- It is recommended that patients requiring amphotericin, pyrimethamine, sulfadiazine, intravenous trimethoprim / sulfamethoxazole, ganciclovir, intravenous pentamidine, intravenous acyclovir or acyclovir = or > 1000 mg/day orally or other bone marrow or renal toxic drugs have an interruption of ddC until they are stable for two weeks on a maintenance dose of the above medications and only then can ddC be restarted.