Recombinant human PTH 1-34 (Forteo): an anabolic drug for osteoporosis.

Abstract

Forteo (teriparatide of rDNA origin), a genetically engineered fragment of parathyroid hormone, is the first of a new class of drugs to treat osteoporosis. The drug's anabolic action increases bone turnover, stimulating osteoblasts to a greater extent than osteoclasts, and reducing both vertebral and nonvertebral fractures. However, a number of issues about its use remain unanswered.

Prevention of breast cancer skeletal metastases with parathyroid hormone

“…Activation of the PTH1R receptor leads to regulation of multiple signaling pathways, including the PKA and PKC pathways. Recombinant PTH [teriparatide, PTH ] administered intermittently (once daily) is the first anabolic treatment available for osteoporosis in the US (29,31). Importantly, activation of PTH1R in osteoblasts in mice increases the numbers and engraftment of HSCs (32,33).…”

The Effects of Supraphysiologic Doses of Vitamin D3 in Conjunction With Teriparatide on Bone Mineral Density in Two Postmenopausal Females With Severe Osteoporosis

“…This could potentially interfere with the action of teriparatide, a PTH analog. The actions of teriparatide on the bone seem to be effective due to its ability to quickly reach peak serum concentrations and decline to non-detectable levels within a few hours [7]. If endogenous PTH levels were to rise in the serum due to vitamin D deficiency or insufficiency, one cannot be certain that teriparatide can effectively achieve its full potential on bone remodeling.…”

“…Historically, chronic exposure to PTH has been observed to lead to osteoporosis, as in diseases such as hyperparathyroidism [7]. This is due to PTH induced stimulation of osteoclasts, leading to an increase in bone resorption [7]. Teriparatide, however, reaches peak serum concentrations in 30 minutes and returns to non-detectable serum levels within a few hours [7].…”

“…Teriparatide, however, reaches peak serum concentrations in 30 minutes and returns to non-detectable serum levels within a few hours [7]. This intermittent burst of PTH given in the form of teriparatide, in contrast to chronic exposure to PTH, has the paradoxical effect of stimulating new bone formation and increasing bone mass by favoring stimulation of osteoblasts more than osteoclasts [7].…”

“…Its mechanism of action differs from other agents currently used. Historically, chronic exposure to PTH has been observed to lead to osteoporosis, as in diseases such as hyperparathyroidism [7]. This is due to PTH induced stimulation of osteoclasts, leading to an increase in bone resorption [7].…”