Patent Evaluation: New Stable Forms of Human Calcitonin

Summary

Novelty: A new stable aqueous solution of human calcitonin (hCT) is disclosed which is said to remain free of hCT fibrils for at least twenty-four hours at 25°C. hCT is a potent hormone for the treatment of Paget's disease, hypercalcaemia and postmenopausal osteoporosis.

Biology: Extrapolated time of fibrillation (in years) is given for hCT concentrations of 3.3 and 6.6 mg/ml in various formulations. The stability of these formulations is said to be in the range twenty-six days to one hundred and eleven years; the latter for a mixture of 0.5% methyl cellulose, 0.01% benzethonium chloride and 0.001% acetic acid containing 3.3 mg/ml hCT.

Chemistry: A typical composition consists of dilute acetic acid at various concentrations, added to hCT powder and solubilized. The resulting solutions contain 5 mg/ml hCT at acetic acid concentrations of 0.0001%, 0.01%, 0.15 and 1.0%, and are said to be stable and perfectly clear after eight months. In vivo experiments appear to show that fresh hCT solutions and solutions stored for forty days have similar biological activity. Absorption spectra and HPLC experiments appear to show that there is no change in hCT properties as a result of storing hCT in aqueous solutions.