stavudine. Adverse events The most common adverse events at the beginning of treatment are nausea and headache. More serious adverse events are peripheral neuropathy, which can occur in up to 33% of patients with advanced disease, oral ulcers, oesophageal ulcers and, rarely, pancreatitis. Resistance Resistance to zalcitabine develops infrequently compared with other nRTIs, and generally only occurs at a low level. The most common mutation observed in vivo is T69D, which does not appear to give rise to cross-resistance to other nRTIs; mutations at positions 65, 74, 75, 184 and 215 in the pol gene are observed more rarely. Specialty drugs In 1992 dideoxycytidine was listed as a specialty drug. Sources Further reading Nucleoside analog reverse transcriptase inhibitors IARC Group 2B carcinogens Pyrimidones Specialty drugs Hoffmann-La Roche brands Hydroxymethyl compounds