Download Lopinavir/ritonavir combined with twice

JAC
Journal of Antimicrobial Chemotherapy (2004) 54, 498–502
DOI: 10.1093/jac/dkh357
Advance Access publication 14 July 2004
Lopinavir/ritonavir combined with twice-daily 400 mg
indinavir: pharmacokinetics and pharmacodynamics
in blood, CSF and semen
Adil Isaac1*, Stephen Taylor1, Patricia Cane2,3, Erasmus Smit2, Sarah E. Gibbons4,
David J. White1, Susan M. Drake1, Saye Khoo4 and David J. Back4
1
Received 22 December 2003; returned 3 February 2003; revised 21 March 2004; accepted 2 June 2004
Objectives: To evaluate the steady-state blood plasma (BP), CSF and seminal plasma (SP) pharmacokinetics (PK) of twice-daily indinavir 400 mg and lopinavir/ritonavir.
Methods: Ten HIV-1-positive men on lopinavir/ritonavir participated in a PK study. PK sampling was
performed before and 2 weeks after adding indinavir to lopinavir/ritonavir-containing regimens. BP,
CSF and SP RNA levels, CD4 counts and blood chemistry were checked at baseline and 2 weeks after
indinavir.
Results: At baseline: lopinavir parameters (n 5 10) in BP were within expected levels. Median lopinavir
trough concentrations (n 5 5) in CSF and SP were below the limit of detection (BLD) (i.e. < 10 ng/mL)
and 248 ng/mL (range 96 –2777), respectively. After indinavir: lopinavir Cmax, Cmin and AUC0 – 12
increased by 9%, 46% and 20%, respectively (P < 0.32, P < 0.32 and P < 0.20). In two of four men
lopinavir concentrations in CSF were detectable at 27 and 29 ng/mL. Median SP lopinavir concentration
was 655 ng/mL (20–2734). Median indinavir PK parameters were Cmax 3365 ng/mL (range 2130–5194),
Cmin 293 ng/mL (14–766), Tmax 2.25 h (1 –3), AUC0 – 12 22452 ng/mL·h (11243 –33661), and t1/2 2.8 h
(1.4 –3.7). Median indinavir concentrations in CSF and SP were 39 ng/mL (21– 86) and 592 ng/mL
(96–983). Two of eight men who initially had detectable BP viral load (VL) became BLD (<50 copies/mL)
after the addition of indinavir, and in 2/4 men with low-level viraemia in SP (BPVL BLD) their SPVL
became BLD after addition of indinavir.
Conclusions: Adding indinavir 400 mg twice daily to lopinavir/ritonavir-containing regimens did not
significantly alter the median lopinavir PK parameters. However, wide interpatient variability in lopinavir concentrations was seen. In contrast plasma indinavir levels were > 80 ng/mL in seven of eight
plasma samples, and all CSF and semen samples collected.
Keywords: sanctuary sites, double boosted, protease inhibitors, drug interactions, HIV
Introduction
Protease inhibitors (PIs) are valuable antiretroviral drugs with
proven efficacy in HIV-1-infected patients.1 However, most PIs
have unfavourable pharmacokinetic (PK) profiles, which have
resulted in complex regimens with frequent dosing, inconvenient
dosing schedules and a large number of pills and dietary restric-
tions. Adding a sub-therapeutic dose of ritonavir to PIs, and
hence boosting PI levels, has largely overcome these problems.2
Combination therapy including two PIs each boosted by a
small dose of ritonavir (double boosted PIs) may be an option
for drug-experienced patients. However, unexpected drug interactions can lead to toxicities or low drug levels such as the interaction seen between lopinavir and amprenavir.3
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*Corresponding author. Tel: +44-787-678-1398; Fax: +44-1227-783-074; E-mail: [email protected]
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JAC vol.54 no.2 q The British Society for Antimicrobial Chemotherapy 2004; all rights reserved.
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Hawthorne House, Department of Genitourinary Medicine, Birmingham Heartlands Hospital, Birmingham
B9 5SS; 2Health Protection Agency, Birmingham Heartlands Hospital, Birmingham, Birmingham;
3
Antiviral Susceptibility Reference Unit, University of Birmingham, Birmingham; 4Department of Pharmacology
and Therapeutics, University of Liverpool, Liverpool, UK
Lopinavir and indinavir concentrations in plasma, CSF and semen
Table 1. Patient demographics and time on indinavir
Person
Age
(years)
1
2
3
4
5
6
7
8
9
10
54
46
47
38
36
58
38
55
37
57
Median
46.5
Co-administered ART
d4T/3TC
3TC/TDF
NVP/ddI
AZT/ddI
NVP/3TC
AZT/ddI
NVP/AZT
AZT/3TC
ddI/d4T
ABC/ddI
Time on indinavir
(days)
20
21
13
13
14
14
14
10
NA
NA
14
ART, antiretroviral therapy; ABC, abacavir; AZT, zidovudine; d4T, stavudine; ddI, didanosine; NVP, nevirapine; 3TC, lamivudine; TDF, tenofovir.
