Hypotensive drug timolol

Blockers can be used topically to reduce intraocular pressure in patients with chronic open-angle glaucoma and ocular hypertension. The mechanism by which ocular pressure is reduced appears to depend on decreased production of aqueous humor. Timolol has a somewhat greater ocular hypotensive effect than do the available cholinomimetic or adrenomimetic drugs. The 3-blockers also are beneficial in the treatment of acute angle-closure glaucoma. 

Nadolol is noteworthy for its very long duration of action its spectrum of action is similar to that of timolol. Timolol is a nonselective agent with no local anesthetic activity. It has excellent ocular hypotensive effects when administered topically in the eye. Levobunolol (nonselective) and betaxolol (E -selective) are also used for topical ophthalmic application in glaucoma the latter drug may be less likely to induce bronchoconstriction than nonselective antagonists. Carteolol is a nonselective 13-receptor antagonist. 

Early in the development of timolol, some reports indicated the relatively rapid development of tolerance to the drug s ocular hypotensive effects, referred to as escape. The lOP is lower early in the conrse of therapy than with chronic treatment. The lOP resnlts, however, are similar with chronic use of either 0.5% timolol or 0.25% timolol. In addition, the fellow untreated eye may show a decrease in lOP, which most likely resnlts from a consensnal (contralateral) effect. Contralateral effects resnlting from systemic drug absorption can be significant. 

Drugs that are metabolized by the cytochrome P-450 (CYP) isoenzymes CYP2D6, CYP2C9, and CYP2C19 also exhibit genetic polymorphisms. An example of CYP2D6 metabolism is debrisoquine. In about 5-10 /o of Caucasians in North America and Europe and about 1% of Asians, 4-hydroxylation of debrisoquine is reduced, and such individuals are at increased risk for toxicity (orthostatic hypotension). Beta blockers (metoprolol and timolol), antiarrhythmic drugs (encainide and flecainide), tricyclic antidepressants... 

A 75-year-old man being treated with timolol eye drops for glaucoma developed bradyeardia and severe hypotension when anaesthetised [drug not... 

New efforts were directed to use this material in novel ophthalmic drug delivery platforms recent reports in scientific literature propose the SH as solid bio-adhesivedrug delivery system. Crosslinked SH films loaded with timolol maleate were successfully used to reduce intra ocular pressure in normotensive rabbits, prolonging the hypotensive effect for longer than commercial timolol maleate eye drops [35]. 

---