The pharmacokinetic and safety profiles of ... - Wiley Online Library

Journal of Clinical Pharmacy and Therapeutics, 2013, 38, 236–240

doi: 10.1111/jcpt.12056

Pharmacokinetics

The pharmacokinetic and safety profiles of zanamivir after single and repeat intravenous administration in healthy Japanese males Y. Shida* BPharm, K. Hara* MPharm, S. Nohda* BSc, T. Soutome† BPharm and T. Hirama* MD PhD *Clinical Pharmacology Department, Medicines Development, Development & Medical Affairs Division, GlaxoSmithKline K.K., Tokyo, and †Biomedical Data Sciences Department, Development & Medical Affairs Division, GlaxoSmithKline K.K., Tokyo, Japan

Received 26 October 2012, Accepted 18 February 2013

Keywords: healthy, influenza, Japanese, pharmacokinetics, safety, zanamivir

tration of the mucosal lining of the respiratory tract and plays an important role in viral replication and spreading.2–4 Because the oral bioavailability of zanamivir is low (mean: 2%),5 an oral inhalation formulation has been developed to direct delivery to the respiratory tract epithelium, the main site of replication of influenza virus.4 Inhaled zanamivir is believed to inhibit viral replication locally in the epithelial cells.6 Patients with underlying illnesses, including chronic respiratory disease, cardiovascular disorders, diabetes mellitus, renal disorders and immunodeficiency, as well as paediatric and pregnant patients, are at risk of developing severe symptoms and complications when infected with the influenza virus.7, 8 In addition, avian H5N1 has been associated with a greater than 50% mortality rate worldwide.9 In clinically severe conditions, influenza patients often need critical care in hospitals. In such circumstances, parenteral therapy is preferred over oral or oral inhalational therapy. Viral resistance associated with mutations of the neuraminidase gene remains an important public health issue. During the 2008/ 2009 influenza season, up to 100% oseltamivir resistance of the seasonal H1N1 circulating virus was reported by many countries.10 An H274Y mutation of the neuraminidase gene confers high-level resistance to oseltamivir with cross-resistance to peramivir.10, 11 H5N1 virus resistant to oseltamivir has also been reported.12 To date, all H1N1 and H5N1 virus strains resistant to oseltamivir are reportedly susceptible to zanamivir.13–15 Therefore, zanamivir solution for intravenous administration would be valuable for patients in need of parenteral therapy, and in particular, when viral resistance is a concern. A study for the pulmonary pharmacokinetics of zanamivir after intravenous administration has shown that zanamivir reaches the respiratory tract.16 To maintain the concentration at the target site, the dosage for intravenous administration has to be significantly higher than for inhalation. The recommended dose of zanamivir for the treatment of influenza is two inhalations (2 9 5 mg) twice daily for 5 days, providing a daily inhaled dose of 20 mg,17 with very low systemic exposure. So far, we do not have knowledge of the safety, tolerability and pharmacokinetics of zanamivir in Japanese with the likely very high exposure achieved by intravenous dosing. A study was conducted to investigate up to 600 mg, twice daily, of intravenous zanamivir in Japanese healthy volunteers. Here, we discuss the results, particularly in relation to data previously reported for nonJapanese subjects, and with those previously reported following oral inhalation in Japanese subjects.

