α1-adrenoceptor

Terazosin does not distinguish between the numerous clonal α1-adrenergic receptor subtypes that are temporarily expressed in COS cells [1].

For the treatment of ureteral stones, terazosin may be given to facilitate stone transit. It has been observed that terazosin is a safe and effective treatment for distal ureteral stones, particularly those that measure more than 5 mm [3].

In the current study, various identification techniques were employed to ascertain the mode of action of the cytotoxic effect. With terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling, apoptotic cells can be identified in situ. After PC-3 cells were treated with 100 μM terazosin for 12 hours, the results indicate a positive response.

Terazosin, a water-soluble alpha 1 antagonist that can be administered in high doses intraventricularly was used to study the relationship between brain alpha 1 adrenoceptor neurotransmission and behavioral activation in the mouse. The antagonist was found to produce a dose-dependent, complete inhibition of motor activity and catalepsy which were reversed preferentially by coinfusion of an alpha 1 agonist (phenylephrine) compared to a D1 (SKF38393) or a D2 agonist, (quinpirole). Blockade of central beta-1 (betaxolol), alpha-2 (RX821002) or beta-2 (ICI 118551) adrenoceptors had smaller or non-significant effects. Terazosin's selectivity for alpha 1 receptors versus dopaminergic receptors was verified under the present conditions by showing that the intraventricularly administered antagonist protected striatal and cerebral cortical alpha 1 receptors but not striatal or cortical D1 receptors from in vivo alkylation by N-ethoxycarbonyl-2-ethoxy-1, 2-dihydroxyquinoline. That its effect was due to blockade of brain rather than peripheral receptors was shown by the finding that intraperitoneal doses of terazosin three to 66 times greater than the maximal intraventricular dose produced less behavioral inhibition. Intraventricular terazosin also produced hypothermia and a reduced respiratory rate suggestive of a reduced sympathetic outflow. However, external heat did not affect the inactivity, and captopril, a hypotensive agent, did not mimic it. Terazosin did not impair performance on a horizontal wire test or the ability to make co-ordinated movements in a swim test suggesting that its activity-reducing effect was not due to sedation and may have a motivational or sensory gating component. It is concluded that central alpha 1-noradrenergic neurotransmission is required for behavioral activation to environmental change in the mouse and may operate on sensorimotor and motivational processes. Neuroscience. 1999;94(4):1245-52.

Absorption, Distribution and Excretion
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.

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Metabolism / Metabolites
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

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Biological Half-Life
Terazosin has a mean half life 12 hours though this can be as high as 14 hours in patients over 70 years and as low as 11.4 hours in patients 20 to 39 years old.

Toxicity Summary
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.

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Hepatotoxicity
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.
Likelihood score: E (unlikely cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Because no information is available on the use of terazosin during breastfeeding, an alternate drug may be preferred, especially while nursing a newborn or preterm infant.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information in nursing mothers was not found as of the revision date. However, the pharmacologically similar drug prazosin does not affect serum prolactin concentration in patients with hypertension. The prolactin level in a mother with established lactation may not affect her ability to breastfeed.

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Protein Binding
90-94%.

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Toxicity Data
LD50: 259.3mg/kg (parental-intravenous, Mouse) (A308)

[1]. Drugs for treatment of benign prostatic hyperplasia: affinity comparison at cloned alpha 1-adrenoceptor subtypes and in human prostate. J Auton Pharmacol. 1996 Feb;16(1):21-8.

[2]. Pharmacological tolerance to alpha 1-adrenergic receptor antagonism mediated by terazosin in humans. J Clin Invest. 1992 Nov;90(5):1763-8.

[3]. Efficacy of combination terazosin and nifedipine therapy in postoperative treatment of distal ureteral stones after transurethral ureteroscopic lithotripsy. J Int Med Res. 2020 Apr;48(4):300060520904851.

Terazosin is a member of quinazolines, a member of piperazines, a member of furans and a primary amino compound. It has a role as an antineoplastic agent, an antihypertensive agent and an alpha-adrenergic antagonist.
Terazosin is a quinazoline derivative alpha-1-selective adrenergic blocking agent indicated for benign prostatic hyperplasia and hypertension. Terazosin blocks adrenaline's action on alpha-1 adrenergic receptors, causing relaxation of smooth muscle in blood vessels and the prostate.
Terazosin is an alpha-Adrenergic Blocker. The mechanism of action of terazosin is as an Adrenergic alpha-Antagonist.
Terazosin is a nonselective alpha-1 adrenergic antagonist used in the therapy of hypertension and benign prostatic hypertrophy. Terazosin therapy is associated with a low rate of transient serum aminotransferase elevations and to rare instances of clinically apparent acute liver injury.
Terazosin is a selective alpha 1 antagonist used for treatment of symptoms of prostate enlargement (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.
See also: Terazosin Hydrochloride (has salt form).

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Drug Indication
Terazosin is indicated for use in treating symptomatic benign prostatic hyperplasia and hypertension.
FDA Label

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Mechanism of Action
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.

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Pharmacodynamics
Terazosin is a quinazoline derivative alpha-1-selective adrenergic blocker.

C19H25N5O4ELEMENTALANALYSIS

387.43

387.191

63590-64-7

Terazosin hydrochloride dihydrate;70024-40-7;(R)-Terazosin;109351-34-0;(S)-Terazosin;109351-33-9;Terazosin hydrochloride;63074-08-8;Terazosin-d8;1006718-20-2

5401

Typically exists as solid at room temperature

1.332 g/cm3

664.5ºC at 760 mmHg

281-283°C

355.7ºC

1.64

1

8

4

28

544

0

VCKUSRYTPJJLNI-UHFFFAOYSA-N

InChI=1S/C19H25N5O4/c1-26-15-10-12-13(11-16(15)27-2)21-19(22-17(12)20)24-7-5-23(6-8-24)18(25)14-4-3-9-28-14/h10-11,14H,3-9H2,1-2H3,(H2,20,21,22)

[4-(4-amino-6,7-dimethoxyquinazolin-2-yl)piperazin-1-yl]-(oxolan-2-yl)methanone

Vasocard; terazosin; 63590-64-7; Terazosine; Fosfomic; Blavin; Flumarc; Vasomet; Terazosina; Hytrin

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)