Teriparatide???

[chillaxbro]

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According to Uworld 11564, Teriparatide is a PTH analog and does the same thing as PTH. It lists stimulation of pre-osteoblasts to mature into bone-forming osteoblasts that will lay down collagen and mineralize the matrix as one of the functions. Therefore it is used in osteoporosis

I thought PTH caused bone breakdown? Why give a PTH analogue for osteoporosis? Since when did it promote osteoblast differentiation?

 

[MudPhud20XX]

According to Uworld 11564, Teriparatide is a PTH analog and does the same thing as PTH. It lists stimulation of pre-osteoblasts to mature into bone-forming osteoblasts that will lay down collagen and mineralize the matrix as one of the functions. Therefore it is used in osteoporosis

I thought PTH caused bone breakdown? Why give a PTH analogue for osteoporosis? Since when did it promote osteoblast differentiation?

PTH stimulates osteoclast via osteblast activation. So the way it works is that PTH stimulates osteoblast osteocytes first by reducing osteoprotegerin and increasing RANK-L receptor. This leads to the binding of the osteoclast via its RANK and leads to activation of osteoclast as well. So this is rather a complex reaction and I think b/c of the involvement of the activation of osteoblast using PTH analogue may be helpful for osteporosis. But I would rather use Denosumab or Raloxifene which is associated with blocking of RANKL via "osteoprtegerin." Hope this helps.

 

[breadlover72]

In addition to the above:
Continuous PTH = bone resorption > bone formation

Intermittent PTH = bone resorption < bone formation (because of the activation of osteoblasts more than osteoclasts) Teriparatide is a once a day SQ injection so considered intermittent exposure or at least that's how I understood it.

 

[Transposony]

PTH given in normal doses exerts anabolic effects on bone but chronic elevation (as in hyperparathyroidism) leads to bone loss.
Unlike any other treatments (eg, bisphosphonates) PTH produces a true increase in bone tissue and restores bone microarchitecture.
It does so by stimulating IGF-1, and collagen production and increases osteoblast number by stimulating replication & recruitment and inhibiting osteoblast apoptosis.
However, it's only given for 2 yrs due to risk of osteosarcoma.

 

[Postictal Raiden]

The way I think about it is that Teriparatide effect on the PTH axes is similar to the effect of leuprolide on the testosterone axes. Pulsatile stimulation results in increase production while continuous stimulation results in decrease of production.