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The following message was posted to: PharmPK
Dear Forum
With regard to the significance of 10ml of drinking water and attempting
to quantify the problem, it happens that I have used 500ml water
hundreds of times as a test "meal" in a human volunteer and patient
model of gastric emptying and over the years the emptying half times in
normal volunteers have all been in the range 5 to 10 minutes. In other
words between 50 and 100 ml leaves the stomach every minute. By simple
arithmetic the 10 ml in question accounts for between 6 and 12 seconds
of that output or 12 to 24 seconds of 250 ml, assuming the same rate of
emptying. I would question whether the amount of drug carried in that
short time, which would be 4% of the total, would make a detectable
difference to assay results, not so much due to the variation in the
assay but the gaps between plasma sample times.
It might interest the forum to know that using this simplest of test
meals as probe rather than more normal calorific meals seems to be
giving good results for detecting delayed gastric emptying. We have
tested posture, opiates, migraine attacks, diabetic neuropathy and
prokinetic drugs and every time the predicted result was obtained. For
example, morphine (0.09mg/kg iv) produced a four-fold increase in
gastric t50% and the delay correlated closely with intensity of nausea.
It was also highly significant statistically in just 11 subjects whereas
using solid meals involves such wide variation that the required group
size would be a great deal larger.
At the University of Surrey UK we are trying to develop this for use in
clinical medicine as it is simple and inexpensive so could easily be
used in Primary Care settings, much like an ECG for the heart. Our
device also detects gastric contractions, so with proprietary software
we can quantify the motility response to our standard meal. This shows
that diabetic neuropathy patients with gastric symptoms do not mount as
much of a response as non-neuropathy patients. It gives us an extra
target for assessing new treatments.
We are actually looking for development partners so if anyone is
interested please do get in touch
Andrew Sutton
Guildford Clinical Pharmacology
Tel: +44 1483 688303
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)