Development and in vitro evaluation of insulin-loaded buccal Pluronic F-127 gels

Insulin-loaded buccal Pluronic F-127 (PF-127) gel formulations were fabricated to study the effect of PF-127 concentration, insulin concentration, presence of salt, addition of polymer, and permeation enhancer on their gelation time, mucoadhesion force, release and permeation characteristics of insulin from the gels. Thereafter, the principle of statistical optimization to prepare a gel formulation having the potential for buccal delivery of basal insulin in diabetic patients was employed. The gelation time decreased as the concentration of PF-127 increased. Presence of salts as well as addition of polymer, such as methyl cellulose (MC) and hydroxypropylmethyl cellulose (HPMC) decreased the gelation time. An increase in PF-127 concentration and addition of MC and HPMC increased the mucoadhesion force of the gel formulations. Release and permeation of insulin from the gel formulations decreased with increased concentration of PF-127, presence of salts, and addition of MC and HPMC. Permeation of insulin from the optimized gel formulation was 93.17 (+/- 0.058, n = 3) microg/cm(2) which was not only found in close agreement with predicted results from the model equations used for the formulation optimization but also considered comparable to clinical setting. Therefore, the development of optimized buccal insulin-loaded Pluronic F-127 gels using a statistical experimental design is feasible.