Terazosin

Pharmaceuticals -> Antihypertensives

Pharmaceuticals

1

1.14

Breast Feeding; Lactation; Milk, Human; Adrenergic alpha-Antagonists; Antihypertensive Agents

Pharmaceuticals

271-274

273 °C

This chemical does not meet GHS hazard criteria for 2.3% (1 of 44) of reports.

Warning

H302 (97.7%): Harmful if swallowed [Warning Acute toxicity, oral]

P264, P270, P301+P317, P330, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 44 reports by companies from 3 notifications to the ECHA C&L Inventory.

Should overdosage of Terazosin lead to hypotension, support of the cardiovascular system is of first importance. Restoration of blood pressure and normalization of heart rate may be accomplished by keeping the patient in the supine position. If this measure is inadequate, shock should first be treated with volume expanders. If necessary, vasopressors should then be used and renal function should be monitored and supported as needed. Laboratory data indicate that Terazosin is highly protein bound; therefore, dialysis may not be of benefit. (L1712)

Terazosin has been associated with a low rate of serum aminotransferase elevations that in controlled trials was no higher than with placebo therapy. These elevations were transient and did not require dose modification. Instances of serum enzyme elevations, but no instances of clinically apparent acute liver injury with jaundice due to terazosin, have been published. Furthermore, product labels do not include discussion of hepatic toxicity. Cholestatic hepatitis and jaundice have been reported with other alpha-adrenergic blockers. Thus, acute symptomatic liver injury due to terazosin must be exceedingly rare if it occurs at all.

Overdose of terazosin may lead to hypotension, and standard life-support protocols should be in place for instances of hemodynamic instability. There are no specific antidotes for terazosin toxicity. Vasopressors may be used to support physiologic blood pressure parameters in the event of terazosin overdose. Terazosin is long-acting, with an elimination half-life of approximately 12 hours, and is highly protein-bound. Elimination is via renal excretion (40%) and excretion of feces (60%).

Terazosin selectively and competitively inhibits vascular postsynaptic alpha(1)-adrenergic receptors, resulting in peripheral vasodilation and a reduction of vascular resistance and blood pressure. Unlike the nonselective alph-adrenergic blockers phenoxybenzamine and phentolamine, terazosin does not block presynaptic alpha(2)-receptors and, hence, does not cause reflex activation of norepinephrine release to produce reflex tachycardia.

Drug-Induced Liver Injury Severity and Toxicity (DILIst)

terazosin

DILI Negative

Oral

DOI:10.1016/j.drudis.2019.09.022

G04CA03

G - Genito urinary system and sex hormones

Terazosin is selective for alpha-1-adrenoceptors but not their individual subtypes. Inhibition of these alpha-1-adrenoceptors results in relaxation of smooth muscle in blood vessels and the prostate, lowering blood pressure and improving urinary flow. Smooth muscle cells accounts for roughly 40% of the volume of the prostate and so their relaxation reduces pressure on the urethra. It has also been shown that catecholamines induce factors responsible for mitogenesis and alpha-1-adrenergic receptor blockers inhibit this effect. A final long term mechanism of terazosin and other alpha-1-adrenergic receptor blockers is the induction of apoptosis of prostate cells. Treatment with terazosin enhances the expression of transforming growth factor beta-1 (TGF-beta1), which upregulates p27kip1, and the caspase cascade.

The majority of terazosin is hepatically metabolized. The metabolites recovered include 6-O-demethyl terazosin, 7-O-methyl terazosin, a piperozine derivative, and a diamine derivative.

Hepatic. One of the four metabolites identified (piperazine derivative of terazosin) has antihypertensive activity. 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. Half Life: 12 hours

8L5014XET7

TERAZOSIN

Mechanisms of Action [MoA] - Adrenergic alpha-Antagonists

Established Pharmacologic Class [EPC] - alpha-Adrenergic Blocker

Terazosin is an alpha-Adrenergic Blocker. The mechanism of action of terazosin is as an Adrenergic alpha-Antagonist.

TERAZOSIN

Drugs that bind to and block the activation of ADRENERGIC ALPHA-1 RECEPTORS.

Drugs used in the treatment of urological conditions and diseases such as URINARY INCONTINENCE and URINARY TRACT INFECTIONS.

Approximately 90%.

Approximately 10% of the oral dose is excreted unchanged in the urine and approximately 20% is excreted in the feces. 40% of the total dose is eliminated in urine and 60% of the total dose is eliminated in the feces.

25L to 30L.

Plasma clearance is 80mL/min and renal clearance is 10mL/min.

Use (kg; approx.) in Germany (2009): >75

Terazosin is indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH). There is a rapid response, with approximately 70% of patients experiencing an increase in urinary flow and improvement in symptoms of BPH when treated with terazosin. The long-term effects of terazosin on the incidence of surgery, acute urinary obstruction or other complications of BPH are yet to be determined. Terazosin tablets are also indicated for the treatment of hypertension. Terazosin tablets can be used alone or in combination with other antihypertensive agents such as diuretics or beta-adrenergic blocking agents.