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 measlesmumps-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 measlesmumps-rubella vaccine.