Production of pH Sensitive Microparticles by Coacervation Technique: Effect of Isopropanol

Chaw, Cheng and Zhenli, C. (2013) Production of pH Sensitive Microparticles by Coacervation Technique: Effect of Isopropanol. In: 2013 AAPS Annual Meeting and Exposition, 10-14 Nov 2013, Henry B Gonzalez Convention Centre, San Antonio.


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The pH sensitive polymers are commonly used for enteric coating. They are also promising carriers for lipoph
ilic drugs. Ethanol is a common solvent added for the production of enteric microparticles by simple coacervation technique. This study investigated the effect of isopropanol as solvent to produce cinnarizine loaded Eudragit L100-55 microparticles by the same technique.

To produce microparticles, an aqueous HPMC solution (2.5 to 8.0 % w/w) was added to a solution (made of isopropanol)
consisting of cinnarizine (15 %w/w) and Eudragit L100-55 (8 to 16 %w/w). Microparticles formed after addition of water.
Different ratios of Eudragit to HPMC (between 4.5:1 and 1:1) were studied. The microparticles obtained were evaluated for particle sizes, encapsulation efficiencies, yields, dissolution profiles and etc.

HPMC ratio of 4.5:1, were produced. Satisfactory yields (75-87%) were obtained with reasonably high drug encapsulation efficiencies (84-95%). No visible cinnarizine crystals were detected from SEM. The endothermic peak related to melting temperature of cinnarizine disappeared and there was shift to a lower value for the transitional peak of Eudragit in the DSC analysis. This result indicated that cinnarizine interacted with the enteric polymer. It exerted a plasticizing effect on the enteric polymer chains. The drug also transformed into amorphous form by coacervation technique. The microparticles exhibited pH responsive characteristics and at the ratios of Eudragit: HPMC between 2:1 and 4:1, over 85% suppression of
drug release in HCl was seen. These particles were least 10 μm in diameter.

When isopropanol was used as solvent, the ratios of Eudragit® L100-55: HPMC required to form stable coacervate droplets with particle size of over 10 μm was lower than those produced from ethanol according to previous work, i.e. isopropanol (2:1 to 4:1) vs. ethanol (3.75:1 and 4.8:1). Nonetheless, to produce similar degree of suppression for release in HCl. The particle size should be over 10 μm.

Item Type: Conference or Workshop Item (Poster)
Subjects: Sciences > Pharmacy and Pharmacology
Divisions: Faculty of Health Sciences and Wellbeing
Faculty of Health Sciences and Wellbeing > School of Pharmacy and Pharmaceutical Sciences
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Depositing User: Hannah Dodd
Date Deposited: 14 Jul 2014 13:46
Last Modified: 18 Dec 2019 15:37
ORCID for Cheng Chaw: ORCID iD

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