Commonest side effect of Dapsone is:

ANTILEPROTIC DRUGS: CLASSIFICATION: Sulfone:dapsone Phenazine derivative:clofazamine Antitubercular drugs:rifampin,ethionamide other antibiotics:ofloxacin,moxifloxacin,minocycline,clarithromycin DAPSONE: Activity and mechanism: Dapsone is chemically related to sulfonamides and has the same mechanism of action, i.e. inhibition of PABA incorporation into folic acid; its antibacterial action is antagonized by PABA. Pharmacokinetics: Dapsone is completely absorbed after oral administration and is widely distributed in the body, though penetration in CSF is poor. It is 70% plasma protein bound, but more impoantly concentrated in skin (especially lepromatous skin), muscle, liver and kidney. Dapsone is acetylated as well as glucuronide and sulfate conjugated in liver. Metabolites are excreted in bile and reabsorbed from intestine, so that ultimate excretion occurs mostly in urine. The plasma tlh of dapsone is variable, though often > 24 hrs. The drug is cumulative due to retention in tissues and enterohepatic circulation. Elimination takes 1-2 weeks or longer. DAPSONE: 25, 50, 100 mg tab. Adverse effects: Dapsone is generally well tolerated at doses 100 mg/ day or less. Mild haemolytic anaemia is common. It is a doserelated toxicity-reflects oxidising propey of the drug. Patients with G-6-PD deficiency are more susceptible; doses > 50 mg/ day produce haemolysis in them. Gastric intolerance-nausea and anorexia are frequent in the beginning, decrease later. Other side effects are methaemoglobinaemia, headache, paresthesias, mental symptoms Contraindications: Dapsone should not be used in patients with severe anaemia with Hb < 7g%, G-6-PD deficiency and in those showing hypersensitivity reactions. Other use In combination with pyrimethamine, dapsone can be used for chloroquine-resistant malaria ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION Page No:751,752