Development and evaluation of orally disintegrating tablets (ODTs) containing Ibuprofen granules prepared by hot melt extrusion.

Purpose. The purpose of this study was to use polymer blends for the coating of pellets and to study the effects of the type of coating technique (aqueous vs. organic) on drug release.

Polymer Blends Used for the Coating of Multiparticulates: Comparison of Aqueous and Organic Coating Techniques

Mechanisms of polymeric film formation

Microencapsulation has been developed by the pharmaceutical industry as a means to control or modify the release of drug substances from drug delivery systems. In drug delivery systems microencapsulation is used to improve the bioavailability of drugs, control drug release kinetics, minimize drug side effects, and mask the bitter taste of drug substances. The application of microencapsulation has been extended to the food industry, typically for controlling the release of flavorings and the production of foods containing functional ingredients (e.g. probiotics and bioactive ingredients). Compared to the pharmaceutical industry, the food industry has lower profit margins and therefore the criteria in selecting a suitable microencapsulation technology are more stringent. The type of microcapsule (reservoir and matrix systems) produced and its resultant release properties are dependent on the microencapsulation technology, in addition to the physicochemical properties of the core and the shell materials. This review discusses the factors that affect the release of bioactive ingredients from microcapsules produced by different microencapsulation technologies. The key criteria in selecting a suitable microencapsulation technology are also discussed. Two of the most common physical microencapsulation technologies used in pharmaceutical processing, fluidized-bed coating, and extrusion-spheronization are explained to highlight how they might be adapted to the microencapsulation of functional bioactive ingredients in the food industry.

Microencapsulation as a Tool for Incorporating Bioactive Ingredients into Food

Statistical optimisation of diclofenac sustained release pellets coated with polymethacrylic films.

Drug release from beads coated with an aqueous colloidal ethylcellulose dispersion, Aquacoat®, or an organic ethylcellulose solution

Tackiness of acrylic and cellulosic polymer films used in the coating of solid dosage forms.

Theophylline or chlorpheniramine maleate pellets were coated with an aqueous ethylcellulose dispersion, Aquacoat. The influence of the plasticization time, curing conditions, storage time, and core properties on the drug release were investigated. The plasticization time (time between plasticizer addition to the polymer dispersion and the spraying process) did not affect the drug release, when the water-soluble plasticizer triethyl citrate, was used because of its rapid uptake by the colloidal polymer particles. In contrast, with the water-insoluble plasticizer acetyltributyl citrate (ATBC), plasticization time (1/2 h vs 24 h) influenced the drug release, the longer plasticization time resulted in a slower drug release because of a more complete plasticizer uptake prior to the coating step. However a thermal aftertreatment of the coated pellets at eleylated temperatures (curing step) reduced/eliminated the effect of the plasticization time with ATBC. In general, curing reduced the drug release and resulted in stable drug release profiles. The time period between the coating and the curing step was not critical when the pellets were cured for a longer time. The structure of the pellet core (high dose matrix vs low dose layered pellet) strongly affected the drug release. A slow, zero-order drug release was obtained with high dose theophylline pellets, while a more rapid, first-order release pattern was obtained with low dose theophylline-layered nonpareil pellets.

Martin Wesseling

Papers

Drug release from beads coated with an aqueous colloidal ethylcellulose dispersion, Aquacoat®, or an organic ethylcellulose solution

Tackiness of acrylic and cellulosic polymer films used in the coating of solid dosage forms.

Influence of plasticization time, curing conditions, storage time, and core properties on the drug release from Aquacoat-coated pellets.