Psychopharmacology 53

Select the adverse drug reaction that is paired correctly according to the Gell and Coombs classification system


Adverse drug reactions


An adverse drug reaction (ADR) describes harm associated with the use of a medication at a normal dose.

Adverse drug reactions are classified in the following way:-

Type A (pharmacological) can be predicted from the pharmacology of the drug involved. They are dose dependent and so are reversible on withdrawal of the drug.

Type B reactions (idiosyncratic) cannot be predicted from the known pharmacology of the drug. Type B reactions include allergic reactions.

Type A account for up to 80% of all ARDs.

Allergic reactions are subdivided by Gell and Coombs into:-

  • Type I (IgE-mediated) reactions
  • Type II (cytotoxic) reactions
  • Type III (immune complex) reactions
  • Type IV (cell mediated) reactions