A simple, specific, accurate and precise reverse phase high pressure liquid
chromatographic method has been developed for the simultaneous determination
of Paracetamol and Lornoxicam from tablets and to characterize degradation
products of Lornoxicam by reverse phase C18 column (Inertsil ODS 3V C-18, 250
x 4.6 mm, 5 ?). The sample was analyzed using Buffer (0.02504 Molar):
Methanol in the ratio of 45:55, as a mobile phase at a flow rate of 1.5
mL/min and detection at 290 nm. The retention time for Paracetamol and
Lornoxicam was found to be 2.45 and 9.40 min respectively. The method can be
used for estimation of combination of these drugs in tablets. The method was
validated as per ICH guidelines. The linearity of developed method was
achieved in the range of 249.09 - 747.29 ?g/mL (r2=0.9999) for Paracetamol
and 4.0125 - 12.0375 ?g/mL (r2=0.9999) for Lornoxicam. Recoveries from
tablets were between 98 and 102%. The method was validated with respect to
linearity, accuracy, precision, robustness and forced degradation studies
which further proved the stability-indicating power. During the forced
degradation studies lornoxicam was observed to be labile to alkaline
hydrolytic stress and oxidative stress (in the solution form). However, it
was stable to the acid hydrolytic, photolytic and thermal stress (in both
solid and solution form). The degraded products formed were investigated by
electrospray ionization (ESI) time-of-flight mass spectrometry, NMR and IR
spectroscopy. A possible degradation pathway was outlined based on the
results. The method was found to be sensitive with a detection limit of 0.193
?g/ml, 2.768 ?g/ml and a quantitation limit of 0.638 ?g/ml, 9.137 ?g/ml for
lornoxicam and paracetamol, respectively. Due to these attributes, the
proposed method could be used for routine quality control analysis of these
drugs in combined dosage forms.
Forced Degradation Studies of Drospirenone: Isolation and Characterization of Degradation Products