Overview
11 DESCRIPTION The active ingredient in famciclovir tablets is famciclovir, USP, an orally administered prodrug of the antiviral agent penciclovir. Chemically, famciclovir, USP is known as 2-[2-(2-amino-9 H -purin-9-yl) ethyl]-1,3-propanediol diacetate. Its molecular formula is C 14 H 19 N 5 O 4 ; its molecular weight is 321.3.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Famciclovir is an orally administered prodrug of the anti-alpha herpes viral agent penciclovir [see Microbiology ( 12.4 )]. 12.3 Pharmacokinetics Famciclovir is the diacetyl 6-deoxy analog of the active antiviral compound penciclovir. Following oral administration famciclovir undergoes rapid and extensive metabolism to penciclovir and little or no famciclovir is detected in plasma or urine. Penciclovir is predominantly eliminated unchanged by the kidney. Therefore, the dose of famciclovir needs to be adjusted in patients with different degrees of renal impairment [see Dosage and Administration ( 2.3 )].
Indications
- 1 INDICATIONS & USAGE Famciclovir tablet, a prodrug of penciclovir, is a deoxynucleoside analog DNA polymerase inhibitor indicated for: Immunocompetent Adult Patients ( 1.1 ) • Herpes labialis (cold sores) o Treatment of recurrent episodes • Genital herpes o Treatment of recurrent episodes o Suppressive therapy of recurrent episodes • Herpes zoster (shingles) Human Immunodeficiency Virus (HIV)-Infected Adult Patients ( 1.
Common Doses
- 1500 mg
- 1000 mg
- 250 mg
- 500 mg
Dosage
2 DOSAGE & ADMINISTRATION Famciclovir tablets may be taken with or without food. Immunocompetent Adult Patients ( 2.1 ) Herpes labialis (cold sores) 1500 mg as a single dose Genital herpes Treatment of recurrent episodes Suppressive therapy Herpes Zoster (shingles) 1000 mg twice daily for 1 day 250 mg twice daily 500 mg every 8 hours for 7 days HIV-Infected Adult Patients ( 2.2 ) Recurrent episodes of orolabial or genital herpes 500 mg twice daily for 7 days Patients with renal impairment: Adjust dose based on creatinine clearance. ( 2.3 ) 2.
Contraindications
- 4 CONTRAINDICATIONS Famciclovir tablets are contraindicated in patients with known hypersensitivity to the product, its components, or Denavir ® (penciclovir cream). Known hypersensitivity to the product, its components, or Denavir ® (penciclovir cream). ( 4 )
Side Effects
- 6 ADVERSE REACTIONS Acute renal failure is discussed in greater detail in other sections of the label [see Warnings and Precautions ( 5 )]. The most common adverse events reported in at least 1 indication by greater than 10% of adult patients treated with famciclovir are headache and nausea. The most common adverse events reported in at least 1 indication by greater than 10% of adult patients are headache and nausea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Hetero Labs Limited at 1-866-495-1995 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.
Interactions
- 7 DRUG INTERACTIONS Probenecid: May increase penciclovir levels. Monitor for evidence of penciclovir toxicity. (7.2) 7.1 Potential for Famciclovir to Affect Other Drugs The steady-state pharmacokinetics of digoxin were not altered by concomitant administration of multiple doses of famciclovir (500 mg three times daily). No clinically significant effect on the pharmacokinetics of zidovudine, its metabolite zidovudine glucuronide, or emtricitabine was observed following a single oral dose of 500 mg famciclovir coadministered with zidovudine or emtricitabine.