Zalcitabine is a medication used to treat HIV/AIDS. Its brand name is Hivid. There are a few synonyms for zalcitabine, including ddC and dideoxycytidine. These names refer to the chemical compound of the drug. Dideoxy refers to a component that is used in the process of synthesizing the medication. Cytidine is a nucleoside that is found in DNA and RNA. DdC and dideoxycytidine have the same mechanism of action as zalcitabine and are sometimes used interchangeably. It is important to remember that these synonyms refer to the same medication, and should only be used as directed by a healthcare professional.