This clinical trial evaluated the independent and combined effects of a tricyclic antidepressant (desipramine) and cognitive behavioral therapy (CBT) for chronic back pain relative to an active placebo treatment. Participants (n = 142) were patients experiencing daily chronic back pain at an intensity of ≥4/10 who were randomized to a single-center, double-blind, 12-week, 4-arm, parallel groups controlled clinical trial of (1) low concentration desipramine titrated to reach a serum concentration level of 15 to 65 ng/mL; (2) CBT and active placebo medication (benztropine mesylate, 0.125 mg); (3) low concentration desipramine and CBT; and (4) active benztropine placebo medication. Participants completed the Differential Description Scale and Roland Morris Disability Questionnaires before and after treatment as validated measures of outcomes in back pain intensity and disability, respectively. Participants within each condition showed significant reductions from pre-treatment to post-treatment in pain intensity (mean changes ranged from = -2.58 to 3.87, Cohen's d's = 0.46-0.84) and improvements in pain disability (mean changes = -3.04 to 4.29, Cohen's d's = 0.54-0.88). However, intent-to-treat analyses at post-treatment showed no significant differences between any condition, with small effect sizes ranging from 0.06 to 0.27. The results from this clinical trial did not support the hypothesis that desipramine, CBT, or their combination would be statistically superior to an active medicine placebo for reducing chronic back pain intensity or disability. Key limitations included recruiting 71% of the planned sample size and use of multiple inclusion/exclusion criteria that may limit generalizability to broader populations of patients with chronic back pain.
BACKGROUND: Amitriptyline has well-established efficacy in several chronic pain conditions. While optimal treatment for chronic neck pain (CNP) remains controversial, amitriptyline was not tested for CNP. We evaluated the effect of bedtime amitriptyline in the management of CNP.
METHODS: A total of 220 patients suffering from idiopathic CNP were randomized to receive either placebo pill (n = 108) or 5 mg of amitriptyline (n = 112) at bedtime for 2 months. Primary outcome measure was visual analog scale (VAS) for pain. Secondary outcome measures were neck pain disability index (NPDI), Bergen Insomnia Score (BIS) and Hospital Anxiety and Depression Scale (HAD), measured before and at the end of 2 months of treatment, with the percentage of patient satisfaction measured at the end of follow-up only.
RESULTS: Eight of 112 patients (7.14%) in the amitriptyline group withdrew from the study because of intolerance. Amitriptyline group showed significantly lower VAS scores than placebo group (3.34 ± 1.45 vs. 6.12 ± 0.92; p < 0.0001), which corresponds to a 53.06 ± 20.29% of improvement from baseline pain as compared to 14.41 ± 11.05%, respectively (p < 0.0001). Similar significant improvements were observed with lesser extents for secondary outcome measures: NPDI, BIS, HAD-A, HAD-D and percentage of patient satisfaction.
CONCLUSION: Low-dose amitriptyline is effective for the management of idiopathic CNP with few side effects and high patients' satisfaction.
SIGNIFICANCE: This randomized controlled trial is the first to show the effectiveness and tolerance of a medication, low-dose amitriptyline, in managing idiopathic chronic neck pain and its related comorbidities. The optimal treatment of this condition was still controversial in the literature. It extends the indication of low-dose amitriptyline to another chronic pain condition.
IMPORTANCE: Antidepressants at low dose are commonly prescribed for the management of chronic low back pain and their use is recommended in international clinical guidelines. However, there is no evidence for their efficacy.
OBJECTIVE: To examine the efficacy of a low-dose antidepressant compared with an active comparator in reducing pain, disability, and work absence and hindrance in individuals with chronic low back pain.
DESIGN, SETTING, AND PARTICIPANTS: A double-blind, randomized clinical trial with a 6-month follow-up of adults with chronic, nonspecific, low back pain who were recruited through hospital/medical clinics and advertising was carried out.
INTERVENTION: Low-dose amitriptyline (25 mg/d) or an active comparator (benztropine mesylate, 1 mg/d) for 6 months.
MAIN OUTCOMES AND MEASURES: The primary outcome was pain intensity measured at 3 and 6 months using the visual analog scale and Descriptor Differential Scale. Secondary outcomes included disability assessed using the Roland Morris Disability Questionnaire and work absence and hindrance assessed using the Short Form Health and Labour Questionnaire.
