Combo Treatment Relieves Shingles, Diabetes Nerve Pain

Taking Neurontin and morphine together relieves nerve pain from shingles and diabetes better than either drug alone, researchers report.

Neurontin and morphine are both used alone to treat nerve pain. But researchers wanted to see if using the two drugs together would offer even greater benefit without causing too many side effects.

Soothing Nerve Pain

The study looked at people with two common forms of nerve pain: 35 men and women with painful nerve damage due to diabetes, and 22 with painful nerve damage from shingles.

Nerve pain from diabetes, called diabetic neuropathy, is common. Over time, high blood sugar levels from diabetes can damage nerves throughout the body, most commonly in the feet.

In shingles, after the rash resolves, people can be left with nerve damage that can cause pain for weeks to years. This is called postherpetic neuralgia.

Least Pain With Neurontin/Morphine Combo

Researchers Ian Gilron, MD, of Queens University in Kingston, Ontario, and colleagues gave study participants four different treatments for five weeks at a time. Patients received Neurontin, morphine, the two drugs in combination, or what researchers call an "active placebo." That’s a drug – in this case, the anti-anxiety drug Ativan – that has some effect and which keeps patients from guessing they are getting a placebo. Ativan causes some sedation but does not relieve pain.

Patients rated their pain on a 1 to 10 scale where 1 is no pain and 10 is the worst pain imaginable. They started out with an average pain score of 5.72. They rated their pain at 3.06 after getting the combination treatment – significantly better than their 3.7 rating for morphine alone, their 4.15 rating for Neurontin alone, and their 4.49 rating for the placebo.

Good News for Side Effects

There was more dry mouth and constipation with the combination treatment. But overall, the combination treatment did not greatly increase side effects. In fact, patients getting combination treatments stopped increasing their dosages at lower drug levels than they did when getting either Neurontin or morphine alone.

The findings likely apply to patients with nerve pain caused by surgery and other common illnesses such as cancer, degenerative spine disease, AIDS and other infectious diseases, and stroke.

The findings appear in the March 31 issue of The New England Journal of Medicine.

In an accompanying editorial, Johns Hopkins researchers Srinivasa N. Raja, MD, and Jennifer A. Haythornthwaite, PhD, note that the recommended practice is to try Neurontin and morphine separately before trying them together. The study findings, however, suggest that trying the two drugs together might result in better pain relief at lower drug dosages. They recommend future "critical scrutiny" of this issue.

By Daniel J. DeNoon, reviewed by Michael W. Smith, MD

SOURCES: Gilron, I. The New England Journal of Medicine, March 31, 2005; vol 352: pp 1324-1334. Raja, S.N. and Haythornthwaite, J.A. The New England Journal of Medicine,March 31, 2005; vol 352: pp 1373-1375.