About dapsonea synthetic sulfone(4,4`-diaminodiphenylsulfone (dds)), antileprotic,antimalarial, antibacterial.mechanism of action of dapsonedapsone is an antileprotic sulfone chemically related to sulfonamides & has same mechanism of action. it exerts it`s bacteriostatic action by acting as an antimetabolite by inhibiting bacterial folic acid synthesis. para amino benzoic acid (paba) is a constituent of bacterial folic acid. dapsone acts as a structural analogue of paba & thus inhibits enzyme bacterial folate synthetase. it competitively inhibits the union of paba with pteridine residue to form dihydropteroic acid which conjugates with glutamic acid to produce dihydrofolic acid. its antileprotic action in smaller doses is due to affinity of m.leprae to dapsone