Famciclovir

Trade name(s)

Famvir

Generic available

Drug class

Anti-viral

Mechanism of action

DNA polymerase inhibition

Dosage form

125 mg, 250 mg, 500 mg tablet

Dermatologic indications

See table

Common side effects

Gastrointestinal: nausea, vomiting Neurologic: headache

Serious side effects

None

► Dermatitis artefacta

Drug interactions

Probenecid

234 Familial atypical mole-melanoma syndrome

Famciclovir. Dermatologic indications and dosage

Disease

Adult dosage

Child dosage

Herpes simplex virus infection, first epidose

250 mg PO 3 times daily for 7-10 days

Not established

Herpes simplex virus infection, prophylaxis

250 mg PO twice daily for up to 1 year

Not established

Herpes simplex virus infection, recurrent episode

125 mg PO twice daily for 5 days

Not established

Herpes zoster

500 mg PO 3 times daily for 7 days

Not established

Varicella

500 mg PO 3 times daily for 7 days

Not established

Definition

Inherited, intraepidermal, blistering disease, affecting the neck, axillae, and groin area

Pathogenesis

Autosomal dominant trait; overall defect in keratinocyte adhesion, apparently secondary to a primary defect in a calcium pump protein, ATP2C1; pump mutation in ATP2C1, a gene localized on chromosome 3

Clinical manifestation

Vesicles and erythematous plaques with overlying crusts, usually occurring in the genital area, the chest, neck, and axillary region; burning sensation and pruritus accompanying the eruption; malodorous drainage with secondary infection; factors known to exacerbate the disease: heat, friction, and infection

Differential diagnosis

Darier disease; impetigo; candidiasis; herpes simplex virus infection; pemphigus vul-garis; pemphigus foliaceus; atopic dermatitis; seborrheic dermatitis; extramammary Paget's disease

Therapy

Topical corticosteroids, mid potency; eryth-romycin, systemic; erythromycin, topical;

Contraindications/precautions

Hypersensitivity to drug class or component; elderly patients or those with renal failure may need lower dose

References

Brown TJ, Vander Straten M, Tyring S (2001) Antiviral agents. Dermatologic Clinics i9(i):23-34

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