Famciclovir INN

Famciclovir INN is used for: Genital herpes, Herpes zoster, Herpes labialis, CMV infections, Mucocutaneous herpes

Acute Herpes Zoster (Shingles) Treatment in immunocompetent adults 500 mg PO q8hr for 7 days; initiated within 72 hours of symptom or lesion onset Herpes Labialis Treatment of initial and recurrent episodes or suppressive therapy in immunocompetent adults Initial episode: 250 mg PO q8hr for 7-10 days Suppressive therapy: 250 mg PO q12hr for 12 months Recurrent episodes: 1500 mg PO once; initiate therapy at first sign (within 1 hour) of symptoms such as tingling, itching or burning Genital Herpes Treatment of initial and recurrent episodes or suppressive therapy in immunocompetent adults Initial episode: 250 mg PO q8hr for 7-10 days Suppressive therapy: 250 mg PO q12hr for up to 12 months Recurrent episodes: 1000 mg PO q12hr for 1 day; initiated within 6 hours of symptom or lesion onset Herpes (HIV-Infected Adults) Prevention of herpes simplex virus (HSV) reactivation and treatment of recurrent episodes Prevention of HSV reactivation: 500 mg PO q12hr Recurrent episodes: 500 mg PO q12hr for 5-10 days; initiated within 48 hours of symptom or lesion onset

Acute herpes zoster CrCl >60 mL/min: Regular dosage CrCl 40-59 mL/min: 500 mg q12hr CrCl 20-39 mL/min: 500 mg once daily CrCl <20 mL/min: 250 mg once daily Hemodialysis: 250 mg after each session Herpes labialis CrCl >60 mL/min: Regular dosage CrCl 40-59 mL/min: 750 mg once CrCl 20-39 mL/min: 500 mg once CrCl <20 mL/min: 250 mg once Hemodialysis: 250 mg once after dialysis Genital herpes (treatment of recurrent disease) CrCl >60 mL/min: Regular dosage CrCl 40-59 mL/min: 500 mg q12hr for 1 day (2 doses total) CrCl 20-39 mL/min: 500 mg once CrCl <20 mL/min: 250 mg once Hemodialysis: 250 mg once after dialysis Genital herpes (suppressive therapy) CrCl >40 mL/min: Regular dosage CrCl 20-39 mL/min: 125 mg q12hr CrCl <20 mL/min: 125 mg/day Hemodialysis: 125 mg after each session Herpes (HIV-infected adults) CrCl >40 mL/min: Regular dosage CrCl 20-39 mL/min: 500 mg/day CrCl <20 mL/min: 250 mg/day Hemodialysis: 250 mg after each session

May be taken with or without food.

Hypersensitivity. Lactation.

Renal impairment. Pregnancy. Lactation: Unknown whether drug is excreted in breast milk; caution advised

Pregnancy Available data from pharmacovigilance reports in pregnant women have not identified a drug- associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes; there are risks to fetus associated with untreated herpes simplex virus during pregnancy; after oral administration, famciclovir (prodrug) is converted to penciclovir (active drug); in animal reproduction studies with famciclovir, no evidence of adverse developmental outcomes observed at systemic exposures of penciclovir (AUC) slightly higher than those at maximum recommended human dose (MRHD) The risk of neonatal herpes infection varies from 30% to 50% for genital herpes simplex virus (HSV) infections that occur in late pregnancy (third trimester), whereas in early pregnancy, infection carries a risk of about 1%; primary herpes outbreak during first trimester of pregnancy associated with neonatal chorioretinitis, microcephaly and, in rare cases, skin lesions; in very rare cases, transplacental transmission can occur resulting in congenital infection, including microcephaly, hepatosplenomegaly, intrauterine growth restriction and stillbirth; co-infection with HSV increases the risk of perinatal HIV transmission in women who had a clinical diagnosis of genital herpes during pregnancy Effects on reproductive potential Decreased fertility, due to testicular toxicity, observed in male animals following repeated administration of famciclovir or penciclovir; no evidence of significant effects on sperm count, motility or morphology during treatment or during an 8-week follow-up Animal data No adverse effects on embryo-fetal (rats and rabbits) or pre/post-natal (rats) development observed up to highest dose administered orally to pregnant rats and rabbits (up to 1000 mg/kg/day) on gestation day(s) 6 to 15, and to rats on gestation day 15 to lactation/post-partum day 25; during organogenesis, systemic exposures of penciclovir (active metabolite) were 3.4 times (rats) and 1.6 times (rabbits) the human systemic exposure of penciclovir based on AUC at the MRHD Lactation There are no data on presence of famciclovir (prodrug) or penciclovir (active drug) in human milk, effects on breastfed infant, or on milk production; animal data indicate that penciclovir is present in the milk of lactating rats; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed infant from therapy or from underlying maternal condition

Reduced renal excretion resulting to increased plasma concentration w/ probenecid. Raloxifen may reduce the formation of penciclovir, the active metabolite of famciclovir.

Side effects of Famciclovir INN : >10% Headache (23%), Nausea (13%) 1-10% Diarrhea (2-9%), Abdominal pain (8%), Dysmenorrhea (<8%), Vomiting (1-5%), Flatulence (5%), Pruritus (4%), Rash (3%), Paresthesia (3%), Neutropenia (3%), Increased transaminases (2-3%), Increased bilirubin (2%), Fatigue (1%) <1% Arthralgia, Confusion, Dizziness, Erythema multiforme, Hallucinations, Jaundice, Rigors, Thrombocytopenia, Upper respiratory tract infection

Famciclovir rapidly undergoes biotransformation to penciclovir, which has inhibitory activity against HSV types 1 (HSV-1) and 2 (HSV-2) varicella-zoster virus (VZV). Thymidine kinase then phosphorylates penciclovir to a monophosphate form, which is then converted to penciclovir triphosphate. This inhibits HSV-2 DNA polymerase by competing with deoxyguanosine triphosphate, thus inhibiting herpes viral DNA synthesis and replication.