Anionic mucoadhesive polymers as auxiliary agents for the peroral administration of (poly)peptide drugs: Influence of the gastric juice

The incorporation of (poly)peptide drugs in mucoadhesive polymers is a prom ising strategy for their peroral administration. In this study, the protect ive effect of various polymers toward an artificial gastric fluid and the i nfluence of an enteric coating on the adhesive properties have been investi gated. Tablets containing 30 mg of carbomer (C934P), neutralized carbomer ( NaC934P), or sodium carboxymethylcellulose (NaCMC), 0.1 mg of the model pro tein peroxidase, and 19.9 mg of mannitol were incubated at 37 degrees C for 2.5 hr with a simulated gastric fluid with and without pepsin. All polymer s-although anionogenic-displayed quick swelling behavior in the acid milieu , leading to an unintended protein release. Moreover, pepsin is capable of penetrating into the polymeric carrier systems, thereby rapidly degrading t he embedded protein. Enteric coating, on the other hand, leads to strongly reduced adhesive properties. Only NaC934P tablets coated with polymethacryl ate containing 9% triethylcitrate displayed no significant (p < .05) reduct ion in adhesive strength. Results give essential basic information for the development of peroral (poly)peptide dosage forms based on mucoadhesive pol ymers.