Anti-Dysrhythmics

Question 1

Give an example of an anti-dsrhythmic

Answer 1

Amiodarone

Question 2

How does amiodarone work?

Answer 2

Blocks sodium, potassium and calcium channels in the myocardial cells
Antagonises the alpha and beta adroenrgic receptors on the myocardial cells
This results in:
- decreased spontaneous depolarisation (automaticity)
- increased resistance to depolarisation (refractioness)
- slows down conduction
**Interferes with AV node conduction overall and thus sinus rhythm

Question 3

What are the common uses for amiodarone?

Answer 3

1. AF
2. SVT
3. VT
4. VF

Question 4

Is amiodarone quickly prescribed?

Answer 4

No - often only used with other therapeutic options e.g. drugs or electrical cardio version is ineffective or inappropriate

Question 5

How long does amiodarone take to work?

Answer 5

Long half life so takes weeks to have an effect

If you want an immediate effect have to give IV

Question 6

When is amiodarone prescribed quickly and what is the dose?

Answer 6

Cardiac arrest!! It is given for VF or pulseless VT immediately after the third shock in the Advanced Life Support algorithm.
The dose is 300 mg IV, followed by 20 mL of 0.9% sodium chloride or 5% glucose as a flush. In this instance, it should be administered first and prescribed later.

Question 7

In a cardiac arrest how is amiodarone given?

Answer 7

As a bolus injection It is often provided in a pre-filled syringe to facilitate easy administration. It should be given through the ‘best’ IV cannula available.

Question 8

In general use how is amiodarone given?

Answer 8

Outside cardiac arrests, if continuous or repeated IV infusions are anticipated, these should be given via a central line. This is because peripheral intravenous administration can cause significant phlebitis.

Question 9

What are the contra-indications of prescribing amiodarone?

Answer 9

Sinus bradycardia
Heart Block
Severe hypotension
Active thyroid disease
Pregnancy/Breast feeding

Question 10

What are the common interactions with amiodarone?

Answer 10

LOADS

• Digoxin, veramapril and diltazam increase the plasma conc of amiodarone therefore increasing risk of bradycardia (amiodarone dose should be halved with these)
• Any drugs that increase QT interval
• Any drugs that reduce heart rate (CCB, beta blockers)

Question 11

What are the common side effects of amiodarone?

Answer 11

Hypotension (when used IV)
Lungs - pneumonitis
Heart- bradycarida/ heart block
Skin- Photosensitivity and grey discolouration
Liver - Hepatitis
Eyes - corneal lipofuscin micro deposits (most patients)
Thyroid abnormalities - due to iodine in amIODarone

Question 12

How is amiodarone eliminated?

Answer 12

Hepatic metabolism
Biliary excretion
Long half life