Thrombocytopenia induced by noncytotoxic drugs in Denmark 1968–91

Objectives. To analyse the distribution of noncytotoxic drugs reported as cause of thrombocytopenia during a 24‐year period, and to draw attention to the most commonly involved drugs in modern clinical practice. Design/setting. Retrospective study of spontaneous case reports from the Danish reporting system on adverse drug reactions. Subjects. A total of 309 critically reviewed cases of drug‐induced thrombocytopenia reported during the period from 1968 to the end of 1991. Results. Sodiumaurothiomalate and the combination sulfamethoxazole with trimethoprim were the most commonly reported single drugs, and nonsteroid anti‐inflammatory drugs were the most frequently reported category of drugs. A pronounced shift in the spectrum of causal drugs was observed due to the introduction of new drugs and alterations in drug consumption. At present, valproic acid and measles–mumps–rubella vaccine are most numerously reported. The still‐growing list of thrombocytopenia‐inducing agents contained 110 different drugs. At present, 20% of reported cases concern drugs not previously registered as causing thrombocytopenia in Denmark. Twenty‐five per cent of all cases were caused by drugs which appeared only sporadically in the material. Conclusions. The spectrum of drugs reported as causing drug‐induced thrombocytopenia is broadening and changing progressively, reflecting changes in drug consumption. The most frequently reported drugs at present are valproic acid and measles–mumps–rubella vaccine.