LAUSR

PurposeSensitive and selective analytical method is required for the estimation of ramipril in human plasma as ramipril has been reported to have high intra-subject variability and phase II inactive metabolite (ramipril acyl glucuronide) back-converted to ramipril in an in vitro system. If this back conversion is not restricted, it could lead to pseudo estimation of ramipril in human plasma.MethodA specific, sensitive, and reproducible high-performance liquid chromatography-tandem mass spectrometric method was developed and validated for determination of ramipril in human plasma, using ramipril-d5 as an internal standard. Ramipril and ramipril-d5 were extracted from human plasma using solid-phase extraction, and compounds are separated on a Luna C18 (2) 100A (150 × 4.6 mm, 5 μm) column with a mobile phase consisting of methanol and ammonium acetate buffer (pH 4.5; 5 mM) (85:15, v/v). Quantification was achieved by monitoring transitions of m/z 415.6 → 154.0 for ramipril and 420.3 → 154.0 for ramipril-d5 in multiple reaction monitoring, using a turbo ion source in negative polarity.ResultsNo matrix effect was observed within the linearity range of 50.3–32,850.6 pg/mL (r > 0.999). The degree of the matrix effect for ramipril was determined as 3.5%, and it had no impact on incurred sample analysis with run time of 7.0 min. The intra- and inter-day precision values were within 5.2 and 5.0%, respectively, for ramipril at the lower limit of quantification level.ConclusionsStability data indicated that ramipril and ramipril acyl glucuronide are stable under various handling conditions and back conversion was not taken place for ramipril acyl glucuronide. The method was successfully applied for the bioequivalence study of ramipril after oral administration of 2.5 mg capsule in healthy Indian volunteers.