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I am looking for some advice regarding MSD for mepivacaine. I am fully aware of how to work out MSDs (mls) but literature regarding MSD in confusing. I know the MSD is 400mg. I always thought that with 400mg (3%) it would work out as 13.3mls but some say it would be 14mls. I can see how this could be, if you work out 6mg/kg x 70kg but this LAs MSD is 400mg and I thought this should never be exceeded. I know it would be rare to use the MSD on a patient during nail surgery but I am curious what other people think/do.

I guess this is the same for Lidocine; 200mg is MSD but if you work out 3mg/kg x 70kg = 210mg.

Thanks in advance for your advice/comments.

 

Firstly, the 'MSD' is based on the patient weight, so a child would be lighter than 70kg. The average rugby player would be heavier. Secondly, the so-called MSD is actually Manufacturers Maximum Safe Recommended Dose. If you work with, or chat to Anaesthetists you will find that they can and do go over, it's a matter of clinical judgement. Thirdly, remember that the LA in any case will be continually metabolised by the liver. Finally, in my copy of Goodman and Gillman, the MMSD is 500mg.

My clinical judgement tells me that for safety, it is sensible to use as small a dose as possible to achieve the desired effect, and not to go over the MMSD (400mg in the UK). If you are dealing with nail surgery only, then, as you state, it really is not a matter of concern.

All the best

Bill Liggins