Potencialização do efeito metemoglobinizante da dapsona em ratos pela N-acetilcisteína / Potentiation of dapsone induced methemoglobinemia by N-acetylcysteine in rats

Dapsona (DDS) (4,4'diaminodifenilsulfona), fármaco de escolha para o tratamento da hanseníase, freqüentemente induz anemia hemolítica e metemoglobinemia. A N-hidroxilação, uma de suas principais vias de biotransformação, é constantemente relacionada com a metemoglobinemia observada com o uso do fármaco. Com o objetivo de prevenir a hemotoxicidade induzida pela DDS, N-acetilcisteína, fármaco precursor de glutationa, foi administrada em associação com DDS em ratos machos Wistar pesando 220-240 g. Os animais foram anestesiados e o sangue coletado da aorta para determinação da concentração plasmática de DDS por CLAE, determinação dos níveis de metemoglobina e de glutationa eritrocitária por espectrofotometria, e avaliação de parâmetros bioquímicos e hematológicos. Os resultados obtidos mostraram que a N-acetilcisteína potenciou o efeito metemoglobinizante da dapsona devido ao aumento de sua concentração plasmática e conseqüente aumento da formação da N-hidroxilamina. Concluímos que as interações medicamentosas com a dapsona exigem estudos individualizados a fim de evitar os efeitos adversos do fármaco.

Dapsone (DDS) (4,4'diaminodiphenylsulfone), the drug of choice for the treatment of leprosy, frequently induces hemolytic anemia and methemoglobinemia. N-hydroxylation, one of the major pathways of biotransformation, has been constantly related to the methemoglobinemia after the use of the drug. In order to prevent the dapsone-induced hemotoxicity, N-acetylcysteine, a drug precursor of glutathione, was administered in combination with DDS to male Wistar rats, weighting 220-240 g. The animals were then anaesthetized and blood was collected from the aorta for determination of plasma DDS concentration by HPLC, determination of methemoglobinemia and glutathione by spectrophotometry, and for biochemical and hematological parameters. Our results showed that N-acetylcysteine enhanced dapsone-induced methemoglobinemia due to increased dapsone plasmatic concentration and consequent increased N-hydroxylamine formation. We concluded that drug interactions with dapsone require individually studies in order to avoid undesirable effects of dapsone.

Biochemical and hematological side effects of clofazimine in leprosy patients.

Gastrointestinal toxicity and red skin discoloration were the major side effects observed in leprosy patients undergoing long-term treatment with clofazimine (CFZ). Hematological and biochemical alterations have been cited among other side effects; however, their real magnitude and clinical significance at the doses currently employed in therapy have not been sufficiently documented. We therefore investigated the correlation between CFZ plasma concentration and biochemical (transaminases, bilirubins, alkaline phosphatase, gamma-glutamyltransferase, amylase, urea, creatinine, and potassium plasma levels) as well as hematological changes blood and reticulocyte counts, osmotic fragility, detection of Heinz bodies and methemoglobinemia (MHM), following in two regimes of treatment: CFZ as a single drug and CFZ as part of multidrug (MDT) therapy, in combination with dapsone and rifampicin. MHM and hemolytic anemia were detected in the MDT group only. Eosinophilia was found in patients of either group. Determination of hepatic, pancreatic and renal biochemical parameters showed rare, occasional changes of apparently no clinical significance. We conclude that CFZ is a generally well tolerated and safe drug when given as a daily dose of 50mg, which is currently used in leprosy patients.

Biochemical and hematological side effects of clofazimine in leprosy patients

Gastrointestinal toxicity and red skin discoloration were the major side effects observed in leprosy patients undergoing long-term treatment with clofazimine (CFZ). Hematological and biochemical alterations have been cited among other side effects; however, their real magnitude and clinical significance at the doses currently employed in therapy have not been sufficiently documented. We therefore investigated the correlation between CFZ plasma concentration and biochemical (transaminases, bilirubins, alkaline phosphatase, gamma-glutamyltransferase, amylase, urea, creatinine, and potassium plasma levels) as well as hematological changes blood and reticulocyte counts, osmotic fragility, detection of Heinz bodies and methemoglobinemia (MHM), following in two regimes of treatment: CFZ as a single drug and CFZ as part of multidrug (MDT) therapy, in combination with dapsone and rifampicin. MHM and hemolytic anemia were detected in the MDT group only. Eosinophilia was found in patients of either group. Determination of hepatic, pancreatic and renal biochemical parameters showed rare, occasional changes of apparently no clinical significance. We conclude that CFZ is a generally well tolerated and safe drug when given as a daily dose of 50mg, which is currently used in leprosy patients.