Dapsone drug compliance study among leprosy patients: a comparison between qualitative and quantitative methods

The methods currently employed to monitor self-administration of dapsone have been evaluated by comparing the results of the qualitative spot test and quantitative DDS/creatinine ratio test. Random urine samples of 242 leprosy patients, periodically attending the Leprosy Clinic were tested. Although a good correlation between the results of the two tests was evident, the DDS/creatinine ratio technique appeared to be more sensitive than the spot test. The concentration of DDS and its metabolites in urine specimens found to be negative by the spot test, ranged from 3.32-12.37 micrograms of DDS/mg creatinine. The spot test was found to be more specific and stays to be the method of choice, when rapidity and reproducibility are the prime objectives, and sensitivity can be marginally compromised. Acidification of urine prior to the spot test was found to be desirable to rule out false negative and false positive reactions.