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Pregabalin (Lyrica) didn't offer any relief from the leg pain associated with acute or chronic sciatica, and was associated with more adverse events in a randomized controlled trial, researchers found.

Over 8 weeks, there were no differences in leg pain intensity score whether patients were on the drug or on placebo (mean unadjusted score of 3.7 versus 3.1), Christine Lin, PhD, of the George Institute for Global Health in Australia, and colleagues reported in the .

There were also significantly more adverse events in the pregabalin group (227 versus 124, P=0.002).

"The lack of treatment effect of pregabalin in these patients with sciatica may reflect differences in pathophysiological features between other types of neuropathic pain and sciatica, and suggests that the recommendations from guidelines regarding neuropathic pain may not extend to sciatica," the researchers wrote.

Sciatica is characterized by radiating pain in the leg, which is sometimes accompanied by back pain, sensory loss, or weakness. There are few clinical guidelines for treating the disease, and the evidence for effective medical treatments is limited.

Pregabalin is approved to treat some types of neuropathic pain -- including postherpetic neuralgia and diabetic peripheral neuropathy -- and thus was thought to be potentially effective in sciatica, the researchers explained.

To test the hypothesis, they conducted a randomized, double-blind, placebo-controlled trial in which 209 sciatica patients from 47 sites were randomized to placebo or to pregabalin at a dose of 150 mg daily adjusted to a maximum dose of 600 mg/day. Most of the patients had sciatica for less than 3 months. (Two patients in the pregabalin group were subsequently determined to be ineligible and were excluded from the analysis.)

The primary outcome was leg pain intensity score (using a 10-point scale, with 10 being the worst pain) over 8 weeks, with additional evaluations at 1 year. Secondary outcomes included the extent of disability, back pain intensity, and quality-of-life.

In addition to there being no significant difference between the groups at 8 weeks (adjusted mean difference 0.5, 95% CI -0.2 to 1.2, P=0.19), no differences were found a year later, the researchers reported (3.4 versus 3.0, adjusted mean difference 0.3, 95% CI -0.5 to 1.0, P=0.46).

Nor were there any significant between-group differences either at 8 weeks or at 1 year in terms of any of the secondary outcomes: extent of disability, back pain intensity, global perceived effect, and physical and mental quality of life.

Dizziness was the most common adverse effect in both groups, but was more common in the pregabalin group. Although overall adverse events were significantly higher in this group, serious adverse events were numerically, but not significantly, higher for those in the placebo group (two versus six).

Lin and colleagues said their results were similar to those of previous trials of pregabalin and gabapentin in chronic low back pain or sciatica, with no benefit over placebo: "Our trial extends this finding by the inclusion of patients who had acute sciatica."

A post-hoc analysis revealed that the duration of leg pain did not modify the effect of pregabalin for sciatica patients.

The researchers added that since the study was not powered to detect the risk of suicidality, a known complication with these drugs, "it is important for doctors to continue to be cautious with regard to prescribing pregabalin to patients who are susceptible to self-harm."