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Opioid Pain Relievers
Make Headlines
Opioids (morphine-like drugs) are generating a lot of press
these days. New versions of these drugs such as Oxycontin®
(sustained released oxycodone) have become the drug of choice
for many addicts who get a high by grinding the pills and
snorting them. The lengths these addicts go in order to
get the pills reads like a bad movie script. They masquerade
as medical staff, they get prescriptions from multiple doctors,
they claim to have lost their pills - they become desperate
for a fix.
Yet, opioids are one of the best treatments available for
the easing of pain and suffering. They are highly effective
for acute pain, and moderately effective for chronic pain.
They are remarkably free of any tissue toxicity, which means
that they do not harm organs even with long-term use. The
main side effects are sedation, constipation, and nausea.
So how did something which has helped thousands of pain
sufferers create such a media scare?
The Nature of Addiction
First, let's try to understand the nature of addiction.
Addiction is a psychological condition characterized by
the inappropriate craving and seeking of opioids for reasons
other than the treatment of a medical condition. When opioids
are given to patients with addiction problems, their craving
increases and their day-to-day functioning deteriorates.
Pain patients, on the other hand, will report less pain
and their day-to-day functioning will improve.
The media, the general public, patients, and even doctors
have always had a difficult time understanding that a person
who takes pain medication for a legitimate ailment has an
extremely rare chance of ever becoming addicted to
pain pills. This has been borne out in study after study.
Furthermore, almost all studies of pain treatment reveal
that pain is undertreated, yet many doctors fear providing
proper pain treatment, and a great many people suffer needlessly.
Fear of addiction is what is driving the current
media frenzy about these medications. The focus of attention
should be on discerning who is an abuser while still making
sure that the person with legitimate pain gets the medication
necessary for recovery. Monitoring that medication is used
as prescribed, and checking for improvement of patient functioning,
will help the clinician screen for patients with addiction
problems.
Exciting Pain Medication Breakthroughs
Let's take a quick look at the new science underlying the
use of opioids. The nervous system functions by the transmission
of nerve signals from one nerve cell (neuron) to another.
One neuron releases a small amount of chemical (called a
neurotransmitter), which fits like a puzzle into the next
nerve and activates a receptor. Thus, the pain signal travels
from one location to the next until it reaches the brain
and causes the sensation of pain. Opioids act like brakes.
They activate opioid receptors, which inhibit the neuron,
making it is less likely to transmit the pain signal.
There is increasing data that the most effective form
of pain management is prevention (see our last Update,
March 2001-Preventing Chronic Pain). The newer long-acting
or sustained release opioid medications provide steady opioid
blood levels, which may help to prevent pain (rather than
the more difficult task of trying to catch up after the
pain has become severe).
There are several new discoveries about how opioids affect
pain signal transmission:
- It has recently been discovered
that some opioids do not only activate opioid receptors,
but are also blockers of the NMDA (n-methyl-d-aspartate)
receptor. NMDA blockers may actually decrease the development
of both chronic pain as well as opioid tolerance.
- Some opioids have been
found to inhibit the nervous system's disposal of the
neurotransmitters norepinephrine and serotonin. Since
these neurotransmitters also act to inhibit pain transmission,
this ability may have important analgesic effects.
- Methadone is a particularly
interesting opioid because it binds to a recently described
sub-type of the opioid receptors, the mu3 receptor. This
receptor is found in significant quantities on immune
system cells, and may help to diminish pain by decreasing
the inflammatory response. (Caution must be used in administering
this medication because it's long half-life can lead to
accumulating blood levels.)
Exciting work is also being
carried out on the anti-cancer effects of opioids, specifically
methadone and morphine, which appear to induce apoptosis,
(a form of cellular suicide) which helps to prevent the
growth of human cancer cells and tumors.
The ominous press reports notwithstanding, there is much
to be excited about with the new pain medication tools we
have!
Until next time…Steven Richeimer, M.D.
Copyright
© 2001, Steven Richeimer, MD.
You may reach The Richeimer Pain Institute at www.helpforpain.com
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