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Home / Drugs / Starting with T / Terazosin
 
Terazosin
 

Terazosin is a selective alpha1-antagonist used for treatment of symptoms of benign prostatic hyperplasia (BPH). It also acts to lower blood pressure, so it is a drug of choice for men with hypertension and prostate enlargement. It works by blocking the action of adrenaline on smooth muscle of the bladder and the blood vessel walls.
BrandsBlavin
Flumarc
Fosfomic
Heitrin
Hytracin
Hytrin
Hytrinex
Itrin
Urodie
Vasomet
Vicard
CategoriesAntineoplastic Agents
Adrenergic alpha-Antagonists
ManufacturersAbbott laboratories pharmaceutical products div
Apotex inc
Cadista pharmaceuticals inc
Ivax pharmaceuticals inc sub teva pharmaceuticals usa
Mylan laboratories inc
Mylan technologies inc
Ranbaxy laboratories ltd
Sandoz inc
Teva pharmaceuticals usa inc
PackagersAdvanced Pharmaceutical Services Inc.
Amerisource Health Services Corp.
Apotex Inc.
A-S Medication Solutions LLC
Cadista Pharmaceuticals Inc.
Cardinal Health
Comprehensive Consultant Services Inc.
Direct Dispensing Inc.
Dispensing Solutions
Diversified Healthcare Services Inc.
Golden State Medical Supply Inc.
H.J. Harkins Co. Inc.
Heartland Repack Services LLC
Intas Pharmaceuticals Ltd.
Ivax Pharmaceuticals
Kaiser Foundation Hospital
Major Pharmaceuticals
Mckesson Corp.
Murfreesboro Pharmaceutical Nursing Supply
Mylan
Nucare Pharmaceuticals Inc.
Palmetto Pharmaceuticals Inc.
PD-Rx Pharmaceuticals Inc.
Pharmaceutical Utilization Management Program VA Inc.
Physicians Total Care Inc.
Preferred Pharmaceuticals Inc.
Prepackage Specialists
Prepak Systems Inc.
Ranbaxy Laboratories
Rebel Distributors Corp.
Redpharm Drug
Remedy Repack
Resource Optimization and Innovation LLC
Sandoz
Southwood Pharmaceuticals
Teva Pharmaceutical Industries Ltd.
Torpharm Inc.
Tya Pharmaceuticals
UDL Laboratories
Va Cmop Dallas
Vangard Labs Inc.
SynonymsAbbott 45975
Terazosin HCl
Terazosin hydrochloride
Terazosina [INN-Spanish]
Terazosine
Terazosine [INN-French]
Terazosinum [INN-Latin]
Trazosin HCl

indication

For the treatment of symptomatic BPH and mild to moderate hypertension.

pharmacology

Terazosin, classified as a quinazoline, is similar to doxazosin and prazosin. As an α-adrenergic blocking agent, terazosin is used to treat hypertension and BPH. Terazosin produces vasodilation and reduces peripheral resistance but in general has only a slight effect on cardiac output. The antihypertensive effect with chronic dosing is not usually accompanied by reflex tachycardia.

mechanism of action

In general, α1-adrenergic receptors mediate contraction and hypertrophic growth of smooth muscle cells. α1-Receptors are 7-transmembrane domain receptors coupled to G proteins, Gq/11. Three α1-receptor subtypes, which share approximately 75% homology in their transmembrane domains, have been identified: α1A (chromosome 8), α1B (chromosome 5), and α1D (chromosome 20). Terazosin is the first α1-receptor antagonist to demonstrate selectivity for the α1A-receptor. All three receptor subtypes appear to be involved in maintaining vascular tone. The α1A-receptor maintains basal vascular tone while the α1B-receptor mediates the vasocontrictory effects of exogenous α1-agonists. Activation of α1-receptors activates Gq-proteins, which results in intracellular stimulation of phospholipases C, A2, and D. This results in mobilization of Ca2+ from intracellular stores, activation of mitogen-activated kinase and PI3 kinase pathways and subsequent vasoconstriction. Terozosin produces its pharmacological effects by inhibiting α1A-receptor activation. Inhibition of these receptors in the vasculature and prostate results in muscle relaxation, decreased blood pressure and improved urinary outflow in symptomatic benign prostatic hyperplasia.

toxicity

LD50=259.3mg/kg (IV in mice)

biotransformation

Hepatic. One of the four metabolites identified (piperazine derivative of terazosin) has antihypertensive activity.

absorption

Essentially completely absorbed in man (90% bioavailability).

half life

12 hours

route of elimination

Approximately 10% of an orally administered dose is excreted as parent drug in the urine and approximately 20% is excreted in the feces.

drug interactions

Acebutolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Alfuzosin: Additive antihypertensive effects may occur. Increase risk of orthostatic hypotension and syncope. Concomitant therapy should be avoided.

Amifostine: Terazosin may increase the hypotensive effect of Amifostine. At chemotherapeutic doses of Amifostine, Terazosin should be withheld for 24 hours prior to Amifostine administration. Use caution at lower doses of Amifostine.

Atenolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Betaxolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Bisoprolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Carteolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Carvedilol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Esmolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Labetalol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Metoprolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Nadolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Nebivolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Oxprenolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Penbutolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Pindolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Propranolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Rituximab: Additive antihypertensive effects may occur. Increased risk of hypotension. Consider withholding Terazosin for 12 hours prior to administration of Rituximab.

Sildenafil: Increased risk of hypotension.

Sotalol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Tadalafil: Tadalafil may enhance the hypotensive effect of Terazosin. Monitor for hypotension during concomitant therapy.

Tamsulosin: Concomitant use of alpha1-adrenergic antagonists, Tamsulosin and Terazosin, may result in additive antihypertensive effects. Combination therapy is not recommended.

Timolol: Increased risk of hypotension. Initiate concomitant therapy cautiously.

Treprostinil: Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.

Vardenafil: Additive hypotensive effects of the PDE5 inhibitor, Vardenafil, and alpha1-blocker, Terazosin, may occur. Monitor for hypotension during concomitant therapy.