An investigation of dapsone compliance using an isoniazid-marked formulation

In a study conducted among out-patients in Hyderabad, it was shown that the precision of the dapsone/creatinine method for monitoring dapsone compliance could be improved if patients were prescribed specially fo rmulated dapsone capsules containing 6 mg isoniazid as an innocuous marker. Urine samples were obtained by means of surprise home visits; the ingestion of the isoniazid marker was revealed by a simple colorimetric procedure which gives reliably positive results for about 18 h. The study showed that such capsules were acceptable to the patients and, in the short run, were taken more regularly than the standard tablets. However, a small proportion of patients took both capsules and tablets very irregularly, indicating that poor compliance was not overcome by simply changing the dapsone formulation.