Until the early 1980s, the chemotherapy of leprosy consisted of using dapsone monotherapy for the control of the disease. This was usually administered as 100 mg daily for a minimum period of 5 years to treat paucibacillary leprosy, and for life long to treat multibacillary leprosy. Dapsone being a slow acting and weak bactericidal drug, lead to wide-spread poor patient compliance and the emergence of dapsone resistant strains of Mycobacterium leprae.
This period of failure and frustration changed dramatically with the introduction of greatly improved treatment through the application of combinations of drugs referred to as multidrug therapy (MDT), which was first recommended by a WHO Study Group in 1981. These regimens include a combination of rifampicin, clofazimine and dapsone for multibacillary leprosy and rifampicin plus dapsone for paucibacillary leprosy. This therapy has proved to be the most reliable and practical method of treating leprosy.
The recommendations on MDT received enthusiastic support from most of the leprosy-endemic countries, WHO regional committees, international and non-governmental organizations (NGOs), donor agencies and professional bodies alike. Follow-up based on sufficiently large number of patients has revealed very low relapse rates following stopping treatment. (A cumulative risk of less than 1% over a nine year period, both for MB and PB leprosy)