Terazosine

OC-Adrenoceptor Blockers. Nonselective a-adrenoceptor blockers (Table 6), such as phentolamine, which block both a - and a2 adrenoceptors, produce vasodilation by antagonizing the effects of endogenous norepinephrine. They also produce severe tachycardia and have been replaced by selective a -adrenoceptor blockers, such as prazosin, terazosin, and doxazosin, which do not usually cause severe tachycardia. 

Terazosin is selective a -adrenoceptor blocker having hypotensive efficacy equal to that of prazosin. Terazosin has a longer duration of action and better gastrointestinal absorption profile than prazosin. 

C4H4O4 110-17-8) see Biotin Ibutilide fumarate Quetiapine fumarate Sodium dioctyl sulfosuccinate furan-2-carbonyl chloride (CjHjClOj 527-69-5) see Diloxanide furoate Mometasone furoate Terazosin 2(5ff)-furanone... 

Terazosin (Hytrin) Prazosin (Minipress) this time... 

Generally, arblockers are considered as second-line agents to be added on to most other agents when hypertension is not adequately controlled. They may have a specific role in the antihypertensive regimen for elderly males with prostatism however, their use is often curtailed by complaints of syncope, dizziness, or palpitations following the first dose and orthostatic hypotension with chronic use. The roles of doxazosin, terazosin, and prazosin in the management of patients with hypertension are limited due to the paucity of outcome data and the absence of a unique role for special populations or compelling indications from JNC 7. 

Requirement for up-titration of dose Yes (for terazosin and doxazosin immediate-release) no (for alfuzosin possibly for doxazosin extended-release and tamsulosin) No... 

Need for up-titration of daily dose. Up-titration is required for terazosin and immediate-release doxazosin. It is minimally required for extended-release doxazosin and tamsulosin. It is not required for extended-release alfuzosin. 

Dosage formulation. Immediate-release formulations of terazosin and doxazosin are quickly absorbed and produce high peak plasma levels. Modified- or extended-release formulations of doxazosin, alfuzosin, and tamsulosin produce lower peak levels, but more sustained therapeutic plasma levels, than immediate-release formulations and have less potential for producing hypotensive episodes, thereby allowing initiation of treatment with a therapeutic dose and once daily dosing.25-27... 

A 75-year-old female with a blood pressure of 180/95 mmllg is treated with terazosin. What is the mechanism of action of terazosin ... 

The answer is b. (tlardman, p 229. Katzung, p 168.) Terazosin blocks a receptors in arterioles and venules It is 0 -selective. Perhaps this selectivity permits NE to exert unopposed negative feedback on its own release because of little or no effect on presynaptic a.2 receptors. Alpha blockers reduce arterial pressure in both resistance and capacitance vessels andT thereforet are quite effective in reducing blood pressure when a patient is in the upright position... 

Prazosin, terazosin, and doxazosin are selective cq-receptor blockers that inhibit catecholamine uptake in smooth muscle cells of the peripheral vasculature, resulting in vasodilation. 

Prazosin (Minipress) Alfuzosin (Uroxatral) Terazosin (Hytrin) Doxazosin (Cardura) Tamsulosin (Flomax) Finasteride (Proscar) Dutasteride (Avodart) Bicalutamide (Casodex) Flutamide (Eulexin) Leuprolide (Lupron) Nafarelin (Synarel) Megestrol acetate... 

Patients should be slowly titrated to a maintenance dose and should take these drugs at bedtime to minimize orthostatic hypotension and first-dose syncope with terazosin and doxazosin. Sample titration schedules for terazosin include ... 

Safer antihypertensives include angiotensinconverting enzyme inhibitors, postsynap-tic a,-adrenergic antagonists (terazosin, doxazosin), calcium channel blockers, and angiotensin II antagonists. 

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