Microencapsulation of theophylline using ethylcellulose: in vitro drug release and kinetic modelling

Preparation and Evaluation of Verapamil Hydrochloride Microcapsules

Verapamil was encapsulated with ethylcellulose (EC) and cellulose acetate (CA) in various ratios of drug and polymer by the hot melt technique and the prepared microcapsules were evaluated for size range, drug content, drug release profiles, and kinetics of drug release. The microcapsules were compressed into tablets to study the variation of drug release between the 2 types of formulations (ie, microcapsules and tablets). The size analysis of prepared microcapsules was done by a standard sieving method and in vitro dissolution studies were carried out in USP XXI dissolution test apparatus in 0.1 N HCl as dissolution media to study the drug release profiles of the microcapsules. Scanning electron microscopy studies were carried out to investigate the surface characteristics of the microcapsules prepared from both type of polymers. Drug release profiles from the compressed non-disintegrating matrix tablets prepared from the microcapsules were also investigated. All the microcapsules were discrete, free flowing, and reproducible with respect to size distribution and drug content. Maximum percentage of the microcapsules belonged to the size range of 35/50. Drug release durations of VERCA1 (drug: CA 3:1), VERCA2 (drug: CA 2:1), and VERCA3 (drug: CA 1:1) microcapsules were extended up to 3, 5, and 6 hours, respectively, and those of VEREC1 (drug: EC 3:1), VEREC2 (drug: EC 2:1), and VEREC3 (drug: EC 1:1) microcapsules were extended up to 4, 5, and 7 hours, respectively. The microcapsules of both types having a drug:polymer ratio of 1:1 had the slowest release rate in their respective categories. The microcapsules were compressed into nondisintegrating matrix tablets. The hardness of the tablets was tested using the Monsanto Hardness Tester and was found to be 6-7 kg/cm. All the tablets contained the drug verapamil within 100% +/- 5%. The drug release data of both the microcapsules and tablets prepared were examined kinetically, and the ideal kinetic model was determined for the drug release. The tablets prepared by compressing the microcapsule formulations were more satisfactory in releasing the drug at a controlled and uniform rate following Higuchian kinetics and the formulations VCACRT3 and VECCRT3 were able to control release of drug up to 12 hours. Thus, it is possible to formulate a single-unit, controlled-release dosage form of verapamil for oral administration at least once every 12 hours using the polymers CA and EC.

Preparation and evaluation of microcapsules using polymerized rosin as a novel wall forming material

Sustained release diclofenac sodium microcapsules were prepared using polymerized rosin as a novel wall-forming material by a solvent evaporation technique. A novel method developed in our laboratory with the potential for scale-up and production of polymerized rosin microcapsules is detailed. These microcapsules might have application for development of implant/depot systems, primarily due to a sustained/controlled release capability and potential biocompatibility of polymerized rosin. The effect of variables like solvent systems, stirring speed and temperature were previously optimized. The solution system of drug and polymerized rosin dissolved in iso-propyl alcohol and acetone is sprayed with the help of a 0.5 mm nozzle spray gun in liquid paraffin maintained at 60 degrees C in the stirring condition. Varying drug:polymer ratios, namely 1:1, 1:2, 2:1, 1:3 and 3:1, were employed for microcapsule preparation. The prepared microcapsules were evaluated for size, shape, drug content and in vitro drug release. The morphology of microcapsules was characterized by scanning electron microscopy. The microcapsules show sustained release curves at pH 7.4 phosphate buffer for up to 10 h. The data obtained from the dissolution profiles were compared in the light of different kinetics models and the regression coefficients were compared. The in vitro dissolution study confirmed the Higuchi-order release pattern. Particle size and release data analysis from five consecutive batches prepared in the laboratory indicated suitable reproducibility of the proposed solvent evaporation process.

Effect of medications on taste: example of amitriptyline HCl

Use of medications is a major factor that contributes to taste losses in the elderly. Epidemiological studies suggest that community-dwelling elderly over the age of 65 use an average of 2.9 to 3.7 medications, and this number increases significantly for elderly living in retirement and nursing homes. The tricyclic antidepressant amitriptyline HCl is used by at least half a million people aged 65 years or more. In human studies performed here, amitriptyline HCl was found to have a bitter, unpleasant taste of its own. In addition, it blocked responses to other taste stimuli in both humans and gerbils. This blockage in humans was greater when amitriptyline HCl was applied continuously to the tongue than when it was applied intermittently. Continuous application of the drug affected all of the taste qualities to varying degrees, while intermittent application led to taste decrements only for salts. Electrophysiological studies in gerbils also revealed taste decrements after a short adaptation to amitriptyline HCl.