Chromosome aberrations induced by clinical medicines.

Inducibility of chromosome aberrations of cultured mammalian cells was examined on 11 clinical medicines which are used for a long term mainly in the field of internal medicine. P-aminosalicilic acid, isonicotinic acidhydrazid, streptomycin A, hydralazine hydrochloride methimazole and theophylline induced definite increase of chromosome aberrations. Among them P-aminosalicilic acid was a little weak in its effect. The effects of rifamycin SV, aminophylline and isosorbide dinitrate were judged as suspicious, because only a slight increase of the aberrations were caused. Reserpine and propylthiouracil induced little chromosome aberrations. Effective concentrations of these medicines in our chromosome test were compared with their maximum blood concentrations in clinical use in human quoted from the published papers. Their ratios by isonicotinic acid hydrazid, streptomycin A, methimazole, theophylline and issorbide dinitrate were very high and those by others were relatively low. Because p-aminosalicilic acid, rifamycin SV, hydralazine hydrochloride and aminophylline were positive or suspicious in our chromosome test, further pursue for the safety evaluation seems necessary.