Evaluation of Oral Acyclovir Therapy

Abstract

Acyclovir is a specific antiviral agent. The triphosphate form inhibits viral DNA replication by competing for incorporation into the replicating DNA chain or by inhibiting viral DNA polymerase. Cells not infected with herpesvirus are generally unaffected. Oral acyclovir inhibits most herpes simplex virus types 1 and 2, and varicella-zoster virus at concentrations used clinically. Oral acyclovir has an average plasma half-life of three hours and is eliminated primarily by renal mechanisms. Peak plasma concentrations occur 1.5 to 2.5 hours after administration and the oral bioavailability is 15 to 30 percent. Acyclovir distributes into most body tissues, including vesicular fluid and the central nervous system. Oral acyclovir is effective treatment of initial and recurrent genital herpes and can suppress frequently recurring genital herpes in both immunocompetent and immunocompromised patients. It is also effective for acute herpes zoster in the immunocompetent and possibly immunocompromised patient. No role is established in either Epstein-Barr virus or cytomegalovirus infections. Oral acyclovir appears to be effective and relatively safe, nontoxic therapy when administered in doses of 1-4 g/d. Oral acyclovir represents a major therapeutic advance in the treatment of herpesvirus infections.

Pharmacokinetics of Acyclovir after Intravenous Infusion of Acyclovir and after Oral Administration of Acyclovir and Its Prodrug Valacyclovir in Healthy Adult Horses

“…This may have some impact on the absorption of the drug. However, in humans, it does not seem that food influences the absorption of acyclovir (9).…”

Design and development of microemulsion drug delivery system of acyclovir for improvement of oral bioavailability

“…Peak plasma values have been shown to be 0.46 to 0.83 or 0.63 to 1.21 µg/L after a single oral dose of 200 or 400 mg, respectively, 2 and have been generally obtained 1.5 to 2.5 hours after oral administration. 2,3 Acyclovir absorption in the gastrointestinal tract is slow, variable, and incomplete. 3 The bioavailability of acyclovir after oral administration ranges from 10% to 30%.…”

“…2,3 Acyclovir absorption in the gastrointestinal tract is slow, variable, and incomplete. 3 The bioavailability of acyclovir after oral administration ranges from 10% to 30%. 3 Approximately 80% of an oral dose is never absorbed and is excreted through the feces.…”

“…3 The bioavailability of acyclovir after oral administration ranges from 10% to 30%. 3 Approximately 80% of an oral dose is never absorbed and is excreted through the feces. The main excretory organ for acyclovir is the kidney.…”

Virus Diagnostics and Antiviral Therapy in Acute Retinal Necrosis (ARN)

“…By deacetylation, famciclovir is metabolized in the liver to the active prodrug penciclovir which is secreted without modification by the kidneys (Chakrabarty et al, 2004). The oral bioavailability of famciclovir is 77% and, thus, approximately 1.5-fold higher than that of valaciclovir (Soul-Lawton et al, 1995) or 3.4-fold higher than that of aciclovir (15-30%; Fletcher & Bean, 1985). By oral administration of 500 mg every eight hours, intravitreal penciclovir concentrations of 1.2 μg/ml can be reached (Chong et al, 2009), which is appropriate for the therapy of nonresistant HSV-1, HSV-2, or VZV strains.…”