ethyl-cellulose and piretanide

Hydroxypropylcellulose (HPC)-ethylcellulose (EC) microcapsules containing piretanide prepared by a solvent evaporation technique, were evaluated on pharmacokinetic, pharmacodynamic and pharmacological parameters in spontaneously hypertensive rats (SHR). HPC-EC10 (5:3) microcapsules showed sustained plasma piretanide levels and almost the same AUC (area under the curve) as compared with piretanide solution. Effect of treatment with the microcapsules (single oral administration per day in doses of 10 and 30 mg/kg) and the solution (double oral administration per day in doses of 5 and 15 mg/kg) was examined for 4 weeks on urine volume and urinary electrolytes excretion and blood pressure. The microcapsules and solution induced dose-dependent diuresis throughout the experimental period and a reduction in blood pressure from 2 weeks of the treatment. HPC-EC10 (5:3) microcapsules containing piretanide were satisfactory as a sustained-release preparation in the light of the anti hypertensive effect even at a half frequency of daily dosing of the solution.

Topics: Administration, Oral; Aldosterone; Animals; Blood Pressure; Body Weight; Cellulose; Diuretics; Drug Administration Schedule; Drug Compounding; Heart Rate; Hypertension; Male; Rats; Rats, Inbred SHR; Renin; Sulfonamides

To modify the release rate of piretanide, a potent loop diuretic, a double-layer tablet was designed, and in vitro release was evaluated. For a rapidly releasing portion, hydrophilic beta-cyclodextrin derivatives were employed to form a water-soluble complex with piretanide. For a sustained-release portion, cellulose derivatives were used to provide appropriate hydrophobicity. The release rate of piretanide in the pH range 1.2-6.8 was automatically monitored by a pH-changeable dissolution testing apparatus. The low solubility of piretanide in acidic medium was significantly improved by complexations with dimethyl-beta-cyclodextrin (DM-beta-CyD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CyD). The pH-independent slow release was attained by use of hydroxypropylcellulose (HPC):ethylcellulose (EC) matrices. Then, an optimal formulation of a double-layer tablet was obtained by the combination of each fraction. For example, the tablet consisting of the [DM-beta-CyD/(HPC:EC)] system in the weight ratio [1/3(1:3)] provided a sufficiently slow release of the drug over a period of 8 h in a wide pH region following an initial rapid dissolution.

Topics: beta-Cyclodextrins; Cellulose; Chemistry, Pharmaceutical; Crystallization; Cyclodextrins; Delayed-Action Preparations; Drug Carriers; Hydrogen-Ion Concentration; Hypromellose Derivatives; Methylcellulose; Solubility; Sulfonamides; Tablets; X-Ray Diffraction

Hydroxy propyl cellulose (HPC)-ethyl cellulose (EC) microcapsules containing piretanide were newly by a solvent evaporation technique and their slow-release properties were evaluated on dissolution properties in vitro and pharmacokinetic and pharmacodynamic parameters in beagle dogs. The dissolution behavior of piretanide from the microcapsules in dissolution media of pH 1.2-6.8 and the plasma piretanide level in beagle dogs varied dependently on the contents of HPC and EC. As compared with ordinary piretanide tablet on the market, the HPC-EC10 (5:3) microcapsule showed the controlled dissolution behavior, sustained plasma piretanide level, almost same AUC (area under curve), slow urinary piretanide excretion, decreased urine excretion maximum rate, and no difference in the cumulative urine volume and cumulative urinary electrolytes (Na+, K+, Cl-) excretion. HPC-EC microcapsules containing piretanide sufficiently satisfied the conditions which slow-release preparations must have.

Topics: Animals; Capsules; Cellulose; Delayed-Action Preparations; Diuretics; Dogs; Electrolytes; Male; Microscopy, Electron, Scanning; Sulfonamides