Fosinoprilat API is the pharmacologically active phosphinic-acid metabolite of fosinopril. It is an angiotensin-converting enzyme (ACE) inhibitor and is responsible for the pharmacological activity produced after enzymatic hydrolysis of the ester prodrug fosinopril. Fosinoprilat has CAS Number 95399-71-6, molecular formula C₂₃H₃₄NO₅P, and molecular weight 435.49 g/mol.
Fosinoprilat is chemically identified as (2S,4S)-4-cyclohexyl-1-[2-[hydroxy(4-phenylbutyl)phosphoryl]acetyl]pyrrolidine-2-carboxylic acid. It contains a phosphinic acid group that participates in binding to the active site of angiotensin-converting enzyme.
| Property | Value |
|---|---|
| CAS Number | 95399-71-6 |
| Molecular Formula | C₂₃H₃₄NO₅P |
| Molecular Weight | 435.49 g/mol |
| Chemical Class | Phosphinic acid / ACE inhibitor |
| Stereochemistry | (2S,4S) |
| Appearance | White to off-white solid |
Fosinoprilat is also known as fosinopril diacid, fosinoprilic acid, and fosfenopril.
Fosinoprilat is available as a USP pharmaceutical primary reference standard and is identified as Fosinopril Related Compound A in the USP reference-standard system.
Important: Fosinoprilat should not be confused with Fosinopril Sodium. Fosinopril Sodium is the ester prodrug and has a different CAS number, formula and molecular weight. The USP monograph for Fosinopril Sodium specifies 97.5%–102.0%, but that assay must not be transferred to Fosinoprilat.
Fosinoprilat is the active metabolite of fosinopril and acts as a specific competitive inhibitor of angiotensin-converting enzyme. ACE inhibition decreases formation of angiotensin II and contributes to the antihypertensive effect of fosinopril.
| Parameter | Specification |
|---|---|
| Appearance | White to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 10 ppm |
| pH (1% Solution) | 5.5 – 6.5 |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |