Formulary
Famciclovir: Indications, Dosing, Side Effects and Interactions
Famciclovir clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 3 min read
Famciclovir: Indications, Dosing, Side Effects and Interactions
Famciclovir clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Herpes zoster infection, treatment**
- **Adult** (By Mouth): 500 mg 3 times a day for 7 days, alternatively 750 mg 1-2 times a day for 7 days.
**Herpes zoster infection, treatment in immunocompromised patients**
- **Adult** (By Mouth): 500 mg 3 times a day for 10 days, continue for 2 days after crusting of lesions.
**Genital herpes, suppression**
- **Adult** (By Mouth): 250 mg twice daily, therapy to be interrupted every 6-12 months to reassess recurrence frequency-consider restarting after two or more recurrences.
**Genital herpes, suppression in immunocompromised or HIV-positive patients**
- **Adult** (By Mouth): 500 mg twice daily, therapy to be interrupted every 6-12 months to reassess recurrence frequency-consider restarting after two or more recurrences.
**Genital herpes infection, treatment of first episode**
- **Adult** (By Mouth): 250 mg 3 times a day for 5 days or longer if new lesions appear during treatment or if healing incomplete.
**Genital herpes infection, treatment of first episode in immunocompromised or HIV-positive patients**
- **Adult** (By Mouth): 500 mg twice daily for 10 days.
**Genital herpes infection, treatment of recurrent infection**
- **Adult** (By Mouth): 125 mg twice daily for 5 days, alternatively 1 g twice daily for 1 day.
**Genital herpes infection, treatment of recurrent infections in immunocompromised or HIV-positive patients**
- **Adult** (By Mouth): 500 mg twice daily for 5-10 days.
**Herpes simplex infection (non-genital), treatment in immunocompromised patients**
- **Adult** (By Mouth): 500 mg twice daily for 7 days.
Side effects
Common or very common Abdominal pain; diarrhoea; dizziness; headache; nausea; skin reactions; vomiting Uncommon Angioedema; confusion; drowsiness Rare or very rare Hallucination; jaundice cholestatic; palpitations; thrombocytopenia
Interactions
**Severe interactions:**
- Effects of other medicinal products on famciclovir No clinically significant interactions have been identified.
- If patients experience severe dizziness, somnolence, confusion or other central nervous system disturbances, a dose reduction of famciclovir to 250 mg three times daily may be considered.
**Other interactions (5):**
- Concurrent use of probenecid may result in increased plasma concentrations of penciclovir, the active metabolite of famciclovir, by competing for elimination.
- Therefore, patients receiving famciclovir at a dose of 500 mg three times daily co-administered with probenecid, should be monitored for toxicity.
- Famciclovir needs aldehyde oxidase to be converted into penciclovir, its active metabolite.
- Co-administration of raloxifene could affect the formation of penciclovir and thus the efficacy of famciclovir.
- When raloxifen is coadministered with famciclovir the clinical efficacy of the antiviral therapy should be monitored.
Pregnancy
Manufacturers advise avoid unless potential benefit outweighs risk.
Breast feeding
No information available-present in milk in animal studies.
Hepatic impairment
Manufacturer advises efficacy may be decreased in severe impairment (risk of impaired conversion to active metabolite, no information available).
Renal impairment
Dose adjustments Reduce dose (consult product literature). M
Medicinal forms
Tablet
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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