• Examples:

  • Systemic lupus erythematosus: induced by hydralazine or procainamide treatment

  • "Lupoid hepatitits": cathartic sensitivity

  • Autoimmune hemolytic anemia: methyldopa

  • Thrombocytopenic purpura: quinidine

  • Agranulocytosis: number of different drugs

• Demonstrated antibodies to the drug or tissue constituents.

• Idiopathic thrombocytopenic purpura: immune mechanisms

  • Granulocytes or blood platelets: damaged or activated by antigen-antibody complexes (may be destroyed by reticuloendothelial system)

• Drug-induced autoimmune reactions: usually result within several months, following drug withdrawal

• Immunosuppressive treatment required only if autoimmune response is unacceptably severe.

 Serum sickness and Vasculitic (Type III) Reactions

• More common then immediate anaphylactic reactions

• Clinical Characteristics:

  • Urticarial skin eruptions

  • Arthritis

  • Arthralgia

  • Lymphadenopathy

  • Fever

  • Duration: six-12 days

  • Subsides after drug is discontinued

• Typically due to complement-fixing antibodies:IgM or IgG class

• Reduction of drug-induced serum sickness symptoms: corticosteroids

• Immune Vasculitis: may be drug-induced (hypersensitivity angiitis)

  • Examples:

    • sulfonamides

    • penicillin

    • thiouracil

    • anticonvulsants

    • iodides

  •  Mild skin disorder: erythema multiforme

    •  More severe reaction: Stevens-Johnson syndrome including:

      • Erythema multiforme

      • Arthritis

      • Myocarditis

      • Nephritis

      • CNS abnormalities

      • Associated with  sulfonamide administration