Abstract
ABSTRACT The present study describes the development of theophylline microcapsules by a non-solvent addition method and the effect of plasticizer addition on microencapsulation. The release was studied in distilled water and the data were analysed by various mathematical models for determining the mechanism of release. Prepared microcapsules were found to be spherical, free flowing and having more than 80% entrapped drug. The polymer - cellulose acetate phthalate and plasticizer - polyethylene glycol was considered to be affecting the properties of microcapsules including drug release (time for 50% drug release, T50). The formulation with the highest proportion of polymer and without plasticizer (F3) showed the slowest release with T50 = 4.3 h, while the formulation with lower proportion of polymer and 20% (w/w) plasticizer (F13 &14) showed the fastest release of drug with T50 values of 1.2 h and 1.3 h, respectively. The drug release from most of the formulations was found to be following Higuchi model. It is concluded from the results of the present study that cellulose acetate phthalate significantly affects the sustained release of the drug in water, whereas the addition of polyethylene glycol slightly enhances the drug release.
Highlights
Theophylline is an effective bronchodilator used for the treatment of chronic asthma and obstructive lung disease (Hendeles, Weinberger, 1983)
The drug is under a narrow therapeutic index and has rapid and uniform absorption throughout the gastrointestinal tract (Ly, 1997)
The present study was launched to prepare theophylline microcapsules using non-solvent addition method, and to evaluate the effect of different blends of the polymer and the plasticizer on the release of theophylline from microcapsule formulations
Summary
Theophylline is an effective bronchodilator used for the treatment of chronic asthma and obstructive lung disease (Hendeles, Weinberger, 1983). The non-solvent addition method has been frequently used by many researchers because it offers several advantages over the others coacervation and spray drying (Pongpaibul and Whitworth, 1986). It is less time consuming and can be done at room temperature in the absence of water, suitable for water-sensitive active pharmaceutical ingredients. Cellulose acetate phthalate (CAP) has served as a polymer (Beyger and Nairn, 1986) It is an enteric polymer and is in need of a plasticizer in microencapsulation to improve its film forming characteristics. The present study was launched to prepare theophylline microcapsules using non-solvent addition method, and to evaluate the effect of different blends of the polymer and the plasticizer on the release of theophylline from microcapsule formulations
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