Hydroxypropyl methylcellulose microspheres with piroxicam and piroxicam-hydroxypropyl-beta-cyclodextrin inclusion complex

Inclusion complexation between piroxicam (PX) and hydroxypropyl-beta-cyclodextrin (HPbetaCD) in the presence of hydroxypropyl methylcellulose (HPMC) was studied in aqueous solution and in the solid state. Phase solubility studies were used to evaluate the HPbetaCD complexation in the presence of HPMC. Stability constants, Ks, of the complexes were determined. The stability of the inclusion complex was improved in the presence of HPMC. Solid microspheres were obtained by spray drying, and were characterized by differential scanning calorimetry (DSC), regarding drug content, and particle size distribution. Scanning electron microscopy (SEM) was also used to characterize the systems prepared. In the solid system HPMC facilitated to some extent the drug dissolution due to increased solubility. The presence of HPMC and HPbetaCD in the microspheres promoted dissolution rate. Cyclodextrin complexation increased PX flux through a semipermeable membrane. Presence of HPMC in the system additionally increased the drug flux more than 80%, by increasing the drug solubility and consequently the affinity of the ternary complex for the aqueous diffusion layer in the donor compartment.

Effect of hydroxypropyl-beta-cyclodextrin on hydrocortisone dissolution from films intended for ocular drug delivery

The formation of an inclusion complex between hydrocortisone and hydroxypropyl-beta-cyclodextrin can affect the in vitro transfer rate of hydrocortisone from the aqueous to the organic phase. The observed first order transfer rate constants showed that the complexation of hydrocortisone with hydroxypropyl-beta-cyclodextrin decreased significantly the transport of the drug depending on the partition coefficient of the drug, and the relative magnitude of the stability constant of the inclusion complex. To optimize the ocular drug delivery, high molecular weight cellulosis and PVA polymeric films were prepared. No unified mathematical model can predict the release profile of drug and complex from films. The drug and complex-polymer interactions in each system could be responsible for the solubility of the drug, and different release behaviours of hydrocortisone and cyclodextrin inclusion complex from the films prepared.