Amiodarone

Key points

• Class III antiarrhythmic: blocks potassium channels → inhibits repolarisation → prolongs action potential (also class I sodium-channel effect).
• Long half-life 20–100 days; ideally give via central vein (thrombophlebitis).
• Proarrhythmic (QT lengthening); P450 inhibitor — decreases warfarin metabolism.
• Monitoring: TFT, LFT, U&E, CXR before treatment; TFT + LFT every 6 months.
• Adverse effects: thyroid dysfunction (hypo & hyper), corneal deposits, pulmonary fibrosis/pneumonitis, hepatitis, peripheral neuropathy, photosensitivity, slate-grey skin, bradycardia.