SUMMARY What is known and Objective: Neuraminidase inhibitors are important options for the treatment of infection by the influenza virus. For the treatment of severe influenza, parenteral administration of a neuraminidase inhibitor may be desirable. This study was conducted to evaluate the pharmacokinetic and safety profiles of intravenous zanamivir, an influenza viral neuraminidase inhibitor, in Japanese subjects to further characterize these profiles particularly following relatively high-doses when compared with inhalation doses and to provide reassurance that there are no marked differences with profiles reported for other ethnically different populations. Methods: Single doses of 100, 300, 600 mg zanamivir were administered to healthy Japanese men in a randomized, double-blind, ascending dose, placebo-controlled, incomplete threeperiod cross-over study. In period 3, subjects were given 600 mg of zanamivir on day 1, followed by a 60 h washout period and then a 5-day course of 600 mg zanamivir twice daily. Each subjects received two of three active dosages of zanamivir from 100, 300 and 600 mg, and placebo. Results: Adverse events reported in the study were all mild in intensity and resolved without any treatment. The mean AUC0–∞ values after single intravenous administration of 100, 300 and 600 mg were 16768, 53462 and 100400 ngh/mL, respectively, demonstrating dose proportionality. No accumulation or time variance was observed after 5 days of twice-daily administration of 600 mg zanamivir. Urinary concentrations of zanamivir after single doses ranging from 100 to 600 mg indicated that over 94% of the zanamivir administered was excreted in urine within 24 h. What is new and Conclusion: Single and 5-day BID repeat dosing of 600 mg were safely administered in Japanese healthy subjects. The pharmacokinetic profile of zanamivir after intravenous administration was consistent with previously reported findings in non-Japanese subjects. WHAT IS KNOWN AND OBJECTIVE Zanamivir is a potent and selective inhibitor of the influenza virus neuraminidase.1 Viral neuraminidase (sialidase) aids initial peneCorrespondence: Yuri Shida, Clinical Pharmacology Department, GlaxoSmithKline K.K., 6-15, Sendagaya 4-chome, Shibuya-ku, Tokyo 151-8566 Japan. Tel.: 03-5786-5078; fax: 03-5786-5223; e-mail: yuri.2. [email protected]

© 2013 Blackwell Publishing Ltd

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Pharmacokinetics of zanamivir IV in japanese

The quantitative analyses of zanamivir in human serum and urine samples were conducted by PharmaNet Canada, Inc. (Quebec, Canada). Zanamivir was extracted from human serum by an automated protein precipitation procedure using a dissolving solution [Milli-Q type water/formic acid 01% (01/ 100)] containing zanamivir 13C,15N2 as internal standard followed by the addition of methanol. Extracts were analysed by liquid chromatography-tandem mass spectrometry (LC-MS/ MS) using a TurboIonSprayTM interface with positive ion multiple reaction monitoring. Calibration curves were established over the range 10 to 10000 ng/mL by weighted 1/92 linear regression, and the coefficient of determination (r2) of the curves were over 09956. The lower limit of quantification (LLQ) was 999 ng/mL using a 0050 mL aliquot of human serum. For urinary zanamivir (unchanged drug) concentration determination, zanamivir was extracted from urine by an automated dilute and shoot procedure using a solution of methanol containing zanamivir 13C,15N2 as internal standard. Extracts were analysed by LC/MS/MS using an Heated Nebulizer interface with positive ion multiple reaction monitoring. Calibration curves were established over the range 10 to 650 lg/mL by weighted 1/92 linear regression, and the coefficient of determination (r2) of the curves were over 09961. The LLQ was 1006 ng/mL using a 0020 mL aliquot of human urine.

METHODS Study design This study was conducted at Shinanozaka Clinic, Medical Co. in compliance with the Declaration of Helsinki and the Good Clinical Practice (GCP) after obtaining approval from the Institutional Review Board of Shinanozaka Clinic as a phase I clinical trial sponsored by GlaxoSmithKline. Written informed consent was obtained from each subject. This was a randomized, double-blind, ascending dose, placebo-controlled, incomplete cross-over, single and repeat dose study. Each subject was randomized to 1 of 3 groups (A-C) and received 2 active treatments and 1 placebo treatment in accordance with the randomization code. The study consisted of 3 periods, with period 1 and period 2 involving singledose treatments. Period 3 consisted of a single dose of 600 mg zanamivir, followed by a 60 h washout period, and then a 5-day course of 600 mg zanamivir twice daily (BID, i.e. every 12 h) (Table 1). Each period was separated by at least 5 days. Subjects Healthy Japanese adult men were enrolled and evaluated. Subjects were 20–55 years of age and had a normal renal function (creatinine clearance (CLcr 80 mL/min) with typical body mass index, 185–250 kg/m2.

