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Lefamulin (BC-3781)
The Pharmacokinetics of Lefamulin (BC-3781) in the Pulmonary
Epithelial Lining Fluid in Healthy Subjects
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M. Zeitlinger1, D.B. Strickmann2, W.W. Wicha2, R. Schwameis1, B. Burian1, M. Müller1, W.T. Prince2
1 Medical
University of Vienna, Austria; 2 Nabriva Therapeutics AG, Vienna, Austria
Nabriva Therapeutics AG
Leberstrasse 20
A-1110 Vienna, Austria
www.nabriva.com
+43-1-74093-0
[email protected]
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ABSTRACT
Background: Lefamulin (BC-3781) is an investigational semisynthetic pleuromutilin derivative inhibiting ribosomal protein
synthesis. Lefamulin is entering Phase 3 clinical development with a
spectrum of activity suitable for treating respiratory tract infections
including multidrug resistant S. pneumoniae, atypical respiratory
pathogens and S. aureus (MRSA and MSSA). Since knowledge of the
pharmacokinetics (PK) at the site of infection is crucial in the
development of antibiotics, for the treatment of respiratory tract
infections such as community- and hospital-acquired bacterial
pneumonia (CABP & HABP) drug penetration into the pulmonary
epithelial lining fluid (ELF) is a pre-requisite. The present study
examines the PK of lefamulin in the ELF in comparison to the plasma.
Methods: A single dose of 150 mg lefamulin was administered
intravenously (i.v.) over 1 hour to 12 healthy male subjects.
Bronchoalveolar lavage (BAL) was used to obtain ELF samples 1, 2, 4
and 8 hours after dosing and the urea dilution method was employed
to correct for the dilution factor. Drug levels in plasma and ELF were
subsequently quantified by LC-MS/MS analysis.
Results: After a single i.v. dose of 150 mg lefamulin the mean area
under the concentration-time curve (AUC0-12h) was 6022
± 1365 ng·h/mL for the total and 782.9  177.5 ng·h/mL for the
calculated free concentration in plasma. For ELF the AUC0-12h
calculated from extrapolated C12h was 4489 ng·h/mL, resulting in an
AUC0-12h ratio of lefamulin in ELF compared to free drug in plasma of
5.7. Approximately 1 h after end of infusion the lefamulin levels in ELF
approached the total plasma levels with elimination from ELF following
the same time course as for plasma. Lefamulin was safe and well
tolerated and there were no clinically relevant changes in laboratory
values.
Conclusions: After a single i.v. dose of lefamulin exposure levels in
ELF were comparable to total plasma levels and considerably
exceeded free plasma levels. The individual lefamulin concentration
levels in ELF equilibrated with the plasma rapidly after the end of
infusion. The exposure levels seen in the ELF are encouraging for the
use of lefamulin in the treatment of respiratory tract infections and will
be used for target attainment analysis.
INTRODUCTION
Lefamulin (BC-3781) is an investigational semi-synthetic
pleuromutilin derivative. Pleuromutilin antimicrobial agents
inhibit protein synthesis through interaction with the
50S ribosomal subunit and cross resistance with other
antimicrobial
classes
is uncommon. Lefamulin
has
demonstrated
potent
antimicrobial
activity
against
Gram-positive cocci and Gram-negative pathogens relevant for
community-acquired bacterial pneumonia and for bacterial skin
and skin structure infections. Since lefamulin is being
developed for the treatment of serious bacterial pneumonia
caused
by
Streptococcus
pneumoniae,
Haemophilus
influenzae,
Moraxella
catarrhalis,
Mycoplasma
spp.,
Chlamydophila pneumoniae, Legionella pneumophila, and
INTRODUCTION (cont‘d)
METHODS (cont‘d)
Staphylococcus aureus, including drug resistant strains such as
MRSA, it is important to investigate the penetration of lefamulin
into the tissues at the site of infection. This study
(NAB-BC-3781-1005) was undertaken to investigate the
penetration of lefamulin into the ELF to support the treatment of
patients with community-acquired pneumonia (CABP) with
intravenous and oral dosing formulations. Lefamulin
concentrations were determined in the plasma and ELF.
