Drugs affecting calcium balance

Question 1

What are the effects of PTH?

Answer 1

Bone- Net increase in resorption and Increases Calcium
Kidney- Increases calcium, ↓reabsorption of phosphate and Stimulates Vitamin D to active form
Intestine- Indirectly increases Calcium and phosphate absorption by enhancing formation of vit D3 (active form) in kidney.

Question 2

What are the actions of Vit D?

Answer 2

Increases calcium
Increases bone turn over
Renal- Increased calcium absorption in distal tubules and
Increased Phosphate absorption.

Question 3

What are the actions of Calcitonin?

Answer 3

Potent inhibitor of osteoclast mediated bone resorption
Decreases renal excretion of Ca2+
Plasma Phosphorus concentration lowered

Question 4

What is MoA of teriparatide?

Answer 4

Synthetic human PTH
Continuous use: Bone demineralization, osteopenia
Intermittent use: Bone growth and increases Bone Mineral Density

Question 5

What is the use of teriparatide?

Answer 5

Used to treat osteoporosis and promotes fracture healing.

Question 6

What are ADR of teriparatide?

Answer 6

Increased risk of osteosarcoma
Nephrolithiasis
Increased serum uric acid levels (gout)

Question 7

What is MoA of cinacalcet?

Answer 7

Increases sensitivity of CaSR (Ca sensing receptor) to extracellular Ca2+ leads to decrease in PTH.

Question 8

What is the use of cinacalcet?

Answer 8

Treats parathyroid carcinoma and secondary hyperparathyroidism.

Question 9

What are ADR of cinacalcet?

Answer 9

Hypocalcemia

Decreases seizure threshold (Not used if <8.4mg/dl)

Question 10

What is MoA of denosumab?

Answer 10

Monoclonal antibody
Binds with high affinity to RANKL, mimicking OPG
Blocks osteoclast formation and activation
Increases Bone Mineral Density

Question 11

What are some Vit D preparations?

Answer 11

Cholecalciferol

Calcitriol

Question 12

What are some calcium salts?

Answer 12

Calcium gluconate- Given in hypocalcemia, rapid infusion can cause cardiac arrhythmias
Calcium carbonate

Question 13

What are some bisphosphonates?

Answer 13

Etidronate
Alendronate, pamidronate
Risedronate, zoledronate

Question 14

What is MoA of bisphosphonates?

Answer 14

Analogs of pyrophosphate
Chelates calcium and sticks it to the bone
Strong affinity for bone, get incorporated in matrix and remain until bone is remodeled
Inhibits recruitment and promote apoptosis of osteoclasts, and inhibit bone resorption by inhibiting farnesyl pyrophosphate synthase

Question 15

What are ADR of bisphosphonates?

Answer 15

Gastric irritant- given on empty stomach
Osteonecrosis of jaw (also caused by denosumab)
Atypical subtrochanteric fracture (never given after a fracture because healing requires ostoclasts).

Question 16

What is MoA of Raloxifene?

Answer 16

Selective Estrogen Receptor Modulator

Question 17

What is the use of Raloxifene?

Answer 17

Used in prevention and treatment of osteoporosis

Increases Bone Mineral density (BMD)

Question 18

What is MoA of calcitonin?

Answer 18

Decreases Ca2+ levels

Question 19

What is the use of calcitonin?

Answer 19

Treatment of hypercalcemia, paget’s disease

Can cause allergic reactions

Question 20

What is Osteoporosis? and treatment

Answer 20

Primary- Loss of trabecular bone
Tx- Bisphosphonates (DOC- Alendronate), Teriparatide
Secondary- Loss of cortical and trabecular bone
Tx- Glucocorticoids

Question 21

What is paget’s disease? and treatment

Answer 21

Increased bone resorption followed exuberant bone formation, new bone disorganized and of poor quality.
Tx- Bisphosphonates-Alendronate
Calcitonin

Question 22

Vit. D deficiency and treatment

Answer 22

Adults- Osteomalacia
Children- Rickets
Tx-Vit D daily

Question 23

What is Hypoparathyroidism and treatment

Answer 23

PTH deficiency- blood calcium level falls and phosphate levels rise
Tx- Dihydrotachysterol

Question 24

What is Secondary hyperparathyroidism and treatment

Answer 24

Caused by renal failure, kidney excretes less phosphate
High blood phosphate precipitates calcium- forms calcium phosphate, blood calcium decreases and stimulates PTH. Bone resorption is increased
Tx- DOC Cinacalcet
Calcitriol

Question 25

What are the symptoms and treatment of Hypercalcemia?

Answer 25

Constipation, lethargy, confusion, polyuria, renal stone, arrhythmia
Tx- Hydration- fluids + Furosemide
Calcitonin

Question 26

What are the symptoms and treatment of Hypocalcemia?

Answer 26

Caused by malabsorption
Tetany, laryngospasm, muscle cramps, tonic clonic convulsions
Tx- Give Ca2+ and Vit. D