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by Kazeem Olalekan MRPharmS

On this blog, I have been very vocal in recent past about the seemingly increasing need to add additional layer of packaging to medication bottle. It started with our post on the 15th of September 2009 (1), then 28th of September 2009 (2) and later in October 2009 (3). It was a conservation stance. It feels counter-intuitive at a time when we are advocating reduction in unnecessary packaging. The manufacturer we questioned at the time said it was an MHRA requirement because: “the Patient Information Leaflet (PIL) that was on the first packaging was of the wrong font size and the only way the manufacturer can accommodate this was to supply the product with a big box around it”. That is funny! Because whilst the MHRA is focused on the “font size” of patient information leaflet, it has let slip a rather important information!


I am of course talking about a potentially serious error of omission we uncovered recently! In my practice, I came across this product which had to be “re-packaged” to include the patient information (see image). The only problem is: the number of millimoles of potassium (an important measure of dosing of this medicines in children) has been omitted! It was in the old packaging but not in the new one! Yes, the number of millimoles can be calculated from the information provided but that introduces another layer of potential calculation error!

If we cannot save the planet, can we at least make sure that we don’t introduce unnecessary areas of potential dosing errors into the dispensing/supply process! My patients deserve that at the very least.

  1. Calculating the number of millimoles of potassium in the solution:

    K^+ + Cl^- = KCl

    K = 39.10 g/mol
    Cl = 35.5 g/mol

    Relative Molar Mass (RMM) of KCl = 74.6 g/mol (~ 75 g/mol)

    Solution is 7.5% potassium chloride = 7.5 g in 100ml of solution
    = 0.075 g/ml

    No of moles = mass (g) / RMM (g/mol)
    = 0.075 / 75 = 0.001 moles = 1 millimole

    Therefore a 7.5% solution of Potassium Chloride contain 1 millimole of Potassium ions and 1 millimole of Chloride ions for every ml of solution

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