Compatibility Studies of Montelukast with Pharmaceutical Excipients used in Tablet Formulations using Thermal and Chromatographic Techniques

Differential Scanning Calorimetry (DSC) and Isothermal Stress Testing (IST) were carried out to screen compatibility of montelukast (MNLT) with some currently employed pharmaceutical excipients. Initially, DSC thermogram was used to screen MNLT-excipients compatibility. Thermal Gravimetry analysis (TGA) thermogram and Fourier Transform Infra Red (FTIR) spectrum of binary mixture of MNLT-excipients were also compared with that of pure MNLT and excipients. Isothermal stress testing was carried out by storing MNLT-excipient binary mixture (1:1 w/w) for 3 weeks under 500 C. Based on the results of DSC, IR, TGA and HPLC, commenly used excipients were found to be compatible with MNLT excluding citric acid which exhibited interaction with montelukast.