In a recent meta-analysis of 38 double-blind randomized controlled trials (RCTs) comparing pregabalin (PGB) to placebo, we found 20 adverse events (AEs) to be significantly associated with PGB treatment. In the present study, we evaluated whether the incidence of these 20 AEs differs across distinct disorders in which PGB was investigated.
Among the 38 previously identified RCTs of PGB, we selected only those including a PGB 600 mg/day arm and subsequently classified them into four distinct groups according to the disorder in which PGB was investigated: (1) drug-resistant partial epilepsy, (2) psychiatric disorders, (3) fibromyalgia, and (4) neuropathic pain. We used risk differences (RDs) to quantify the placebo-corrected proportion of subjects discontinuing PGB due to intolerable AEs and to determine the placebo-corrected incidence of each of the 20 PGB AEs across the four disorders.
Twenty-two RCTs were included in this study. Neither the proportion of subjects discontinuing PGB due to intolerable AEs nor the incidence of PGB AEs (with the exception of ataxia) differed significantly across the four disorders. Ataxia was more common in drug-resistant partial epilepsy compared to fibromyalgia. When limiting analyses to subjects on placebo, most vestibulo-cerebellar AEs (ataxia, diplopia, and blurred vision) were found to be more common in drug-resistant partial epilepsy compared to all other disorders. Diplopia and blurred vision were more common in epilepsy than in neuropathic pain; and ataxia had a higher incidence in epilepsy than in anxiety disorder and fibromyalgia. Among other CNS AEs, somnolence was more common in epilepsy compared to neuropathic pain and in anxiety disorders alone compared to neuropathic pain and fibromyalgia. Asthenia was also more common in epilepsy than in neuropathic pain and fibromyalgia.
Although drug-resistant partial epilepsy is associated with a higher probability of developing vestibulo-cerebellar AEs, the risk for PGB toxicity does not differ across distinct disorders.