Morphine, gabapentin, or their combination for neuropathic pain

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N Engl J Med. 2005 Mar 31;352(13):1324-34.

Morphine, gabapentin, or their combination for neuropathic pain.

Gilron I, JM, Tu D, Holden RR, Weaver DF, Houlden RL.

Department of Anesthesiology, Queen's University, Kingston, Ont,

Canada.

BACKGROUND: The available drugs to treat neuropathic pain have

incomplete efficacy and dose-limiting adverse effects. We compared

the efficacy of a combination of gabapentin and morphine with that of

each as a single agent in patients with painful diabetic neuropathy

or postherpetic neuralgia.

METHODS: In this randomized, double-blind, active placebo-controlled,

four-period crossover trial, patients received daily active placebo

(lorazepam), sustained-release morphine, gabapentin, and a

combination of gabapentin and morphine--each given orally for five

weeks. The primary outcome measure was mean daily pain intensity in

patients receiving a maximal tolerated dose; secondary outcomes

included pain (rated according to the Short-Form McGill Pain

Questionnaire), adverse effects, maximal tolerated doses, mood, and

quality of life.

RESULTS: Of 57 patients who underwent randomization (35 with diabetic

neuropathy and 22 with postherpetic neuralgia), 41 completed the

trial. Mean daily pain (on a scale from 0 to 10, with higher numbers

indicating more severe pain) at a maximal tolerated dose of the study

drug was as follows: 5.72 at baseline, 4.49 with placebo, 4.15 with

gabapentin, 3.70 with morphine, and 3.06 with the gabapentin-morphine

combination (P<0.05 for the combination vs. placebo, gabapentin, and

morphine). Total scores on the Short-Form McGill Pain Questionnaire

(on a scale from 0 to 45, with higher numbers indicating more severe

pain) at a maximal tolerated dose were 14.4 with placebo, 10.7 with

gabapentin, 10.7 with morphine, and 7.5 with the gabapentin-morphine

combination (P<0.05 for the combination vs. placebo, gabapentin, and

morphine). The maximal tolerated doses of morphine and gabapentin

were lower (P<0.05) with the combination than for each drug as single

agent. At the maximal tolerated dose, the gabapentin-morphine

combination resulted in a higher frequency of constipation than

gabapentin alone (P<0.05) and a higher frequency of dry mouth than

morphine alone (P<0.05).

CONCLUSIONS: Gabapentin and morphine combined achieved better

analgesia at lower doses of each drug than either as a single agent,

with constipation, sedation, and dry mouth as the most frequent

adverse effects.

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I take the combo and the constipation is severe. The best treatment I have found

is a good slug of peanut oil daily.

in San Angelo