Gastrointestinal mucoadhesive patch system (GI-MAPS) for oral administration of G-CSF, a model protein

A new gastrointestinal mucoadhesive patch system (GI-MAPS) has been designed for the oral delivery of protein drugs. The system consists of four layered films, 3.0 x 3.0 mm2, contained in an enteric capsule. The 40 microm backing layer is made of a water-insoluble polymer, ethyl cellulose (EC). The surface layer is made of an enteric pH-sensitive polymer such as hydroxypropylmethylcellulose phthalate (HP-55), Eudragit L100 or S100 and was coated with an adhesive layer. The middle layer, drug-containing layer. made of cellulose membrane is attached to the EC backing layer by a heating press method. Both drug and pharmaceutical additives including an organic acid, citric acid, and a non-ionic surfactant, polyoxyethylated castor oil derivative (HCO-60), were formulated in the middle layer. The surface layer was attached to the middle layer by an adhesive layer made of carboxyvinyl polymer (Hiviswako 103). Fluorescein (FL), 30mg, was first used as a model drug for oral administration of GI-MAPS having different surface layers in beagle dogs. The plasma FL concentration vs. time profiles demonstrated that the targeting of the systems was obtained, because the Tmax, the time when plasma FL concentrations reaches to its maximum lelev, was 2.33+/-0.82 h for HP-55 system, 3.33+/-0.41 h for Eudragit L100 system and 5.00+/-0.00 h for Eudragit S100 system. The same three kinds of GI-MAPSs containing 125 microg of recombinant human granulocyte colony-stimulating factor (G-CSF) were prepared and orally administered to dogs and the increase in total white blood cell (WBC) counts were measured as the pharmacological index for G-CSF. Comparison with the total increase of WBCs after iv injection of the same amount of G-CSF (125 microg) indicated the pharmacological availabilities (PA) of G-CSF were 23%, 5.5% and 6.0% for Eudragit L100, HP-55 and Eudragit S100 systems. By decreasing the amount of HCO-60 and citric acid, the PA of G-CSF decreased. These results suggest the usefulness of GI-MAPS for the oral administration of proteins.