Original design: To provide zalcitabine (dideoxycytidine; ddC) for patients with AIDS or advanced AIDS-related complex (ARC) who have failed treatment with or are intolerant to zidovudine (AZT) and who are also intolerant to dideoxyinosine (ddI); to demonstrate that ddC monotherapy is safe and tolerable in the treatment of patients who previously experienced either treatment failure, hematologic intolerance or myositis with AZT treatment and pancreatitis or other toxicities (except peripheral neuropathy with ddI).