Aciclovir
Synthetic analogue of guanosine, which is phosphorylated to become an active compound, aciclovir triphosphate. Aciclovir triphosphate competes....
Pharmacologic profile and clinical uses
Description/Definition
Aciclovir is an antiviral medication primarily used in the treatment of infections caused by certain types of viruses. It is particularly effective against herpes simplex virus (HSV) types 1 and 2, and varicella-zoster virus (VZV), the virus responsible for chickenpox and shingles.
Mechanism of action
Aciclovir works by inhibiting viral DNA synthesis. It is a guanine analogue that becomes activated by viral thymidine kinase, converting it into aciclovir triphosphate, which then incorporates into viral DNA and results in chain termination during replication.
Indications
- Herpes Simplex Virus Infections: Including genital herpes and cold sores.
- Varicella-Zoster Virus Infections: Such as chickenpox and shingles.
- Prophylaxis: In immunocompromised patients to prevent HSV infections.
Key aspects of drug therapy management
Dosage and administration
- Oral: Commonly prescribed as 200 mg five times daily for HSV infections. For VZV, the dose can be increased to 800 mg five times daily.
- Topical: Used for cold sores, applied as a cream every 3 hours, six times a day.
- Intravenous: For severe infections or in immunocompromised patients, usually administered with careful monitoring for renal function.
Side effects
- Common: Nausea, diarrhea, headache, and vertigo.
- Serious: Acute renal failure, particularly with intravenous administration, due to crystallization in renal tubules.
- Others: Neurological effects such as confusion and tremors, especially in high doses or renal impairment.
Drug interactions
- Probenecid: Can increase aciclovir levels by decreasing renal clearance.
- Zidovudine: May enhance the risk of neurotoxicity.
Monitoring
- Renal Function: Dosage adjustment is necessary in patients with renal impairment.
- Hydration: Adequate hydration is advised to prevent renal complications.
- Resistance: Long-term use may lead to resistance, though rare.
- Prognosis Aciclovir is generally effective and well-tolerated, reducing the duration and severity of viral infections when administered promptly.
