DSC study of crystallinity changes of naproxen in ground mixtures with linear maltooligomers

Differential scanning calorimetry has been applied to the analysis of cogrinding-induced crystallinity changes of naproxen in binary mixtures with linear maltooligomers. Factors which play a role in the amorphization process were the mixture composition, the duration of mechanical treatment and the degree of polymerization of the carrier. Maltopentaose was about as active as amorphous hydroxypropyl alpha- and beta-cyclodextrin MS 0.6, while maltotetraose displayed practically the same amorphizing capacity as native alpha- and beta-cyclodextrin. The melting peak temperature of naproxen was substantially unaltered by cogrinding with maltooligomers, while it considerably dropped in coground mixtures with cyclodextrin derivatives. This might be due to formation of a true inclusion complex in the solid state.