Active ingredient: Famciclovir - Basic Profile / Key Facts

Basic Profile / Key Facts

Drug Category

• Prodrugs
• Antivirals
• Nucleosides and Nucleotides

Dosage Forms

• Tablet

Indications

For the treatment of acute herpes zoster (shingles). Also for the treatment or suppression of recurrent genital herpes in immunocompetent patients and treatment of recurrent mucocutaneous herpes simplex infections in HIV infected patients.

Pharmacology

Famciclovir is a prodrug that undergoes rapid biotransformation to the active antiviral compound penciclovir. Penciclovir is an anti-viral drug which has inhibitory activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) and varicella zoster virus (VZV). Therefore, herpes viral DNA synthesis and replication are selectively inhibited.

Mechanism of Action

Famciclovir undergoes rapid biotransformation to the active antiviral compound penciclovir, which has inhibitory activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) and varicella zoster virus (VZV). In cells infected with HSV-1, HSV-2 or VZV, viral thymidine kinase phosphorylates penciclovir to a monophosphate form that, in turn, is converted to penciclovir triphosphate by cellular kinases. In vitro studies demonstrate that penciclovir triphosphate inhibits HSV-2 DNA polymerase competitively with deoxyguanosine triphosphate. Consequently, herpes viral DNA synthesis and, therefore, replication are selectively inhibited.

Absorption

77 %

Toxicity

Symptoms of overdose include constipation, diarrhea, dizziness, fatigue, fever, headache, nausea, and vomiting.

Biotrnasformation / Drug Metabolism

Hepatic

Contraindications

Famvir (famciclovir) is contraindicated in patients with known hypersensitivity to the product, its components, and Denavir^® (penciclovir cream).

Drug Interactions

Concurrent use with probenecid or other drugs significantly eliminated by active renal tubular secretion may result in increased plasma concentrations of penciclovir.

The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Interactions with other drugs metabolized by this enzyme could potentially occur.