I wound up answering a question on one of the Connect list servers I get and the need to answer it caused me to again reflect on the value of a basic science education, and the disservice I think we do to current graduates by not requiring those basics.
The question, you see, was about a "stability" for Potassium Chloride 10 mEq in 100 mL 0.9% Sodium Chloride. Please note that I am not taking pot shots at the Pharm D who asked the question. I have no doubt that their education lacked what was necessary to know the answer. I am taking potshots at a professional education system that would put that person in that position.
For those of you who similarly have no idea how to address that question, it turns out that most of the medications we place into solutions in the IV room are organic chemicals subject to a variety of degradation paths (oxidation being one of the more prominent). As a result, a variety of factors can cause those drugs to degrade over time and lose potency.
The difference, of course, is that Potassium Chloride is not an organic chemical; it is, in fact, an inorganic salt. Over time, a solution containing it may lose water, causing it to become more concentrated, but it will still be Potassium Chloride long after all of us reading this blog have died. Short of intentional treatment with a strong acid or base, it has no degradation path at all. So what this means is that beyond use dating that we give to a preparation containing only Potassium Chloride as an active ingredient is almost entirely a discussion of our confidence in its sterility
. So, unless these doses are being made one-at-a-time from single-dose vials, these fall under the current USP <797> definition of medium risk
which means the longest they can have is 30 hours.
I suppose that it is possible that the person asking the question is using the term "stability" to mean "shelf-life" which is a combination of a number of factors. If so, that still represents a problem, which is our tendency to overload words with multiple meanings rather than adopt a precision of speech that would permit us as a profession to at least communicate clearly among ourselves. But this person bemoaned the lack of stability data in our literature, which suggests pretty strongly to me that they were talking about stability as a concept, and had no idea how stability (and its counterpart, degradation) relate to inorganic compounds. And that's pretty basic.
Since then, I have seen several other posts asking the same question and looking for a reference that gives an answer. One of those indicated to me in a follow-up conversation that their State Board would not accept basic science as an answer, but rather require them to produce a reference.
Sadly this isn't new. Back in 1994 when the Tripler incident
caused us to all evaluate our knowledge of the stability of lipid emulsions and calcium/phosphorus interactions in TPN's, I found any number of well-educated pharmacists in the field who had no idea how emulsions worked or the science behind calcium and phosphorus interactions in TPN's. They were the products of educational systems who no longer valued providing that knowledge.
I will go back to a previous blog
and opine that we as a profession are losing that role, that knowledge, that information that makes us unique in the healthcare world; and offer this most recent discussion as an example.
Dennis A Tribble, Pharm.D., FASHP
Ormond Beach, FL
The opinions expressed herein are my own and not necessarily those of ASHP or of my employer