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The World Health Organization (WHO) regimens of multidrug therapy (MDT) for the treatment of leprosy have proved to be highly safe and efficacious, resulting in a remarkable reduction in the worldwide prevalence of leprosy. ' Dapsone, along with rifampin (RMP) and clofazamine (CFZ) are the three drugs used in these regimens.
In Oman, leprosy has been eliminated as a public health problem (prevalence rate 0.18/10,000); 17 new cases were detected in the year 1996. The number of cumulative cases registered and treated between 1991-1996 was 166. An important feature of the leprosy situation in Oman is the high prevalence of G6PD deficiency in the local population. It has been reported that the prevalence of the deficiency may be as high as 27% in males and 11% of homozygous females-the second highest in any population.2 The most common prevalent variants of the enzyme are G6PD Mediterranean and G6PD A-. These enzyme variants have reduced functional activity, and often are associated with oxidative hemolysis in the presence of stress factors such as drugs, ingestion of fava beans and infections.3
Dapsone, an extremely safe, cheap and effective drug, is known to cause oxidative hemolysis in patients with G6PD deficiency.3,4 Caution has to be exercised in the use of the drug in such individuals. The hemolysis caused by dapsone in these patients has been reported to be variable and depends on a number of factors, such as the type of enzyme variant, dose of drug used, and the acetylator status of the patient.5-9 This has led to differences in opinion about whether the drug should be omitted in all patients with G6PD deficiency.3-7 WHO has recommended that the drug needs to be discontinued in patients developing severe hemolysis, and alternative drugs instituted as follows:1 Paucibacillary (PB) leprosy = RMP 600 mg once monthly + CFZ...