General
Denavir should only be used on herpes labialis on the lips and face. Because no data are available, application to human mucous membranes is not recommended. Particular care should be taken to avoid application in or near the eyes since it may cause irritation. Lesions that do not improve or that worsen on therapy should be evaluated for secondary bacterial infection. The effect of Denavir has not been established in immunocompromised patients.
Carcinogenesis, Mutagenesis, Impairment of Fertility
In clinical trials, systemic drug exposure following the topical administration
of penciclovir cream was negligible, as the penciclovir content of all plasma
and urine samples was below the limit of assay detection (0.1 mcg/mL and 10
mcg/mL, respectively). However, for the purpose of inter-species dose comparisons
presented in the following sections, an assumption of 100% absorption of penciclovir
from the topically applied product has been used. Based on use of the maximal
recommended topical dose of penciclovir of 0.05 mg/kg/day and an assumption
of 100% absorption, the maximum theoretical plasma AUC0- 24 hrs for
penciclovir is approximately 0.129 mcg.hr/mL.
Carcinogenesis: Two-year carcinogenicity studies were conducted with
famciclovir (the oral prodrug of penciclovir) in rats and mice. An increase
in the incidence of mammary adenocarcinoma (a common tumor in female rats of
the strain used) was seen in female rats receiving 600 mg/kg/day (approximately
395x the maximum theoretical human exposure to penciclovir following application
of the topical product, based on area under the plasma concentration curve comparisons
[24 hr. AUC]). No increases in tumor incidence were seen among male rats treated
at doses up to 240 mg/kg/day (approximately 190x the maximum theoretical human
AUC for penciclovir), or in male and female mice at doses up to 600 mg/kg/day
(approximately 100x the maximum theoretical human AUC for penciclovir).
Mutagenesis: When tested in vitro, penciclovir did not cause
an increase in gene mutation in the Ames assay using multiple strains of S.
typhimurium or E. coli (at up to 20,000 mcg/plate), nor did it cause an increase
in unscheduled DNA repair in mammalian HeLa S3 cells (at up to 5,000 mcg/mL).
However, an increase in clastogenic responses was seen with penciclovir in the
L5178Y mouse lymphoma cell assay (at doses ≥ 1000 mcg/mL) and, in human lymphocytes
incubated in vitro at doses ≥ 250 mcg/mL. When tested in vivo,
penciclovir caused an increase in micronuclei in mouse bone marrow following
the intravenous administration of doses ≥ 500 mg/kg ( ≥ 810x the maximum
human dose, based on body surface area conversion).
Impairment of Fertility: Testicular toxicity was observed in multiple
animal species (rats and dogs) following repeated intravenous administration
of penciclovir (160 mg/kg/day and 100 mg/kg/day, respectively, approximately
1155 and 3255x the maximum theoretical human AUC). Testicular changes seen in
both species included atrophy of the seminiferous tubules and reductions in
epididymal sperm counts and/or an increased incidence of sperm with abnormal
morphology or reduced motility. Adverse testicular effects were related to an
increasing dose or duration of exposure to penciclovir. No adverse testicular
or reproductive effects (fertility and reproductive function) were observed
in rats after 10 to 13 weeks dosing at 80 mg/kg/day, or testicular effects in
dogs after 13 weeks dosing at 30 mg/kg/day (575 and 845x the maximum theoretical
human AUC, respectively). Intravenously administered penciclovir had no effect
on fertility or reproductive performance in female rats at doses of up to 80
mg/kg/day (260x the maximum human dose [BSA]).
There was no evidence of any clinically significant effects on sperm count, motility or morphology in 2 placebo-controlled clinical trials of Famvir® (famciclovir [the oral prodrug of penciclovir], 250 mg b.i.d.; n=66) in immunocompetent men with recurrent genital herpes, when dosing and follow-up were maintained for 18 and 8 weeks, respectively (approximately 2 and 1 spermatogenic cycles in the human).
Pregnancy
Teratogenic Effects-Pregnancy Category B. No adverse effects on the
course and outcome of pregnancy or on fetal development were noted in rats and
rabbits following the intravenous administration of penciclovir at doses of
80 and 60 mg/kg/day, respectively (estimated human equivalent doses of 13 and
18 mg/kg/day for the rat and rabbit, respectively, based on body surface area
conversion; the body surface area doses being 260 and 355x the maximum recommended
dose following topical application of the penciclovir cream). There are, however,
no adequate and well-controlled studies in pregnant women. Because animal reproduction
studies are not always predictive of human response, penciclovir should be used
during pregnancy only if clearly needed.
Nursing Mothers
There is no information on whether penciclovir is excreted in human milk after topical administration. However, following oral administration of famciclovir (the oral prodrug of penciclovir) to lactating rats, penciclovir was excreted in breast milk at concentrations higher than those seen in the plasma. Therefore, a decision should be made whether to discontinue the drug, taking into account the importance of the drug to the mother. There are no data on the safety of penciclovir in newborns.
Pediatric Use
An open-label, uncontrolled trial with penciclovir cream 1% was conducted in 102 patients, ages 12-17 years, with recurrent herpes labialis. The frequency of adverse events was generally similar to the frequency previously reported for adult patients. Safety and effectiveness in pediatric patients less than 12 years of age have not been established.
Geriatric Use
In 74 patients ≥ 65 years of age, the adverse events profile was comparable to that observed in younger patients.
Last updated on RxList: 12/9/2008
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