Alternative solvent-free preparation methods for felodipine surface solid dispersions.Drug Dev Ind Pharm. 1998 Apr; 24(4):359-63.DD
Surface solid dispersions were prepared via physical mixture and were either heated in a vacuum dryer or in a microwave oven for different periods of time. The physical state of felodipine in solid dispersions was studied using differential scanning calorimetry and x-ray powder diffractometry. USP paddle method was used for felodipine dissolution studies. The use of vacuum or microwave energy led to a significant improvement of felodipine dissolution which was caused partly by the amorphous state of felodipine and a large surface area of amorphous silicon dioxide.