Drug-specific characteristics of thrombocytopenia caused by non-cytotoxic drugs

OBJECTIVE: To analyse drug-specific clinical characteristics and to investigate the possible influence of epidemiological and other factors on thrombocytopenia induced by selected non-cytotoxic drugs.

METHODS: A retrospective analysis of drug-induced thrombocytopenia reported to the Danish Committee on Adverse Drug Reactions. One-hundred and ninety-two cases induced by the most frequently reported drugs were included and analysed from data extracted from report forms and discharge summaries.

RESULTS: Pronounced drug-specific differences in the clinical appearance of thrombocytopenia were registered. Severe thrombocytopenia with haemorrhagic manifestations was reported following exposure to gold salts, non-steroid anti-inflammatory drugs, sulfonamide antibiotics, cinchona alkaloids and vaccines. Valproic acid-induced thrombocytopenia was dose-dependent. The differences were primarily determined by the drug itself and also by its usage pattern. No specific patient-related factor responsible for the heterogeneity of the clinical appearance of the adverse reaction was identified. Factors related to the physician, such as monitoring recommendations or level of attention towards the adverse reaction, seemed to be of little significance.

CONCLUSION: The primary determinant of the clinical characteristics of thrombocytopenia induced by noncytotoxic drugs is the offending drug.