saline and ELF was collected. Since BAL yields just a portion of ELF
with the rest being saline, the dilution of ELF must be determined to
translate measured drug concentrations in BAL to drug concentrations
in ELF. For ELF dilution assessment in BAL the urea dilution method
was used. The use of urea to quantify the amount of recovered ELF is
based on the observation that urea freely diffuses through several
body compartments including ELF. Hence, if the concentration of urea
in plasma and BAL is known, the volume of recovered ELF can be
calculated and consequently also the concentration of lefamulin in
ELF.[2] Concentrations of lefamulin in BAL samples were corrected for
the procedure related dilution of ELF by saline as follows:
c(lefamulin in ELF)corr =
METHODS
c(lefamulin in BAL)measured/[c(urea in BAL)/c(urea in plasma)]
Study population: 12 healthy male subjects aged between 18 and 55
years with no relevant medical history. Subjects underwent a
screening visit including physical examination, body weight, vital
signs, laboratory tests, 12-lead electrocardiography and 24 hours
Holter monitoring. Subjects had to be of normal weight (BMI 1928 kg/m2 inclusive) and satisfy all the inclusion and exclusion criteria.
Volunteers received standardized meals on study days and were
instructed to avoid coffee, tea and any other food containing xanthines
(i.e. coke, chocolate, etc.), alcohol and grapefruit juice during the
entire study period.
Study procedures: In the morning of the study day a peripheral venous
catheter was inserted in the arm. 150 mg lefamulin in 400 mL 0.9 %
saline were administered over 60 min using an infusion pump.
Afterwards, subjects fasted until midday or two hours after BAL
procedure, whichever was later. Lefamulin concentrations in plasma
were determined at 0.5, 1, 1.25, 1.5, 2, 3, 4, 6, 8, 12, 16, and 24 h
after dosing. At 1, 2, 4, or 8 h after drug administration BAL was
performed to determine lefamulin concentrations in ELF. BAL was
performed by an experienced professional of the Division of
Pulmology, as previously described.[1] Each volunteer underwent only
one BAL and time points were randomized between the subjects in
order to obtain three samples per time point. Local anesthesia of the
pharynx and the nasal passages was provided by applying 2%
lidocain spray as an aersosol and application of 2% lidocain gel to the
nose. Additionally, the tip of the bronchoscope was coated with
lidocain gel. Subsequently, subjects were sedated intravenously with
2-10 mg midazolam. During the entire procedure vital signs, ECG,
frequent blood pressure and O2 saturation monitoring was performed.
Oxygen was delivered by nasal cannula up to 10 L/min as needed to
maintain adequate oxygenation (O2 saturation >90%). A
bronchoscope was inserted through nose and pharynx until the larynx
was seen and vocal cords were anaesthetized by application of 1 mL
2% lidocain in triplicate. The trachea was passed and after inspection
of the tracheobronchial tree the bronchoscope was guided to the right
or left lower lobe and wedged at segments B8-B10. Afterwards, 3
aliquots of 20 mL saline were infused and subsequently retrieved
gently by suction. The first aliquot was discarded, while the two other
aliquots were mixed, prepared for analysis and consecutively snap
frozen at -80º C. During BAL the bronchoalveolar tree was rinsed with
54th
Plasma and BAL samples were analyzed for lefamulin concentrations
using a validated and a partially validated LC-MS/MS method,
respectively. The LLOQ was 1 ng/mL in both methods.
RESULTS (cont‘d)
Table 1. Mean pharmacokinetic parameters of lefamulin following a single oral dose of 150 mg
AUC0-12
[ng·h/mL]
Cmax
[ng/mL]
Plasma total
6022 ±1365
2576 ±492
7.0 ± 1.1
NA
Plasma free*
783 ±178
335 ±64
7.0 ± 1.1
NA
4489
932
NA
5.7
ELF
t1/2
[h]
Penetration rate
* For plasma a free fraction of 13 % was used in the calculations.
