HWN Suggests

Isoproterenol

The drug is not commonly used anymore but is effective in treating persistent bradycardia or for overdrive pacing in patients with intermittent torsades de pointes when magnesium is ineffective. Be wary, though, that the beta-2 effect produces vasodilation so there may be a mild reduction in blood pressure when the drug is used.

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Articles of Interest

How safe do you feel...Epinephrine versus isoproterenol

Sorry if it's a silly question. The health authorities/regions I have worked with have policies to guide ER/Critical Care practice, and at times, have strongly recommended not to administer epinephrine concurrently with isoproterenol AND wait for a certain period of time (at least an hour) after epinephrine before starting isoproterenol. Rationale being that both may have aggressive additive cardiac effect leading to worsening arrhythmias. Just pace them. The few cases of refractory bradycardia (CHB usually) I’ve come across in 15 years of emergency care, if epi/dopa doesn’t work, just externally pace until you can drop a transvenous pacemaker. If they are that sick, they need a pacer now.

Prevent torsades from recurring

Speed up the heart (to decrease the QT interval). This can be done either medically (using isoproterenol) or electrically... Start at 5mcg/min (0.1mcg/kg/min in children). Titrate to 30 beats/min above patient’s natural rate (or whatever rate is needed to suppress torsades).

Emergency Medicine: Surviving the Chaos

Isuprel is an old ACLS making a comeback used for chemical pacing...

Isoproterenol Citations: The Vasopressor & Inotrope Handbook

Collection of articles...

The Rising Costs of Isoproterenol

The most commonly used cardiac medication in the EP laboratory is isoproterenol (Isuprel). It has been used for years to increase sympathetic tone in patients who are sedated, and is titrated to mimic a broad spectrum of autonomic states, from a more awake status to that during exercise. Now likely used in a majority of EP procedures, isoproterenol has proven to be invaluable.

Vasopressors

Mechanism: Pure beta-agonist. Physiologic effect: Very powerful chronotrope, with positive inotropic effects as well. Clinical use: Bradycardia (will work in some patients who are refractory to epinephrine). How to titrate: typically, against heart rate. Pro/Con? Isoproterenol is probably the most powerful chronotrope. It doesn't cause vasoconstriction, so it's safe to give peripherally. Its main drawback is pricing & availability: in the United States the price is astronomical and some hospitals don't have it. If you don't have it, epinephrine can usually be used as an alternative agent.

Resources

Isuprel

Isoproterenol hydrochloride is 3,4-Dihydroxy-α-[(isopropylamino)methyl] benzyl alcohol hydrochloride, a synthetic sympathomimetic amine that is structurally related to epinephrine but acts almost exclusively on beta receptors.

StatPearls

Isoproterenol (also known as isoprenaline) is a drug used to treat bradycardia conditions. the drug has a structural resemblance to epinephrine. It first received approval for use in the United States in 1947.