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Modulation of microenvironmental pH and crystallinity of ionizable telmisartan using alkalizers in solid dispersions for controlled release

journal contribution
posted on 2008-07-02, 00:00 authored by Phuong TranPhuong Tran, H T T Tran, B J Lee
The present work is an original evaluation of the microenvironmental pH (pHM) and crystallinity of an ionizable drug in order to enhance its dissolution using alkalizers in polyethylene glycol 6000 (PEG 6000) based solid dispersions (SDs). Telmisartan (TEL) was chosen as a model drug due to its poor and pH-dependent water solubility. The nine alkalizers used to modify the pH of TEL were MgO, NaOH, KOH, Na2CO3, NaHCO3, bentonite, Na2HPO4, K2HPO4 and arginine. MgO, NaOH, KOH and Na2CO3 in the SD system significantly increased the drug dissolution rate in intestinal fluid (pH 6.8) and water. Modulation of pHM was clearly observed as a function of time at different fractional dimensions of tablet. Structural change in drug crystallinity to an amorphous form was also a contributing factor based on differential scanning calorimetry (DSC) thermograms and powder X-ray diffraction (PXRD) patterns. The drug frequency of the C{double bond, short}O band decreased and the O-H broad band in the Fourier transform infrared (FTIR) spectra disappeared when these alkalizers were added. It was evident that the alkalizers in PEG 6000 based SDs synergistically enhanced dissolution of TEL not only by modulating pHM but also by changing drug crystallinity to an amorphous form via molecular interactions. © 2008 Elsevier B.V. All rights reserved.

History

Journal

Journal of Controlled Release

Volume

129

Issue

1

Pagination

59 - 65

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

0168-3659

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal