Antiarrhythmics

Question 1

Adenosine

• Class
• MoA
• Side effects
• Extra info

Answer 1

Class:
Antiarrhythmic type V (miscellaneous)

MoA:
Causes transient heart block in the AV node
Agonist of the A1 receptor in the atrioventricular node, which inhibits adenylyl cyclase thus reducing cAMP and causing hyperpolarization by increasing outward potassium flux

Side effects:
Chest pain, bronchospasm, transient flushing
Can enhance conduction down accessory pathways, resulting in increased ventricular rate (e.g. WPW syndrome)

Extra info: Should be given via wide bore cannula due to short half life

Question 2

Amiodarone

• Class
• MoA
• Side effects
• Monitoring
• Extra info

Answer 2

Class:
Antiarrhythmic type III (potassium channel blocker)

MoA:
Blocks potassium channels which inhibits repolarisation and hence prolongs the action potential.

Side effects:
Thyroid dysfunction: both hypothyroidism and hyper-thyroidism, corneal deposits, pulmonary fibrosis/pneumonitis, liver fibrosis/hepatitis, peripheral neuropathy, myopathy, photosensitivity, ‘slate-grey’ appearance, thrombophlebitis and injection site reactions, bradycardia, lengths QT interval

Monitoring:
TFT, LFT, U&E, CXR prior to treatment
TFT, LFT every 6 months

Extra info:
Thrombophlebitic so should be administered via central veins