Amiodarone Flashcards
When is amiodarone indicated for use?
Tachyarrythmias
- AF
- Atrial flutter
- SVT
- VT
- Refractory VF
What is the mechanism of action of amiodarone?
Class III antiarrythmic
Many effects:
- Blockade of sodium, calcium and potassium channels
- Antagonism of α- and β-adrenergic receptors
These effects reduce spontaneous depolarisation (automaticity), slow conduction velocity, and increase resistance to depolarisation (refractoriness), including in the atrioventricular (AV) node.
- Primary MOA: antiarrhythmic effect via blockage of voltage-gated potassium channels → prolonged repolarization of the cardiac action potential
- Secondary MOA: inhibits β-receptors and sodium and calcium channels → decreases conduction through the AV and sinus node
How does amiodarone stop re-entry SVT?
If it involves the AV node, amiodarone may break the circuit and restore sinus rhythm
What are adverse side effects of amiodarone in the lung?
Pulmonary toxicity
- Pulmonary fibrosis
- Chronic interstitial pneumonitis
- Organizing pneumonia
- ARDS
- Solitary pulmonary mass
What are adverse side effects of amiodarone on the thyroid gland?
- Hypo/hyoperthyroidism
- May aggravate thyroid conditions
Why can amioderone cause thyroid abnormalities?
It is structurally similar to thyroid hormone, and contrains idoine
When should amiodarone be avoided?
Patients with
- Severe hypotension
- Heart block
- Active thyroid disease
What is important to remember when considering prescribing amiodarone?
Always requires a senior review
When is amiodarone used in cardiac arrest?
VF or pulseless VT - immediately after 3rd shock
How is amiodarone given in cardiac arrest?
Bolus injection through best IV cannula available, followed by saline/glucose flush (20 mL)
What is the dose of amiodarone given in cardiac arrest?
300mg/mL
What is the preferred access for administration of amiodarone?
PICC line
Why should repeated or continuous IV infusions of amiodarone be given via a central line rather than a peripheral cannula?
IV administration causes significant phlebitis
What is the maximum dose of amiodarone that can be given IV in 24 hours?
1.2 grams
What investigations would you consider doing in someone you are considering giving amiodarone (outside of a cardiac arrest)?
- CXR
- LFTs
- TFTs
If someone is on long-term amiodarone and develops a cough or shortness of breath, what would you consider doing?
May indicate serious pulmonary toxicity - Withdraw immediately
If someone on amiodarone long term developed new neurological symptoms, what would you do?
Stop amiodarone immediately - likely neurotoxicity
If someone on amiodarone long term develops blurred vision and visual haloes, what might you consider doing?
Refer to opthalmologist
How often should you repeat LFTs and TFTs in someone on long term amiodarone?
6-montlhy
What are adverse side effects of amiodarone on the liver?
Deranged liver function
What are adverse side effects of amiodarone on the heart?
- Bradycardia
- AV block
- Proarrythmia
What are adverse effects of amiodarone on the eyes?
- Corneal micro-deposits
- Optic neuritis
What adverse side effects does amiodarone have on the GI tract?
- Nausea
- Anorexia
- Constipation
What adverse side effects does amiodarone have on the skin?
- Photosensitivity
- Blue discolouration of the skin
What are adverse side effects of amiodarone on the nervous system?
- Peripheral neuropathy
- Ataxia
- Parastheasias
- Sleep disturbances
- Impaired memory
- Tremor
What are adverse side effects of amiodarone on genitourinary system?
- Epidydimitis
- Erectile dysfunction
What systems does amiodarone affect in terms of adverse effects?
- CNS
- Lungs
- Heart
- GU tract
- Skin
- Eyes
- GI tract
- Thyroid disease
- Liver
How long does it take for IV amiodarone take to reach peak effect?
15 minutes
How is amiodarone metabolised?
Metabolized in the liver by CYP3A4 with biliary excretion
