Brands, Medical Use, Clinical Data
Drug Category
- Antivirals
- Nucleosides and Nucleotides
Dosage Forms
- Intravenous infusion
- Capsule
- Tablet
- Suspension
- Topical cream
- Topical ointment
Brands / Synonyms
AC2; Aciclovier; Aciclovir; Acycloguanosine; Acyclovir; Acyclovir Sodium; Alti-Acyclovir; Avirax; Valtrex; Vipral; Virorax; Wellcome-248u; Xerese; Zovirax; Zovirax Injection; Zovirax Wellstat Pac; Zovirax Zostab Pac
Indications
For the treatment and management of herpes zoster (shingles), genital herpes, and chickenpox
Pharmacology
Acyclovir is a synthetic deoxyguanosine analog and it is the prototype antiviral agent that is activated by viral thymidine kinase. The selective activity of acyclovir is due to its affinity for the thymidine kinase enzyme encoded by HSV and VZV.
Mechanism of Action
Viral (HSV-1, HSV-2 and VZV) thymidine kinase converts acyclovir to the acyclovir monophosphate, which is then converted to the diphosphate by cellular guanylate kinase, and finally to the triphosphate by phosphoglycerate kinase, phosphoenolpyruvate carboxykinase, and pyruvate kinase. Acyclovir triphosphate competitively inhibits viral DNA polymerase and competes with the natural deoxyguanosine triphosphate, for incorporation into viral DNA. Once incorporated, acyclovir triphosphate inhibits DNA synthesis by acting as a chain terminator.
Absorption
Oral: bioavailability 10 to 20%
Toxicity
Acyclovir may cause nephrotoxicity (crystallization of acyclovir within renal tubules, elevation of serum creatinine, transient), and neurotoxicity (coma, hallucinations, lethargy, seizures, tremors). Nephrotoxicity and neurotoxicity usually resolve after cessation of acyclovir therapy. However, there is no well-defined relationship between acyclovir concentrations in the blood and these adverse effects.
Biotrnasformation / Drug Metabolism
Hepatic, the only major urinary metabolite that has been detected is 9-carboxymethoxymethylguanine.
Contraindications
ZOVIRAX is contraindicated for patients who develop hypersensitivity to acyclovir or
valacyclovir.
Drug Interactions
Co-administration of probenecid with acyclovir has been shown to increase the mean half-life and the
area under the concentration-time curve. Urinary excretion and renal clearance were correspondingly reduced.
The clinical effects of this combination have not been studied.
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