Thesis (M.Sc. in Pharm)--Chulalongkorn University, 2004

The simultaneous determination of chlorzoxazone and paracetamol in pharmaceutical preparation are simple and rapid method by principal component regression (PCR) and partial least-squares (PLS) regression were performed. In this study both of PCR and PLS are successfully applied to quantify both drugs using the information obtained from ultraviolet absorption spectra of appropriate solutions. The concentration ranges used to construct the calibration set were varied between 3.7185-18.5925 and 4.6650-23.3250 μg/ml for chlorzoxazone and paracetamol, respectively. The absorbances were measured in the wavelength range of 270-295 nm (2 principal components) for chlorzoxazone using PCR and PLS and 230-270 nm (3 principal components), 230-350 nm (2 principal components) for paracetamol using PCR, and PLS respectively. The methods were validated and linearity was found in range 1-50 μg/ml (chlorzoxazone) and 0-30 μg/ml (paracetamol) with good accuracy and precision, not more than 2 % RSD and the percentage of average recovery of both drugs using both methods were nonstatistically significant. Applying two algorithms to the calibration set, the calibration data were modeled and results were applied to two different commercial tablets containing chlorzoxazone and paracetamol were analyzed. The results obtained from application of two methods were satisfactory. The studied methods were proved to be suitable for determination of the two drugs in tablets without extraction. Thus, the developed method can be applied successfully in quantitative analysis of other pharmaceutical preparations in the market.