SPECIFICITY OF THE ISONIAZID DROP TEST FOR CONTROL OF DOMICILIARY TREATMENT OF TUBERCULOSIS.
A method for determining N-acetyl isoniazid in urine was found to be specific in a double-blind experiment on 1673 urine specimens of which 328 were positive and 1345 were negative. The urine specimens were obtained from patients in a sanatorium ((a) Tuberculosis Division, (b) Mental Health Division) and a general hospital. The patients in the Tuberculosis Division were receiving isoniazid and other antituberculosis drugs alone or in combination. The patients in the Mental Health Division and in the general hospital were receiving a wide variety of other drugs. After a single dose of 300 mg. of isoniazid, N-acetyl isoniazid could be detected in urines of 36 patients for at least 12 hours. In three 24-hour urine specimens trace amounts could still be demonstrated.This test provides evidence that isoniazid is being ingested by home-treated tuberculous patients, and it can be performed by a doctor or nurse during routine visits to the home or clinic.