Some drugs may cause thrombocytopenia in a small number of patients that take them. Drugs that have been implicated in development of thrombocytopenia include heparin, quinidine, quinine, and sulfonamides, among others. Thrombocytopenia is most likely the result of an antibody forming against the drug. This antibody binds to a glycoprotein on the platelet and then the platelet is taken out of circulation by the reticuloendothelial (RE) system.
The platelet count will rise once the drug is discontinued.