ATC Group: H05AA Parathyroid hormones and analogues

Abaloparatide is a 34 amino acid peptide that shares 41% homology to parathyroid hormone [PTH] and 76% homology to parathyroid hormone related peptide [PTHrP(1-34)], and is an activator of the PTH1 receptor signalling pathway. Abaloparatide stimulates new bone formation on trabecular and cortical bone surfaces by stimulation of osteoblastic activity. Abaloparatide causes transient and limited increases in bone resorption and increases bone density.

Palopegteriparatide is a prodrug, consisting of PTH conjugated to a methoxypolyethylene glycol carrier (mPEG) via a proprietary TransCon Linker. PTH and its main metabolite, PTH, have similar affinity to and activation of PTH1R as endogenous PTH. At physiological conditions, PTH is cleaved from palopegteriparatide in a controlled manner to provide a continuous systemic exposure of active PTH.

Endogenous parathyroid hormone (PTH) is secreted by the parathyroid glands as a polypeptide of 84 amino acids. PTH exerts its action via cell-surface parathyroid hormone receptors, present in bone, kidney and nerve tissue. PTH has a variety of critical physiological functions that include its central role in modulating serum calcium and phosphate levels within tightly regulated levels, regulating renal calcium and phosphate excretion, activating vitamin D, and maintaining normal bone turnover.

Teriparatide (rhPTH(1-34)) is the active fragment (1-34) of endogenous human parathyroid hormone. Teriparatide is a bone formation agent to treat osteoporosis. The skeletal effects of teriparatide depend upon the pattern of systemic exposure.