Classifications: antiviral; Therapeutic: antiviral
Pregnancy Category: B
125 mg, 250 mg, 500 mg tablets
Prodrug of the antiviral agent penciclovir; may have an advantage over acyclovir because of its greater stability intracellularly
in infected cells. Prevents viral replication by inhibition of DNA synthesis in herpes virusinfected cells.
Effectiveness is indicated by decreasing pain and crusting of lesions followed by loss of vesicles, ulcers, and crusts. Interferes
with DNA synthesis of herpes simplex virus type 1 and 2 (HSV-1 and HSV-2) infections, varicella-zoster virus, and cytomegalovirus.
Management of acute herpes zoster, genital herpes, recurrent episodes of genital herpes in immunocompromised adults. Suppression
of recurrent episodes of genital herpes in immunocompetent adults.
Hypersensitivity to famciclovir, lactation.
Renal or hepatic impairment, carcinoma, older adults, pregnancy (category B). Safety in children <18 y is not established.
Route & Dosage
|Herpes Zoster, Treatment
Adult: PO 500 mg q8h for 7 d, start within 4872 h of onset of rash
Clcr 4059 mL/min: 500 mg q12h; 2039 mL/min: 500 mg q24h
Treatment of Recurrent Genital Herpes
Adult: PO 125 mg b.i.d. x 5 d
Suppression of Recurrent Genital Herpes
Adult: PO 250 mg b.i.d. for up to 1 y
- Reduce dosage in patients with reduced kidney function.
- Store at room temperature, 15°30° C (59°86° F).
Adverse Effects (≥1%)CNS: Headache,
somnolence, dizziness, paresthesias, fatigue
, fever, rigors. Hematologic:
Nausea, diarrhea, vomiting, constipation
, anorexia, abdominal pain. Body as a Whole:
may decrease elimination; famciclovir may increase digoxin
Readily absorbed from GI tract and rapidly converted to penciclovir
in intestinal and liver tissue. Onset:
Median times to full crusting of lesions, loss of vesicles, loss of ulcers, and loss of crusts were 6, 5, 7, and 19 d, respectively;
median time to loss of acute pain was 21 d. Peak:
1 h. Distribution:
Distributes into breast milk of animals. Metabolism:
Metabolized in liver and intestinal tissue to penciclovir
, which is the active antiviral
Approximately 60% recovered in urine as penciclovir
Penciclovir 23 h.
Assessment & Drug Effects
- Lab tests: Baseline CBC and routine blood chemistry studies prior to and after short courses of therapy; periodically during
- Monitor digoxin level and assess for S&S of digoxin toxicity when digoxin is used concurrently with famciclovir.
Patient & Family Education
- Learn potential adverse effects and report those that are bothersome to physician.
- Be aware that a full therapeutic response may take several weeks.
- Report S&S of hypersensitivity immediately to physician.