Mean percentage recovery was determined. Specificity The absence of any secondary spot having spectra different from LORN and PCM in the typical constituted placebo chromatogram of the tablet preparation, which may interfere with LORN and PCM peak, indicates the specificity find protocol of the analytical method. Limit of detection and limit of quantitation The limit of detection (LOD) and limit of quantitation (LOQ) were obtained by calculating using the standard formula as per the ICH guidelines, LOD=3.3��(��/S),LOQ=10��(��/S). Where �� is Standard deviation of the response and S is slope of the calibration curve. Formulation analysis Ten combined tablets of two different LORN and PCM tablet samples Lornasafe-plus and Lorsaid-P were finely powdered and powder equivalent to 1000 mg of PCM and 16 mg of LORN was dissolved in acetonitrile to obtain 100 ml stock solution (10 000:160 ��g/ml).
It was sonicated and filtered through the milipore filter and further diluted with acetonitrile to get final concentration. RESULTS AND DISCUSSION Development of the optimum mobile phase Different mobile phases were tried to resolve LORN and PCM. The optimum results were obtained with mobile phase consisting of toluene: chloroform: methanol: formic acid (3:5:1.5:0.2 v/v/v/v). The Rf values of LORN and PCM peak were observed about 0.75 �� 0.02 and 0.57 �� 0.02, respectively. The representative densitogram is given in [Figure 1]. Figure 1 HPTLC densitogram of Paracetamol (PCM) and Lornoxicam (LORN).
Validation of the developed stability-indicating method Linearity The response for the drugs was found to be linear in the concentration range 160�C560 ng/band for LORN and 10 000�C35 000 ng/band for PCM with correlation coefficient of 0.995 and 0.997, respectively. The linear regression equation obtained are y = 0.901(x) + 335.4 and y = 0.062(x) + 1023 for LORN and PCM, respectively [Table 1]. Table 1 Calibration data for linearity Precision The % RSD values for intraday precision study were found to be not AV-951 more than 1.95% and 1.44% for LORN and PCM, respectively and for interday precision were found to be not more than 1.98% and 1.95% for LORN and PCM, respectively, thus confirming precision of the method [Table 2]. Table 2 System precision of the analytical method Accuracy Excellent recoveries were obtained at each level of added concentration. The results obtained (n = 3 for each 80%, 100%, 150% level) indicated the mean recovery for LORN 98.67�C99.06% and for PCM 99.14�C101.77% [Table 3]. Table 3 Recovery study of the analytical method Limit of detection The LOD as calculated by standard formula as given in ICH guidelines was found to be 63 ng/band and 1478 ng/band for LORN and PCM, respectively.