Nucleoside analogue

Nucleoside analogues are nucleosides which contain a nucleic acid analogue and a sugar. Nucleotide analogs are nucleotides which contain a nucleic acid analogue, a sugar, and a phosphate groups with one to three phosphates.

Nucleoside and nucleotide analogues can be used in therapeutic drugs, include a range of antiviral products used to prevent viral replication in infected cells. The most commonly used is acyclovir, although its inclusion in this category is uncertain, because it acts as a nucleoside but contains no actual sugar, as the sugar ringis replaced by an open-chain structure.