Nastech Pharmaceutical Company Inc, of Bothell, Washington, reported pharmacokinetic data from a phase I study of parathyroid hormone (PTH1-34) nasal spray for the treatment of postmenopausal osteoporosis that demonstrated a similar pharmacokinetic profile to the approved subcutaneous product, Forteo® (teriparatide, Eli Lilly).

PTH1-34 is a fragment of the naturally occurring human parathyroid hormone that is an important regulator of calcium and phosphorus metabolism. When given by daily injection, PTH1-34 has been shown to increase bone mineral density and significantly reduce both vertebral and nonvertebral fractures in postmenopausal women. Daily injections of PTH1-34 are approved for the treatment of postmenopausal osteoporosis.

The study was conducted in 12 healthy human subjects between the ages of 20 and 40. Each subject received a single 20 mg subcutaneous injection of teriparatide followed by successive doses of an intranasal formulation of PTH1-34 to allow for pharmacokinetic comparison in the same subject. The bioavailability of each PTH1-34 nasal spray formulation relative to the subcutaneous injection was also measured. Results showed that the PTH1-34 nasal spray formulations had bioavailability relative to the subcutaneous injection of up to 15 percent. Intersubject variability for the intranasal formulations was similar to, or lower than, the subcutaneous injection, suggesting that intranasal dosing may provide consistent exposure among individuals. There were two occurrences of hypercalcemia following subcutaneous administration of teriparatide, and no cases of hypercalcemia following any of the nasal spray doses.

In February 2006, Nastech and P&G entered into a development and commercialization collaboration for PTH1-34 nasal spray.

—A. Techman