Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Where are the Black Box Warnings on These Drugs – I

There is a black box warning on droperidol for prolonging the QT segment, but there is no black box warning for this commonly used EMS drug (Drug X) that also prolongs the QT segment. Are we supposed to think that Drug X is safer than droperidol?

Like all antiarrhythmic agents, Drug X I.V. may cause a worsening of existing arrhythmias or precipitate a new arrhythmia. Proarrhythmia, primarily torsades de pointes (TdP), has been associated with prolongation by Drug X I.V. of the QTc interval to 500 ms or greater. Although QTc prolongation occurred frequently in patients receiving Drug X I.V., torsades de pointes or new-onset VF occurred infrequently (less than 2%). Patients should be monitored for QTc prolongation during infusion with Drug X I.V. Combination of Drug X with other antiarrhythmic therapy that prolongs the QTc should be reserved for patients with life-threatening ventricular arrhythmias who are incompletely responsive to a single agent.

What is Drug X?

If you know, have you ever been warned about the possibility of inducing torsades de pointes or new-onset VF with Drug X?

What is the incidence of torsades de pointes or new-onset VF with droperidol?

Much much less than 2%, so where is the black box for Drug X?

Image credit.

Electrolyte Disturbances
Patients with hypokalemia or hypomagnesemia should have the condition corrected whenever possible before being treated with Drug X I.V., as these disorders can exaggerate the degree of QTc prolongation and increase the potential for TdP. Special attention should be given to electrolyte and acid-base balance in patients experiencing severe or prolonged diarrhea or in patients receiving concomitant diuretics.

What is Drug X?

If you know, have you ever been warned to avoid giving Drug X to hypokalemic or hypomagnesemic patients?

In EMS, other than guessing based on the patient’s history, how would we know that the patient has hypokalemia or hypomagnesemia?

In the ED (Emergency Department), do they check magnesium or potassium levels before giving Drug X?


What is Drug X?


Where’s the black box warning for Drug X?



[1] Drug X
FDA label
The answer next week, although most medics, nurses, and doctors should know what it is.



  1. I know what it is!!!!!!!

    I’ll keep my fingers quiet for now, though.

  2. I’m pretty sure it’s a drug we all know and those of us stuck in the stone ages love. It is a useful adjunct for a certain type of airway control though.

  3. A number of our antiarrhythmics are also proarrhythmics, but I recall reading that statement when checking inventory one day and reading drug inserts when things got really boring. My bet is it is a Class III agent (#2 guess is a class Ia).

  4. Zofran?

    • Mordy,


      Ondansetron (Zofran) does cause these problems, but I don’t think it is used as commonly as the drug I am looking for.

      VinceD mentioned the problems with Zofran, and the many other QT prolonging drugs, here.


      • I know in my neck of the woods we give Zofran far more often than Drug X (if my hunch is right it’s a Vaughn-Williams Class III drug); but we give it in the lower 4-8mg range.

        • Same here! I was always sold on the fact that “Zofran was developed for Chemo patients so it must be completely benign” – I still like to use it as it works very well and in most cases makes my patient feel much better. They are generically on the monitor anyway so I just keep an eye out for any funny business. Worst comes to worse they’ll go into v-fib and I’ll hit them with drug X 🙂

          • Never trust people who come up with an explanation for why something is completely benign. Just because a drug can be used on patients taking chemotherapy, does not mean that the drug is benign – and nothing is completely benign.

            Chemotherapy definitely weakens patients, but we could state the same thing about any medication used to treat very sick patients. A patient with an unstable arrhythmia may be much more vulnerable to medication side effects than someone receiving chemotherapy.

            We worry about giving sedatives to patients prior to cardioversion, because a sedative may cause hypotension, or worsen any hypotension that already exists.

            Hypotension is the most common adverse effect seen with amiodarone I.V. In clinical trials, treatment-emergent, drug-related hypotension was reported as an adverse effect in 288 (16%) of 1836 patients treated with amiodarone I.V.

            In some cases, hypotension may be refractory resulting in fatal outcome

            Bradycardia and AV Block
            Drug-related bradycardia occurred in 90 (4.9%) of 1836 patients in clinical trials while they were receiving amiodarone I.V. for life-threatening VT/VF; it was not dose-related.

            Like all antiarrhythmic agents, amiodarone I.V. may cause a worsening of existing arrhythmias or precipitate a new arrhythmia.

            Amiodarone I.V. should be administered only by physicians who are experienced in the treatment of life-threatening arrhythmias, who are thoroughly familiar with the risks and benefits of amiodarone therapy, and who have access to facilities adequate for monitoring the effectiveness and side effects of treatment.

            How many of us are thoroughly familiar with the risks of amiodarone?

            AMIODARONE HYDROCHLORIDE injection, solution
            [Bedford Laboratories]

            FDA Label

            How much time do we spend explaining the following risk to the patients?

            In some cases, hypotension may be refractory resulting in fatal outcome


        • With QT segment prolonging drugs, the dose does seem to be important – but when QT segment prolonging drugs are used to treat conditions that may protect against arrhythmia.

          This seems to be ignored in the consideration of the risk of using droperidol for excited delirium. Many of these patients have taken QT segment shortening medications, such as methamphetamine and cocaine, but in higher than therapeutic levels.


  5. Amiodarone.


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