How are drug induced thrombocytopenias?

The drug (quinine, quinidine…) acts as a hapten, coats platelets or cells, antibodies and complement bind and cells are lysed The most common cause of type II reactions are medications including methyldopa, penicillins, cephalosporins, and hydrochlorothiazide which become associated with red blood cells or platelets leading to anemia and thrombocytopenia