From Mr S. Keeling, MRPharmS and Ms V. Tudor, RGN
SIR,—We report a medication error associated with the new low strength warfarin tablet.
The error was the patient taking a single 500mg warfarin tablet in place of two-and-a-half brown 1mg tablets previously taken. The problem was identified by our nurse-led anticoagulant clinic investigating a downwards drift in INR results for a patient previously stable on 2mg/2.5mg on alternate days. (Computer dosing at the clinic uses 0.5mg increments to achieve target INRs.)
The patient had been successfully halving the 1mg tablets with a pill cutter, when the general practitioner surgery prescribed the new 500mg strength tablet. This was issued and labelled quite correctly as 500mg tablets. However our patient had no perception of what 500mg meant and assumed they replaced the two-and-a-half brown tablets.
"If it aint broken, don't fix it" might well apply here.
Do the benefits gained from not halving tablets disappear when we see the inevitable confusions with an extra strength of warfarin?
Steve Keeling
Principal Pharmacist Clinical Services
Val Tudor
Sister, Anticoagulant Services, North East Wales NHS Trust