Show notes at pharmacyjoe.com/episode573.
In this episode, I’ll discuss the ceiling dose of ketorolac for renal colic in the ED.
Critical Care and Hospital Pharmacy Resources for Hospital Pharmacists, PGY-1 Pharmacy Residents, PharmD students, and Preceptors
Show notes at pharmacyjoe.com/episode573.
In this episode, I’ll discuss the ceiling dose of ketorolac for renal colic in the ED.
There is one issue related to the analgesic ceiling dose that I haven’t heard discussed much in the EM community – the duration of action.
Ironically, despite all the attention the ceiling dose is getting lately, this really shouldn’t have come as a surprise. The package insert reads “The peak analgesic effect of ketorolac occurs within 2 to 3 hours and is not statistically significantly different over the recommended dosage range”
But nobody seems to be paying attention to the next sentence in the PI. “The greatest difference between large and small doses of ketorolac is in the duration of analgesia.”
Reading from Table 2 in the PI single IV doses of 15 and 30 mg achieved 2.5 and 5 mcg/mL. The half life in healthy patients is 5 hours. This means I should expect for every doubling of the dose the duration will be extended by ~5 hours. 30 mg should last 5 hours longer than 15 mg. 60 mg should be 5 hours longer than 30 and 10 hours longer than 15.
Maybe now we see the problem. All the recent single dose ED studies evaluated patients at ONE hour and concluded there was no difference. I’m glad they were published and have gotten the message out but it should have been a NO DUH moment. I went back further to some studies in the late 80s and early 90s. Joe already reviewed these in episode 473. They evaluated outcomes at 6 hours and found no difference. Again, maybe we shouldn’t have expected to see a difference until after 6 hours.
The problem here is that I don’t really know how long 10-15 mg lasts. Apparently it is at least 6 hours but until someone does a single dose study beyond 6 hours I don’t think it is fair to say there is never a reason to use doses > 10 mg.
So my question is, are there circumstances where the longer duration of analgesia might avoid a bounce back or just make somebody more comfortable? Certainly, there seems to be a trade off with increasing injection site pain as doses increase. Do we need more nuance in this discussion?