The NPSA has recommended that patients are given the same dose each day rather than varying the dosage throughout the week. They have suggested prescribing 0.5mg warfarin to make it easier. On of our GPs has asked if RATs will be able to do this for us. Can you enlighten us. Thanks

RAT use on 'named day' dosing to:
1. Allow for 1mg increments/decrements on a weekly basis.
2. Explicitly detail the dose for every day of the week to reduce confusion.

Using 0.5mg is not usually recommended. There can be confusion with the 5mg tablets. There have been 'significant events' with the 0.5mg tablet.
1mg and 3mg tablets are the preferred tablets to use. Our local health Board have actively encouraged practices not to use 0.5mg tablets and I'm sure there are other PCTs that give the same guidance.

Using the same dose every day limits the sensitivity in which you can increase and decrease warfarin. Even if you use 0.5mg you are limited to 3.5mg increments weekly which is really no better than the historical alternate day dosing e.g 2/3mg alternate days.

The publication in November 06 by the British committee for Standards in Haematology and the National Patient Safety Agency, Baglin et al, (You can find it online [www.bcshguidelines.com]) do not mention equal dosing every day. They do say: 'Supplying warfarin tablets in more than one strength may increase the risk of accidental overdose'. They also say that '0.5mg tablets have been recently introduced to enable more accurate dose adjustment'.
If you are using a manual system it is much more difficult to have a 'named day' dosing system, but using computer software it is very straight-forward.

I hope this is helpful.

Regards
Colm Rafferty

We have a patient who takes 1.5 mg Warfarin a week.
Reading 26/3/08 of 1.9 (where our nurse James would have expected to say increase, though he said he wouldn't have done so) the message actually read:
DOSE TOO HIGH..... CONSIDER WARFARIN RESISTANCE
there was then a RUN TIME ERROR
Can you advise regarding this please?

Dear Susan,
I believe this was a bug in an old version of RAT
Please update to the lastest version by going to the website and downloading the update.
[www.formulae.co.uk]

Make sure RAt is not running when you run this update file.
If you have RAt on more than one PC you must run this update on all Pcs that have RAt installed.

Then restart RAT
Go to top menu and choose 'Database'. A submenu will appear.
Choose 'Database utilities'
A Window will appear.
Choose 'Repair database' and click OK
Then retry accessing the patient

Regards
Colm Rafferty

Hello Dr Rafferty
Thank you for your reply. I have followed your instructions and hopefully all will be well with the RAT v3.8. I appreciate your help.
regards,
Susan