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Editor, – I would like to make a comment regarding dicloxacillin, which was listed in 'New drugs' (Aust Prescr 1998;21:25-7).

With regard to adverse effects, I have recently been askedto see two patients having difficulty achieving adequate warfarinisation after taking dicloxacillin.

I realise that not all adverse effects can be listed in a summary of a new drug. However, I believe that the prolonged warfarin antagonism that occurs with drugs such as this should be brought to the attention of prospective users of a new drug.

John Gallo
Liverpool, N.S.W.

The Editor comments:
Dr Gallo is correct to highlight the interaction between warfarin and dicloxacillin. As it is not possible to mention all the adverse effects of new drugs in a brief comment, readers are always advised to consult the product information before prescribing. The interaction is included in the product information for dicloxacillin, but is not specifically mentioned in the product information