A drug that curbs the action of an ENZYME in blood controlling the production of carbonic acid or bicarbonate from CARBON DIOXIDE. The enzyme is present in ERYTHROCYTES and has a key part in maintaining blood acid-base balance. Inhibiting drugs include ACETAZOLAMIDE and DORZOLAMIDE, and these are used as weak DIURETICS to reduce the increased intra-ocular pressure in ocular hypertension or open-angle GLAUCOMA (see EYE, DISORDERS OF).