Thermoreversible gel formulation for intranasal delivery of salmon calcitonin and comparison studies of in vivo bioavailability.

INTRODUCTION: The reason for studying thermoreversible gel form is to arrange viscosity of formulations for a reversible adequate fluidity in different temperatures. This situation may facilitate use of drug as spray and increase bioadhesive ability to mucosa
METHODS: In the current study, we developed original thermoreversible nasal solgel formulations of salmon calcitonin (sCT). The solgel has been compared with the commercial intranasal spray. same amount of commercial and solgel dosages were sprayed into the noses of the rabbits. Blood samples collected from the ear veins of rabbits and analyzed by EIA.
RESULTS: Using AUC0→tlast in primary pharmacokinetic data, the absolute bioavailability of the formulation at pH: 4 was found to be comparable to that of a commercial product. The absolute bioavailability of the commercial product was measured as 1.88 based on the Cmax. Cmax of the optimum formulation pH: 4 was 0.99 and the relative bioavailability was 53.3%.
DISCUSSION AND CONCLUSION: It is thought that the adhered formulation to the nasal mucosa releases sCT slowly and less. In vivo pharmacokinetic data of solgel formulation with pH: 3 showed significantly higher Vd parameter than commercial product (111167 > 35408). Such being this case the affinity of drug can be more to tissues rather than blood plasma in solgel formulation.