Pharmacokinetic and statistical analysis Treatments

Pharmacokinetic parameters were calculated from the serum zanamivir concentrations and actual sampling times with standard non-compartmental methods using WinNonlin Professional Ver. 41 (Pharsight Corp., Mountain View, CA, USA) for each treatment. AUC was calculated with log-linear trapezoidal rule. Cmax, Tmax, concentration at the dosing interval for repeat dose (Cτ), concentration at 12 h after single dose (C12), AUC from time zero (predose) extrapolated to infinite time (AUC0–∞) for single dose, AUC over a dosing interval (AUC0–τ), t1/2, volume of distribution at steady state (Vss) and total clearance (CLtot) were calculated after single dose and on the final day of 5days repeat doses (Day 8). CLtot after single dose was also calculated. In addition, accumulation index Rs (AUC0–τ on Day 8 of repeat dose/AUC0–∞ on Day 1) was calculated. Amount of urinary excretion (Ae), fraction of urinary excretion (% of dose) (fe) and renal clearance (CLr) were calculated from the urinary zanamivir concentrations and urine volume for each subject. To investigate the linearity of exposure after single doses of 100–

From zanamivir (200 mg) solution (10 mg/mL), 100 mg/05 vial (10 mL), 300 mg/15 vial (30 mL), or 600 mg/3 vials (60 mL) was aliquoted and diluted with normal saline. Each dose was administered intravenously at a constant rate over 30 min using an infusion pump (500 mL/h). Bioanalytical assessments For determination of zanamivir concentrations in serum, blood samples were taken predose and at 05, 075, 1, 15, 2, 4, 6, 8, 10, 12, 24 h post-dose on the day of each single dose and on Day 8 of Period 3 (i.e. in conjunction with the last dose of 5-day BID dosing). Samples for measuring trough concentration were taken at 12 h (predose of PM dose) on Day 3, 4, 5, 6, 7 (i.e. prior to 1st, 3rd, 5th, 7th and 9th dose of BID 9 5-day dosing). Urine samples were collected predose and over 0–4, 4–8, 8–12, 12–24 h post-dose of single-dose phase for each dosage.

Table 1. Study design Period 1

Period 2

Period 3

Treatment Schedule of Period 3

Day AM PM

Sequence

Single dose

Single dose

Single dose (Day 1) + 5-days repeat doses (BID, Day 3–8)

A (n = 6) B (n = 6) C (n = 6)

100 mg 100 mg Placebo

300 mg Placebo 300 mg

Placebo 600 mg 600 mg


1 X

2

3 X

4 X X

5 X X

6 X X

7 X X

8 X

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is provided in Fig. 1. Following each treatment, maximum serum concentrations of zanamivir were observed 05 h after the initiation of infusion, when infusion was complete. The mean terminal half-life was 21–27 h after single doses and 40 h after repeat doses.

600 mg, the slope versus dose was calculated using the power model. logðyik Þ ¼ a þ b logðdi Þ þ pk þ ik yik: PK parameter; a: Intercept; b: Slope for loge-transformed dose; di: Dose; pk: Random subject effect; eik: Random error. In addition, analysis of variance (ANOVA) using mixed effects model on loge-transformed AUC0–∞ and Cmax was conducted. These statistical analyses were performed using SAS version 9.1.3 on a UNIX platform (SAS Institute, Cary, NC, USA).

Dose proportionality of zanamivir. The results of dose-proportionality analysis of the single-dose data using the power model were as follows: the point estimates [90% confidence interval (CI)] for Cmax and AUC0–∞ were 099 (095–103) and 100 (098–103). They were close to 1, and their 90% CI included 1. In addition, the ANOVA using mixed effect models on loge-transformed AUC0–∞ and Cmax (100 mg vs. 600 mg, 100 mg vs. 300 mg, 300 mg vs. 600 mg) was also conducted. The 90% CI included 1 except for AUC0–∞ of 300 mg vs. 600 mg, in which the ratio was 094 and 90% CI was 091 to 098. The lower boundary of 90% CI exceeded 090. The ratios in the other two comparisons were 096–106 and the 90% CI included 1. Therefore, it can be concluded that systemic exposure (Cmax and AUC0–∞) increased in an approximately dose-proportional manner with increasing single doses of zanamivir.

RESULTS Demographic characteristics All 18 eligible subjects enrolled in the study completed the study. Enrolled subjects were healthy Japanese adult men aged 22– 39 years (296 years on average), weighing 564–777 kg (656 kg on average) with normal renal function (1042–1800 mL/min, 1336 mL/min on average based on the CLcr calculated with the Cockcroft-Gault formula). CLcr and CLcr/body surface area (mL/ min/173 m2) were also calculated from serum creatinine and urinary creatinine in 24-h pooled urine. All calculations of the CLcr were normal and were similar among the treatment groups.

