Aciclovir 💊
Related Subjects:
|Herpes Varicella-Zoster (Shingles) Infection
|Chickenpox Varicella Infection
|Varicella Cerebral Vasculopathy
|Herpes Viruses
|Herpes Zoster Ophthalmicus (HZO) Shingles
|MonkeyPox
|Mumps
|Measles
|Rubella (German Measles)
|Epstein-Barr Virus infection
|Cytomegalovirus (CMV) infections
|CMV retinitis infections
|Toxoplasmosis
💊 Aciclovir is a life-saving antiviral that treats HSV-1, HSV-2, and Varicella-Zoster.
❌ It is not active against CMV (→ use Ganciclovir instead).
⚠️ Only activated inside infected cells (via viral thymidine kinase), giving it high selectivity.
🌍 About
- Key agent for severe herpes infections, shingles, chickenpox, and HSV encephalitis.
- Prodrug relatives: Valaciclovir, Famciclovir (better oral bioavailability).
- Active form = Aciclovir triphosphate, which inhibits viral DNA polymerase.
⚙️ Mode of Action
- Viral thymidine kinase converts aciclovir → aciclovir monophosphate.
- Cellular kinases convert it further → triphosphate form.
- Active triphosphate blocks viral DNA polymerase → halts replication.
- Only occurs in infected cells → high therapeutic index.
📋 Indications
- HSV Encephalitis / Meningitis
- Genital herpes (mild → severe)
- Varicella-Zoster virus (shingles, severe chickenpox)
- Immunocompromised HSV / VZV infection
💊 Dose Range (Always check BNF)
| Indication |
Typical Dose |
| 🧠 Herpes Simplex Encephalitis |
10 mg/kg IV every 8 hrs for 14–21 days (1 hr infusion) |
| 🌸 Mild/Moderate Oral or Genital HSV |
200 mg PO 5×/day for 5 days
OR 400 mg PO TDS for 3–5 days
OR 800 mg PO TDS for 2 days |
| 🔥 Severe Genital HSV |
5–10 mg/kg IV every 8 hrs for 5 days (1 hr infusion) |
| 🦠 Varicella Zoster (Shingles/Severe Chickenpox) |
800 mg PO 5×/day for 7 days
OR 10 mg/kg IV every 8 hrs for 10–14 days if CNS involved |
⚠️ Cautions
- 💧 Ensure hydration to prevent AKI (due to crystalluria).
- ⚠️ Dose adjust in renal impairment.
- ❗ Use with caution in pregnancy & breastfeeding.
🚨 Side Effects
- AKI (crystal deposition in renal tubules)
- Neurotoxicity → encephalopathy, tremor, seizures (esp. high dose)
- Hepatotoxicity, bone marrow suppression (rare)
- Skin rashes, headache, GI upset
- Reversible CNS effects if dehydrated
🔄 Interactions
- Few significant ones, but Probenecid ↑ aciclovir levels.
📚 References
