Pharmacokinetics of modified oral calitonin product in health volunteers

Study Objective. To assess the preliminary pharmacokinetics, pharmacodynamics, safety, and tolerability of single oral doses of a chemically modified salmon calcitonin product, CT-025, in healthy volunteers. Design. Phase I, exploratory, five-way, open-label, nonrandomized, crossover study. Setting. Clinical research center. Subjects. Twelve healthy volunteers aged 22-44 years. Intervention. A single oral dose of CT-025 was administered on 5 separate days with a 72-hour washout period between doses. Each dose consisted of CT-025 160 or 320 mug in varying relative concentrations of a mixture of excipients (formulations A, B, and C). Measurements and Main Results. Serial blood samples were collected for determination of plasma CT-025, total serum calcium, and ionized serum calcium concentrations during the 4-hour period after dose administration. The data are the results from four of the five dosing days, when subjects received CT-025 in high and low concentrations of excipients. The data indicate that CT-025 was rapidly absorbed from the gastrointestinal tract. Mean peak plasma concentrations ranging from 51 +/- 51-110 +/- 59 pg/ml were observed 36-54 minutes after administration. Mean terminal elimination half-lives ranged from 54-76 minutes. There was a trend for the mean maximum concentration and area under the plasma concentration-time curve (AUC) from time zero to the time of the last quantifiable plasma concentration to increase with dose. Single oral doses of CT-025 160 and 320 mug were pharmacologically active, inducing a statistically significant decrease in total and ionized serum calcium concentrations. The rate of decrease in ionized serum calcium concentration was significantly related to the CT-025 dose. Single oral doses were well tolerated; some subjects experienced mild and transient nausea. Conclusion. Single doses of CT-025 were absorbed into the systemic circulation after oral administration and were well tolerated in healthy volunteers at doses up to 320 mug. These data suggest that oral delivery of salmon calcitonin becomes feasible with this product and support further clinical investigation of CT-025 as a treatment for osteoporosis and osteoporotic bone pain.