from Dr Charles Shepherd: charlesbshepherd@LINEONE.NET
MAY BE REPOSTED
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.
Dr Charles Shepherd
Medical Adviser, ME Association.
