Stability indicating spectrophotometric methods for determination of Tiemonium methylsulphate in the presence of its degradation products.

Simple, selective and sensitive stability indicating spectrophotometric methods have been developed and validated for Tiemonium methylsulphate (TIM) determination in pharmaceutical dosage form. Method A, isoabsorptive point comprised of measurement the total content of the mixture of TIM and its acid degradation product at 250 nm, while the content of acid degradation product was determined by measuring the peak amplitude of the 2D at 295.6nm, then TIM concentration can be determined by subtraction. Method B, the first derivative of ratio spectra was applied by measuring amplitudes of TIM at 224.4 nm and 247.2 nm using 20μg/mL of acid degradation product as a divisor. Method C is the ratio subtraction method. While method D is based on the measurement of first derivative amplitudes of TIM at the zero crossing point of its oxidative degradation product at 250 nm. The percentages mean accuracy for TIM was 100.39±0.33 for method A, 100.59±0.57 and 100.40±0.56 for B, 100.47±0.54% for C and 100.24±0.58% for D methods. The developed methods were validated as per International Conference of Harmonization guidelines. Furthermore, elucidation of the degradation pathway is described based on the use of the infrared spectroscopy and HPLC/MS techniques.

Stability indicating chromatographic techniques for the determination of pipoxolan HCl.

Two simple, accurate and sensitive methods were developed for the determination of pipoxolan HCl in presence of its degradation product. HPLC method (A), performed on C18 column using acetonitrile: 1mM ammonium acetate (80:20 v/v) as a mobile phase with a flow rate of 1.8ml/min. Detection was performed at 210 nm. TLCdensitometric method (B), using silica gel 60 F254 plates; the optimized mobile phase was chloroform: toluene: methanol: 10% ammonia (6:5:3:0.1 v/v). Quantitatively the spots were scanned densitometrically at 210 nm. Linearity ranges were 1 – 10 μg/ml for method A and 2-20 μg/band for method B, with mean percentage recoveries 99.38±0.672% and 99.32±0.97% for methods A and B, respectively. The proposed methods were found to be specific for pipoxolan HCl in presence of up to 90% of its degradation product. Statistical comparison between the results obtained by these methods and the manufacturer’s method was done,and it was found that there was no significant differences between them.