Combination therapy with flupirtine and opioid: open-label case series in the treatment of neuropathic pain associated with cancer.

OBJECTIVES

This study is a case series that was designed to provide data on the efficacy and the incidence and duration of adverse effects of flupirtine in the treatment of cancer-related neuropathic pain.

DESIGN

This was an 8-day, open-label study of palliative care patients with neuropathic pain despite maximal opioid treatment. They received an initial dose of flupirtine 100 mg orally four times daily (QID) that could be titrated. Efficacy measures included: a neuropathic pain discriminant score; scales measuring average pain and quality of life activities; and a score of percentage pain relief.

RESULTS

Ten patients were recruited. Only one patient was withdrawn because of side effects. Several pain measurements were used. All patients were able to participate in these measurements apart from two who did not understand the concept of percentage pain relief. There were significant reductions of average pain (P < 0.01) and neuropathic pain discriminant scores (P < 0.01), as well as an increase in percentage pain relief (P < 0.01). There was no statistically significant change in overall opioid use but 8/10 patients had some reduction in opioid use and three of those required substantially reduced doses of opioid when flupirtine was added to their treatment regime. Eight patients elected to continue to take flupirtine after the trial, two taking 200 mg QID and the others 100 mg QID. Of these eight, six said that flupirtine was of considerable help and two said it helped a little. All of these continued to take flupirtine with very good pain control until death, one of which was 18 months after the trial course.

CONCLUSIONS

These results in humans follow animal studies that suggest a role for flupirtine in the treatment of neuropathic pain. This short duration open-label study in 10 subjects suggests that flupirtine may be useful in the treatment of neuropathic pain when used in combination with opioids.