alpha-chymotrypsin and 6-hydroxyethoxzolamide

A newly synthesized topical carbonic anhydrase inhibitor, 6-hydroxyethoxy-2-benzothiazole sulfonamide (6-HS), was administered systemically and topically to alpha-chymotrypsin-induced glaucoma rabbits to evaluate its ocular hypotensive effect. A significant IOP lowering effect was observed after topical application of 50 microL of 3% 6-HS gel, but a dose of 50 microL of 3% 6-HS suspension failed to reduce IOP. The maximal magnitude of reduced IOP after topical gel instillation was 24.4%, very close to the result obtained following intravenous injection of 6 mg/kg of 6-HS (23.3%). However, the blood levels of 6-HS after topical instillation with 3% 6-HS gel was much lower than that following 6 mg/kg of 6-HS injected intravenously (less than 5%). Since a lower dose of 6-HS (1 mg/Kg) administered intravenously did not cause a significant drop in IOP, it is reasonable to deduct that the ocular hypotensive effect of 6-HS applied topically can then be attributed to the inhibition of intraocular carbonic anhydrase activity. It was also noted that a larger dose of intravenous administration of 6-HS (20 mg/Kg) had a more profound IOP and blood pressure reducing effect with moderate metabolic acidosis.

Topics: Animals; Benzothiazoles; Carbonic Anhydrase Inhibitors; Chymotrypsin; Disease Models, Animal; Ethoxzolamide; Female; Glaucoma; Intraocular Pressure; Male; Rabbits

A newly synthesized topical carbonic anhydrase inhibitor, 6-hydroxyethoxy-2-benzothiazole sulfonamide (6-HS), was used as a model drug to determine its corneal and scleral permeabilities in rabbit eyes. The corneal permeability coefficient of 6-HS for short duration glaucoma and normal rabbit eye was not significantly different (its mean value was around 2.9 x 10(-6) cm/sec), while the corneal permeability coefficient for long duration glaucoma rabbit eye was 1.8 times greater than that for the normal eye. The sclera was found to have a higher permeability than the cornea in that after four hours perfusion the amount of drug which passed through the sclera was 11 times greater than that of the cornea. In addition, it was also noted that after topical instillation of 50 microL of 3% 6-HS gel the aqueous humor concentrations of 6-HS in short duration glaucoma eye and normal eye were not statistically different.

Topics: Administration, Topical; Animals; Aqueous Humor; Benzothiazoles; Carbonic Anhydrase Inhibitors; Chymotrypsin; Cornea; Ethoxzolamide; Female; Gels; Glaucoma; Male; Permeability; Rabbits; Sclera; Time Factors

An analogue of ethoxzolamide, 6-hydroxyethoxzolamide, was synthesized to enhance corneal permeability yet retain carbonic anhydrase inhibitory activity for use in lowering intraocular pressure. In a 1% suspension, the analogue caused a small but statistically significant unilateral reduction of IOP when applied to one eye of normal rabbits. When formulated in a gel vehicle, 6-hydroxyethoxzolamide caused a more prolonged and larger reduction in IOP in normal and ocular hypertensive rabbits compared with its effect in suspension or with the parent compound.

Topics: Animals; Benzothiazoles; Carbonic Anhydrase Inhibitors; Chymotrypsin; Ethoxzolamide; Gels; Glaucoma; Intraocular Pressure; Ophthalmic Solutions; Rabbits; Suspensions; Thiazoles