What is the recommended use and dosage of Famcyclovir (famciclovir) for treating herpes simplex virus?

Famciclovir for Herpes Simplex Virus Treatment

For herpes simplex virus infections, famciclovir is recommended as a 1,000 mg twice daily dose for 1 day for recurrent genital herpes, or as a single 1,500 mg dose for recurrent herpes labialis (cold sores), with therapy initiated at the first sign or symptom of an outbreak. 1

Dosing Recommendations by HSV Type

Recurrent Genital Herpes

• Episodic treatment:

  • 1,000 mg twice daily for 1 day 1
  • Therapy should be initiated at the first sign or symptom (tingling, itching, burning, pain, or lesion)
  • The efficacy when initiated more than 6 hours after onset of symptoms has not been established 1

• Suppressive therapy:

  • 250 mg twice daily 1
  • Safety and efficacy beyond 1 year have not been established 1

Recurrent Herpes Labialis (Cold Sores)

• 1,500 mg as a single dose 1
• Therapy should be initiated at the first sign or symptom 1

For HIV-Infected Patients

• 500 mg twice daily for 7 days for recurrent orolabial or genital herpes 1
• Initiate at first sign or symptom of recurrence 1

Efficacy Data

Famciclovir has demonstrated significant clinical benefits in controlled trials:

• For recurrent genital herpes, the 1,000 mg twice daily dosing reduces time to heal lesions, prevents progression of lesions beyond the papule stage, and improves time to resolution of all symptoms 2

• For herpes labialis, a single 1,500 mg dose shortens lesion healing time, time to normal skin, and results in faster resolution of pain and tenderness 2

Dosage Adjustments for Renal Impairment

Dosage reductions are required for patients with renal impairment 1:

Creatinine Clearance	Genital Herpes (Single Day)	Suppressive Therapy	Herpes Labialis
≥60 mL/min	1,000 mg twice daily	250 mg twice daily	1,500 mg single dose
40-59 mL/min	500 mg twice daily	250 mg twice daily	750 mg single dose
20-39 mL/min	500 mg single dose	125 mg twice daily	500 mg single dose
<20 mL/min	250 mg single dose	125 mg daily	250 mg single dose

Important Clinical Considerations

• Famciclovir is well tolerated with a safety profile comparable to placebo 3
• Most common adverse effects are headache, nausea, and diarrhea 3
• Acute renal failure has been reported in patients with underlying renal disease who received inappropriately high doses 1
• Treatment should be initiated as early as possible during an outbreak for maximum efficacy 4
• Famciclovir has not been established for first episodes of genital herpes 1

Patient Counseling

Patients should be advised to:

• Start treatment at the first sign of prodrome or lesions 4
• Abstain from sexual activity when lesions or prodromal symptoms are present 4
• Inform sex partners about their herpes infection 4
• Be aware that transmission can occur during asymptomatic periods 4
• Use condoms during all sexual exposures with new or uninfected partners 4

Famciclovir offers the advantage of less frequent dosing compared to traditional acyclovir regimens, potentially improving patient adherence while maintaining comparable efficacy 5.