Avirax - General Information

A guanosine analog that acts as an antimetabolite. Viruses are especially susceptible. Used especially against herpes.


Pharmacology of Avirax

Avirax (INN) or acyclovir (USAN, former BAN) is a synthetic deoxyguanosine analog and it is the prototype antiviral agent that is activated by viral thymidine kinase. The selective activity of aciclovir is due to its affinity for the thymidine kinase enzyme encoded by HSV and VZV.


Avirax for patients

Patients are instructed to consult with their physician if they experience severe or troublesome adverse reactions, they become pregnant or intend to become pregnant, they intend to breastfeed while taking orally administered ZOVIRAX, or they have any other questions.

Herpes Zoster: There are no data on treatment initiated more than 72 hours after onset of the zoster rash. Patients should be advised to initiate treatment as soon as possible after a diagnosis of herpes zoster.

Genital Herpes Infections: Patients should be informed that ZOVIRAX is not a cure for genital herpes. There are no data evaluating whether ZOVIRAX will prevent transmission of infection to others. Because genital herpes is a sexually transmitted disease, patients should avoid contact with lesions or intercourse when lesions and/or symptoms are present to avoid infecting partners. Genital herpes can also be transmitted in the absence of symptoms through asymptomatic viral shedding. If medical management of a genital herpes recurrence is indicated, patients should be advised to initiate therapy at the first sign or symptom of an episode.

Chickenpox: Chickenpox in otherwise healthy children is usually a self-limited disease of mild to moderate severity. Adolescents and adults tend to have more severe disease. Treatment was initiated within 24 hours of the typical chickenpox rash in the controlled studies, and there is no information regarding the effects of treatment begun later in the disease course.


Avirax 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.


Avirax Contraindications

ZOVIRAX is contraindicated for patients who develop hypersensitivity to acyclovir or valacyclovir.


Additional information about Avirax

Avirax Indication: For the treatment and management of herpes zoster (shingles), genital herpes, and chickenpox
Mechanism Of Action: Viral (HSV-1, HSV-2 and VZV) thymidine kinase converts aciclovir to the aciclovir 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. Avirax triphosphate competitively inhibits viral DNA polymerase and competes with the natural deoxyguanosine triphosphate, for incorporation into viral DNA. Once incorporated, aciclovir triphosphate inhibits DNA synthesis by acting as a chain terminator.
Drug Interactions: Aminophylline Acyclovir increases the effect and toxicity of theophylline
Dyphylline Acyclovir increases the effect and toxicity of theophylline
Theophylline Acyclovir increases the effect and toxicity of theophylline
Dyphylline Increases the effect and toxicity of theophylline
Oxtriphylline Increases the effect and toxicity of theophylline
Theophylline Increases the effect and toxicity of theophylline
Food Interactions: Take without regard to meals.
Increase liquid intake.
Generic Name: Aciclovir
Synonyms: Wellcome-248u; Acycloguanosine; Acyclovir Sodium; AC2; Aciclovier; Acyclovir; Aciclovir Sodium; 9-Hyroxyethoxymethylguanine
Drug Category: Nucleosides and Nucleotides; Antiviral Agents
Drug Type: Small Molecule; Approved

Other Brand Names containing Aciclovir: Alti-Acyclovir; Avirax; Vipral; Virorax; Zovir; Zovirax;
Absorption: Oral: bioavailability 10 to 20%
Toxicity (Overdose): Aciclovir may cause nephrotoxicity (crystallization of aciclovir within renal tubules, elevation of serum creatinine, transient), and neurotoxicity (coma, hallucinations, lethargy, seizures, tremors). Nephrotoxicity and neurotoxicity usually resolve after cessation of aciclovir therapy. However, there is no well-defined relationship between aciclovir concentrations in the blood and these adverse effects.
Protein Binding: 9%-33%
Biotransformation: Hepatic, the only major urinary metabolite that has been detected is 9-carboxymethoxymethylguanine.
Half Life: 2.5-3.3 hours
Dosage Forms of Avirax: Solution Intravenous
Ointment Topical
Powder, for solution Intravenous
Tablet Oral
Cream Topical
Suspension Oral
Chemical IUPAC Name: 2-amino-9-(2-hydroxyethoxymethyl)-3H-purin-6-one
Chemical Formula: C8H11N5O3
Aciclovir on Wikipedia:
Organisms Affected: Human Herpes Virus