[Alpha.sub.1]-Adrenergic blockers. (Medication Update).MODE OF ACTION Relax smooth muscle of the bladder neck and prostatic urethra by blocking post-synaptic [alpha.sub.1]-adrenergic receptors. CONTRAINDICATIONS Known hypersensitivity to the particular [alpha.sub.1]-adrenergic or components in their formulation. Pregnancy Category C Pregnancy category C No adequate human or animal studies; or adverse fetal effects in animal studies, but no available human data. Mentioned in: Antianxiety Drugs . ADVERSE EFFECTS Asthenia, edema edema (ĭdē`mə), abnormal accumulation of fluid in the body tissues or in the body cavities causing swelling or distention of the affected parts. , dizziness, drowsiness, dyspnea, headache, and hypotension. DRUG-DRUG INTERACTIONS Beta blockers and verapamil verapamil /ve·rap·a·mil/ (ve-rap´ah-mil) a calcium channel blocker that dilates coronary arteries and decreases myocardial oxygen demand, used as the hydrochloride salt in the treatment of angina pectoris and of hypertension and the may increase the first-dose hypotension associated with prazosin prazosin /pra·zo·sin/ (pra´zah-sin) an alpha-adrenergic blocking agent with vasodilator properties, used as the hydrochloride salt in the treatment of hypertension. pra·zo·sin n. . [alpha.sub.1]-adrenergic blockers may decrease the antihypertensive antihypertensive /an·ti·hy·per·ten·sive/ (-ten´siv) counteracting high blood pressure, or an agent that does this. an·ti·hy·per·ten·sive adj. Reducing high blood pressure. n. efficacy of clonidine clonidine /clo·ni·dine/ (klo´ni-den) a centrally acting antihypertensive agent, used as the hydrochloride salt; also used in the prophylaxis of migraine and the treatment of dysmenorrhea, menopausal symptoms, opioid withdrawal, and . DRUG-FOOD INTERACTIONS Tamsulosin should be taken at the same time each day, 30 minutes before a meal. OTHER POINTS OF INTEREST Tamsulosin is reported to cause less hypotension and vasodilatory effects due to its specificity for [alpha.sub.1a] receptors. Most normotensive normotensive /nor·mo·ten·sive/ (-ten´siv) 1. characterized by normal tone, tension, or pressure, as by normal blood pressure. 2. a person with normal blood pressure. patients do not have significant problems with hypotension with the non-selective [alpha.sub.1] blockers. References (1.) Hutchison TA, Shahan DR (eds): DRUGDEX System. MICROMEDEX, Inc., Greenwood Village, Colo (Edition expires 3/2002) (2.) Hebel SK. Katstrup EK (eds): Drug Facts and Comparisons. St. Louis, Mo, 2001
TABLE
[Alpha.sub.1]-Adrenergic Blockers Available
Trade Starting Usual
Drug Names Doses Dose Range Comments
Doxazosin Cardura 1 mg QD 1 to 8 mg First dose may
or QHS QD cause signifi-
cant hypoten-
sion
Prazosin Minipress 1 mg BID- 6 to 15 First dose may
TID mg/day cause signifi-
in divided cant hypoten-
doses sion
Tamsulosin Flomax 0.4 mg QD 0.4 to 0.8
mg QD
Terazosin Hytrin 1 mg QHS 1 to 20 First dose may
mg/day; cause signifi-
may use cant hypoten-
divided sion
doses
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