Skip to Content

Flavonoid-based pH-responsive hydrogels as carrier of unstable drugs in oxidative conditions.

Flavonoid-based pH-responsive hydrogels as carrier of unstable drugs in oxidative conditions.

Pharmaceutical development and technology (2013-12-03)

Umile Gianfranco Spizzirri, Giuseppe Cirillo, Manuela Curcio, Nevio Picci, Francesca Iemma

ABSTRACT

In this study, pH-responsive hydrogels, synthesized by the coupling reaction of polyacrylic acid and catechin, are proposed as carriers of oxidable drugs toward the GI tract. The presence of polyphenolic moieties in the network gives the polymers properties suitable for the release of unstable drugs in oxidative conditions. The characterization of the hydrogels is obtained by means of morphological and physico-chemical analyses, antioxidant assays and evaluation of the swelling behavior in media simulating the gastric (pH 1.0) and the intestinal (pH 7.4) tracts. The hydrogels are tested as pH-responsive carriers in in vitro release studies of folic acid and thiamine, two model drugs easily degraded by oxidative conditions simulated by UV irradiation and t-butyl hydroperoxide treatment, respectively. Results show that catechin-based carriers are able to control the release of drugs at different pH values, giving a remarkable improvement in the stability of the therapeutics.

MATERIALS

Product Number

Brand

Product Description

Sigma-Aldrich

Ethanol, JIS first grade, 94.8-95.8%

Sigma-Aldrich

Hydrochloric acid solution, 1 M

Sigma-Aldrich

N,N-Dimethylformamide, JIS special grade, ≥99.5%

Sigma-Aldrich

Hydrochloric acid solution, 6 M

Sigma-Aldrich

Methanol, SAJ first grade, ≥99.5%

Sigma-Aldrich

Methanol, JIS 300, ≥99.8%, for residue analysis

Sigma-Aldrich

Hydrochloric acid solution, 12 M

Sigma-Aldrich

Hydrochloric acid solution, 0.2 M

Sigma-Aldrich

Hydrochloric acid solution, 0.05 M

Sigma-Aldrich

Hydrochloric acid, SAJ first grade, 35.0-37.0%

Sigma-Aldrich

Hydrochloric acid solution, 0.02 M

Sigma-Aldrich

Diethyl ether, ≥99.5%

Sigma-Aldrich

Hydrogen chloride solution, 3 M in cyclopentyl methyl ether (CPME)

Sigma-Aldrich

Methanol, SAJ special grade

Sigma-Aldrich

Diethyl ether, for residue analysis, JIS 5000

Sigma-Aldrich

N,N-Dimethylformamide, SAJ first grade, ≥99.0%

Sigma-Aldrich

Diethyl ether, JIS special grade, ≥99.5%

Sigma-Aldrich

Methanol, NMR reference standard

USP

Dehydrated Alcohol, United States Pharmacopeia (USP) Reference Standard

Sigma-Aldrich

N,N-Dimethylformamide, suitable for HPLC, ≥99.9%

Sigma-Aldrich

Methanol, HPLC Plus, ≥99.9%, poly-coated bottles

Supelco

Dehydrated Alcohol, Pharmaceutical Secondary Standard; Certified Reference Material

Supelco

Sodium carbonate, reference material for titrimetry, certified by BAM, >99.5%

Sigma-Aldrich

Sodium carbonate, BioUltra, anhydrous, ≥99.5% (calc. on dry substance, T)

Sigma-Aldrich

Hydrochloric acid solution, 32 wt. % in H₂O, FCC

Supelco

Hydrogen chloride – ethanol solution, ~1.25 M HCl, for GC derivatization, LiChropur^™

Supelco

Hydrogen chloride – methanol solution, ~1.25 m HCl (T), for GC derivatization, LiChropur^™

Sigma-Aldrich

Sodium carbonate, anhydrous, powder, 99.999% trace metals basis

Sigma-Aldrich

Diethyl ether, contains 1 ppm BHT as inhibitor, anhydrous, ≥99.7%

Sigma-Aldrich

Methanol, suitable for HPLC, gradient grade, 99.93%