Design and Evaluation of Hydrophilic Matrix System for pH-Independent Sustained Release of Weakly Acidic Poorly Soluble Drug

Abstract

The aim of this research was to design and evaluate a hydrophilic matrix system for sustained release of glipizide, a weakly acidic poor soluble drug. A combination of inclusion complexation and microenvironmental pH modification techniques was utilized to improve the dissolution and pH-independent release of glipizide. Hydroxypropyl-β-cyclodextrin (HP-β-CD) was used as the complexation agent while sodium citrate and magnesium oxide (MgO) were used as model pH modifiers. The hydrophilic matrix tablets were prepared by powder direct compression and evaluated by in vitro dissolution study respectively in pH 6.8 and pH 1.2 dissolution media. The formulations containing MgO exhibited increased cumulative drug release from less than 40% in the reference formulation to 90% within 24 h in acidic media (pH 1.2). The release profile in acidic media was similar to the alkaline media (pH 6.8) with a similarity factor (f) of 55.0, suggesting the weakening of the effect of pH on the dissolution efficiency of glipizide. The release profile fitted well into the Higuchi model and the dominant mechanism of drug release was Fickian diffusion while case II transport/polymer relaxation occurred. In conclusion, combining inclusion complexation agents and pH modifiers had improved the dissolution of glipizide as well as achieved the pH-independent release profile.

Preparation and application of pH-responsive composite hydrogel beads as potential delivery carrier candidates for controlled release of berberine hydrochloride

“…If n > 0.85, it indicates that BH release is mainly related to the relaxation (or swelling ratio) of hydrogel beads, and BH release is case II transport. It was worthwhile to note the M t /M ∞ in the Korsmeyer-Peppas model was below 60% as reported in the literature[38].…”

Construction of a photothermal controlled-release microcapsule pesticide delivery system

“…The release kinetics of the AVM@CS/CMA/PDA sample was examined as previously described. [35][36][37][38] The zero-order, rst-order, Higuchi, and Korsmeyer-Peppas equations were used to t the release curve of avermectin so as to study the release mechanism of the avermectin in the AVM@CS/CMA/PDA pesticide delivery system.…”

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“…Conclusions point out that, with this formulation, the frequency of the dose can be reduced, and consequently, compliance by the patient can be improved 35 . Huang et al (2018) designed GPZ tablets with a hydrophilic matrix; they used HPMC K4M, hydroxypropyl-βcyclodextrins (HP-β-CD), pH modifiers (magnesium oxide and sodium citrate), spray-dried lactose monohydrate, and magnesium stearate, tablets were made by direct compression. This research pointed out that magnesium oxide is a better pH modifier than sodium citrate; the pH effect on the GPZ release was improved, and the accumulated GPZ release in acid dissolution media increased in 24 h from less than 40% to more than 90%.…”

“…This research pointed out that magnesium oxide is a better pH modifier than sodium citrate; the pH effect on the GPZ release was improved, and the accumulated GPZ release in acid dissolution media increased in 24 h from less than 40% to more than 90%. The drug was released through a Fickian diffusion mechanism 36 .…”