Skip to main content

Acute renal failure is discussed in greater detail in other sections of the label [see WARNINGS AND PRECAUTIONS].

The most common adverse events reported in at least 1 indication by > 10% of adult patients treated with FAMVIR are headache and nausea.

Clinical Trials Experience in Adult Patients

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Immunocompetent patients

The safety of FAMVIR has been evaluated in active-and placebo-controlled clinical studies involving 816 FAMVIR-treated patients with herpes zoster (FAMVIR, 250 mg three times daily to 750 mg three times daily); 163 FAMVIR-treated patients with recurrent genital herpes (FAMVIR, 1000 mg twice daily); 1,197 patients with recurrent genital herpes treated with FAMVIR as suppressive therapy (125 mg once daily to 250 mg three times daily) of which 570 patients received FAMVIR (open-labeled and/or double-blind) for at least 10 months; and 447 FAMVIR-treated patients with herpes labialis (FAMVIR, 1500 mg once daily or 750 mg twice daily). Table 2 lists selected adverse events.

Table 2 : Selected Adverse Events (all grades and without regard to causality) Reported by ≥ 2% of Patients in Placebo-Controlled Famvir Trials*

Events Incidence
Herpes Zoster† Recurrent Genital Herpes‡ Genital Herpes-Suppression§ Herpes Labialis‡
Famvir
(n=273)
%
Placebo
(n=146)
%
Famvir
(n=163)
%
Placebo
(n=166)
%
Famvir
(n=458)
%
Placebo
(n=63)
%
Famvir
(n=447)
%
Placebo
(n=254)
%
Nervous System
Headache 22.7 17.8 13.5 5.4 39.3 42.9 8.5 6.7
Paresthesia 2.6 0.0 0.0 0.0 0.9 0.0 0.0 0.0
Migraine 0.7 0.7 0.6 0.6 3.1 0.0 0.2 0.0
Gastrointestinal
Nausea 12.5 11.6 2.5 3.6 7.2 9.5 2.2 3.9
Diarrhea 7.7 4.8 4.9 1.2 9.0 9.5 1.6 0.8
Vomiting 4.8 3.4 1.2 0.6 3.1 1.6 0.7 0.0
Flatulence 1.5 0.7 0.6 0.0 4.8 1.6 0.2 0.0
Abdominal Pain 1.1 3.4 0.0 1.2 7.9 7.9 0.2 0.4
Body as a Whole
Fatigue 4.4 3.4 0.6 0.0 4.8 3.2 1.6 0.4
Skin and Appendages
Pruritus 3.7 2.7 0.0 0.6 2.2 0.0 0.0 0.0
Rash 0.4 0.7 0.0 0.0 3.3 1.6 0.0 0.0
Reproductive (Female)
Dysmenorrhea 0.0 0.1 1.8 0.6 1.6 6.3 0.4 0.0
* Patients may have entered into more than one clinical trial.
†7 days of treatment
‡1 day of treatment
§daily treatment

Table 3 lists selected laboratory abnormalities in genital herpes suppression trials.

Table 3 : Selected Laboratory Abnormalities in Genital Herpes Suppression Studies*

Parameter Famvir
(n = 660) †
%
Placebo
(n = 210) †
%
Anemia ( < 0.8 x NRL) 0.1 0.0
Leukopenia ( < 0.15 x NRL) 1.3 0.9
Neutropenia ( < 0.8 x NRL) 3.2 1.5
AST (SGOT) ( > 2 x NRH) 2.3 1.2
ALT (SGPT) ( > 2 x NRH) 3.2 1.5
Total Bilirubin ( > 1.5 x NRH) 1.9 1.2
Serum Creatinine ( > 1.5 x NRH) 0.2 0.3
Amylase ( > 1.5 x NRH) 1.5 1.9
Lipase ( > 1.5 x NRH) 4.9 4.1
* Percentage of patients with laboratory abnormalities that were increased or decreased from baseline and were outside of specified ranges.
†n values represent the minimum number of patients assessed for each laboratory parameter.
NRH = Normal Range High.
NRL = Normal Range Low.

HIV-infected patients

In HIV-infected patients, the most frequently reported adverse events for FAMVIR (500 mg twice daily; n=150) and acyclovir (400 mg, 5x/day; n=143), respectively, were headache (17% vs. 15%), nausea (11% vs. 13%), diarrhea (7% vs. 11%), vomiting (5% vs. 4%), fatigue (4% vs. 2%), and abdominal pain (3% vs. 6%).

Postmarketing Experience

The adverse events listed below have been reported during postapproval use of FAMVIR. Because these events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure:

Blood and lymphatic system disorders: Thrombocytopenia

Hepatobiliary disorders: Abnormal liver function tests, cholestatic jaundice

Nervous system disorders: Dizziness, somnolence

Psychiatric disorders: Confusion (including delirium, disorientation, and confusional state occurring predominantly in the elderly), hallucinations

Skin and subcutaneous tissue disorders: Urticaria, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema (e.g., face, eyelid, periorbital, and pharyngeal edema), leukocytoclastic vasculitis

Cardiac disorders: Palpitations