Today in nursing pharmacology, we will take a quick study at a very interesting drug, Amiodarone, I will try as much as possible to make the notes easy to understand.
It is a benzofuran-derived, iodine-rich compound with some structural similarity to thyroxine (T4).
Relate these to the reason why you assess for allergic reactions to iodine among possible recipients.
• Amiodarone contains approximately 37% iodine by weight.
• Amiodarone was first made in 1961 and came into medical use in 1962 for chest pain.
Amiodarone Drug Profile:
• Group/Class: Antiarrhythmic medication, Adrenergic Blocker, [Potassium channel blocker].
• Routes of administration: Oral route, Intravenous, Intra osseous
- Loading dose: 800–1,600 mg/day PO in divided doses, for 1–3 wk; reduce dose to 600–800 mg/day in divided doses for 1 mo; if the rhythm is stable, reduce dose to 400 mg/day in one to two divided doses for a maintenance dose. Adjust to the lowest possible dose to limit side effects.
- 1,000 mg IV over 24 hr—150 mg loading dose over 10 min, followed by 360 mg over 6 hr at a rate of 1 mg/min. For maintenance infusion, 540 mg at 0.5 mg/min over 18 hr. May be continued up to 96 hr or until the rhythm is stable. Switch to oral form as soon as possible.
• Mechanism of action:
– It is a class III antiarrhythmic agent, it prolongs phase 3 of the cardiac action potential [prolongs the duration of the action potential by interacting among other cellular functions with K+ channels].
– It prolongs the refractory periods of the SA node and Av nodes, ventricles, the bundle of HIS and Purkinje fibres.
On the electrocardiogram, this increases the Q-T Interval.
Decrease in repolarization and refractory periods are the major elements of the mechanism of action of amiodarone.
NOTE: Potassium-channel blockers comprise the Class III antiarrhythmic compounds according to the Vaughan-Williams classification scheme. These drugs bind to and block the potassium channels that are responsible for phase 3 repolarization. Therefore, blocking these channels slows (delays) repolarization, which leads to an increase in action potential duration and an increase in the effective refractory period (ERP).
Adverse effects of amiodarone
- CNS: Malaise, fatigue, dizziness, tremors, ataxia, paresthesias, lack of coordination
- CV: Cardiac arrhythmias, CHF, cardiac arrest, hypotension
- EENT: Corneal microdeposits (photophobia, dry eyes, halos, blurred vision); ophthalmic abnormalities including permanent blindness
- Endocrine: Hypothyroidism or hyperthyroidism
- GI: Nausea, vomiting, anorexia, constipation, abnormal LFTs, hepatotoxicity
- Respiratory: Pulmonary toxicity—pneumonitis, infiltrates (shortness of breath, cough, rales, wheezes)
- Other: Photosensitivity, angioedema
- Follow the rules of medication administration when administering any kind of medication.
- History taking; find out if; the patient is hypersensitive to amiodarone, is lactating or pregnant [Pregnancy Category D].
- Regular monitoring of vital signs; Blood pressure, ECG, heart sounds, baseline chest x-ray, [Side effects of amiodarone include various pulmonary effects. The most serious reaction that is due to amiodarone is interstitial lung disease. Risk factors include high cumulative dose, more than 400 milligrams per day, duration over two months, increased age, and preexisting pulmonary disease]. Monitoring these physiological values enables quick detection of deviations from normal physiological functions.
Corneal micro-deposits (cornea verticillata, also called vortex or whorl keratopathy) are almost universally present (over 90%) in individuals taking amiodarone longer than 6 months, especially doses greater than 400 mg/day. Herein lies the need for regular ophthalmic assessments.
- Periodic chest x-rays as described earlier.
- Periodic blood tests for liver enzymes. [Abnormal liver enzyme results are common in patients on amiodarone].
- Explain side effects to the patient/client.
- Instruct patient/client to report any form of abnormality quickly.
- Ensure continuous medical follow-up, which will include regular and continuous monitoring of cardiac functions.
Notes are updated regularly.
- CV Pharmacology | Class III Antiarrhythmics (Potassium Channel Blockers). (n.d.). https://www.cvpharmacology.com/antiarrhy/potassium-blockers
- Rnpedia. (2019). amiodarone hydrochloride Nursing Considerations & Management. RNpedia. https://www.rnpedia.com/nursing-notes/pharmacology-drug-study-notes/amiodarone-hydrochloride/
- Wikipedia contributors. (2023). Amiodarone. Wikipedia. https://en.m.wikipedia.org/wiki/Amiodarone
DISCLAIMER: These materials are for educational purposes only, and are not a source of medical decision-making advice.