A positive Coombs’ test and hemolytic anemia

A positive Coombs’ test and hemolytic anemia may follow the administration of which antihypertensive drug?

  1. Methyldopa
  2. Clonidine
  3. Guanabenz
  4. Prazosin
  5. Captopril

Many drugs can cause an immunohemolytic anemia. Methyldopa may cause a positive Coombs’ test in as many as 20% of patients, along with hemolytic anemia. Other drugs with similar actions on red blood cells are penicillins, quinidine, procainamide, and sulfonamides. These form a stable or unstable hapten on the red cell surface, which induces an immune reaction [immunoglobulin G (IgG) antibodies] and leads to dissolution of the membrane.