Ca2+ pharm Flashcards
FGF action on VIt D
prev. P reabsorption in the kidney
inhibits D
Vit D effects on PTH synthesis
inhibits its synth and release from PT glands
Effects of excess PTH vs low and intermittent doses of PTH stimulation
Excess PTH: increase bone resorption
Low/intermittent doses of PTH stim: stimulate bone formation w/o first increasing bone resorption
*nl: PTH acts on osteoblasts → induce RANKL → increase activity of osteoclast → bone resorption → osteoblastic bone formation
how does 7-dehydrocholesterol → 1,25(OH)2 Vit D?
7-dehydrocholesterol → skin →
Vit D3 → liver →
25 (OH) Vit D → kidney →
1,25 (OH)2 Vit D
Name these Vitamin D supplements: Cholecalciferol: Ergocalciferol: Calcifediol: Calcitriol: Hytakerol:
Cholecalciferol: D3 Ergocalciferol: D2 Calcifediol: 25 OH D3 Calcitriol: 1,25 OH2 D3 Hytakerol: dihydro tachy sterol (1a-OHD3 equiv)
What should be used D3 (Cholecalciferol) or D2 (ergocalciferol)?
D3 - more efficient in elevating serum 25-OHD3
Most useful in pts with liver disease
23-OH D3 (calcifediol)
Alternative for use in disorders that calcitriol is used.
Dihydro tachy sterol
(1a-OHD3 equiv) - req. 25 hydroxylation by kidney to become active
Most useful in pts with decreased synthesis of calcitriol
(chronic renal failure or type 1 Vit D dep rickets)
Give Calcitriol sup - (1,25)
Primary stimulus for calcitonin synth and release
hypercalcemia
Glucagon
TSH/Thyroxine
Adrenergic agents
Gastrin
*calcitonIN keeps ca IN bones
↓ Ca and ↓ PO4
*usefull in tx of osteoporosis and not prevention
Effects of estrogen on osteoblast and osteocytes
E increase osteoblast production of osteoprotegerin (OPG), which competes with RANK to activate osteocytes
- decrease # and activity of osteoclasts by altering cytokine signals from osteoblasts
- E increase osteoclast apoptosis
- E decrease apoptosis of OSTEOCYTES
how can glucocorticoids DECREASE bone density?
- lowers serum Ca by antag. Vit D intestinal abs. → increase PTH →
stim osteoclast activ. - Increase production of RANK ligand by osteoblasts
but Decrease prod of OPG
- activ. osteoclast activ. - Suppress osteoblasts
*note physiologic lvls of gc are req for osteoblast diff. and
GC are used to decrease bone resorption in LARGE doses
- used for chronic hypercalcemia
3 drugs that reduce Osteoclast action and decrease bone resorption
1: bisphosphonates
2/3. Oestrogens, raloxifene
4. Glucocorticoids
Do GC decrease or increase bone resorption in LARGE doses?
decrease bone resorption
(once used for tx of hypercalcemia of malignancy, but bisphosphonates are more effective now)
But , gc can decrease bone density by stimulating osteoclast activity, inhib. osteoblasts (+ osteoclasts)
1 drug that inhibit and stimulates osteoblasts
Inhibited by Glucocorticoids
(it also inhibits Osteoclasts)
Stimulate by Teriparatide
Oestrogens, raloxifene action on osteoclasts
causes apoptosis of osteoclasts
keeps bones from being reab.
Secondary osteoporosis can result from which drugs?
glucocorticoids
phenytoin
Non pharm therapy of osteoporosis
- diet
- exercise - weight bearing
- stop smoking