ABSTRACT
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.