Synthetic human calcitonin (Cibacalcin, Ciba-Geigy): use for radioimmunoassay and bioassay.

Two batches of synthetic human calcitonin batch A = delivered until 1976, and batch B = distributed since 1977 from Ciba-Geigy, have been tested and compared biologically and radioimmunologically. In the biossay B is almost twice as active as A when compared ampoule content and exerts a biological activity of 188 IU per mg pure hCT. In the radioimmunoassay there is no difference from each other in radioiodination and purification, but using them as standard and again comparing them on declared ampoule content, B contains twice as much immunological activity as A. For those, who are using hCT for analytic or biological purposes it is of importance to consider the increased hormone content of batch B with a twofold biological and immunological activity, in comparison to the preparations delivered before 1977.