Development and validation of molnupiravir assessment in bulk powder and pharmaceutical formulation by the RP-HPLC-UV method.

An accurate, sensitive and selective RP-HPLC-UV method has been established for the estimation of Molnupiravir (MOL) in pure bulk powder and pharmaceutical formulation. Separation was achieved on an Inertsil C18 column (150.0 mm × 4.6 mm, 5.0 µm), using a mobile phase of 20 mM phosphate buffer pH 2.5 : acetonitrile (80 : 20, v/v%) in isocratic mode with a flow rate of 1.0 mL min-1. The λ max of MOL prepared in the chosen diluent (ethanol : water in equal proportions) was found to be 230.0 nm. The constructed calibration curve was found to be linear in the concentration range of 0.2-80.0 µg mL-1. The recovery% of MOL using the proposed method was 100.29%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.04 µg mL-1 and 0.12 µg mL-1, respectively. No significant interference was detected in the presence of the common pharmaceutical formulation excipients. The method was validated following the ICH recommendations. All the obtained results were statistically compared with those using reported methods and there were no significant differences. The method developed in this work was successfully employed for the assessment of MOL in bulk powder and pharmaceutical formulation.

Simultaneous determination of Avanafil and Dapoxetine in human plasma using liquid chromatography/tandem mass spectrometry (LC-MS/MS) based on a protein precipitation technique.

A rapid and selective LC-MS/MS method is described for the simultaneous assay of Avanafil and Dapoxetine in human plasma via a protein precipitation (PP) sample preparation technique. Tadalafil was chosen as the internal standard reaching good recovery and reproducibility while diminishing the effects of the matrix. An Agilent Zorbax Eclipse XDB C18 column (4.6 × 50 mm, 1.8 µm) was used for the chromatographic separation and analysis, while 0.1% formic acid : acetonitrile (60 : 40, v/v) was utilized at a flow rate of 0.5 mL min-1. It was revealed that 6 min stop time accomplished the best separation. The assay was linear over the range of 10-6000 ng mL-1 for both drugs. The established bio-analytical method validation was demonstrated following US-FDA recommendations including sensitivity, selectivity, linearity, accuracy and precision. Furthermore, other validation parameters were assessed such as the dilution integrity, matrix effect, carryover, and analyte stability during both short- and long-term sample processing and storage. The adopted method was efficaciously applied to a clinical study for the concurrent determination of Avanafil and Dapoxetine in human plasma.