Alendronate

Question 1

What class does Alendronate belong to?

Answer 1

Agents affecting calcium and bone metabolism

Bisphosphonates

Question 2

What is Alendronate?

Answer 2

Marketed as Fosamax.

It is a nitrogen containing 2nd generation bisphosphonate.

Question 3

What is Alendronate indicated for?

Answer 3

Osteoporosis treatment
Prevention of postmenopausal osteoporosis
Paget’s disease

Question 4

What are examples of other drugs in the same class as Alendronate?

Answer 4

Zoledronic acid

Disodium etidronate

Question 5

What is the mechanism of action of Alendronate?

Answer 5

At the cellular level, alendronate preferentially localises to sites of bone resorption specifically under osteoclasts.
Alendronate inhibits osteoclast activity.
It needs to be continuously administered to suppress osteoclasts on newly formed resorption surfaces.
This results in bone formation exceeding bone resorption at these remodelling sites, resulting in progressive gains in bone mass.

Question 6

What is the dose of Alendronate given to patients with postmenopausal osteoporosis?

Answer 6

10mg daily

OR

70mg once weekly

Question 7

What is the dose of Alendronate given to osteoporosis treatment in men?

Answer 7

10mg daily

Question 8

What is the dose of Alendronate given for the prevention and treatment of corticosteroid induced osteoporosis in post-menopausal women not receiving HRT?

Answer 8

10mg daily

Question 9

How should Alendronate be taken?

Answer 9

Tablets should be swallowed whole with plenty of water while sitting/standing.

Needs to be taken on an empty stomach 30 minutes before breakfast or another oral medicine.

The patient should stand/sit upright for at least 30 minutes after taking the tablet

Question 10

What are the characteristic pharmacokinetic/pharmacodynamic parameters of Alendronate?

Answer 10

mean F 0.64% similar in men and women
distributes to soft tissues first, then rapidly to bone or excreted in urine. VD (steady state) = at least 28L
Protein binding in human plasma = 78%

No evidence of metabolism in animals or humans

~50% eliminated in urine within 72 hours, very little eliminated via faeces.

Terminal half life exceeds 10 years.

Question 11

What is the role of Alendronate in osteoporosis therapy?

Answer 11

First line treatment of bisphosphonates as generally well tolerated by patients, however, requires special authority.

Question 12

What are the precautions associated with Alendronate?

Answer 12

upper GI disorders
active GI bleeds
correct disturbances of Ca and mineral metabolism like vit D deficency, hypocalcaemia
osteonecrosis of the jaw, atypical fermoal fractures,

Avoid in pregnancy and breastfeeding

Question 13

What are the contraindications associated with Alendronate?

Answer 13

abnormalities of oesophagus and other factors which delay emptying (e.g. stricture or achalasia); hypocalcaemia (within reason)

avoid if eGFR less than 35mL/min/1.73m^2

Question 14

What are the adverse effects associated with Alendronate?

Answer 14

severe oesophageal reactions (oesophagitis, oesophageal ulcers, oesophageal stricture, oesophageal erosions), abdominal pain and distension, dyspepsia, regurgitation, melaena, diarrhoea or constipation, flatulence, headache, musculoskeletal pain;

Question 15

What are the drug interactions associated with Alendronate?

Answer 15

as with all bisphosphonates,

antacids, calcium, iron: reduce absorption of bisphosphonates

aminoglycosides: increased risk of hypocalcaemia
cytotoxics: increases plasma concentration of cytotoxics

Question 16

What are the alarm bells associated with Alendronate use?

Answer 16

Patients to stop and seek medical attention if they develop symptoms of oesophageal irritation such as dysphagia, , new or worsening heart burn, pain on swallowing or retrosternal pain.