Opioid-based pain medications may cause sleep apnea, according to an
article in the September issue of Pain Medicine, the journal of the
American Academy of Pain Medicine.
“We found that sleep-disordered breathing was common when chronic pain
patients took prescribed opioids,” explains lead author Lynn R.
Webster, MD, from Lifetree Clinical Research and Pain Clinic in Salt
Lake City, Utah. “We also found a direct dose-response relationship
between central sleep apnea and methadone and benzodiazepines, an
association which had not been previously reported.”
Opioids, effective medications for chronic pain treatment, are often
used for cancer patients, but are now gaining widespread acceptance as
long-term therapy for chronic pain unrelated to cancer. An increasing
number of patients with nonmalignant chronic pain are receiving
around-the-clock pain relief through opioid therapy.
What was surprising was the finding that 75% of
patients receiving chronic opioid therapy had sleep apnea…
The authors note that it had been thought that persons
receiving opioids chronically developed complete tolerance to the
respiratory depressant effect. That clearly is not the case.
The other thing that was not known previously was the
association between benzodiazepines and central sleep apnea.
The muscle relaxant properties were known to increase the
risk for obstructive sleep apnea, but the relationship to central sleep
apnea is a new finding. The study does not tell us whether
that finding would be the case in the absence of the opioid medication.
This study included 147 patients. The median opioid dose was
the equivalent of 187.5mg of morphine per day. It is not
known yet how generalizable the findings are.
A few things come to mind about this. One is that it is
important to not attribute sedation in these patients entirely to the
opioid medication. The second is that driving an automobile
is probably dangerous for the majority of these patients. The
third is that we probably need to be doing a lot more screening for
sleep disorders in patients being treated for pain.