Fixed dose combination of low dose pregabalin and duloxetine, or pregabalin monotherapy for neuropathic pain: A double-blind, randomized, parallel-group study.

Background: Treatment of neuropathic pain is challenging. Pregabalin and duloxetine are used as first-line therapy. Various international guidelines recommend a combination of first-line agents for the management of neuropathic pain. The objective of this study was to evaluate the efficacy and safety of a fixed-dose combination (FDC) of low-dose pregabalin and duloxetine compared to pregabalin monotherapy at week 7 in patients with moderate to severe neuropathic pain. Methods: This was a phase 3, randomized, double-blind, double-dummy parallel-group non-inferiority study conducted at 17 sites across India. Three hundred and twenty-eight adult patients with moderate to severe neuropathic pain were randomized in a ratio of 1:1 to receive a FDC of pregabalin and duloxetine or pregabalin monotherapy for 7 weeks followed by a one-week follow-up. The pregabalin-duloxetine combination was initiated at 50 plus 20 mg per day and gradually titrated to a maximum of 75mg plus 30mg twice daily. Pregabalin was initiated at 75mg/day and gradually titrated to a maximum of 150mg twice daily. The main efficacy outcome was a mean change in pain intensity at the end of 7 weeks. Results: Two hundred and ninety-eight patients completed the study, 148 in the pregabalin-duloxetine group and 150 in the pregabalin group. The mean change in daily pain at 7 weeks was as follows: -4.49 with FDC and -4.66 with pregabalin (p<0.0001). The non-inferiority of a low-dose FDC compared to pregabalin monotherapy was demonstrated at the end of the study. The incidence of dizziness and somnolence was comparable between both treatments. A higher frequency of peripheral oedema was observed with pregabalin monotherapy than in the FDC group (p>0.05). Conclusions: A FDC of low doses of pregabalin and duloxetine and high dose of pregabalin monotherapy achieved similar analgesia with dizziness, and somnolence as the most frequent adverse event. Trial registration: CTRI/2020/09/027555.