Amiodarone + Angina + AGII blockers + Antiplatelets

Question 1

What is amiodarone?

Answer 1

Class III antiarrhythmic agent used in the treatment of:

• atrial
• nodal
• ventricular tachycardias

Question 2

How does amiodarone work?

Answer 2

1. Blocks potassium channels
2. Inhibits repolarisation
3. Prolongs the action potential
4. Amiodarone also blocks sodium channels (a class I effect)

Question 3

How is amiodarine use limited?

Answer 3

1. Very long half-life (20-100 days) :. loading doses are frequently used
2. Should be given into central veins (causes thrombophlebitis)
3. Has proarrhythmic effects due to lengthening of the QT interval
4. Interacts with drugs commonly used concurrently (p450 inhibitor) e.g. Decreases metabolism of warfarin

Question 4

What do you monitor when taking amiodarone?

Answer 4

1. TFT, LFT, U&E, CXR prior to treatment
2. TFT, LFT every 6 months

Question 5

What are adverse effects of amiodarone?

Answer 5

1. thyroid dysfunction: both hypothyroidism and hyper-thyroidism
2. corneal deposits
3. pulmonary fibrosis/pneumonitis
4. liver fibrosis/hepatitis
5. peripheral neuropathy, myopathy
6. photosensitivity
7. ‘slate-grey’ appearance
8. thrombophlebitis and injection site reactions
9. bradycardia
10. lengths QT interval

Question 6

What is the management of angina pectoris?

Answer 6

Medication:

• All patients: aspirin + statin (if no c/i)
• Sublingual GTN for attacks
• Beta-blocker or a calicum channel blocker first-line based on ‘comorbidities, contraindications and the person’s preference

Question 7

What is the guidance on nitrate tolerance?

Answer 7

• many patients who take nitrates develop tolerance and experience reduced efficacy
• patients who develop tolerance should take the second dose of isosorbide mononitrate after 8 hours, rather than after 12 hours
  
  • allows blood-nitrate levels to fall for 4 hours and maintains effectiveness
• this effect is not seen in patients who take modified release isosorbide mononitrate

Question 8

When do you use angiotensin II receptor blockers?

Answer 8

• used in situations where patients have not tolerated an ACE inhibitor
  
  • usually due to the development of a cough

Example:

• candesartan
• losartan
• irbesartan

Question 9

What are the contraindications of angiotensin II receptor blockers?

Answer 9

• Like ACE inhibitors they should be used with caution in patients with renovascular disease
• Side-effects include hypotension and hyperkalaemia.

Question 10

What is the mechanism of angiotensin II receptor blockers?

Answer 10

block effects of angiotensin II at the AT1 receptor

Question 11

What evidence is there for angiotensin II blockers?

Answer 11

• shown to reduce progression of renal disease in patients with diabetic nephropathy
• evidence base that losartan reduces CVA and IHD mortality in hypertensive patients

Question 12

What are the guidelines for antiplatelet therapy?

Answer 12