Timolol

**Semantic type:** Pharmacologic Substance

**Definition:** A propanolamine derivative and a non-selective beta-adrenergic antagonist with antihypertensive property. Timolol competitively binds to beta-1-adrenergic receptors in the heart and vascular smooth muscle and beta-2-receptors in the bronchial and vascular smooth muscle, resulting in a decrease in beta-adrenergic stimulation. Beta-1-receptor blockade results in a decrease in resting and exercise heart rate and cardiac output, a decrease in both systolic and diastolic blood pressure, and, possibly, a reduction in reflex orthostatic hypotension. Beta-2-blockade results in an increase in peripheral vascular resistance. The ultimate results include vasodilation, and negative chronotropic and inotropic cardiac effects. In addition, timolol reduces intra-ocular pressure possibly by decreasing aqueous humor production by reduction of blood flow to the ciliary processes and cAMP synthesis.

**Synonyms:** - (S)-1-(tert-Butylamino)-3-((4-morpholino-1,2,5-thiadiazol-3-yl)oxy)propan-2-ol - 2-Propanol, 1-((1,1-dimethylethyl)amino)-3-((4-(4-morpholinyl)-1,2,5-thiadiazol-3-yl)oxy)-, hemihydrate, (S)- - Betimol - Blocadren - TIMOLOL