Calcium & Bone Meds

Question 1

What’s the general action of parathyroid hormone (PTH)?

Answer 1

it increases the extracellular calcium concentration

Question 2

Which chemical is lost when Calcium absorption is increased at the renal tubule (by PTH)

Answer 2

Phosphate

(PO3/4)

Question 3

PTH and phosphate, what’s the link?

Answer 3

PTH decreases reaborption of phosphate at the renal tubules.

a DECREASE in extracellular phosphate leads to an INCREASE in extracellular calcium.

Question 4

PTH - increases or decreases bone?

Answer 4

decreases.

It stimulates osteoclasts so that bone calcium can enter the extracellular pool.

Question 5

Which thyroid hormone inhibits bone resorption and decreases plasma calcium levels?

Answer 5

Calcitonin

Question 6

Which group of drugs can interfer with Vit D absorption?

Answer 6

anti-convulsant drugs (eg. phenytoin)

Question 7

What is osteomalacia?

(rickets in children)

Answer 7

Softening of the bones caused by impaired bone metabolism.

• to inadequate levels of available phosphate, calcium, and vitamin D, or because of resorption of calcium.

Question 8

Who is at risk of osteomalacia?

Answer 8

elderly px in nursing homes due to << sun exposure and << Vit D absorption in the gut due to aging, chronic renal impairment (loss of phosphate)

Question 9

What chemical gives bones its strength?

Answer 9

Calcium Phosphate

Question 10

Why would the elderly, and px on PPIs, benefit from calcium citrate medication and NOT calcium carbonate?

Answer 10

The absorption of calcium carbonate requires stomach acid.

Question 11

What’s the most common effect of calcium supplements?

Answer 11

constipation

Question 12

Why do patients with chronic renal failure need calcitriol (Vit D)?

Answer 12

They lack an enzyme to synthesize the active form of Vit D.

(Vit D is hydroxlated in the kidneys and liver)

Question 13

What’s the MOA of most drugs used to treat bone disorders?

Answer 13

Inhibit bone resorption by osteoclasts.

(eg. bisphosphonate, calcitonin, ostrogen, raloxifene, denosumab)

Question 14

Bisphosphonates

(most drugs end in -nate)

eg. alendronate

+ adminstration advice

Answer 14

Inhibit bone resorption

Needs to be taken on an empty stomach with large glass of water. Absorption is poor, and even worse with food, meds, etc., in stomach.

Take standing up to prevent oseophageal erosion.

Question 15

What are bisphosphonates indicated for?

(NB side effect << risk of breast cancer)

Answer 15

osteoporosis

Paget disease of bone

hypercalcaemia

osteolytic bone lesions of metastatic cancer

Question 16

If patient has been taking bisphosphonates for over five years and complains of dull, aching pain in thigh or groin, what is the danger?

Answer 16

>> risk of atypical femur fractures.

Question 17

What’s unique about calcitonin?

Answer 17

increases BMD in the spine, but has variable effect on the BMD in the hips.

Must have Calcium and Vit D during calcitonin therapy.

Usually reserved for woman who can’t tolerate other treatments. Maybe indicated for women who have taken bisphosphonates for many years.

Question 18

How can hypercalcamia be treated?

Answer 18

subcutaneous or intramuscular injections of calcitonin.

Question 19

What causes hypercalcaemia?

Answer 19

hyperparathyroidism

cancer

Question 20

Tx of gout

Answer 20

Acute; NSAIDs, (+PPIs) or if can’t tolerate then colchicine or steroids.

Chronic; allopurinol or if not tolerated, try febuxostat

Question 21

What is Febuxostat?

Answer 21

Competitive inhibitor of xanthine oxidase. This enzyme is used in the production of uric acid.

First new drug in 40 years to treat gout.

Greater efficacy than allopurinol.

Question 22

What are DMARDs?

Answer 22

Disease-Modifying Antirheumatic Drugs

eg. gold salts, glucocorticords (problem with long-term use), methodrexate, infliximab, etanercept, leflunomide.
- have a delayed onset of action and take weeks/ months for therapeutic effect.
- used to slow progression of joint erosion.

Question 23

What is the DMARD of choice for RhA?

Answer 23

Methotrexate

(often combined with other DMARDs)

Question 24

What’s the problem with allopurinol?

Answer 24

25% of px can’t tolerate it because of adverse effects; nausea, vomiting, hepatitis, skin rashes, hypersensitivity reactions.

Question 25

What is allopurinol?

Answer 25

inhibitor of xanthine oxidase

(like Febuxostat)

• used to tx gout.