Intramuscular Midazolam for Seizures – Part IV

Also posted over at Rogue Medic (now at EMS Blogs).

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What does this study mean for the treatment of patients who are having seizures?

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The median time to administration of active treatment was significantly shorter by the intramuscular route than by the intravenous route (1.2 vs. 4.8 minutes), but the onset of action (i.e., termination of convulsions) occurred sooner after intravenous administration than after intramuscular administration (1.6 vs. 3.3 minutes).^[1]

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Click on images to make them larger.

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The good news for fans of IV (IntraVenous) drugs for seizures is that giving IV lorazepam at the same time as giving IM (IntraMuscular) midazolam will result in faster termination of seizures.

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If an IV is already in place, the average time for the IV lorazepam to stop the seizure is about 1.6 minutes after the lorazepam is pushed into the IV line.

The average time for the IM midazolam to stop the seizure is about 3.3 minutes after the midazolam is injected into the muscle.

If an IV is already in place, IV lorazepam should be significantly faster.

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Would IV midazolam also work faster than IM midazolam?

Probably, but that was not demonstrated in this study. My preference is to give IV midazolam, rather than IV lorazepam, because the midazolam will wear off more quickly.

I am initially much more interested in stopping the seizure, than in the side effects that might be present as a result of aggressive dosing of benzodiazepine.

After the seizure, I want any side effects to stop as quickly as possible. Midazolam is going to be metabolized much more quickly than lorazepam. In the hospital, the continuing treatment of the patient will be in the hands of the emergency physician who will have a much broader selection of medications available to treat against further seizures.

Benzodiazepines appear to be the best emergency treatment for seizures, but they may not be good for longer term treatment of the same seizures.

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The problem is that EMS and ED (Emergency Department) patients rarely have an IV in place when seizures begin and it is not easy to start an IV on a patient while the patient is seizing.

Image credit.

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If an IV is NOT in place, then the delay in giving the medication is both dramatic and significant enough to completely eliminate the difference in absorption that favors giving IV medication.

With average times of 1.2 minutes from opening the medication box to injecting the medication IM and 4.8 minutes from opening the medication box to injecting the IV medication, the difference is 3.6 minutes.

The IV lorazepam works 1.7 minutes faster, but it takes 3.6 minutes longer before the IV lorazepam can be given, on average.

That difference means that the IM midazolam stops the seizure 1.9 minutes faster than the IV lorazepam.

The average total time to termination of seizure after opening the medication container was 6.4 minutes with IV lorazepam.

The average total time to termination of seizure after opening the medication container was 4.5 minutes with IM midazolam.

After 4.5 minutes, the medic is still working on starting the IV, but the seizure has already stopped in the IM midazolam group.

This should not be a difficult decision.

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See also Part I, Part II, and Part III. To be continued in Part V.

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Footnotes:

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^[1] Intramuscular versus intravenous therapy for prehospital status epilepticus.
Silbergleit R, Durkalski V, Lowenstein D, Conwit R, Pancioli A, Palesch Y, Barsan W; NETT Investigators.
N Engl J Med. 2012 Feb 16;366(7):591-600.
PMID: 22335736 [PubMed - in process]

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