Bone Mineral Homeostasis Flashcards
- clotting of blood
- ossification of bone
- muscle contraction
- release of endocrine hormones and neurotransmitters
calcium
treats:
- hypocalcemia due to dietary insufficiency or malabsorption states, renal disease, or hypoparathyroidism
- hypocalcemic tetany
- prophylaxis and treatment of osteoporosis
- toxicity: ectopic calcification
calcium
- oral, cheap
- more likely to cause gas, bloating, constipation
- neutralizes gastric acid and can cause rebound acid secretion
- more concentrated calcium, smaller pills
- need to take with food
calcium carbonate
- oral, fewer GI problems
- does not affect gastric pH
- can take without food
calcium citrate
- for severe symptomatic hypocalcemia
- least irritating to veins of IV calcium preps
- rapid infusion can cause arrhythmias
IV calcium gluconate
- formed in skin by UV irradiation and certain foods
- intrinsic (D3) and dietary (D3, D2) are inactive precursors that must be converted to active metabolites of which calcitriol is most active
- circulates bound to a binding protein
- regulates calcium homeostasis (bones increase bone formation and resorption, kidneys to increase tubular reabsorption, SI to increase calcium and phosphate absorption)
vitamin D
vitamin D deficiency causes ________ resulting in abnormal and retarded bone growth
Rickets
toxicities of _______ include hypercalcemia and hypercalciuria, causing n/v/decreased appetite, frequent urination, and renal failure
vitamin D
vitamin D3 analog, has longer half life so it’s better for supplementation unless metabolism is compromised
cholecalciferol
1,25-dihydroxyvitamin D, most active analog of vitamin D, used if kidney unable to convert active vitamin D
calcitriol
- inadequate dietary intake
- inadequate exposure to sunlight
- renal dysfunction
- administration of anticonvulsants (phenobarbital, phenytoin) that increases its metabolism
vitamin D deficiency
Treats:
- nutritional rickets
- metabolic rickets duet o genetic defect in renal hydroxylase or chronic renal failure, calcitriol used
- osteoporosis and osteomalacia
- psoriasis, topical calcipotriene
- hypoparathyroidism
- secondary hyperparathyroidism
pharmacological uses of vitamin D
vitamin D form that has higher affinity for receptors in human tissues, more effective in increasing plasma D concentrations
D3
vitamin D derivative that has lower affinity for the D binding protein and shorter half life
D2
- analogs of pyrophosphate, suppress activity of osteoclasts and inhibit bone resorption
- used for osteoporosis, bone metastases, Paget’s, hypercalcemia
bisphosphonates
- esophageal and gastric irritation
- osteonecrosis of the jaw
- renal failure
- side effects of what drug?
bisphosphonates
etidronate, alendronate, and risedronate are ______ bisphosphonates
oral
ibandronate is given _________ bisphosphonate give monthly or quarterly
oral and IV
zoledronic acid and pamidronate are ______ bisphosphonates
IV
administered SQ, stimulates new bone that is structurally normal, not recommended for use >2 years, black box warning for osteosarcoma
teriparatide (PTH1-34)
increases bone mass, not as effective as bisphosphonates or teriparatide
calcitonin
administed SQ biannually, suppresses bone resorption, could have immunosuppressive effects
denosumab (RANKL inhibitor)
- reduce bone resorbing effects of PTH
- not recommended for postmenopausal osteoporosis due to effects on breast, uterus, and CV system
estrogens
- stabilizes hydroxyapatite crystals in bone and teeth
- used to prevent dental caries
- toxicity at doses 3-5 mg/kg
fluoride
- activates calcium sensing receptor in parathyroid gland
- used for secondary hyperparathyroidism in renal disease and parathyroid carcinoma
cinacalcet
- decrease calcium absorption and increase excretion
- block bone formation
- can lead to osteoporosis
glucocorticoids
- decrease renal calcium excretion
- can augment effects of PTH
- used for hypercalciuria
thiazide diuretics
cholecalciferol, ergocalciferol, calcitriol, calcipotriene, doxercalciferal, paracalcitrol
vitamin D drugs
etidronate, alendronate, risedronate, ibandronate, zoledronic acid, pamidronate
bisphosphonates
