The new challenges for chemotherapy research.

Scientific knowledge is constantly expanding, and needs are changing; therefore, efforts must be made to adapt the treatment of leprosy and the manner in which it is implemented to the newly identified needs. Because an effective vaccine against leprosy remains to be identified, multidrug therapy (MDT) is the only tool available for leprosy control. At present, therefore, the priority is to make MDT available in all endemic countries for all patients, even those living in difficult-to-access areas. The remaining important issues in chemotherapy research are to improve the quality of leprosy case-finding, improve the quality of MDT, identify the areas in which leprosy patients are not receiving proper MDT, and find the means necessary to ensure delivery to all of appropriate MDT. The MDT regimens recommended by the World Health Organization are of too long duration, require correct classification of the patients as PB or MB, and rely upon the daily self-administration of dapsone and clofazimine to prevent selection of rifampicin resistant mutants among MB patients. Thus, research leading to the development of new drug regimens should be directed toward overcoming the shortcomings of the presently recommended regimens. The drugs required to permit use of regimens of shorter duration, that may be employed among both PB and MB patients, and that enable fully supervised drug administration may be already in hand, and the necessary clinical trials to confirm efficacy and acceptability should be carried out.