Seventeen studies (622 participants) were included in the review. Nine studies evaluated pregabalin. Seven studies evaluated use of lidocaine plasters. One study summarised an active controlled study of duloxetine (18 participants). Withdrawals were reported in seven pregabalin trials (5% to 30%) and four lidocaine plaster studies (6% to 11%), but not in the study of duloxetine. Most of the included studies were single-arm trials. One randomised controlled trial of lidocaine plasters was included in which lidocaine plasters were compared to placebo plasters. Follow-up across the studies ranged from four weeks to 18 months.
Use of pregabalin (nine studies, 422 participants) was associated with statistically significant reductions in pain intensity (all nine studies) and complete pain relief achieved by 25% of patients. The proportion of patients who reported at least 50% reductions in pain ranged from 33% to 49%. A range of 26% to 46% did not respond to pregabalin medication at all. Significant improvements with the administration of pregabalin were observed in one study each in overall quality of life, function interference, sleep interference, interference associated with mood, daily activities and pain-associated distress. One study showed that more than 60% of patients were satisfied with pregabalin treatment. Adverse events associated with pregabalin treatment were dizziness (16% to 66% of patients) and somnolence (15% to 40% of the patients). Withdrawals due to adverse events ranged from 5.5% to 14.3%.
Use of lidocaine plasters was investigated by seven studies (182 participants), one of which was a randomised controlled trial. One of the three studies that reported efficacy outcomes with the use of lidocaine plasters reported statistically significant reductions in pain. Between 13% and 22% of patients reported complete pain relief with application of lidocaine plasters. Adverse events included application site reactions or papules (4% to 28%) and local erythema (14% to 15%). Withdrawals due to adverse events ranged from 2.8% to 8.5%.
One trial of duloxetine in patients with trigeminal neuralgia found that pain severity was significantly reduced after 12 weeks compared to baseline. No safety or tolerability data were reported for duloxetine on specific adverse events or withdrawals.