bone- mineral homeostasis

drug action exam 1

Fosamax

Alendronate

bisphosphate

Fosamax ADRs

Evista

Raloxifene

SERM

Evista ADRs

Boniva

Ibandronate

biphosphonate

Actonel

Risedronate

Biphosphonate

Actonel ADRs

bone remodeling

roles of osteoblasts

roles of osteoclasts

Ca+, PO4-, vitamin D, PTH-calcitonin homeostasis

malabsorption of calcium, phosphate & vitamin D can be due to GI or hepatic disease

imbalance of Calcium & phosphate can cause bone diseases, 2nd hyperparathyroidism, renal osteodystrophy

vitamin D promotes intestinal absorption of calcium. When renal disease occurs, conversion to activate vitamin D is impaired, causing vitamin D deficiency, decreased phosphate clearance leading to hyperphosphatemia, decreasing calcium and increasing PTH

hormones involved in bone homeostasis

calcitonin, thyroid, estrogen, glucocorticoids- secondary regulators

PTH, vitamin D-primary regulators

Calcium carbonate

40% elemental Ca

should be taken with food, PO

calcium preparations ADRs

constipation, kidney stones, hypercalcemia, headache, bone pain, coma

Calcium preparations DDIs

iron, tetracycline, biphosphonates, fluoroquinolones, phynotin, fluoride

separate 2 hrs before or after taking calcium

digoxin (potential toxicity)

calcium phosphate

25% elemental Ca

PO

Calcium citrate

21% elemental calcium

prefer when gastric pH is increased, elderly, use of PPI

PO

calcium lactate

13% elemental Ca

PO

calcium gluconate

<18% elemental Ca

PO

Calcium IV preparations

Ca-gluceptate, Ca-chloride, Ca-gluconate (preferred, less irritable to veins)

Phosphate binding agents MOA

bind to dietary phosphate in the GI tract→ forming insoluble AL, Ca or Mg (depending on the products) → excreted in feces → decreasing phosphate in the blood

phosphate binding agents indications

chronic kidney disease

Ca containing Phosphate binders ADRs

constipation, hypercalcemia (need to restrict diet high in Ca)

aluminum containing phosphate binders ADRs

constipation, worsening of anemia (due to accumulation of AL)

avoid if possible

Mg containing phosphate binders ADRs

diarrhea

iron containing phosphate binders ADRs

nausea, dark/discolored feces, diarrhea, bloating, abdominal pain, constipation

take with meals

inorganic phosphates