Calcitonin is a singlechain peptide composed of 32 amino acids with isoelectric pH of 8.86 which isproduced in parafollicular cells of the thyroid gland . Overally three classesof calcitonin including teleost/avian, artyodactyl and primate have been identifiedwhich have highest to lowest bone resorption inhibitory potency, respectively 1. Thebasic stracture of non mamalian calcitonin is the resaon of its high biologicalactivity. Salmon calcitonin is belonged to teleost/avian calcitonin classes andbecause of its high activity is used as a treatment of disease likeOsteoporosis and Paget’s disease in mammals.
Hypercalcemia and bonemetastases are two other disease which are treated with exogenous calcitoninadminstration. In the case of osteoporosis disease density of bone willdecrease and consequently the tissue within bone will deteriorated and lead tobone fragility23. Just like many hormones injection is the primary adminstration ofcalcitonin. Another more favorable way is the oral adminstration which resultedin significant improvement in life quality of pationts4.
The uses of hydrogel compounds in formulation of calcitonin hormone forits oral delivery is an interesting issue for protecting hormon from harshcondition of gut and intestin in combination with preparing a control releasemethod for locally admionstration of this peptide. It is demonstrated that theupper small intestin and dominant stimulus are the most interesting parts fororal peptide delivery5.Because of this acidic environment attacntions to the use of pH sensitivehydrogels is increasing. In an study performed by Torres-Lugo et all salmoncalcitonin was sucseccfully incorporated in hydrogel of poly(methacrylic acid)grafted with poly(ethylene glycol) (PMAA-g-EG) which is a pH sensitive hydrogeland the constant release of calcitonin around 7 h and completely releasewhithin 3 days was achived6.
In another study the high loading efficiency of complexation hydrogels poly(methacrylicacid-g-ethylene glycol) (henceforth designated as P(MAA-g-EG)) which waspreviously used for insulin oral delivery was demonstrated. The polymer loadedwith calcitonin showed ph sensitive and complexation/decomplaxation releasebehavior7