RESULTS: Of the 146 randomized participants (90 [61.6%] male; mean [SD] age, 54.8 [13.7] years), 118 (81%) completed 6-month follow-up. Treatment with low-dose amitriptyline did not result in greater pain reduction than the comparator at 6 (adjusted difference, -7.81; 95% CI, -15.7 to 0.10) or 3 months (adjusted difference, -1.05; 95% CI, -7.87 to 5.78), independent of baseline pain. There was no statistically significant difference in disability between the groups at 6 months (adjusted difference, -0.98; 95% CI, -2.42 to 0.46); however, there was a statistically significant improvement in disability for the low-dose amitriptyline group at 3 months (adjusted difference, -1.62; 95% CI, -2.88 to -0.36). There were no differences between the groups in work outcomes at 6 months (adjusted difference, absence: 1.51; 95% CI, 0.43-5.38; hindrance: 0.53; 95% CI, 0.19-1.51), or 3 months (adjusted difference, absence: 0.86; 95% CI, 0.32-2.31; hindrance: 0.78; 95% CI, 0.29-2.08), or in the number of participants who withdrew owing to adverse events (9 [12%] in each group; χ2 = 0.004; P = .95).
CONCLUSIONS AND RELEVANCE: This trial suggests that amitriptyline may be an effective treatment for chronic low back pain. There were no significant improvements in outcomes at 6 months, but there was a reduction in disability at 3 months, an improvement in pain intensity that was nonsignificant at 6 months, and minimal adverse events reported with a low-dose, modest sample size and active comparator. Although large-scale clinical trials that include dose escalation are needed, it may be worth considering low-dose amitriptyline if the only alternative is an opioid.
TRIAL REGISTRATION: anzctr.org.au Identifier: ACTRN12612000131853.
Antidepressants are frequently prescribed as co-analgesics in chronic pain. While their efficacy is well documented for neuropathic pain, the evidence is less clear in musculoskeletal pain conditions. The present study therefore evaluated the effect of the tricyclic antidepressant imipramine on chronic low-back pain in a randomized, double-blinded placebo-controlled design. To explore the mechanisms of action and the influence of drug metabolism, multimodal quantitative sensory tests (QST) and genotyping for cytochrome P450 2D6 (CYP2D6) were additionally performed. A single oral dose of imipramine 75 mg was compared to active placebo (tolterodine 1 mg) in 50 patients (32 females) with chronic non-specific low-back pain. Intensity of low-back pain was assessed on a 0-10 numeric rating scale at baseline and every 30 minutes after drug intake. Multimodal QST were performed at baseline and in hourly intervals for 2 hours. Pharmacogenetic influences of cytochrome P450 were addressed by CYP2D6 genotyping. No significant analgesic effect was detected neither on low-back pain nor on any of the sensory tests in the overall analyses. However, evidence for an interaction of the imipramine effect and CYP2D6 genotype was found for electrical and for pressure pain detection thresholds. Intermediate but not extensive metabolizers had a 1.20 times greater electrical pain threshold (95%-CI 1.10 to 1.31) and a 1.10 times greater pressure pain threshold (95%-CI 1.01 to 1.21) 60 minutes after imipramine than after placebo (p<0.001 and p = 0.034, respectively). The present study failed to demonstrate an immediate analgesic effect of imipramine on low-back pain. Anti-nociceptive effects as assessed by quantitative sensory tests may depend on CYP2D6 genotype, indicating that metabolizer status should be accounted for when future studies with tricyclic antidepressants are undertaken.
BACKGROUND: Among patients with chronic low back pain (CLBP), approximately 37% show signs of a neuropathic pain component (radicular pain). Treatment of this condition remains challenging. Therefore, the current study aimed to investigate the efficacy of duloxetine in the treatment of CLBP patients with neuropathic leg pain.
METHODS: The study was conducted as a prospective, randomized, placebo-controlled, double-blind crossover trial. CLBP with a visual analog scale (VAS) score greater than 5 and a neuropathic component that was assessed clinically and by the painDETECT questionnaire (score > 12) were required for inclusion. Patients were randomly assigned to either duloxetine or placebo for 4 weeks followed by a 2-week washout period before they crossed over to the alternate phase that lasted another 4 weeks. Duloxetine was titrated up to 120 mg/day. The primary outcome parameter was mean VAS score during the last week of treatment in each phase (VAS(week4)).
RESULTS: Of 41 patients, 21 patients completed both treatment phases. In the intention-to-treat analysis (n = 25), VAS(week4) was significantly lower in the duloxetine phase compared with placebo (4.1 ± 2.9 vs. 6.0 ± 2.7; P = 0.001), corresponding to an average pain reduction of 32%. The painDETECT score at the end of each treatment phase was significantly lower in the duloxetine phase compared with placebo (17.7 ± 5.7 vs. 21.3 ± 3.6 points; P = 0.0023). Adverse events were distributed equally between the duloxetine (65%) and placebo phases (62%) (P = 0.5).
CONCLUSION: In this crossover study, duloxetine proved to be superior to placebo for the treatment of CLBP with a neuropathic leg pain.
STUDY DESIGN: A 14-week, randomized, double-blind, multicenter, placebo-controlled study of Japanese patients with chronic low back pain (CLBP) who were randomized to either duloxetine 60 mg once daily or placebo.
OBJECTIVE: This study aimed to assess the efficacy and safety of duloxetine monotherapy in Japanese patients with CLBP.
