About dorzolamidecarbonic anhydrase inhibitor, thiophene derivative, a sulfonamide, antiglucoma.mechanism of action of dorzolamidedorzolamide is a sulfonamide used as topical carbonic anhydrase inhibitor. inhibition of carbonic anhydrase-2 in ciliary processes of eye leads to reducing intra ocular tension by decreasing aqueous humor secretion by slowing the formation of bicarbonate ions with subsequent decrease in sodium and fluid transport.about timololnonselective beta adrenergic,blocker,ophthalmic- antiglaucoma,antimigraine.mechanism of action of timololtimolol is a non selective beta blocker. it inhibits the beta receptors (?2) present in the eye such as in the ciliary body epithelium and blood vessels. this will leads to decreased aqueous production and reduced intraocular pressure. aqueous humor production is activated by ? receptor mediated cyclic amp phosphokinase pathway. beta receptor blockers will decreases the intracellular cyclic amp level and reduces intraoc