Dapsone and sulfapyridine.

Dapsone and sulfapyridine are structurally related compounds with anti-microbial and anti-inflammatory effects. Dapsone remains the most important drug for leprosy and is useful in the prophylaxis of Pneumocystis pneumonia in patients with HIV disease. The medical treatment of choice for dermatitis herpetiformis is dapsone; and sulfapyridine also can be used for those patients who are intolerant of dapsone. Other neutrophilic disorders also may respond to these drugs. Toxic side effects of both dapsone and sulfapyridine are mediated through the hydroxylamine metabolite. These include hemolysis, methemoglobinemia, and agranulocytosis. Careful monitoring for possible adverse reactions includes frequently performing complete blood counts and regular blood chemistry profile determinations.

Sulfapyridine and sulfones decrease glycosaminoglycans viscosity in dermatitis herpetiformis, ulcerative colitis, and pyoderma gangrenosum.

Shortly after the introduction of sulfa drugs, sulfapyridine was found to have unique therapeutic properties, unrelated to antibacterial activity. Later, sulfones were found to share the same properties. The disorders initially improved were dermatitis herpetiformis, pyoderma gangrenosum, subcorneal pustular dermatosis, acrodermatitis continua, impetigo herpetiformis and ulcerative colitis. They were also sometimes helpful in many other disorders. They are effective in select disorders characterized by edema followed by granulocytic inflammation or edema followed by vesicle or bullae formation. The sulfones work in low doses in leprosy and their mode of action is not fully understood. Several pieces of experimental information are available. It is proposed that these drugs are entering or influencing the protein moiety of glycosaminoglycans and decreasing tissue viscosity. This decreased tissue viscosity prevents edema and dilution of tissue fluid and decreases acute inflammation and vesicle and bullae formation.