Telmisartan

CAS No.: 144701-48-4
Synonyms: 4′-[(1,4′-Dimethyl-2′-propyl[2,6′-bi-1H-benzimidazol]-1′-yl)methyl]-[1,1′-biphenyl]-2-carboxylic acid
Target: Angiotensin II receptor (AT1)

Product Attributes

Attribute	Details
Molecular Formula	C33H30N4O2
Molecular Weight	514.62
Appearance	White or off-white crystalline powder
Odor	Odorless
Purity (Pharmacopeial)	99.0%–101.0% (dried basis, JP); USP: 98.0%–102.0%
Melting Point	261–263°C
Solubility	Soluble in chloroform; slightly soluble in dichloromethane or DMF; sparingly soluble in methanol; very slightly soluble in ethanol; practically insoluble in water; freely soluble in 1 mol/L NaOH
Storage	Cool, dry place, protected from light; sealed container

Note on Molecular Weight: USP and JP both list 514.62. Some commercial supplier listings report 514.63 or 514.617 due to rounding differences; 514.62 is the pharmacopeial reference value.

Biological Activity & Mechanism

Telmisartan is a non-peptide angiotensin II receptor blocker (ARB) with high selectivity for the AT1 receptor subtype.

Binding Selectivity: Telmisartan exhibits approximately 3,000-fold higher affinity for AT1 receptors than for AT2 receptors, with no partial agonist activity at the AT1 site.

Mechanism of Action: Telmisartan selectively antagonizes angiotensin II binding to AT1 receptors in vascular smooth muscle and adrenal gland, thereby inhibiting angiotensin II-induced vasoconstriction and aldosterone secretion. This leads to reduced sodium and water reabsorption and decreased blood pressure. Unlike ACE inhibitors, telmisartan does not inhibit the enzyme responsible for bradykinin degradation, which may account for its lower incidence of dry cough.

Additional Activity: Telmisartan is also a selective modulator of peroxisome proliferator-activated receptor gamma (PPARγ), a regulator of glucose metabolism, which distinguishes it pharmacologically from other ARBs.

Pharmacodynamic Profile: The antihypertensive effect becomes apparent within 3 hours of the first dose, with maximal effect achieved after 4 weeks of therapy. The inhibitory effect on angiotensin II-induced pressor response persists for 24 hours and remains measurable at 48 hours. Abrupt discontinuation does not produce rebound hypertension.

Pharmacokinetics (Clinical Reference)

Parameter	Value
Plasma Protein Binding	>99.5% (primarily albumin and α1-acid glycoprotein)
Volume of Distribution	Approximately 500 L
Metabolism	Conjugation to inactive acyl glucuronide; not metabolized by cytochrome P450 isoenzymes
Elimination	>97% excreted unchanged in feces via biliary excretion; <1% in urine
Total Plasma Clearance	>800 mL/min

Hepatic Impairment: Plasma concentrations are increased; absolute bioavailability approaches 100%.

Gender Difference: Plasma concentrations are generally 2–3 times higher in females than in males, though no dosage adjustment is required based on clinical trial data.

Quality Specification Highlights (Pharmacopeial)

Identification (JP/ChP):

• Iodobismuthate test: brownish-yellow precipitate forms

• UV absorption: maxima at 228 nm and 290 nm; minimum at 268 nm

• IR spectrum should correspond to the reference spectrum

Related Substances: HPLC method with C18 column; gradient elution using methanol and phosphate buffer (pH 5.0); detection at 230 nm. Limit for impurity I (4′-bromomethyl-biphenyl-2-carboxylate) controlled.

Handling & Storage Precautions

• For research or pharmaceutical manufacturing use only. Not for direct human administration without appropriate formulation.

• Store in a tightly closed container in a cool, dry place away from light.

• Telmisartan is practically insoluble in water; for analytical or formulation purposes, dissolution in 1 mol/L NaOH or organic solvents (chloroform, DMF) is recommended.

• Reproductive Toxicity Warning (Clinical Reference): Drugs acting on the renin-angiotensin system can cause injury and death to the developing fetus. Telmisartan should be discontinued as soon as pregnancy is detected.

Data Verification Summary

Verification Item	Sources	Conclusion
CAS–Name correspondence	USP / JP / ChemicalBook	Consistent; CAS 144701-48-4 verified
Molecular Formula / Weight	USP / JP / GuideChem	C??H??N?O? / 514.62, consistent
Purity Standard	JP / USP	JP: 99.0–101.0%; USP: 98.0–102.0%
Mechanism / AT1 Selectivity	Made-in-China supplier data / ChemicalBook	AT1 antagonist, ~3000-fold selectivity over AT2
Pharmacokinetics	DailyMed (FDA labeling)	Protein binding, metabolism, elimination data from approved labeling

Data Discrepancy Noted: One Made-in-China listing states “State: Liquid” in its basic information section, which contradicts the established crystalline powder form of telmisartan. This has been disregarded as a listing error; the pharmacopeial description (white or off-white crystalline powder) is authoritative.

Supplier Note: Alibaba International and Made-in-China listings were consulted for commercial specification patterns (purity grades, packaging, certifications) but were not used as primary sources for physicochemical or pharmacological data due to inconsistent quality. Pharmacopeial (USP/JP) and FDA labeling data were prioritized for accuracy.