Accumulation of zanamivir after repeat doses of 600 mg. The trough zanamivir concentrations profile on Day 3 to Day 8 (pre-PM dose on Day 3–7 and pre-AM dose on Day 8) is shown in Fig. 1. Although the concentration at predose of final AM dose on Day 8 was slightly higher than at other time points, the concentration reached a steady state within 1 day. The 90% CI of Rs did not include 1, but its geometric mean was 096 with the interval 092– 099. These results suggest no accumulation or time-variance after 5 days BID repeat intravenous administrations of 600 mg.

Safety and tolerability No serious adverse events or deaths were reported during the study. Seven adverse events (AE) were reported in 7 of 18 subjects, and all these events were laboratory abnormalities. The AEs reported in the study were all mild in intensity and resolved without treatment. Among seven AEs, three events (two of alanine aminotransferase increased, one on zanamivir and one on placebo, and one of blood triglycerides increased on zanamivir) reported in the repeat dose period were judged to be related to the investigational product.

Urinary pharmacokinetic parameters of zanamivir. From urinary concentration in pooled urine and urine volume, fe, and CLr were calculated. More than 70% of zanamivir was eliminated within 4 h after dosing, and over 94% of dose (mean) of zanamivir was recovered within 24 h after 100–600 mg of single doses (Fig. 2). CLr after single administration of 600 mg was 566 067 L/h (mean SD).

Pharmacokinetics DISCUSSION

Serum pharmacokinetic parameters of zanamivir. The pharmacokinetic parameters after single and repeat intravenous administrations are given in Table 2. Serum zanamivir concentration-time profile of single and 5-day BID repeat intravenous doses of 600 mg

Following single intravenous administration of zanamivir 100, 300, 600 mg, the systemic exposure in Japanese healthy men increased approximately proportionately. Mean t1/2 was 21–27 h after

Table 2. Summary of pharmacokinetic parameters after single and 5-day BID repeat intravenous doses of zanamivir in healthy Japanese men Dose

n

Cmax (ng/mL)

Tmax (h)

C12 (Cτ) (ng/mL)

AUC (ngh/mL)

t1/2 (h)

Vss (L)

CLtot (L/h)

12 12 12

8926 1323 27126 4275 52448 5675

0483 (0483–0483) 0508 (0483–0583) 0483 (0467–0567)

785 310 2583 1024 4491 1085

16768 1943 53462 5172 100400 5774

212 031 272 038 272 025

146 189 144 162 148 115

604 075 567 060 600 035

12

53412 5510

0483 (0483–0483)

4332 1252

96425 9589

395 033

155 122

612 064

Single doses 100 mg 300 mg 600 mg Repeat doses 600 mg

Parameters are given as mean SD, except for Tmax which is given as median (range). AUC are provided as AUC0–∞ for single dose and as AUC0–τ for repeat dose.



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Fig. 1. Mean serum zanamivir concentration-time profile following single and 5-days BID repeat intravenous doses (11 doses in total) of 600 mg in 12 healthy Japanese men. Dosings are denoted by X. Dosings in the repeat dose period were from the evening of Day 3 to the morning of Day 8. Each treatment was infused over 30 min. Serum concentration was measured over 24 h following initial dose (Day 1) and final dose (Day 8). Samples for measuring trough concentration were taken prior to 1st, 3rd, 5th, 7th and 9th dose of BID 9 5-day dosing. Zanamivir concentration is shown against semi-logarithmic scale. Lower limit of quantification (LLQ) for the determination was 999 ng/mL.

Fig. 2. Urine zanamivir excretion ratio (% of dose)-time plot after single intravenous doses of 100, 300 and 600 mg (Mean + SD, n = 12 for each dose). Each healthy Japanese men were infused two of the doses of zanamivir over 30 min with incomplete crossover design. Fractions of urinary excretion of zanamivir (fe, as % of dose) in fractionated pooled urine (0–4, 4–8, 8–12, 12–24 h) are shown by dose with bars. Cumulative urinary excretion of zanamivir (Cumulateve fe, as % of dose) is shown by dose with lines.

