The other day I noted news of the Texas compounding pharmacy mistake that led to three deaths when an injectable colchicine preparation was found to be ten times more concentrated than labeled. Several readers commented on the reasons for the mistake, but I may have found another.
The source illustrating my pet peeve is the pharmacy’s own drug recall announcement posted this week on the FDA MedWatch site:
Recent deaths have been reported in connection with compounded Injectable Colchicine .5mg/ml, 4ml vials, lot number 20070122@26. As a result, ApothéCure is issuing an immediate drug recall at the request of the Texas State Board of Pharmacy for all strengths, sizes and lots of compounded Injectable Colchicine that we have sold in the last year.
Note specifically, “Injectable Colchicine .5mg/ml.”
The proper way to refer to fractional decimals less than one is with the leading zero: 0.5 mg/mL (or 0,5 mg/mL for my European colleagues).
Using “.5 mg/mL” just simply invites a ten-fold error. Is that decimal point a fleck on the prescription or the compounding instruction sheet (or computer screen)?
In that sense, it’s easy to see how the concentration could have been perceived as 5 mg/mL by the compounding pharmacist (especially if he/she shares my eyesight). It’s amazing to me that the unconventional use of “.5 mg/mL” even made it to the official recall notice that was them disseminated by the FDA.
Rick at Shrimp & Grits already noted that he would use this case to support why he does not give partial credit to his chemistry students for calculation errors. I wonder if Rick is also bothered by the lack of attention to including the leading zero?
I don’t treat patients so my calculation errors just end up wasting time. But I am still bothered when a new person in the lab makes up SDS-PAGE stacking gel buffer concentration and labels it .5M Tris-HCl, pH 6.8. I know that 5M is beyond the solubility of Tris, but please use “0.5M.” Maybe I’m finally just getting to be a cranky, old codger.
It’s finals time, students….doublecheck your calculations.