SUMMARY OF BACKGROUND DATA: In Japan, duloxetine is approved for the treatment of depression, diabetic neuropathic pain, and pain associated with fibromyalgia; however, no clinical study of duloxetine has been conducted for CLBP.
METHODS: The primary efficacy measure was the change in the Brief Pain Inventory (BPI) average pain score from baseline to Week 14. Secondary efficacy measures included BPI pain (worst pain, least pain, pain right now), Patient's Global Impression of Improvement, Clinical Global Impressions of Severity, and Roland-Morris Disability Questionnaire, among other measures, and safety and tolerability.
RESULTS: In total, 458 patients were randomized to receive either duloxetine (n = 232) or placebo (n = 226). The BPI average pain score improved significantly in the duloxetine group compared with that in the placebo group at Week 14 [-2.43 ± 0.11 vs. -1.96 ± 0.11, respectively; between-group difference (95% confidence interval), - 0.46 [-0.77 to-0.16]; P = 0.0026]. The duloxetine group showed significant improvement in many secondary measures compared with the placebo group, including BPI pain (least pain, pain right now) (between-group difference: -1.69 ± 0.10, P = 0.0009; -2.42 ± 0.12, P P = 0.0230, respectively), Patient's Global Impression of Improvement (2.46 ± 0.07, P = 0.0026), Clinical Global Impressions of Severity (-1.46 ± 0.06, P = 0.0019), and Roland-Morris Disability Questionnaire (-3.86 ± 0.22, P = 0.0439). Adverse events occurring at a significantly higher incidence in the duloxetine group were somnolence, constipation, nausea, dizziness, and dry mouth, most of which were mild or moderate in severity and were resolved or improved.
CONCLUSION: Duloxetine 60 mg was effective and well tolerated in Japanese CLBP patients.
LEVEL OF EVIDENCE: 2.
BACKGROUND: Less than 50% of patients experience sufficient pain relief with current drug therapy for neuropathic pain. Minocycline shows promising results in rodent models of neuropathic pain but was not studied in humans with regard to the treatment of neuropathic pain.
METHODS: In this randomized, double-blind, placebo-controlled clinical trial, patients with subacute lumbar radicular pain received placebo, amitriptyline 25 mg, or minocycline 100 mg once a day (n = 20 per group) for 14 days. Primary outcome measure was the pain intensity in the leg as measured by a numeric rating scale ranging from 0 to 10 on days 7 and 14. Secondary outcome measures were the reduction of neuropathic pain symptoms in the leg as determined with a neuropathic pain questionnaire, consumption of rescue medication, and adverse events on days 7 and 14.
RESULTS: Sixty patients were randomized and included in an intention-to-treat analysis. After 14 days, patients in the minocycline and amitriptyline groups reported a reduction of 1.47 (95% confidence interval, 0.16-2.83; P = 0.035) and 1.41 (95% confidence interval, 0.05-2.78; P = 0.043), respectively, in the numeric rating scale compared to the placebo group. No differences were seen in the neuropathic pain questionnaire values at any time point during treatment between the three groups. The rate of adverse events in the amitriptyline group was 10% versus none in the minocycline and placebo groups. No differences were noted in the consumption of rescue medication.
CONCLUSIONS: Although both groups differed from placebo, their effect size was small and therefore not likely to be clinically meaningful.
This clinical trial evaluated the independent and combined effects of a tricyclic antidepressant (desipramine) and cognitive behavioral therapy (CBT) for chronic back pain relative to an active placebo treatment. Participants (n = 142) were patients experiencing daily chronic back pain at an intensity of ≥4/10 who were randomized to a single-center, double-blind, 12-week, 4-arm, parallel groups controlled clinical trial of (1) low concentration desipramine titrated to reach a serum concentration level of 15 to 65 ng/mL; (2) CBT and active placebo medication (benztropine mesylate, 0.125 mg); (3) low concentration desipramine and CBT; and (4) active benztropine placebo medication. Participants completed the Differential Description Scale and Roland Morris Disability Questionnaires before and after treatment as validated measures of outcomes in back pain intensity and disability, respectively. Participants within each condition showed significant reductions from pre-treatment to post-treatment in pain intensity (mean changes ranged from = -2.58 to 3.87, Cohen's d's = 0.46-0.84) and improvements in pain disability (mean changes = -3.04 to 4.29, Cohen's d's = 0.54-0.88). However, intent-to-treat analyses at post-treatment showed no significant differences between any condition, with small effect sizes ranging from 0.06 to 0.27. The results from this clinical trial did not support the hypothesis that desipramine, CBT, or their combination would be statistically superior to an active medicine placebo for reducing chronic back pain intensity or disability. Key limitations included recruiting 71% of the planned sample size and use of multiple inclusion/exclusion criteria that may limit generalizability to broader populations of patients with chronic back pain.
