Medicine & USMLE


Cardio Drugs - Antiarrhythmics
  1. Diltiazem and Verapamil (Calcium Channel Blockers)
  2. Class 1A Antiarrhythmics
  3. Class 1B Antiarrhythmics
  4. Class 1C Antiarrhythmics
  5. Class 3 Antiarrhythmics
  6. Amiodarone Side Effects
  7. Adenosine


Adenosine is a short acting medication that only lasts around 15 seconds. It works by slowing conduction through the A/V node.

Adenosine is an antiarrhythmic, and can be used to treat pSVT.

Dipyridamole increases the effect of adenosine, while theophylline and caffeine decrease its effect.

Side effects of adenosine include flushing, bradycardia, temporary asystole, and dyspnea.

When administering adenosine, give via rapid IV push and immediately follow with a saline flush to ensure that the medication has its full effect in the body.

Key Points

  • Adenosine (Adenocard)
    • Mechanism
      • Slows conduction through the AV node
        • The AV node is responsible for sending the electrical signal down to the ventricles of the heart
      • Short acting (<15 seconds)
        • The half life of the drug is less than 10 seconds, meaning its effects only last for a matter of seconds
    • Clinical Use
      • Antiarrhythmic
        • Treats Paroxysmal Supraventricular Tachycardia (PSVT)
          • Converts PSVT to normal sinus rhythm
          • First-line drug of choice for treating PSVT
          • If multiple doses are not successful, adenosine is usually followed by cardioversion
        • Treats Wolff-Parkinson-White syndrome
          • An extra electrical pathway between upper and lower heart chambers that causes an extra fast rhythm
      • Used in pharmacological stress testing
    • Side Effects
      • Because of its short duration, side effects usually only last a minute or two
      • Temporary asystole
        • A brief period of asystole following administration is expected, with the goal of the heart restarting in normal sinus rhythm
        • Requires continuous cardiac monitoring and frequent assessment of vital signs
      • Bradycardia
      • Flushing
        • Adenosine has a slight vasodilation effect, causing flushing of the facial skin
      • Dyspnea
        • Monitor the patient’s breathing during treatment
      • Drug Interactions
        • Theophylline and caffeine decrease effectiveness
        • Dipyridamole intensifies effect of adenosine
    • Administration
      • Give via rapid IV push
        • The dose should be pushed into the IV in a matter of seconds
        • This is unique to adenosine, since most medications you want to administer slowly over several minutes
        • Give through IV closest to the heart
          • Because adenosine has such a short half life, administering it through the IV access closest to the heart will ensure the drug is as effective as possible
      • Immediately follow with saline flush
        • This ensures that the full dose enters the bloodstream and none remains in the IV tubing