Hydrogels Could Soon Replace Animal Tissues in Drug Tests

Synthetic polymeric hydrogels could soon be used instead of animal tissue to test the adhesive power of future medicines, according to a new study.

Researchers from the University of Reading (UK) synthesized the hydrogels by three-dimensional copolymerization of 2-hydroxyethylmethacrylate (HEMA) with 2-hydroxyethylacrylate (HEA), and subsequently purified by extracting the unreacted monomers with de-ionized water. The researchers found that the ability to mimic animal tissue depended on the HEMA-HEA ratio in the hydrogels, affecting transparency, swelling behavior, mechanical properties, and porosity of the hydrogels; samples containing more 2-hydroxyethyl methacrylate were less transparent, had lower swelling capacity, higher elastic moduli, and pores of smaller size. The best results were achieved from samples with intermediate swelling capacity and intermediate mechanical characteristics.

The selected polymeric hydrogels proved just as effective as porcine tissues for testing the mucoadhesive properties of tablets designed to stick to the slippery mucosal linings of the mouth. Additionally, the assessment of the biocompatibility of the copolymers using the slug mucosal irritation test revealed that they were also less of an irritant than polyacrylic acid (PAA). The study results were presented at the British Pharmaceutical Conference; held during September 2009 in Manchester (UK).

"Glass, polyethylene, polypropylene, and polystyrene have all been used as substitutes, but none has the elasticity, moisture content and porosity needed to mimic animal tissue,” said study presenter Vitaliy Khutoryanskiy, Ph.D., of the Reading school of pharmacy. "The new synthetic hydrogels mimicked the porcine mucosal tissues better than any other material we tested, and could prove a real alternative to using animal material for testing the mucoadhesive properties of future medicines.”

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