STUDYING THE EFFECT OF DISPERSED DRUG CRYSTAL IN THE ORGANIC PHASE ON THE ENCAPSULATION BY SOLVENT EVAPORATION TECHNIQUE; (2) X-RAY DIFFRACTION AND DSC AS TOOLS TO STUDY THE MICROCAPSULE STRUCTURE IN RELATION TO THE SUGGESTED DIVISION MECHANISMAbstract
The method of entrapment of the drug in the microcapsules structure prepared with different theoretical drug content (TDC) and having different particle size ranges were studied using x-ray diffraction and DSC analysis methods. Also, in the light of the analysis methods, a trial to correlate the actual microcapsule structure with the actual drug content (ADC) and the division mechanism suggested by the author was also studied. The results showed that the drug entrapped in more than one form in the microcapsule structure. At the first, the drug entrapped in the microcapsules structure as a solid solution form which is concluded as the result of disappearance of all characteristic peaks of the drug in both x-ray diffraction pattern and DSC. The amount of drug in solid solution form depends on the physico-chemical characters of the drug and the polymer. After that increasing TDC leads to increasing the amount of the drug crystal in the microcapsule structure. Between those two forms another minute form may be formed as a result of increasing TDC or /and certain kind of physic-chemical interaction between the drug and the polymer. The physical interaction between the drug and the polymer could be concluded from x-ray diffraction patterns and DSC but the chemical one needs further explanations using FTIR. The entrapment process of the drug was found to be reflected on the product sphericity. All analysis results supported what is suggested mechanism during microcapsules formation (Division Mechanism) as a result of appearances or disappearances of drug crystals in addition to its effect on actual drug content.