Chemometrical Approach in Fosinopril-Sodium and its Degradation Product Fosinoprilat Analysis

A sensitive and efficient LC-MS/MS method for the bioanalysis of fosinopril diacid from human plasma and its application for a bioequivalence study in humans

Fosinopril diacid is an angiotensin converting enzyme inhibitor with efficient antihypertensive action. It is an active metabolic product formed in the body from hydrolysis of its prodrug Fosinopril. A sensitive, rapid method with high recovery for Fosinopril diacid from human plasma was developed. Solid-phase extraction technique employing Waters Oasis SPE cartridges gave clean samples with very high recovery of 97%. The analyte along with its internal standard (Benazepril hydrochloride) were chromatographed on an XTerra RP₈ column (4.6 × 50 mm, 5 μm) using methanol-ammonium acetate buffer (10 mm; 90:10, v/v) as the mobile phase. A triple quadrupole mass spectrometer equipped with electrospray ionization source operated in the negative ion mode was used for detection. Multiple reaction monitoring scan mode was used for monitoring the transitions from m/z 434.00 → 237.15 for Fosinopril diacid and m/z 423.10 → 174.00 for Benazepril hydrochloride. Beer-Lambert's law was obeyed in the range of 0.50-1,500.00 ng/ml (r = 0.9993). The stability of the drugs in human plasma and in stock solution was proved by performing stability tests as per US Food and Drug Administration guidelines. The method was successfully applied for a bioequivalence study of Fosinopril diacid in 36 healthy, adult, male volunteers under fasting conditions.

Microemulsion liquid chromatographic method for characterisation of fosinopril sodium and fosinoprilat separation with chemometrical support

The properties of the eluent are the essential factors governing the efficiency in the high-performance liquid chromatography (HPLC) method. A novel approach in retention modelling in the liquid chromatographic separation of fosinopril sodium and its degradation product, fosinoprilat, applying a microemulsion as the mobile phase, was used. The modifications of the mobile phase included the changes to the type of the lipophilic phase, the type and concentration of co-surfactant and surfactant, as well as the pH of the mobile phase. In this study, a full factorial 2(3) design, as the optimal method for screening of the experiment, was applied for selecting factors which had an influence on separation. Optimisation was done by a central composite design. An appropriate resolution with reasonable retention times was obtained with a microemulsion containing 0.9% w/w of cyclohexane, 2.2% w/w of sodium dodecyl sulphate (SDS), 8.0% w/w of n-butanol and 88.9% of aqueous 25 mM disodium phosphate, the pH of which was adjusted to 2.8 with 85% orthophosphoric acid. Separations were performed on an X-Terra 50-mmx4.6-mm, 3.5-mum particle size column at 30 degrees C. UV detection was performed at 220 nm and with a flow rate of 0.3 mL min(-1). The established method was validated and applied for analysis of appropriate tablets. The proposed chromatographic procedure for the separation of fosinopril sodium and its degradation product is less expensive compared with the conventional reversed-phase HPLC method, as well as being simple and rapid. The optimised and validated method can be used for separation, identification and simultaneous determination of fosinopril sodium and fosinoprilat in bulk drug and in pharmaceutical dose forms.