Ratio Derivative S~ectrophotometricM ethod for the Determination of Some Oxicams in Presence of their Alkaline Dearadation Products

A new spectrophotometric method has been developed for the determination of some oxicams namely, lornoxicam (LX) , tenoxicam (TX) and meloxicam (MX), in the presence of their main alkaline degradation products, 2-aminopyridine ( I ) and 2-amino-5-methylthiazole (II) for (TX&MX), 2-aminopyridine and TX for lornoxicam. The method is based on the use of the first derivative of the ratio spectra (¹DD) of the mentioned compounds and their corresponding degradates. The procedure does not require any separation steps. Linear calibration graphs of ¹DD were obtained by measurement of the amplitudes at 316, 249 and 260nm for LX, 248.8 , 258.8 nm for TX and 287.2nm for MX. On carrying out measurements at the above mentioned wavelengths, the linearity range is found to be 2.5 - 35 μg ml^-1 for LX and TX, 1.25 - 30 μg ml^-1 for MX. The validity of the method was assessed by applying the standard addition technique. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The suggested procedure could be used for the determination of the above mentioned drugs in pure and dosage forms as well as in presence of their degradation products.