Ethionamide, prothionamide and thiacetazone self-administration. Studies of patient compliance using isoniazid-marked formulations

Abstract

The acceptability of ethionamide, prothionamide and thiacetazone as potential companion drugs for the treatment of lepromatous leprosy was assessed in two small scale studies carried out among out-patients in Hyderabad. Specially formulated tablets or capsules containing 6 mg isoniazid as an innocuous marker were prescribed and their ingestion demonstrated by collecting urine samples at surprise home visits and testing for the presence of isoniazid metabolites by a simple colorimetric procedure. About three-quarters of the prescribed thioamide doses were ingested and daily doses of 125 mg ethionamide, and 125 or 250 mg prothionamide were of similar acceptability to the patients. Furthermore, prothionamide and dapsone could be given together in a single daily capsule without compromising the dapsone compliance of the patients. However more extensive studies of thioamide compliance are required before these drugs can be confidently recommended for the treatment of lepromatous patients unable to tolerate clofazimine. Thiacetazone compliance was poorer supporting the conclusion that thiacetazone should not be recommended for the treatment of leprosy.