Bone Flashcards
What are ergocalciferol and cholecalciferol used to treat? What is the difference between them?
Vit D deficiency with normal renal function.
Ergo= 25 hydroxy vit D2
Chole= 25 hydroxy vit D3
What is alfacalcidol used to treat? What is it? What can it cause?
Vit D deficiency with renal failure. = 1,25 dihydroxy vitD (basically calcitriol). Can cuase vit D intoxication leading to hypercalcaemia and hypercalciuria.
What can oestrogen (HRT) be used to treat? 3 concerns.
Treats post-menopausal osteoporosis due to anti-resorptive effects on bone. Concerns: 1) proliferative effect on endometrium (intact uterus needs co treatment with progesterone to prevent hyperplasia and cancer) 2) increases risk of breast cancer and 3) increases risk of VTE.
What does SERM stand for? Name 2 that are used as osteoporosis treatments
Selective oEstroegn Receptor Modulator. Tamoxifen is an ANTAGONIST- anto-oestogenic in breats but has oestrogenic activity on bone. Limited use becuase of oestrogenic effects on endometrium. Raloxifene is an AGONIST- oestrogenic in bone, anti-oestrogenic in breast and uterus. Risks include VTE and stroke.
Bisphosphonates- how do they work?(3) 4 uses. Describe pharmacokinetics and 4 unwanted actions.
Bind to hydroxapapitite crystals and are ingested by osteclasts, reducing their ability to reabsorb bone. Prevent osteoclast progenitor development and recruitment. Promote osteoclast apoptosis. Net result= reduced bone turnover. 4 uses= osteoporosis, Paget’s disease, malignancy, severe hypercalcaemic emergency (after rehydration). Taken orally but without food- complicated instructions. Unwanted actions: oesophagitis, flu, osteonecrosis of the jaw, atypical fractures (over-supression of bone remodelling in prolonged bisphosphonate use).
Densoumab- mechanism? Why is it second line for osteoporosis?
Human monoclonal antibody- binds to RANKL (on osteoblast), inhibiting osteoclast formation and hence reducing osteoclast-mediated resorption. Expsive
Teriparatide- what is it? How does it work? Why is it third line for osteoporosis?
A recombinant PTH fragment, so increases both bone formation and resorption but formation outweighs resorption. Third line because daily SC injections required- very expensive.
