Quinaprilat is the active dicarboxylic acid metabolite of quinapril and belongs to the angiotensin-converting enzyme (ACE) inhibitor class. Quinapril is converted by deesterification to quinaprilat, which is responsible for the principal ACE-inhibitory pharmacological activity.
Quinaprilat is a synthetic dicarboxylic acid and peptidyl-dipeptidase A inhibitor. It inhibits ACE, reducing the conversion of angiotensin I to the vasoconstrictor angiotensin II.
These chemical identity and physicochemical values are reported by PubChem.
Quinaprilat is classified as an ACE inhibitor and antihypertensive agent. It acts by inhibiting angiotensin-converting enzyme, also known as peptidyl-dipeptidase A.
Quinaprilat inhibits angiotensin-converting enzyme (ACE), preventing the conversion of angiotensin I into angiotensin II.
Reduced angiotensin II formation decreases vasoconstriction and reduces aldosterone-mediated sodium and fluid retention. ACE also functions as kininase II, an enzyme involved in bradykinin degradation; therefore, ACE inhibition can additionally influence bradykinin levels.
Quinapril itself is a prodrug and is deesterified after absorption to form quinaprilat. Current U.S. labeling identifies quinaprilat as the principal active metabolite of quinapril.
Quinaprilat is principally relevant as:
Quinapril-containing pharmaceutical products are used for hypertension and congestive heart failure, with quinaprilat providing the principal ACE-inhibitory activity.
Quinaprilat is a dicarboxylic acid with molecular weight 410.50 g/mol. PubChem reports a calculated XLogP3-AA of 0.5 and a topological polar surface area of 107 Ų.
A hydrate form is also separately identified as Quinaprilat hydrate, CAS 1435786-09-6, with molecular formula C₂₃H₂₈N₂O₆ and molecular weight 428.5 g/mol. The anhydrous/free-acid form and hydrate should therefore not be treated as interchangeable for CMS chemical specifications.
Quinaprilat API/reference material can be characterized using:
Chromatographic analysis is particularly important for distinguishing Quinaprilat from quinapril and controlling process-related or degradation impurities.
Quality control should address:
Because Quinaprilat is structurally and stereochemically defined, analytical control should ensure that the intended chemical form is maintained throughout manufacturing and storage.
Important: I could not verify a current publicly accessible USP/Ph. Eur. API monograph providing universal numerical assay and impurity limits specifically for Quinaprilat. Therefore, unsupported limits should not be presented as universal release specifications.
Quinaprilat has three defined stereocenters, corresponding to the stereochemical configuration represented in its PubChem structure and IUPAC name as (3S,2S,1S). Its InChI explicitly specifies three stereochemical centers.
Stereochemical purity can therefore be an important quality attribute for Quinaprilat, particularly where the API is manufactured as a defined stereochemical form.
Storage conditions should be established using validated stability data for the specific Quinaprilat form, including whether the material is anhydrous or hydrated.
Recommended handling practices include:
Typical pharmaceutical API documentation may include:
Quinaprilat manufacturing requires controlled chemical synthesis, purification, isolation and analytical characterization. Particular attention should be given to stereochemical integrity, carboxylic-acid form, impurity control and hydrate/solvate state.
Where Quinaprilat is intended as a pharmaceutical API or reference material, the final material should comply with the applicable registered or customer-approved specification.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.2% |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.50% |
| Water Content | NMT 0.5% |