Tuesday, July 04, 2006

Dr Charles Shepherd wants information on possible morphine resistance in ME/CFS

News from The ME Association:

Information on possible morphine resistance in ME/CFS required

I have recently been discussing the cases of a small number of people with ME who form part of the database operated by the UK charity CHROME (Case History Research on ME). This small group of people appear to have a degree of resistance to morphine - a very potent analgesic that is occasionally used for the management of severe pain.

The pharmacology of morphine resistance is interesting in that the drug is broken down by enzymes in the liver into two metabolites known as morphine 3 glucuronide (M3G) and morphine 6 glucuronide (M6G).

M6G may be even more potent than the parent morphine whereas M3G antagonises the action of morphine and M6G and so is known as an anti-analgesic.

The individual response to morphine therefore depends on the balance of activity between these two metabolites with an excess of M3G producing varying degrees of morphine resistance or intolerance. This aspect of morphine pharmacology may also help to explain the presence of the paradoxical pain that people sometimes experience when given morphine.

Morphine resistance is very unusual and I have only come across one person with this reaction so far in my whole medical career - that was in hospital practice and did not involve ME/CFS.

If anyone has further information on possible morphine resistance or intolerance in ME/CFS I would be pleased to receive it.

And if morphine resistance does appear to be more common in people with ME/CFS than the normal population, then this could link in to some of the research work currently being carried out in the UK and USA into abnormal gene expression.

Please email ME Connect putting FAO Dr Shepherd in the subject line.
Dr Charles Shepherd
Medical Adviser, The ME Association.


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