DDI

ddI is the abbreviation for didanosine, also known as 2',3'-dideoxyinosine, a nucleoside analog used as an antiretroviral drug. It belongs to the class of medications called nucleoside reverse transcriptase inhibitors (NRTIs) and was once a common component of antiretroviral therapy for HIV infection. The compound is a purine nucleoside analog that requires intracellular phosphorylation to the active triphosphate form to inhibit viral replication.

Mechanism and pharmacology: Didanosine triphosphate competes with natural nucleotides for incorporation into viral DNA by reverse transcriptase and causes chain termination due to the absence of a 3' hydroxyl group. This halts DNA synthesis and slows or stops HIV replication. The drug can also affect mitochondrial DNA at higher exposures, contributing to certain toxicities.

Clinical use and status: Didanosine saw extensive use in the 1990s and early 2000s as part of combination antiretroviral regimens. Over time, its use has diminished due to safety concerns and the availability of newer NRTIs with more favorable side-effect profiles. It remains relevant historically and in some resource-limited settings or specific regimens, but is generally less common in contemporary therapy.

Safety and adverse effects: Known toxicities include pancreatitis, peripheral neuropathy, nausea, diarrhea, and potential hepatic steatosis or lactic acidosis with prolonged use. Because of these risks, patients on didanosine require careful monitoring. The drug can interact with alcohol and with certain other antiretrovirals, increasing the risk of serious adverse effects; coadministration with zidovudine, in particular, can elevate toxicity.

See also: HIV treatment, NRTIs, didanosine brand Videx.