Aciclovir dosage, side effects

Aciclovir dosage, side effects:

Aciclovir (also spelled acyclovir) is an antiviral medication primarily used to treat infections caused by herpes simplex virus (HSV) and varicella-zoster virus (VZV). It is effective against:

Herpes simplex type 1 (HSV-1) – Causes oral herpes (cold sores)
Herpes simplex type 2 (HSV-2) – Causes genital herpes
Varicella-zoster virus (VZV) – Causes chickenpox and shingles

Mechanism of Action

Aciclovir works by inhibiting viral DNA replication. It is converted into its active form (acyclovir triphosphate) inside infected cells, where it competes with natural nucleotides, leading to chain termination and preventing viral DNA synthesis.

Dosage of Aciclovir

1. Oral Tablets/Capsules

Herpes Simplex (Cold Sores/Genital Herpes)
- Initial episode: 200 mg 5 times daily (every 4 hours) for 5–10 days
- Recurrent episodes: 200 mg 5 times daily for 5 days
- Suppressive therapy: 400 mg twice daily (long-term to prevent outbreaks)
Chickenpox (Varicella)
- Adults & Children (>40 kg): 800 mg 4 times daily for 5 days
- Children (<40 kg): 20 mg/kg (max 800 mg) 4 times daily for 5 days
Shingles (Herpes Zoster)
- Adults: 800 mg 5 times daily for 7–10 days

2. Intravenous (IV) Injection

Severe HSV/VZV infections (immunocompromised patients)
- Adults & Children (>12 yrs): 5–10 mg/kg every 8 hours
- Infants & Children (<12 yrs): 10–20 mg/kg every 8 hours

3. Topical Cream/Ointment (5%)

Applied to cold sores or genital herpes lesions 5–6 times daily for 5–10 days

4. Eye Ointment (3%)

Used for herpes simplex keratitis (applied inside the lower eyelid 5 times daily)

Brand Names of Aciclovir

Aciclovir is sold under various brand names worldwide, including:

International Brands:

Zovirax (original brand by GSK)
Acivir
Acyclo-V
Herpex
Ciclovir
Xovir

Country-Specific Brands:

USA/Canada: Zovirax, Sitavig (buccal tablet)
UK/EU: Zovirax, Virasorb
India: Acivir, Herpex, Zyclir
Australia: Zovirax, Lovir

Side Effects

Common: Nausea, headache, diarrhea, dizziness
Rare but serious: Kidney dysfunction, neurological effects (confusion, seizures), allergic reactions

Precautions

Hydration is key (to prevent kidney damage)
Avoid in severe kidney impairment (dose adjustment needed)
Not a cure for herpes, but reduces outbreaks and transmission risk