INTERACTIONS BETWEEN CYCLODEXTRINS AND PILOCARPINE - AS AN EXAMPLE OFA HYDROPHILIC DRUG

Investigations of interactions between cyclodextrins (CyDs) and piloca rpine (P) were carried out by means of several common methods. Subject s of interest were aqueous solutions and solid dispersions of the drug and various cyclodextrins. The solid dispersions were prepared by spr ay-drying and by lyophilization of the aqueous solutions. These produc ts and the equivalent physical mixtures were compared by scanning elec tron microscopy (SEM), differential thermal analysis (DTA), powder X-r ay diffractometry (XRD) and Fourier transformation infrared (FTIR) spe ctroscopy. Methods for investigations of the aqueous solutions were H- 1-NMR,C-13-NMR, correlation, rotating frame Overhauser effect and nucl ear Overhauser effect spectroscopy, reversed phase high performance li quid chromatography (HPLC), UV-spectroscopy and conductometry. The res ults obtained may be interpreted as an inclusion of pilocarpine in cyc lodextrins. In vitro and in vivo studies yielded results of a modified release and a slightly higher bioavailability of pilocarpine in the p resence of the tested cyclodextrins. Therefore we assume that the use of cyclodextrins in ophthalmic preparations could be advantageous not only for lipophilic drugs but also for hydrophilic drugs.