On-Line SPE on Restricted Access Adsorbent for HPLC-MS/MS Analysis of Felodipine in Plasma Samples

Validated RP-HPLC method for quantification of felodipine in rabbit plasma: Application in a bioequivalence study

OBJECTIVE

The aim of present study was to develop a simple, rapid, selective, sensitive and robust reverse phase high performance liquid chromatographic method for quantification of felodipine in rabbit plasma at the wavelength of 360nm.

METHOD

Protein was precipitated from rabbit plasma sample by addition of acetonitrile as a vehicle. An isocratic elution of samples was performed on capcell pak C₈ DD S5 column (4.6mm×250mm particle size 5μm) column with mobile phase consisting 5mM Phosphate Buffer (pH 4.8 adjusted with dilute ortho-phosphoric acid solution): acetonitrile (25:75:v/v) delivered at flow rate 1.0mLmin^-1.

RESULT

A good linear response was achieved over the range of 0.25-20.00μgmL^-1. LODs and LOQs for felodipine were found to be 0.055 and 0.201μgmL^-1, respectively. The method was quantitatively evaluated in terms of linearity, precision, accuracy (recovery), selectivity robustness and stability study as per standard guidelines. The validated RP-HPLC method was successfully applied for the bioavailability studies of felodipine. The pharmacokinetic parameters were calculated for all the investigated drugs in rabbit after single-dose administrations of pure drug and formulation of felodipine. Finally, the obtained results for the application of the proposed RP-HPLC method proved its efficiency to be applied to the therapeutic drug monitoring (TDM) and bioequivalence (BE) studies.

CONCLUSION

Thus, developed method is simple, convenient and suitable for the analysis of felodipine in bulk and pharmaceutical formulations.

Alternative sample diluents in bioanalytical LC–MS

The problem of sample diluent in bioanalytical LC–MS is reviewed with a special focus on large-volume injections and non-miscible solvents with mobile phase components. These issues are related to the sample preparation approach, which in many instances provides the sample diluent before injecting this into the chromatographic column. The sample volume influences the quantitation limit of the chromatographic method, while its nature may influence the retention process of the injected analytes. The literature reports a few papers that are focused on alternative sample diluents in bioanalytical LC–MS that are generally non-miscible with mobile phase. The principle of this approach and some of its current bioanalytical applications from literature are discussed. However, more applications and more publications from HPLC users and vendors are expected in this field, which could prove its analytical importance and potential in bioanalysis.