famciclovir (fam-sye-kloe-veer) Famvir

 Acute herpes zoster infections (shingles). Treatment/

suppression of recurrent herpes genitalis in immunocompetent

patients. Treatment of recurrent herpes labialis

(cold sores) in immunocompetent patients. Treatment

of recurrent mucocutaneous herpes simplex virus

(HSV) infection in HIV-infected patients.

Action

Inhibits viral DNA synthesis in herpes-infected cells

only. Therapeutic Effects: Decreased duration of

herpes zoster infection with decreased duration of viral

shedding. Decreased time to healing for cold sores. Decreased

lesion formation and improved healing in recurrent

HSV infection.

Pharmacokinetics

Absorption: Following absorption, famciclovir is

rapidly converted in the intestinal wall to penciclovir,

the active compound.

Distribution: Unknown.

Metabolism and Excretion: Penciclovir is mostly

excreted by the kidneys.

Half-life: Penciclovir—2.1–3 hr (qin renal impairment).

TIME/ACTION PROFILE (penciclovir blood

levels)

ROUTE ONSET PEAK DURATION

PO rapid 0.9 hr 8–12 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity.

Use Cautiously in: Patients with impaired renal

function (qdose interval/pdose recommended if CCr

40–60 mL/min); OB, Lactation: Limited information;

use only if maternal benefit clearly outweighs potential

risks to fetus or infant; Pedi: Safety not established in

children 18 yr; Geri: Consider age-relatedpin renal

function when prescribing.

Adverse Reactions/Side Effects

CNS: SEIZURES, headache, dizziness, fatigue. CV: palpitations.

Derm: hypersensitivity vasculitis. GI: diarrhea,

nausea, vomiting. Misc: ANAPHYLAXIS.

Interactions

Drug-Drug: Probenecidqplasma concentrations

of penciclovir.

Route/Dosage

Herpes Zoster

PO (Adults): 500 mg every 8 hr for 7 days.

Renal Impairment

PO (Adults): CCr 40–59 mL/min—500 mg every 12

hr; CCr 20–39 mL/min—500 mg every 24 hr; CCr

20 mL/min—250 mg every 24 hr; Hemodialysis—

250 mg after each dialysis.

Recurrent Genital Herpes Simplex Infections

PO (Adults): 1000 mg twice daily for one day.

Renal Impairment

PO (Adults): CCr 40–59 mL/min—500 mg twice

daily for 1 day; CCr 20–39 mL/min—500 mg as a

single dose; CCr 20 mL/min—250 mg as a single

dose; Hemodialysis—250 mg as a single dose after dialysis.

Suppression of Recurrent Herpes Simplex

Infections

PO (Adults): 250 mg every 12 hr for up to 1 yr.

Renal Impairment

PO (Adults): CCr 20–39 mL/min—125 mg every 12

hr for 5 days; CCr 20 mL/min—125 mg every 24 hr

for 5 days; Hemodialysis—125 mg after each dialysis.

Recurrent Herpes Labialis Infections

(cold sores)

PO (Adults): 1500 mg as a single dose.

Renal Impairment

PO (Adults): CCr 40–59 mL/min—750 mg as a single

dose; CCr 20–39 mL/min—500 mg as a single

dose; CCr 20 mL/min—250 mg as a single dose;

Hemodialysis—250 mg as a single dose after dialysis.

Herpes Simplex in HIV-Infected Patients

PO (Adults): 500 mg every 12 hr for 7 days.

Renal Impairment

PO (Adults): CCr 20–39 mL/min—500 mg every 24

hr for 7 days; CCr 20 mL/min—250 mg every 24 hr

for 7 days; Hemodialysis—250 mg after each dialysis.

Availability (generic available)

Tablets: 125 mg, 250 mg, 500 mg.