Timolol is a non-selective beta-adrenergic blocker used in the treatment of elevated intraocular pressure in ocular hypertension or open angle glaucoma. Timolol competes with adrenergic neurotransmitters for binding to beta(1)-adrenergic receptors in the heart and the beta(2)-receptors in the vascular and bronchial smooth muscle. This leads to diminished actions of catecholamines, which normally bind to adrenergic receptors and exert sympathetic effects leading to an increase in blood pressure and heart rate. The blockade of beta(2) receptors by timolol in the blood vessels leads to a decrease in peripheral vascular resistance, reducing blood pressure. The exact mechanism by which timolol reduces ocular pressure is unknown at this time, however, it likely decreases the secretion of aqueous humor in the eye. Timolol, when administered by the ophthalmic route, rapidly reduces intraocular pressure. When administered in the tablet form, it reduces blood pressure, heart rate, and cardiac output, and decreases sympathetic activity. It can be found under the brand names Azarga, Betimol, Combigan, Cosopt, Duotrav, Istalol, Timoptic, and Xalacom. Some side effects of using Timolol may include eye pain, swollen eyelids, and dry mouth.

Timolol B2-Adrenergic Ciliary Muscle Contraction Pathway References