Study on the thermal decomposition of famciclovir

The thermal decomposition of famciclovir (FCV) was measured with thermogravimetry, differential scanning calorimetry, and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The IR spectra, high-performance liquid chromatography, and liquid chromatography–mass spectrometry of FCV and the residues of its thermal decomposition at various temperatures were determined. The molecular bond orders were calculated using an ab initio method from the GAMESS program of quantum chemistry. The mechanism of thermal decomposition for FCV was discussed. The kinetic parameters for thermal decomposition such as activation energy E a and the pre-exponential factor A were obtained using the Ozawa method. The prospective lifetime of FCV was estimated using the Dakin equation. The results indicated that the thermal decomposition of FCV is a two-step process. The initial decomposition temperature in either nitrogen or air is about 205 °C. The decomposition of FCV does not go through 2-amino-purine stage, 2-amino-purine, and alkane chain segment both decompose simultaneously during the first stage. For decomposition in nitrogen, the E a and A for the initial thermal decomposition are 107.8 kJ mol −1 and 2.19 × 10 9  min −1 , respectively. For decomposition in air, the corresponding E a and A are 96.4 kJ mol −1 and 1.45 × 10 8  min −1 , respectively. The FCV has good thermal stability under routine temperature.