Simultaneous determination of plasma lopinavir and ritonavir by chemometrics-assisted spectrophotometry and comparison with HPLC method

Chemometrics-assisted spectrophotometry for the determination of two protease inhibitors, lopinavir and ritonavir, in plasma was evaluated. A set of calibration mixtures (calibration set) was designed according to central composite design. The UV spectra obtained from the calibration set were subjected to partial least square regression (PLS-1) to construct the prediction models for lopinavir and ritonavir in unknown samples, which were then validated in a randomly selected set of synthetic mixtures of the drugs. An optimum model was obtained in the wavelength ranges of 215-249 nm and 240-279 nm with principal components 8 for both lopinavir and ritonavir respectively. The prediction models were used to analyse the two drugs in plasma and the results were compared with those obtained by high-performance liquid chromatography (HPLC). The PLS-1 model and the HPLC method were found to be comparable.