An Open-Label, Single-Dose, Human Mass Balance Study of Amenamevir in Healthy Male Adults

Real-world safety and efficacy of amenamevir in patients with herpes zoster in Japan: A postmarketing observational study (REWARD)

The helicase-primase inhibitor amenamevir (AMNV) was approved for herpes zoster in Japan in 2017. The authors conducted a 1-month postmarketing observational study to evaluate the real-world safety and efficacy (cutaneous improvement and pain resolution) of AMNV in patients with herpes zoster. Of the 3453 patients registered between March 2018 and December 2020, 3110 were included in the safety analyses. The mean age (±standard deviation) was 63.7 ± 17.5 years, with 57.9% of patients aged ≥65 years. Most patients had mild (53.3%) or moderate (41.0%) cutaneous lesions. Regarding pain, 43.9%, 25.6%, and 12.5% of patients had pain at the levels of 1-3, 4-6, and 7-10 on the numerical rating scale. In total, 30.0%, 27.2%, and 16.1% of patients were concomitantly treated with analgesics: acetaminophen, nonsteroidal anti-inflammatory drugs, and Ca2+ channel α 2δ ligands, respectively, and 10.6% were treated with topical antiherpetic drugs. Adverse drug reactions occurred in 0.77% of patients, including four serious adverse drug reactions in four patients (hyponatremia, thrombocytopenia, rash, and rhabdomyolysis). Regarding important potential risks, renal disorder, cardiovascular events, and decreased platelets were observed in one, one, and two patients, respectively. Concerning efficacy, the cutaneous improvement rate (significantly improved or improved) was 95.5%, with significantly higher improvement rates in patients treated with AMNV for 7 days and in patients with less severe cutaneous lesions or less pain. Factors affecting the time to pain resolution were the severity of cutaneous lesions and pain at the start of AMNV treatment and older age. This study demonstrated that the AMNV is safe and effective in patients with herpes zoster in a real-world clinical setting.

Pharmacokinetics and Dialyzability of a Single Oral Dose of Amenamevir, an Anti-Herpes Drug, in Hemodialysis Patients

Introduction

Amenamevir (ASP2151), a herpesvirus helicase-primase inhibitor, is currently used for the treatment of herpes zoster in Japan. Amenamevir is mainly metabolized in the liver, and urinary excretion of amenamevir is approximately 10% in healthy adults. The increase of systemic exposure in non-dialysis patients with severe renal impairment was much less than that associated with nucleoside antiviral agents. The aim of this study was to evaluate the pharmacokinetics and dialyzability of a single oral dose (400 mg) of amenamevir in hemodialysis patients.

Methods

This was a single-arm, open-label, multicenter clinical pharmacology study. Nine patients aged 20–80 years with end-stage kidney disease and undergoing maintenance hemodialysis three times weekly were enrolled. Pharmacokinetics and dialyzability were investigated by serial collection of blood samples until 48 h post-dose during the study.

Results

The maximum plasma concentration and time to reach maximum plasma concentration during 24 h post-dose were 1585 ng/mL and 6.2 h, respectively. The area under the plasma concentration–time curve (AUC) from time zero to 24 h was 23,890 ng h/mL. The median terminal elimination half-life within 24 h before, during, and after hemodialysis was 14.7, 15.2, and 12.4 h, respectively. The AUC in hemodialysis patients was approximately double that in healthy adults. This increase in AUC was much less than that reported in nucleoside antiviral agents. The hemodialysis clearance, elimination fraction percentage, and amount of amenamevir removed were 37.8 mL/min, 28.1%, and 132.0 μg, respectively. The amount of amenamevir removed by hemodialysis was minimal. None of the hemodialysis parameters were associated with serum albumin. This study revealed no clinically relevant safety concerns.

Conclusion

There were no clinically relevant safety concerns when 400 mg of amenamevir was administered as a single dose to hemodialysis patients without dose adjustment and/or modification of the dosing schedule.

Trial Registration

JapicCTI-184242.

Electronic Supplementary Material

The online version of this article (10.1007/s12325-020-01375-1) contains supplementary material, which is available to authorized users.