The aim of the present study was to enhance the dissolution rate of gliclazide using its solid dispersions (SDs) with polyethylene glycol (PEG) 6000. The phase solubility behavior of gliclazide in presence of various concentrations of PEG 6000 in 0.1 N HCl was obtained at 37 degrees C. The solubility of gliclazide increased with increasing amount of PEG 6000 in water. Gibbs free energy (deltaG(o)(tr)) values were all negative, indicating the spontaneous nature of gliclazide solubilization and they decreased with increase in the PEG 6000 concentration, demonstrating that the reaction conditions became more favorable as the concentration of PEG 6000 increased. The SDs of gliclazide with PEG 6000 were prepared at 1:1, 1:2 and 1:5 (gliclazide/PEG 6000) ratio by melting-solvent method and solvent evaporation method. Evaluation of the properties of the SDs was performed by using dissolution, Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies. The SDs of gliclazide with PEG 6000 exhibited enhanced dissolution rate of gliclazide, and the rate increased with increasing concentration of PEG 6000 in SDs. Mean dissolution time (MDT)of gliclazide decreased significantly after preparation of SDs and physical mixture with PEG 6000. The FTIR spectroscopic studies showed the stability of gliclazide and absence of well-defined gliclazide-PEG 6000 interaction. The DSC and XRD studies indicated the microcrystalline or amorphous state of gliclazide in SDs of gliclazide with PEG 6000.

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The release of verapamil hydrochloride from tablets with Eudragit RLPO or Kollidon SR with different drug-to-polymer ratios were investigated with a view to develop twice-daily sustained-release dosage form by solid dispersion (SD) technique. The SDs containing Eudragit RLPO or Kollidon SR at drug-polymer ratios of 1:1, 1:2, and 1:3 with verapamil hydrochloride were developed using solvent evaporation technique. The physical mixtures of drug and both polymers were prepared by using simple mixing technique at the same ratio as solid dispersion. The physicochemical properties of solid dispersion were evaluated by using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The study of DSC, XRD, and FTIR could not show significant interaction between verapamil HCl and Kollidon SR or Eudragit RLPO. The solid dispersions or physical mixtures were compressed to tablets. The tablets were prepared with solid dispersions containing Eudragit RLPO or Kollidon SR, with all the official requirements of tablet dosage forms fulfilled. Tablets prepared were evaluated for the release of verapamil hydrochloride over a period of 12 h in pH 6.8 phosphate buffer using US Pharmacopoeia type II dissolution apparatus. The in vitro drug release study revealed that the tablet containing Eudragit has extended the release rate for 12 h whereas the tablet containing Kollidon SR at the same concentration has extended the release rate up to 8 h. The in vitro release profile and the mathematical models indicate that release of verapamil hydrochloride can be effectively controlled from a tablet containing solid dispersions of Eudragit RLPO. The reduction of size fraction of the SD system from 200-250 to 75-125 microm had a great effect on the drug release.

The release of propranolol hydrochloride from matrix tablets with hydroxy propyl methyl cellulose (HPMC K15M) or KollidonSR at different concentrations was investigated with a view to developing twice daily sustained release dosage form. A hydrophilic matrix-based tablet using different concentrations of HPMC K15M or KollidonSR was developed using direct compression technique to contain 80 mg of propranolol hydrochloride. The resulting matrix tablets prepared with HPMC K15M or KollidonSR fulfilled all the official requirements of tablet dosage forms. Formulations were evaluated for the release of propranolol hydrochloride over a period of 12 h in pH 6.8 phosphate buffer using USP type II dissolution apparatus. Propranolol hydrochloride and pure KollidonSR or HPMC K15M compatibility interactions was investigated by using Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopic and DSC studies revealed that there was no well defined chemical interaction between propranolol hydrochloride with KollidonSR or HPMC K15M. Tablets were exposed to 40 degrees C/75% of RH in open disc for stability. The in vitro drug release study revealed that HPMC K15 at a concentration of 40% of the dosage form weight was able to control the release of propranolol hydrochloride for 12 h, exhibit non-Fickian diffusion with first-order release kinetics where as at 40% KollidonSR same dosage forms show zero-order release kinetics. In conclusion, the in vitro release profile and the mathematical models indicate that release of propranolol hydrochloride can be effectively controlled from a single tablet using HPMC K15M or KollidonSR matrix system.