Amiodarone Flashcards
Class
Class III anti-arrhythmic drug
Alters sinus rhythm to restore normal heartbeat
Dose
Requires loading dose.
200 mg TDS for 7 days
200 mg BD for 7 days
200 mg OD maintenance
Half-life
Long half-life
Side effects can occur up to a year after stopping due to the long half-life.
Side effects - overview
NTELLS
(Nafisa TELLS)
- Eyes
- Skin
- Nerves
- Lungs
- Liver
- Thyroid
Side effects - eyes
Corneal micro-deposits
- Reversible on withdrawal.
- Common
- Rarely impairs vision
- Drivers may be dazzled by headlights at night
Optic neuropathy/neuritis
- STOP if impaired vision
Side effects - skin
Phototoxicity
- Burning sensation
- Erythema
- Slate grey skin discoloration on light exposed areas
- Cover skin + high SPF sunscreen during and for months after treatment.
Side effects - Nerves
Peripheral neuropathy
- Numbness
- Tingling hands and feet
- Tremors
Side effects - Lungs
Pneumonitis
Pulmonary fibrosis
- New/progressive SoB
- Dry cough
Side effects - Liver
Hepatotoxicity
- Jaundice
- N + V
- Malaise
- Itching
- Bruising
- Abdominal pain
- LFTs 3x ULN
Side effects - Thyroid dysfunction
Amiodarone contains Iodine which can cause hypo or hyperthyroidism.
Hyperthyroidism
Withdraw amiodarone and give carbimazole if necessary.
- Weight loss
- Heat intolerance
- Tachycardia
Hypothyroidism
Start levothyroxine if needed, without withdrawing amiodarone.
- Weight gain
- Cold intolerance
- Bradycardia
Monitoring
Before:
- LFTs
- Thyroid function
- Chest x-ray
- Serum potassium (hypokalaemia = enhanced anti-arrhythmic effect of amiodarone)
6 months:
- LFTs
- Thyroid function
Annual
- Eye test
IV
- BP + ECG
Amiodarone interactions
Statins - increased risk of myopathy
Grapefruit juice (enzyme inhibitors) - increased plasma conc. of amiodarone
Amiodarone interactions - enzyme inhibitors
Amiodarone is an enzyme inhibitor. Therefore, when taken with the following drugs enhances their effects and potency.
- Warfarin
- Phenytoin
- Digoxin (half the dose)
Interactions - bradycardia
Amiodarone when taken with the following drugs can lead to bradycardia, AV block and myocardial depression
- Beta-blockers
- Rate limiting CCBs (verapamil and diltiazem)
Interactions - QT prolongation
QT prolongation = increased risk of ventricular arrhythmias
- Antipsychotics (esp pimozide, sulpride, amisulpride)
- Antimalarials (chloroquine, mefloquine)
- Hydroxychloroquine
- Lithium
- Macrolides
- Quinine
- Quinolones
- SSRIs
- TCAs
Interactions - plasma conc.
Increases the plasma concentration of:
- Coumarins
- Dabigatran
- Digoxin
- Flecainide
- Phenindione
- Phenytoin
Pregnancy
Risk of neonatal goitre
Only use if no alternative
Breastfeeding
Avoid - significant amounts present in milk.
Theoretical risk of neonatal hypothyroidism from
release of iodine