Study design
ritonavir/indinavir combinations were taken with food (fat
content ± 15 g, 320 kcal); additional fluid intake was recommended.
On study visit 2 the same PK and other sampling was as
described above; then indinavir was stopped. Participants filled in
tolerability questionnaires at both study visits.
Heparinized tubes (5 mL) were used to obtain blood for PK
samples, which were then processed within 4 h of production. CSF
and semen samples were obtained in sterile wide-rimmed tubes after
accurate documentation of the times of drug ingestion. Blood and
semen were spun at 3000g for 10 min to separate plasma and cell
fractions. Samples were then frozen at 708C until analysis.
The study was designed as an observational PK study, and pilot
study of antiviral activity within the CSF and semen.
Pharmacokinetic analysis
Materials and methods
Patients
Ten HIV-1-positive men were enrolled prospectively from
Birmingham Heartlands Hospital, UK to participate in the pharmacokinetic study of indinavir 400 mg and lopinavir/ritonavir
400/100 mg in blood plasma (BP), CSF and semen plasma (SP).
Local ethics committee approval and informed written consent were
obtained for the study.
Eligible participants had to meet the following criteria: age >18
years, documented HIV-1 infection and on stable ongoing antiretroviral therapy containing lopinavir/ritonavir (Table 1).
All 10 participants also took combinations of nucleoside
analogues, and three took nevirapine as part of their combination.
Participants were advised to take lopinavir/ritonavir doses strictly
12 h apart for 2 weeks before study visit 1.
Drug administration and sampling
On study visit 1 each participant attended 2 h before their usual
morning medication dose, and provided semen by masturbation
and/or underwent a lumbar puncture for CSF sampling.
Blood was sampled by insertion of a venous cannula and drawn
into a heparinized tube at 0 h and then 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 10,
12 h after an observed dose of drug. Also, all participants underwent
HIV RNA virus load, CD4 and blood chemistry (liver and kidney
function tests, triglyceride and cholesterol levels) measurements.
They were instructed to add indinavir 400 mg to their stable
regimens and attend a second PK study day 2 weeks later. Lopinavir/
An HPLC/MS/MS system, with a lower level of detection of
10 ng/mL, was used to measure drug levels in BP, CSF and SP.12
Lopinavir and indinavir drug concentrations were evaluated for
maximum concentration (Cmax), time to peak (Tmax) and the area
under the curve to 12 h (AUC0 – 12), and elimination half-life
(t1/2) values were determined by non-compartmental analysis using
TOPFIT computer software (Gustav Fischer Verlag, Stuttgart,
Germany). The elimination rate constant lz was calculated by
log-linear regression of the terminal portion of the plasma drug
concentration – time curve using the least squares method. The terminal elimination half-life (t1/2,z) was calculated from ln 2/lz. The
area under the drug – time curve was determined by the log-linear
trapezoid rule.
HIV RNA determinations
Blood plasma viral load (BPVL) was determined by the Roche
Ultrasensitive assay (Brachburg, NJ, USA) as per the manufacturer’s
instructions. CSF viral load and semen plasma viral load (SPVL)
were determined by NASBA Nuclisens. The lower limit of quantification was 50 copies/mL for BP and 400 copies/mL for CSF and
semen. The latter was 400 copies due to the small volume of CSF
and semen analysed (1 mL).
Statistical analysis
The Wilcoxon matched pairs signed rank test was used to compare
PK and other parameters.
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Both indinavir and lopinavir/ritonavir are metabolized by
cytochrome P450 (CYP3A4) isoenzyme; indinavir, lopinavir and
ritonavir are inhibitors of CYP3A4, and therefore co-administration of these drugs can lead to significant drug interactions.
Nonetheless, favourable pharmacokinetics have been demonstrated in combinations including lopinavir/ritonavir and indinavir
600 mg twice daily.4
Twice-daily indinavir 400 mg boosted with a small dose of
ritonavir of 100 mg was shown in a recently published pilot
study5 to be efficacious and well tolerated; this is most likely
due to higher drug exposure coupled with low indinavir Cmax.
