sulfonamide mainly distributed to erythrocytes. Probably insignificant systemic load. CYP metabolised, long duration of the final elimination phase.

sulfonamide used in eyedrops (20 mg/mL) to reduce the intraocular pressure in glaucoma. Converted to N-desethyl dorzolamide which binds to carbanhydrase. Reaches circulation in topical application but due to effective bindnding to erytrocyte carboanhydrases the plasma levels are very low. Metabolized by CYPs 3A3/4 and 2C9/10. A final elimination phase with a half time of four months takes place after termination of treatment.