single doses and 40 h after the last 600 mg repeat doses. T1/2 estimated after repeat doses were, thus, slightly longer than that after single doses. However, systemic exposure (AUC) was quite similar after single and repeat doses. The difference in t1/2 between single dose and repeat doses might be insignificant and due to the small difference of concentrations at 24 h after dose, in terminal phase. The trough zanamivir concentration on Day 3 to Day 8 (pre-PM dose on Day 3–7 and pre-AM dose on Day 8) reached a steady state within 1 day after initiation of repeat BID dosing of 600 mg. Of note, the predose concentration on Day 8 was slightly higher than at other predose time points. As the Day 8 predose sample was taken in the morning 12 h after PM dose, there might be a possibility the renal clearance was decreased during sleep.18, 19 In previous pharmacokinetic studies of zanamivir solution for intravenous use with non-Japanese healthy subjects, zanamivir had linear pharmacokinetics after single intravenous doses and the volume of distribution was approximately 16 L, similar to the volume of extracellular fluid. It was cleared rapidly with a terminal elimination half-life of approximately 2–5 h with relatively small interindividual variability.5 These pharmacokinetic profiles reported in previous studies with non-Japanese subjects are consistent with our findings in Japanese subjects. Urinary concentrations of zanamivir after single intravenous administration in Japanese healthy men showed that over 94% of zanamivir administered was recovered within 24 h after single doses. Urinary parameters, fe and CLr, were comparable across 100–600 mg of single doses. By comparing the CLr and CLtot, it was confirmed that the elimination of zanamivir was primarily via the kidney. These urinary profiles are also consistent with the findings in non-Japanese subjects.5

The mean Cmax and AUC0–24 observed after single inhalation of 10 mg in healthy Japanese men were 298 ng/mL and 1668 ngh/ mL, respectively.17 The mean Cmax and AUC0–∞ observed after 600 mg single intravenous dose in the present study were 52448 ng/ mL and 100400 ngh/mL, which were 1700-fold and 600-fold higher, respectively, compared with the exposures after inhalation of 10 mg. Both after single inhalation and intravenous administration, mean t1/2 of zanamivir were similar, in the range of 21–27 h. The deposition and clearance of orally inhaled zanamivir 10 mg in the respiratory tract have been determined using radiolabelled zanamivir aerosol and gamma scintigraphy. The major deposition site was the oropharynx (mean 776%) and a mean of 132% of 10 mg dose was deposited in the bronchi and lungs.20 In another report, zanamivir concentrations in airway surface fluid using sputum samples 12 h after oral inhalation of 10 mg was 304 ng/mL.6 Following twice-daily intravenous administration of 600 mg zanamivir, penetration into the pulmonary compartment was good, and the concentration of zanamivir in the bronchoalveolar epithelial lining fluid at 12 h of dose was 419 ng/mL, which corresponded to 73% of serum concentration at the same time point and was 552–1653 times higher than in vitro 50% inhibitory concentrations (IC50) (076 for A/H1N1, 182 for A/H3N2, 228 nM for B neuraminidases; 1 nM is approximately 0332 ng/mL) for influenza A and B viruses.16 It is considered the concentration of zanamivir in the bronchoalveolar epithelial lining fluid after intravenous administration of 600 mg was comparable to that after inhalation of 10 mg, presumably resulting in sufficient pharmacological effect at the target site. In the study that demonstrated pulmonary penetration of zanamivir, two intravenous doses of 600 mg in non-Japanese healthy men resulted in the geometric mean (%CV) of AUC0–τ, Cmax



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and C12 of 86630 (116) ngh/mL, 39430 (117) ng/mL and 586 (382) ng/mL, respectively.16 In the present study, the mean of AUC0–τ, Cmax and C12 after repeat doses of 600 mg in healthy Japanese men corresponded to 111%, 135% and 74% of the values in non-Japanese subjects, respectively. Taking into consideration the body size difference (mean body weight was 831 kg in non-Japanese subjects, 656 kg in Japanese subjects), it was not considered a marked difference. It is thus likely that intravenous administration of 600 mg zanamivir in Japanese subjects also results in sufficient concentration in the respiratory tract epithelium.

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WHAT IS NEW AND CONCLUSION A 5-day regimen of twice-daily intravenous doses of 600 mg zanamivir was safely administered in Japanese healthy subjects. The pharmacokinetic profiles obtained in the study were consistent with those reported in previous studies of non-Japanese subjects. The known pulmonary distribution of zanamivir after intravenous administration suggests that sufficient concentration should be reached in the epithelial lining fluid in Japanese subjects with twice-daily intravenous administration of 600 mg zanamivir.

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