Certain aspects of dapsone metabolism in leprosy patients as studied by high performance liquid chromatography (HPLC) and qualitative screening tests.

Dapsone (DDS) in urine of 250 leprosy patients collected on surprise visits were screened by simple paper spot, tile tests and sensitive Enzyme linked immunosorbent assay (ELISA) and Haemagglutination inhibition (HI) tests. The urinary DDS concentration as well as DDS/C ratios were also studied. Simultaneously, 50 microliter of blood was collected from each of these patients and its dapsone content was estimated by HPLC. Urine samples with means of 25 to 30 micrograms/ml DDS and 55-64 micrograms/mg DDS/C ratios were found to give positive tests by any of the above screening procedures, while their mean blood DDS concentration was found to be 0.91 microgram/ml. The corresponding values for those specimens giving negative tests were 3.8 to 5.7 micrograms DDS per ml and 9 to 13 micrograms/mg DDS/C ratio. The blood DDS concentration in this group was ranging from 0.16 to 0.18 micrograms/ml. The findings are discussed in relation to their metabolic significance and their application in a leprosy control programme.

Application of HI test for dapsone in urine under field conditions.

One hundred and two specimens of urine collected from leprosy patients attending the field clinics of Central Leprosy Teaching and Research Institute, Chingleput, Tamil Nadu, India, were screened for dapsone by the paper spot test and Haemagglutination Inhibition (HI) tests. A concordance of about 90% was observed between the two tests. Both tests showed their merits. The lower sensitivity of the spot test finds more cases of irregular compliance (1-2 days), whereas the higher sensitivity of the HI allows the demonstration of the intake of lower doses and the detection of those cases, who have grossly missed their tablets (longer than a week).