Microencapsulation of allopurinol by solvent evaporation and controlled release investigation of drugs

Abstract

The microencapsulation of drugs is gaining importance in many research activities. A common technique for preparing microcapsules is the solvent evaporation method which is simple but has a large number of reaction control parameters. This study reports the microcapsulation of allopurinol by the solvent evaporation method and the release of the drug from the microcapsules. The effect of concentration of poly(vinyl alcohol) (as a surfactant), molecular weight of ethyl cellulose and stirrer speed in the preparative method were studied. The effect of molecular weight of ethyl cellulose and particle size on drug release were also investigated. It has been found that the drug release is decreased with increasing molecular weight of polymer and increasing particle size.

Ethyl cellulose polymer microspheres for controlled release of norfluazon

“…The microspheres selected were from experiments 2 and 4, in which the PVA content was 0.077 and 0.136% respectively, the concentration of the herbicide constant at 5% and the solvent chloroform. In general, if the particle size decreases, the surface area of the microspheres increases and the release rate will increase 31. However, if the differences in the microsphere diameter are small, the differences in liberation profiles will also be small, as occurred in our experiments, where the particle sizes of the microspheres were very similar, and therefore the profiles of liberation were as well.…”

Novel controlled release of antihypertensive drug: preparation, in-vitro and in-vivo evaluation

“…There are several techniques used to produce polymeric microspheres drug delivery systems, which include physicochemical processes such as solvent evaporation method (Li et al, 2007;Lekshmi et al, 2010;Jose et al, 2011) or phase separation method (Das et al, 2005;Lekshmi et al, 2012), mechanical processes such as spray drying (Davis and Illum, 1999), and a non-solvent addition process (Elbagory et al, 2007;Aamir and Ahmad 2009), or by crosslinking with glutaraldehyde using poly(vinyl alcohol)-guar gum interpenetrating network microspheres (Soppimath et al, 2000). The emulsion solvent evaporation method is commonly used for the preparation of controlled release drugs, for example, allopurinol microspheres (Arabi et al, 1996), Zidovudine sustained release (Abu-Izza et al, 1996) and nicardipine hydrochloride microspheres were prepared using acrylic polymers Eudragit RS and L, different concentration of sucrose stearate as a droplet stabilizer, and acetone-methanol mixture as a solvent (Yüksel and Baykara, 1997); and the amphiphilic block copolymers were used to prepare nifedipine microspheres by the solvent evaporation technique (Shelke and Aminabhavi, 2007). Also, the emulsion solvent evaporation method was optimized using ethyl acetate as a dispersing solvent to encapsulate nifedipine and verapamil hydrochloride with cellulose-based polymers (Soppimath et al, 2001).…”