Druginduced haemolytic anaemia

Large number of drugs shown to cause haemolysis of RBCs. Mechanisms variable. May be immune or non-immune.

• Some drugs interfere with lipid component of RBC membrane.

• Oxidation and denaturation of Hb: seen with e.g. sulphonamides, espe-108 cially in G6PD deficient subjects, but may occur in normal subjects if drugs given in large doses e.g.

- Dapsone.

- Sulfasalazine.

• Hapten mechanism describes the interaction between certain drugs and the RBC membrane components generating antigens that stimulate antibody production. DAT +ve.

- Penicillins.

- Cephalosporins.

- Tetracyclines.

- Tolbutamide.

• Autoantibody mediated haemolysis is associated with warm antibody mediated AIHA. DAT +ve.

- Cephalosporins.

- Mefenamic acid.

- Methyldopa.

- Procainamide.

- Ibuprofen.

- Diclofenac.

• Innocent bystander mechanism occurs when drugs form immune complexes with antibody (IgM commonest) which then attach to RBC membrane. Complement fixation and RBC destruction occurs.

- Quinine.

- Quinidine.

- Rifampicin.

- Antihistamines.

- Chlorpromazine.

- Melphalan.

- Tetracycline.

- Probenecid.

- Cefotaxime.

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