[Study on pulmonary delivery system of salmon calcitonin in rats].

OBJECTIVE

To study the serum calcitonin(CT) levels in vivo after pulmonary delivery to rats and the effects of absorption enhancers.

METHODS

Salmon calcitonin (sCT) solution was delivered by intramuscular injection or intratracheal administration to rats. The absorption of sCT was determined by radioimmunoassay method. Changes in serum drug levels after the pulmonary administration of sCT with various absorption enhancers or in different pH conditions were investigated.

RESULTS

Compared with intramuscular administration, the relative bioavailability of sCT solution (2 micrograms.kg-1) given by intratracheal route was 121.0%. Transpulmonary absorption of sCT solution, with some absorption enhancers (Brij78, sodium cholate, lecithin, chitosan and sodium caprylate) or under acidic conditions (pH3.0), was significantly greater than the values obtained in controls.

CONCLUSION

sCT solution showed higher bioavailability after pulmonary administration.