Subject dapsone

Drugs that carry a definite risk of haemolysis in most G6PD deficient subjects include dapsone (and other sulphones), methylene blue, niridazole, nitrofurantoin, pamaquin, primaquine, quinolone antimicrobials, some sulphonamides. 

Drugs that have been shown to be subject to phar-macogenetic differences in biotransformation include debrisoquine, perhexiline, phenformin, mephenytoin, tolbutamide, dapsone, isoniazid and sulfadimidine. The latter three drugs are primarily biotransformed by Y-acetylation, a pathway for which about 50 /o of the United Kingdom population can be classified as slow acetylators and the rest as fast acetylators. 

Dapsone (alone or in combination with pyrimethamine) can cause methemoglobinemia and hemolytic anemia. These complications tend to be dose-related and are more often encountered in G6PD-deficient subjects (SEDA-18, 287). 

A comparison of the pharmacokinetics of aspirin in 8 healthy subjects and 8 patients with uncomplicated lepromatous leprosy found that the pharmacokinetics of a single 600-mg dose of aspirin was not affected by either leprosy, or by treatment with dapsone 100 mg daily for 8 days. No special precautions would seem likely to be needed on concurrent use. 

Dapsone 100 mg daily had no effect on the pharmacokinetics of a single 200-mg dose of zidovudine in 8 TUV-positive subjects. In a further study, which considered the safety of dapsone in combination with zidovudine, dapsone was shown to increase the risk of zidovudine-related blood dys-crasias. Therefore it would seem that dapsone and zidovudine can be given concurrently, but monitoring for an increase in adverse events would seem advisable. 

Comparative Acetylator Characteristics of Human Subjects Receivinc IsoNiAziD (INH), Dapsone (DDS), and Sulfamethazine (SMZ) ... 

Treatment involves withdrawal of the causative drug and supportive measures. Many cases are self-limiting however, severe cases may require systemic steroids. Subjects with A type of G6PD deficiency can no longer be regarded as mild variants as these subjects too can have a life-threatening form of dapsone-induced acute haemolytic anaemia, as shown by Pamba A et al. [76 ]. 

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