The Anti Hypertensive Properties Of Doxazosin - 996 Words

Pharmacology Doxazocin is an â€Å"alpha-adrenoceptor blocking drug† and it is used in both hypertension and benign prostatic hyperplasia (Joint Formulary Committee, 2014). For the purpose of this essay, the main focus will be on the anti-hypertensive properties of Doxazosin. Selective ÃŽ ±1 antagonists work on the post-synaptic ÃŽ ±1 adrenoreceptors predominantly found in vascular smooth muscle. These receptors are normally bound by norepinephrine or epinephrine to mediate regulation of the cardiovascular system by the sympathetic nervous system. As can be seen in Figure 1, these receptors are bound to Gq-proteins which have two signal transduction pathways. One of the pathways forms IP3 (Inositol triphosphate) which then stimulates the release of Calcium from the sarcoplasmic reticulum in a cardiac monocyte (Klabunde, R.E., 2013). The release of calcium then stimulates contraction in the heart. By selectively inhibiting these adrenoceptors, vasodilation occurs which in turn causes a decrease in arterial pressure (Rang and Dale). With a mean half-life of 22 hours (Martindale, 2013), Doxazosin is considered to be a long acting hypertensive drug. This means that it can be administered once daily, rather than multiple times. With a good absorption when administered orally, the maximum plasma concentration happens two to three hours after a dose (Martindale, 2013). It also states that doxazosin is roughly â€Å"98.3%† bound to plasma, which means that it has an excellent distribution around