[*Anya*]

Better Pain Control by...Cutting Back on Opioids?
Dr. Charles Argoff, Professor of Neurology at Albany Medical College and Director of the Comprehensive Pain Center at Albany Medical Center in Albany, New York.

Posted: 02/13/2012
I want to talk about a new approach to chronic pain care, based on a recent, exciting study.[1] I certainly see many people with chronic pain in my role as director of a pain center in an academic institution. Many patients do not respond to typically prescribed medications for osteoarthritis and for various neuropathic pain states. I am certain that those of you who are not working at pain centers also see patients who do not respond to available treatments that provide pain relief for other patients.
We are all concerned that sometimes we do not always have a treatment for each individual patient. We need new and improved analgesics and, absent those, at least a more creative way to benefit from what we have.

One approach to this quest has been to try to capitalize on the endocannabinoid system through the use of cannabinoids in various oral pharmacologic tactics. Some cannabinoid agents are available, but with marginal benefit. A second approach has been to develop a better, more effective, and safer way of using opioid analgesics.

The study I want to discuss, "Cannabinoid-Opioid Interaction in Chronic Pain," by Abrams and colleagues,[1] demonstrates how combining the 2 agents may provide promise. I live in New York State, where using marijuana is illegal, medically or otherwise; I am not speaking for or against this. I am merely reporting this particular study.

This study involved individuals with various chronic pain states, including musculoskeletal pain from osteoarthritis and other causes, neuropathic pain, sickle cell disease, and others. These patients were already using long-acting opioids: either time-released oxycodone twice daily at mean doses of 100 mg/day or time-released morphine twice daily at mean doses of about 120 mg/ day. More than 300 individuals were screened, and ultimately 21 of these participated in the study. Participants had to be stable on their opioid regimens before they were enrolled.

The 21 participants were managed as inpatients over 5 days. On the first day, they received 1 evening dose of vaporized cannabis; on days 2-4, they received 3 doses; and on day 5, they received a morning dose, in addition to their typical opioid regimens.

On average, these participants experienced an added 27% reduction in pain with the addition of vaporized cannabis. Pharmacokinetic studies demonstrated that although there was an effect on reducing absorption of morphine by the addition of vaporized cannabis, there was no change in the area under the curve. Therefore, the patients were exposed to a similar amount of morphine, although the peak concentration of morphine was also slightly reduced. Adding vaporized cannabis seemed to independently magnify the response the person was experiencing to the analgesia.

This brings to mind a couple of things. First, this was a limited, 5-day study; the investigators recognized this limitation. However, this shows a new and potentially very helpful combined approach to treatment that comes at an important time when we are searching for improved and novel analgesics that can provide us with additional relief for our patients, and also could spare opioid dosing.

Most important, we're looking for ways to safely treat patients who have chronic pain. This study of vaporized cannabis in addition to long-acting opioid found no significant changes in the plasma opioid level with the combination, even though it proved more effective than the opioid alone. This may be a gateway to future studies using lower doses of opioids in combinations with endocannabinoids or other agents that act on cannabinoid receptors -- or, in certain settings, use of cannabis itself.

Ultimately, this may point to a new way we can effectively treat outpatients.

References

1. Abrams DI, Couey P, Shade SB, Kelly ME, Benowitz NL. Cannabinoid-opioid interaction in chronic pain. Clin Pharmacol Ther. 2011;90:844-851. Abstract
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