The detection of isoniazid in urine.
Gangadharam, P.R.J.; Mitchison, D.A.; Subbaiah, T.V.; Short, Eileen I.
Tubercle; 1958; 39; 191-200 .
Three tests for the presence of free isoniazid in urine have been compared in trials on volunteers and patients. Of these, the Short and Case Direct Naphthoquinonemercuric chloride N-M test was found to be the most sensitive. However, it failed to detect the excretion of isoniazid after a 100 mg. dose by mouth in about 10 per cent of individuals.
A simple alkaline hydrolysis procedure for conversion of isoniazid metabolites to free isoniazid has been developed and applied to the Direct N-M test. The resulting Combined N-M test detects isoniazid in 98 per cent of urine specimens collected from 0 to twelve hours after taking 100 mg. by mouth and in 80 per cent of specimens collected between twelve and twenty two hours.
Since PAS gives positive results in this test, it cannot be used to detect isoniazid when PAS and isoniazid are being given together to patients. However, when both these drugs are given in the same cachet, the ferric chloride test for PAS can be used to investigate drug taking.
Back to List of publications / Home |