Terazosin Hydrochloride

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Cat Number

API0232207

CAS Number

70024-40-7

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CAS Number

70024-40-7

Storage

Store at room temperature

Synonyms

Urodie; Itrin; Hytracin; Abbott-45975; TEZRULY; 1-(4-Amino-6,7-dimethoxy-2-quinazolinyl)-4-(tetrahydro-2-furoyl)piperazine monohydrochloride dihydrate; D32S14F082

Molecular Formula

C19H30ClN5O6

Molecular Weight

459.9

Smiles

COC1=C(C=C2C(=C1)C(=NC(=N2)N3CCN(CC3)C(=O)C4CCCO4)N)OC.O.O.Cl

Appearance

White, crystalline substance

Melting Point

281-283°C

Boiling Point

664.5°C at 760 mmHg

Relative Density

1.332

General Description

Terazosin hydrochloride is a selective alpha‑1 adrenergic receptor antagonist belonging to the quinazoline class, with a piperazine ring and a furanyl group. Its chemical structure is 1‑(4‑amino‑6,7‑dimethoxy‑2‑quinazolinyl)‑4‑[(tetrahydro‑2‑furanyl)carbonyl]piperazine hydrochloride, and it is a white to off‑white powder.

Mechanism of Action

Terazosin binds selectively to alpha‑1 receptors on the smooth muscle of the prostate, bladder neck, and vasculature, blocking the vasoconstrictor effects of norepinephrine. This causes relaxation of the smooth muscle, leading to improved urinary flow and decreased peripheral vascular resistance. The drug has a longer duration of action than prazosin and is effective as a once‑daily agent.

Application

Terazosin is indicated for the treatment of benign prostatic hyperplasia (BPH) and for the management of hypertension. In BPH, it improves symptoms of urinary obstruction and reduces the need for surgery. In hypertension, it lowers blood pressure by reducing total peripheral resistance. The drug is associated with a higher risk of orthostatic hypotension and syncope, particularly at initial doses.

Terazosin (TZ), an α₁-adrenergic antagonist, alleviated organ damage and improved survival in rodent models of stroke and sepsis. Through enzymology and X-ray crystallography, TZ was found to bind and activate phosphoglycerate kinase 1 (Pgk1), probably promoting ATP release. ATP enhances Hsp90 chaperone activity, promoting multistress resistance. TZ has a new target, Pgk1, and may be repurposed for stroke and sepsis.

Fig. 1 Crystal structure of Pgk1 and TZ binding. (Chen X, et al., 2015)

References

Chen X, et al. Terazosin activates Pgk1 and Hsp90 to promote stress resistance. Nat Chem Biol. 2015;11(1):19-25.

A transdermal iontophoresis delivery system for terazosin hydrochloride (IDDS‑TEH) was developed. Steady‑state penetration increased with current intensity (80.36 to 304.93 µg·cm⁻²·h⁻¹) and was influenced by pH. In spontaneously hypertensive rats, IDDS‑TEH achieved significantly higher blood concentrations (AUC: 5873 vs 2493 ng·mL⁻¹·h for high vs low current) and reduced blood pressure compared to passive diffusion.

Fig. 2 Effect of pH and NaCl concentrations on the penetration of IDDS-TEH. (Jiang C, et al., 2021)

References

Jiang C, et al. Transdermal iontophoresis delivery system for terazosin hydrochloride: an in vitro and in vivo study. Drug Deliv. 2021;28(1):454-462.

Does Terazosin Hydrochloride require protection from light during long-term storage?

Yes, it is photosensitive. UV exposure can cause photodegradation and discoloration of the quinazoline ring. Store in light-resistant containers, preferably amber glass.

What is the recommended storage temperature for Terazosin Hydrochloride?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can accelerate oxidative degradation of the piperazine ring.

Is Terazosin Hydrochloride stable under high-humidity conditions?

It is slightly hygroscopic. Under high humidity (>70% RH), it may absorb moisture and clump. Storage in tightly sealed containers with desiccant is recommended.

How is the impurity terazosin N-oxide (an oxidative degradation product) monitored?

This degradation product is quantified using a stability-indicating HPLC method, ensuring it remains within pharmacopoeial limits.