Synthetic human parathyroid hormone 1-34 replacement therapy: a randomized crossover trial comparing pump versus injections in the treatment of chronic hypoparathyroidism.

CONTEXT: Vitamin D therapy for hypoparathyroidism does not restore PTH-dependent renal calcium reabsorption, which can lead to renal damage. An alternative approach, PTH 1-34 administered twice daily, provides acceptable long-term treatment but is associated with nonphysiological serum calcium fluctuation. OBJECTIVE: Our objective was to compare continuous PTH 1-34 delivery, by insulin pump, with twice-daily delivery. RESEARCH DESIGN AND METHODS: In a 6-month, open-label, randomized, crossover trial, PTH 1-34 was delivered by pump or twice-daily sc injection. After each 3-month study period, serum and 24-h urine mineral levels and bone turnover markers were measured daily for 3 d, and 24-h biochemical profiles were determined for serum minerals and 1,25-dihydroxyvitamin D(3) and for urine minerals and cAMP. STUDY PARTICIPANTS AND SETTING: Eight patients with postsurgical hypoparathyroidism (mean ± sd age 46 ± 5.6 yr) participated at a tertiary care referral center. RESULTS: Pump vs. twice-daily delivery of PTH 1-34 produced less fluctuation in serum calcium, a more than 50% reduction in urine calcium (P = 0.002), and a 65% reduction in the PTH dose to maintain eucalcemia (P < 0.001). Pump delivery also produced higher serum magnesium level (P = 0.02), normal urine magnesium, and reduced need for magnesium supplements. Finally, pump delivery normalized bone turnover markers and significantly lowered urinary cross-linked N-telopeptide of type 1 collagen and pyridinium crosslinks compared with twice-daily injections (P < 0.05). CONCLUSION: Pump delivery of PTH 1-34 provides the closest approach to date to physiological replacement therapy for hypoparathyroidism.

ZT-031, a cyclized analog of parathyroid hormone(1-31) for the potential treatment of osteoporosis.

ZT-031 is a cyclic 31-amino acid analog of parathyroid hormone (PTH) that is in development by Zelos Therapeutics Inc for the treatment of osteoporosis and other bone-related disorders. ZT-031 activates the PTH type 1 receptor - the molecular target of the currently marketed osteogenic peptides PTH and PTH(1-34). Daily subcutaneous injections of ZT-031 prevented bone loss and replaced bone that had already been lost in an ovariectomized rat model of osteoporosis. Daily subcutaneous injections of ZT-031 in gonad-intact monkeys increased bone mineral density (BMD) at cortical and cancellous bone sites and increased serum levels of bone formation markers. The daily subcutaneous administration of ZT-031 to postmenopausal women with osteoporosis elicited a dose-dependent increase in BMD of the lumbar spine, proximal femur and total hip area. Plasma levels of bone formation markers were significantly increased above baseline after 1 month of dosing, and prior to increases in bone resorption markers. ZT-031 was demonstrated to be safe and well tolerated; episodes of hypercalcemia were infrequent and observed with a frequency greater than with placebo only at the highest doses tested for the drug. Although available data are limited, the results obtained following treatment with ZT-031 have generally been at least as favorable as those obtained with other osteogenic PTH peptides. A novel dosing paradigm has been planned for the drug.