In contrast, twice-daily regimens containing higher doses of
indinavir/ritonavir were not so well tolerated despite virological
effectiveness.6,7
Recent studies have suggested that lopinavir penetrates poorly
into the CSF and male genital tract.8,9 Hence these viral reservoirs may be potential sites for ongoing viral replication in the
face of a suppressed plasma viral load. In contrast, studies with
indinavir have demonstrated good penetration of this drug into
these anatomical sites with good antiviral activity.10,11
The rationale for this study is two-fold. First, to obtain PK
data, as they are not available from the manufacturers, to evaluate the feasibility of combining twice-daily indinavir 400 mg and
lopinavir/ritonavir 400/100 mg, utilizing the low-dose ritonavir
that is co-formulated with lopinavir. Secondly, to evaluate indinavir and lopinavir penetration and antiviral activity in the CSF
and semen, when these drugs are co-administered.
A. Isaac et al.
Table 2. Summary of lopinavir and indinavir parameters in blood
plasma
Day 2
Parameter
Cmax (ng/mL),
range
Cmin (ng/mL),
range
AUC0 – 12
(ng/mL·h),
range
Day 1
LPV (n = 10)
LPV (n = 8)
IDV (n = 8)
11449
8179– 17407
4811
1168– 10945
104414
14387
8668– 19552
5612
1181– 13255
114845
3365
2130– 5194
293
14 –766
22452
52502– 169106
58163– 203960
11243– 33661
LPV, lopinavir; IDV, indinavir. Day 1, at baseline; Day 2, after indinavir
was added.
Patient characteristics
Ten men were enrolled between September 2002 and June 2003.
Their median age was 46.5 years (range, 36– 58), median
CD4 381 cells/mm3 (range, 96 –774) and HIV-1 RNA VL
<50 copies/mL in 80% of patients. Seven patients were on at
least their second, and two were on their first, PI-containing
regimen.
Lopinavir pharmacokinetics
Ten men provided BP for 0–12 h PK determinations. Five
patients provided CSF and SP samples. Table 2 shows the
median BP lopinavir PK parameters. All patients had undetectable (i.e. <10 ng/mL) lopinavir concentrations in CSF. Median
SP lopinavir concentrations were 248 ng/mL (range 96 –2777).
Eight men provided blood samples for the second 0–12 h
study. Four patients provided CSF and four provided semen. The
median PK parameters for lopinavir when co-dosed with indinavir are shown in Table 2. Median (range) lopinavir t1/2 and Tmax
were 11.6 h (3.1 –21.5) and 2.7 h (1.5 –4).
Two of four men had lopinavir concentrations in CSF detectable at 27 and 29 ng/mL, respectively. The median SP lopinavir
concentration was 655 ng/mL (20–2734).
Post-indinavir the median increase from baseline for lopinavir
Cmax, Cmin and AUC0 – 12 was +9% (range 23% to +78%),
+46% ( 68% to +130%) and +20% ( 36% to +102%), respectively. None of these was statistically significant, P < 0.32, 0.32
and 0.2 (see Figure 1).
Indinavir pharmacokinetics
Table 2 and Figure 2 show indinavir PK parameters in BP.
Median indinavir (range) t1/2 and Tmax were 2.8 h (1.4 –3.7) and
2.25 h (1 –3). Median indinavir CSF and SP concentrations were
39 ng/mL (21–86) and 592 ng/mL (96 –983).
Pharmacodynamic data
Viral load data: in two of eight men with detectable BPVL of 310
and 200 copies/mL, viral load became below the limit of detection (BLD) (<50 copies/mL) after addition of indinavir. In two of
Figure 2. Pharmacokinetic parameters of indinavir 400 mg twice daily
in blood plasma (filled diamonds) when dosed with twice-daily lopinavir/
ritonavir 400/100 mg. The broken line is the target trough indinavir concentration for wild-type virus.
four men with low-level viraemia in SP (BPVL BLD), at 779 and
970 copies/mL, viral load became BLD (<400 copies/mL) postindinavir.12
All subjects had VL BLD (<400 copies/mL) pre- and postindinavir in the CSF. No significant changes in CD4 counts or
blood chemistry post-indinavir were noted.
Tolerability
The lopinavir/ritonavir/indinavir combination was well tolerated.
There were no differences in adverse events before and after
adding indinavir. The main side effect was mild to moderate
diarrhoea (30%). However, no patient stopped indinavir before
the end of the study, but two withdrew their consent from the
second arm of the study due to headaches from the lumbar
puncture.
