Famciclovir

INTRODUCTION

Indications

Acute herpes zoster infections (shingles). Treatment/suppression of recurrent herpes genitalis 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 lesion formation and improved healing in recurrent HSV infection.

Adverse Reactions/Side Effects

CNS: headache, dizziness, fatigue. GI: diarrhea, nausea, vomiting.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess skin and mucosal lesions to help document whether drug therapy is successful in controlling infection.

• Assess dizziness or fatigue that might affect gait, balance, or other functional activities (See Appendix C). Report balance problems and functional limitations to the physician and nursing staff, and caution the patient and family/caregivers to guard against falls and trauma.

Interventions

• Avoid contact with cutaneous or mucosal lesions when treating patients.

• Always wash hands thoroughly and disinfect equipment (whirlpools, electrotherapeutic devices, treatment tables, and so forth) to help prevent the spread of infection. Use universal precautions as indicated for specific patients.

Patient/Client-Related Instruction

• Advise patient to take or apply medication as directed. Famciclovir should not be used more frequently or longer than prescribed.

• Remind patient that famciclovir does not cure herpes infections. The virus lies dormant in the ganglia, and this drug will not prevent the spread of infection to others.

• Instruct patient and family/caregivers to report other troublesome side effects, including severe or prolonged headache or GI problems (diarrhea, nausea, vomiting).

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 (increased in renal impairment).

Contraindications/Precautions

Contraindicated in: Hypersensitivity.

Use Cautiously in: Patients with impaired renal function (increased dosage interval/decreased dose recommended if CCr <40–60 mL/min); Geri: Geriatric patients (because of age-related decrease in renal function); OB/Pedi: Pregnancy, lactation, or children <18 yr (safety not established).

Interactions

Drug-Drug: Probenecid ↑ plasma concentration of penciclovir.

Route/Dosage

Herpes Zoster

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

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