Application of TA and kinetic study to compatibility and stability problems in some commercial drugs. Remarks on statistical data

A thermal analysis and kinetic study on decomposition processes of some com mercial drugs have been carried out to find their thermal stability. DSC/TG curves of some commercial drugs were compared with those of their ac tive components, the excipients, the active component/excipient and the exc ipient/excipient mixtures. A kinetic study was carried out using both isothermal and dynamic TG curves . Both active components and commercial drugs tested show a first order dec omposition mechanism. The kinetic data showed that excipients cause a decre ase of the kinetic stability of the active components. Statistical analysis allowed us to select reliable kinetic parameters relat ed to decomposition processes. This procedure showed that the values obtain ed by extrapolation, outside the temperature range where the processes occu rred must be used with caution. Indeed half-time and shelf-time values, com monly used at room temperature, seemed to be unrealistic.