Zalcitabine

Absorption

Bioavailability is over 80% following oral administration.

Toxicity

Acute overdose: Inadvertent pediatric overdoses have occurred with doses up to 1.5 mg/kg zalcitabine. Chronic overdose: in an initial dose-finding study in which zalcitabine was administered at doses 25 times (0.25 mg/kg every 8 hours) the currently recommended dose, one patient discontinued zalcitabine after 1? weeks of treatment subsequent to the development of a rash and fever.

Description

Zalcitabine is an orally active dideoxynucleoside andog for combination use with zidovudine in advanced HIV infection and also as monotherapy for AIDS patients who cannot tolerate or have not responded to zidovudine. It has a similar mechanism of action (inhibition of reverse transcriptase) to didanosine. Like didanosine, its side effect profile includes peripheral neuropathy. Unlike zidovudine, zalcitabine does not cause bone marrow suppression.

The Uses of Zalcitabine

A pyrimidine nucleoside analogue with antiviral activity

Background

A dideoxynucleoside compound in which the 3'-hydroxyl group on the sugar moiety has been replaced by a hydrogen. This modification prevents the formation of 5' to 3' phosphodiester linkages, which are needed for the elongation of DNA chains, thus resulting in the termination of viral DNA growth. The compound is a potent inhibitor of HIV replication at low concentrations, acting as a chain-terminator of viral DNA by binding to reverse transcriptase. Its principal toxic side effect is axonal degeneration resulting in peripheral neuropathy.

What are the applications of Application

2′,3′-Dideoxycytidine is an antiviral pyrimidine nucleoside analogue effective against HIV replication

Indications

For the treatment of Human immunovirus (HIV) infections in conjunction with other antivirals.

Pharmacokinetics

Zalcitabine is an analog of 2'-deoxycytidine that is pharmacologically related to but structurally different from other nucleotide reverse transcriptase inhibitors (NRTIs). Zalcitabine inhibits the activity of HIV-1 reverse transcriptase (RT) both by competing with the natural substrate dGTP and by its incorporation into viral DNA.

Metabolism

Zalcitabine is not reported to undergo significant hepatic metabolism; it is mainly phosphorylated intracellularly to zalcitabine triphosphate, the active substrate for HIV-reverse transcriptase. The concentration of zalcitabine triphosphate remains low for quantitative detection and measurement in the plasma following administration of therapeutic doses .