We characterized hydrogels, prepared from aqueous blends of poly(methyl vinyl ether-co-maleic acid) (PMVE/MA) and poly(ethylene glycol) (PEG 10,000 Daltons) containing a pore-forming agent (sodium bicarbonate, NaHCO3). Increase in NaHCO3 content increased the equilibrium water content (EWC) and average molecular weight between crosslinks (Mc) of hydrogels. For example, the %EWC was 731, 860, 1109, and 7536% and the Mc was 8.26, 31.64, 30.04, and 3010.00 x 10(5) g/mol for hydrogels prepared from aqueous blends containing 0, 1, 2, and 5% w/w of NaHCO3, respectively. Increase in NaHCO3 content also resulted in increased permeation of insulin. After 24 h, percentage permeation was 0.94, 3.68, and 25.71% across hydrogel membranes prepared from aqueous blends containing 0, 2, and 5% w/w of NaHCO3, respectively. Hydrogels containing the pore-forming agent were fabricated into microneedles (MNs) for transdermal drug delivery applications by integrating the MNs with insulin-loaded patches. It was observed that the mean amount of insulin permeating across neonatal porcine skin in vitro was 20.62% and 52.48% from hydrogel MNs prepared from aqueous blends containing 0 and 5% w/w of NaHCO3. We believe that these pore-forming hydrogels are likely to prove extremely useful for applications in transdermal drug delivery of biomolecules. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012