Morphine, Nortriptyline Alone or in Combination Not Effective Treatment for Lumbar Radicular Pain
Lumbar radicular pain, or sciatic pain, is the most common nerve pain experienced by patients with back problems. Unfortunately, not many studies have been done on how best to treat this type of pain, which is caused by injury or trauma to lumbar nerve roots, or by irritation from of deterioration of the disks in the back. It's so common, in fact, that doctors estimate that adults over the age of 30 have a 4.5 percent chance of developing this type of pain at some point in their life.

In this single-center, four-period, crossover, randomized trial, researchers investigated the effect of nortriptyline with an opioid-based medication. By using this approach, the investigators hoped to attack the pain problem from the different ways or paths that pain is caused. The drugs used were MS Contin, which is a long-acting form of morphine, nortriptyline, a combination of the two, and a placebo. The investigators felt that the result would be that the combination of the two drugs would be more effective than either medication alone, which in turn would be better than placebo.

Of the 61 patients who underwent the initial screening, 28 patients entered and completed the study. They had to have evidence of lumbar radiculopathy, or irritation of the lumbar root nerves. This included pain in one or both buttocks and/or legs for at least three months and for at least five days per week. Other symptoms were included in the list. Their pain must have been rated at 4 out of 10 or higher on the pain scale of 1 to 10, with 10 being the worst pain.

During the study, the patients rated at bedtime their average back and leg pain, and overall pain, as well as worst leg and back pain, and overall pain over the previous 24 hours. These pain diaries were collected at the follow-up visits. The investigators also assessed patient pain through the Global pain relief (GPR) scale, the Oswestry Low Back Pain Disability questionnaire, the Beck Depression Inventory, and the 36-item Short Form of Health Survey (SF-36).

There were four treatment sessions. In treatment session A, there were 55 patients total, 15 who took MS Contin, 13 nortriptyline, 13 combination, and 14 placebo. In treatment session B, there were 37 patients total, 10 who took MS Contin, 9 nortriptyline, 9 combination, and 9 placebo. In treatment session C, there were 28 patients. Seven took MS Contin, 5 nortriptyline, 7 combination, and 9 placebo. Finally, in treatment session D, there were still 28 patients total. Nine patients took MS Contin, 7 nortriptyline, 5 combination, and 7 placebo. With the patients who dropped out between sessions A and B, and then sessions B and C, 28 patients remained to study end.

The researchers found that there were no significant differences between the four groups, including the placebo group, for the relief of average leg pain. There was a 7 percent reduction in average leg pain in the MS Contin group, 14 percent in the nortriptyline group, and 7 percent in the combination group, compared with placebo. The other outcomes were also not significant.

When the investigators looked at the findings of the GPR questionnaires, reporting moderate relief or better, there was a 42% increase among those who took MS Contin, 40% nortriptyline, 67% for the combination, and 37% for the placebo.

The authors concluded that their assumption wasn't met by their surprising findings. Neither the tricyclic antidepressant (nortriptyline) nor the opioid (MS Contin) were significantly effective in treating the pain, even in combination. The authors point out that there may have been some drawbacks to the study, including that the findings could have been affected by chance effect and the modest sample size. They also suggest that the study should be repeated because of their sample size and high drop-out rate. Their recruitment, through newspaper ads, may also have encouraged participation from patients who were already treatment-resistant.
Suzan Khoromi et al. Morphine, nortriptyline and their combination vs. placebo in patients with chronic lumbar root pain. In Pain July 2007. Vol. 103. No. 1-2. Pp. 1220-1226.