Thermal behavior and phase identification of Valsartan by standard and temperature-modulated differential scanning calorimetry.
Thermal behavior of angiotensin II type 1 (AT1) receptor antagonist, Valsartan (VAL), was examined employing thermogravimetric analysis (TGA), standard differential scanning calorimetry (DSC) and temperature-modulated differential scanning calorimetry (TMDSC). The stability of VAL was measured by TGA from 25 to 600°C. Decomposition of Valsartan starts around 160°C. The DSC curve shows two endotherms, occurring around 80°C and 100°C, related to evaporation of water and enthalpy relaxation, respectively. Valsartan was identified by DSC as an amorphous material and it was confirmed by X-ray powder diffraction. The glass transition of fresh Valsartan appears around 76°C (fictive temperature). TMDSC allows separation of the total heat flow rate into reversing and nonreversing parts. The nonreversing curve corresponds to the enthalpy relaxation and the reversing curve shows changes of heat capacity around 94°C. In the second run, TMDSC curve shows the glass transition process occurring at around 74°C. Results from standard DSC and TMDSC of Valsartan were compared over the whole range of temperature.
Department of Pharmaceutical Technology, Poznan University of Medical Sciences, Poznań, Poland.
Marcin
M
Skotnicki
Agnieszka
A
Gaweł
Peggy
P
Cebe
Marek
M
Pyda
D047228:Angiotensin II Type 1 Receptor Blockers / Q000737:chemistry*; D000959:Antihypertensive Agents / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004355:Drug Stability; D006358:Hot Temperature / Q000009:adverse effects; D044367:Phase Transition; D033362:Powder Diffraction; D011208:Powders; D015203:Reproducibility of Results; D013777:Tetrazoles / Q000737:chemistry*; D013818:Thermogravimetry; D014633:Valine / Q000031:analogs & derivatives* / Q000737:chemistry; D000068756:Valsartan
D047228:Angiotensin II Type 1 Receptor Blockers; D000959:Antihypertensive Agents; D011208:Powders; D013777:Tetrazoles; D000068756:Valsartan; D014633:Valine