Discussion
To our knowledge, these are the first data on the pharmacokinetics and tolerability of lopinavir/ritonavir and indinavir
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Results
Figure 1. Pharmacokinetic parameters of lopinavir in blood plasma at baseline (filled triangles), and after addition of indinavir (filled squares).
The broken line is the target trough lopinavir concentration for wild-type
virus.
Lopinavir and indinavir concentrations in plasma, CSF and semen
showed excellent tolerability throughout the study duration
(2 weeks); and there were no significant changes from baseline in
CD4 counts, blood chemistry or lipids. Also, participants stated
that they would take this combination again if offered to them.
Our results suggest that indinavir 400 mg and lopinavir/ritonavir 400/100 mg twice daily is a promising, convenient and welltolerated regimen. However, larger efficacy trials, including both
treatment-naive and -experienced patients, are needed to confirm
these results, and ascertain whether the favourable PK profile
will translate into clinical benefit.
Acknowledgements
We thank all patients and staff involved with this study. This
study was partially supported by a West Midlands NHSE
Research grant to S.T. and was not funded by a pharmaceutical
company.
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400 mg. By combining these drugs, we have demonstrated:
therapeutic drug concentrations of both lopinavir and indinavir
in blood plasma, the lack of negative drug–drug interactions,
good tolerability, and the added benefit of drug penetration into
CSF and semen.
We have shown that the pharmacokinetics of lopinavir when
combined with indinavir were within the expected ranges.13
Unlike the case of lopinavir and amprenavir, no negative drug –
drug interactions took place.3 However, there was a trend toward
increased lopinavir parameters, which did not reach statistical
significance
Our study confirmed previous reports that, unlike indinavir,
lopinavir penetrates poorly into the CSF and semen;8,13 interestingly, two patients had lopinavir concentrations in CSF of 27
and 29 ng/mL, which are above both the limits of detection
(10 ng/mL) and the non-protein-corrected EC50 of lopinavir,
after the addition of indinavir. Together with the upward trend in
lopinavir BP concentrations, these results suggest that indinavir
probably exerts some added inhibition of lopinavir metabolism.
Several groups have reported previously that ritonavir, at various doses, improves indinavir pharmacokinetics compared with
the standard indinavir 800 mg three times daily dose. Investigated doses have included indinavir/ritonavir 400/400, 800/100,
600/100 and 400/100 mg. However, the former two were poorly
tolerated unlike 600/100 and 400/100 mg.6,7
Combined with lopinavir, indinavir 600 mg was shown to
have favourable pharmacokinetics and tolerability in both
healthy volunteers and HIV-1-positive individuals.4,14 Our results
showed: a two-fold decrease in indinavir Cmax; a two-fold
increase in Cmin; and a similar AUC compared with the licensed
dose of indinavir of 800 mg three times daily.15 While confounding, due to nevirapine taken by three patients, could not be ruled
out, these results are comparable to published data on singleboosted indinavir/ritonavir 400/100 mg. In addition, a comparison between our data and indinavir 600 mg (historical data)
revealed no significant difference in indinavir parameters
(M. Harris, personal communication).
Consistent with previous reports, indinavir concentrations in
CSF and semen were above the non-protein-corrected IC50
values of 21 ng/mL and 100 ng/mL, respectively, in all samples
collected. These results confirmed our hypothesis that the
lopinavir/ritonavir/indinavir combination may result in levels
above the threshold concentration in CSF and semen and, therefore, may control viraemia in these sites, which are virtually
closed to lopinavir/ritonavir alone. This is due to the high protein binding of lopinavir and hence its small volume of distribution. Nevertheless, as all patients in this study were taking
HAART regimens containing nucleoside and non-nucleoside
reverse transcriptase inhibitors, some of which have good penetration into such sites, detectable viraemia was found in only a
small minority in semen and in none in the CSF.
Two patients had BP viraemia that became BLD after the
addition of indinavir; despite the small numbers, this suggests
that indinavir might be a useful add-on to failing regimens containing lopinavir/ritonavir. Moreover, two other patients had
detectable viraemia in the SP with BPVL BLD (<50 copies/mL),
which became undetectable (<400 copies/mL) after indinavir
was added, confirming that indinavir may be useful in controlling HIV in semen.
In contrast to previously reported double boosted combinations
such as lopinavir/ritonavir and saquinavir soft gel,16 our results
A. Isaac et al.
14. Bertz, R. J., Foit, C., Ashbrenner, E. et al. (2002). Assessment
of steady-state pharmacokinetic interaction of lopinavir/ritonavir with
either indinavir or saquinavir in healthy subjects. In Abstracts of the
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pharmacokinetics of double boosted regimens of lopinavir, plus
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