API

Acyclovir (400mg)

Drug classification

Dosage form

Dispersible tablet

API strength per dosage

400 mg

Dose

Adults: 400 mg orally 3–5 times daily for 5–10 days (herpes simplex); 800 mg 5 times daily for 7–10 days (herpes zoster). Pediatrics: 20 mg/kg (max 800 mg) 4 times daily for 5 days. Renal impairment: Dose adjustment required based on creatinine clearance.

Mechanism of action

Acyclovir is phosphorylated by viral thymidine kinase to acyclovir monophosphate, then by host enzymes to acyclovir triphosphate, which competitively inhibits viral DNA polymerase (UL30), incorporates into viral DNA, and causes chain termination, thereby inhibiting herpesvirus DNA synthesis and replication.

Indications

Herpes Simplex Virus Infections Chickenpox Herpes labialis Shingles Genital herpes infection

Side effects

Headache Dizziness Vomiting Nausea Fatigue Fever Stomach pain Diarrhea Skin rash Photophobia

Pregnancy category

Precautions

Contraindications

Hypersensitivity to acyclovir or valacyclovir, dehydration, renal impairment, neurological disorders, elderly patients (dose adjustment needed), pregnancy and lactation (use only if clearly needed).