The effect of dimethyl-beta-cyclodextrin and sodium taurocholate on the nasal bioavailability of salmon calcitonin in rabbits

The effect of two types of absorption enhancers, i.e, dimethyl-beta-cyclode xtrin and sodium taurocholate, on nasal absorption of salmon calcitonin was studied in rabbits. The gel formulations were prepared using polyacrylic a cid (Carbopol941). Dimethyl-beta-cyclodextrin (5%) and sodium taurocholate (1%) were incorporated into a gel formulation containing salmon calcitonin (400 IU/ml). We compared the nasal absorption of salmon calcitonin gel form ulations, which included absorption enhancers, with a formulations without enhancer and with a commercial intravenous product and a commercial nasal s pray. The plasma calcitonin levels were measured by radioimmunoassay. To ev aluate nasal absorption of salmon calcitonin, we estimated t(max), Delta C- max, AUC and absolute bioavailability (F%). The highest calcitonin level wa s obtained with the commercial intravenous product. The results showed that dimethyl-beta-cyclodextrin and sodium taurocholate had markedly increased the nasal absorption of salmon calcitonin. The absolute bioavailability of salmon calcitonin was found to be 12.9 and 11.2% for the salmon calcitonin formulation without absorption enhancer and the commercial nasal spray, res pectively. On the other hand the bioavailabilities of salmon calcitonin wer e calculated as 33.9 and 42.4% for the salmon calcitonin/dimethyl-beta-cycl odextrin and salmon calcitonin/sodium taurocholate formulations, respective ly.