Effects of Kollicoat IR and hydroxypropyl-beta-cyclodextrin on the dissolution rate of omeprazole from its microparticles and enteric-coated capsules.

Omeprazole microparticles were prepared by different drying techniques using Kollicoat IR nd hydroxypropyl-beta-cyclodextrin hydrophilic polymers. Physico-chemical properties were investigated using differential scanning calorimetry and powder X-ray diffractometry. Dissolution rate was determined and compared to the physical mixtures and the morphology was studied using a scanning electron microscope. Omeprazole transformed from the crystalline state to the amorphous state as confirmed by the disappearance of its melting peak and the characteristic of the crystalline peaks. Omeprazole dissolution rate was enhanced significantly from its spray- and freeze-dried microparticles as compared to the corresponding physical mixtures and drug alone (P < 0.05). F3 and F5 formula possessed superior release rate over other formulations. In acidic medium, the release of drug from enteric-coated capsules was not detectable, while it is completely released within 40 min after changing dissolution medium to phosphate buffer (pH 7.4). The transformation of OME from crystalline to amorphous state by using either Kollicoat IR or hydroxylpropyl-beta-cyclodextrin is considered a promising way to improvement of drug dissolution.