Zevin Cream Mechanism of Action

Pharmacology: Pharmacodynamics: ZEVIN (Aciclovir) is a synthetic acyclic nucleoside analogue with in vitro inhibitory activity against herpes simplex type 1 and 2 (HSV-1 and HSV-2), varicella-zoster, Epstein-Barr, and cytomegalovirus. In cell cultures, the inhibitory activity of aciclovir for herpes simplex virus is highly selective.
Mechanism of action: Aciclovir is converted to aciclovir monophosphate, a nucleotide, by herpes simplex virus (HSV)-coded thymidine kinase. Aciclovir monophosphate is converted to the diphosphate by cellular guanylate kinase and to the triphosphate by a number of cellular enzymes. Aciclovir triphosphate interferes with HSV DNA polymerase and inhibits viral DNA replication. The triphosphate can be incorporated into growing chains of DNA by viral DNA polymerase, resulting in termination of the DNA chain. Since aciclovir is preferentially taken up and selectively converted to the active triphosphate form by HSV-infected cells, it is much less toxic to normal uninfected cells.
Pharmacokinetics: Aciclovir is a synthetic nucleoside analogue antiviral drug. It is converted to aciclovir triphosphate, which is the pharmacological active form of the drug in infected cells. It has antiviral activity against herpes simplex virus type 1 and 2, varicella zoster, Epstein-Barr virus, and cytomegalovirus.
Aciclovir is poorly absorbed following oral administration, with peak plasma levels occurring in 1.7 hours. Aciclovir is metabolized in liver.
Plasma protein-binding is low. The half-life is 3.3 hours. Approximately 14% of total dose is excreted unchanged in urine.
Absorption of aciclovir is usually slight following topical application to intact skin. In disease skin (Herpes zoster), moderate plasma concentrations up to 0.28 μg/ml have been reported in patients with normal renal function.
Approximately 9% of the total daily dose may be excreted in the urine.