letter]. Am
J Health Syst Pharm 1995;52:1463-4.
83. Persson U, Tennvall GR, Andersson S, et al. Cost-effectiveness analysis
oftreatment with liposoma1 amphotericin B versus conventional amphotericin B in organ or bone marrow transplant recipients with systemic
mycosis. PharmacoEconomics 1992;2:500-8.