Figure 1. Unbound concentration – time profiles of lefamulin
in plasma and ELF
CONCLUSIONS
PK parameters were calculated using a computer software package
(SAS 9.1.3; SAS Institute,USA). Cmax, tmax, t½, AUC0-8h, and AUC0-12h
were calculated from non-fitted data by employing the trapezoidal rule.
For AUC0-inf, individual extrapolation based on the last observed
concentration and the elimination constant kel was performed.
Additionally, the apparent volume of distribution (Vd) was calculated
for plasma. In ELF, tmax, Cmax, and AUC0-8h were calculated. In
addition, to determine AUC0-12h in ELF C12h was calculated as well.
C12h was estimated by use of the formula (C = C0h · e kel · t), where C
represents the concentration at a defined time point, C0h is the last
concentration measured, kel is the elimination rate constant and t is
the time between the measurement of C0h and the defined time point.
• Lefamulin was safe and well tolerated
• Lefamulin showed rapid penetration into ELF after a single
150 mg one hour intravenous infusion
• Therapeutic exposure levels of lefamulin in the lung are
expected to be reached within the first day of treatment and
are similar to the levels reached in blood plasma
• Elimination from ELF followed the same time course as for
plasma
• The exposure levels seen in the ELF are encouraging for the
use of lefamulin in the treatment of respiratory tract infections
and will be used for target attainment analysis
RESULTS
• All subjects completed the study according to the protocol.
• Lefamulin was safe and well tolerated. No serious adverse
events were reported and all observed adverse events
resolved spontaneously. There were no clinically relevant
changes in laboratory values.
• The mean area under the concentration-time curve (AUC0-12h)
was 6022 ± 1365 ng·h/mL for the total and 783
 178 ng·h/mL for the calculated free concentration in plasma
following a single i.v. dose of 150 mg lefamulin.
• Mean PK parameters are presented in Table 1.
• AUC0-12h in the ELF was 4489 ng·h/mL, similar to the
exposure of total drug in the blood plasma.
• As shown in Figure 1 after an intravenous dose of 150 mg of
lefamulin equilibration between the ELF and the total fraction
in plasma occurred quickly. Thereafter, free concentration
time profiles in ELF and plasma closely resemble each other,
indicating very fast exchange of lefamulin within central
compartment and interstitium. This finding is supported with
the results from a QWBA study in rats where the
concentrations measured in the majority of tissues, including
the lung were high compared to the amounts measured in the
circulating blood.[3].
• The penetration ratio of lefamulin into ELF compared to free
drug in plasma was 5.7 (Table 1).
• Approximately 1 h after end of infusion the lefamulin levels in
ELF reached equilibrium with the total plasma levels.
• Elimination from ELF followed the same time course as for
plasma with a similar t1/2.
• A high volume of distribution of 215 L reflected the fast and
good penetration into tissues.
Interscience Conference on Antimicrobial Agents and Chemotherapy, September 5-9, 2014 | Washington, DC
REFERENCES
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Pharmacokinetics of gatifloxacin after a single oral dose in healthy young
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of drug concentrations obtained by bronchoscopic microsampling and
bronchoalveolar lavage. Clin Ther 2007; 29(1): p. 123-30.
[2] Rennard SI, Basset G, Lecossier D, et al. Estimation of volume of epithelial
lining fluid recovered by lavage using urea as marker of dilution. J Applied
Physiol 1986; 60(2): p. 532-8.
[3] Wicha WW, Ivezic-Schoenfeld Z, Novak R. Pharmacokinetic, Mass Balance
and Tissue Distribution of [14C]-BC-3781 in Non-pigmented Rats. Poster
P909. 2010. 20th ECCMID, Vienna, Austria.