Zalcitabine

It was the first cytosine analog developed. However, due to severe toxicity, it was removed from the market.Zalcitabine has a high oral bioavailability. Dosage adjustment is needed in patients with renal insufficiency and nephrotoxic drugs (eg, amphotericin B, aminoglycosides) increase toxic potential. Dose-limiting peripheral neuropathy is the major adverse effect of ddC. Pancreatitis, esophageal ulceration, stomatitis, and arthralgias may also occur.