Yili L. Pritchett

A randomized, double-blind, placebo-controlled trial of duloxetine in the treatment of women with fibromyalgia with or without major depressive disorder

&NA; This was a 12‐week, randomized, double‐blind, placebo‐controlled trial to assess the efficacy and safety of duloxetine, a selective serotonin and norepinephrine reuptake inhibitor, in 354 female patients with primary fibromyalgia, with or without current major depressive disorder. Patients (90% Caucasian; mean age, 49.6 years; 26% with current major depressive disorder) received duloxetine 60 mg once daily (QD) (N=118), duloxetine 60 mg twice daily (BID) (N=116), or placebo (N=120). The primary outcome was the Brief Pain Inventory average pain severity score. Response to treatment was defined as ≥30% reduction in this score. Compared with placebo, both duloxetine‐treated groups improved significantly more (P<0.001) on the Brief Pain Inventory average pain severity score. A significantly higher percentage of duloxetine‐treated patients had a decrease of ≥30% in this score (duloxetine 60 mg QD (55%; P<0.001); duloxetine 60 mg BID (54%; P=0.002); placebo (33%)). The treatment effect of duloxetine on pain reduction was independent of the effect on mood and the presence of major depressive disorder. Compared with patients on placebo, patients treated with duloxetine 60 mg QD or duloxetine 60 mg BID had significantly greater improvement in remaining Brief Pain Inventory pain severity and interference scores, Fibromyalgia Impact Questionnaire, Clinical Global Impression of Severity, Patient Global Impression of Improvement, and several quality‐of‐life measures. Both doses of duloxetine were safely administered and well tolerated. In conclusion, both duloxetine 60 mg QD and duloxetine 60 mg BID were effective and safe in the treatment of fibromyalgia in female patients with or without major depressive disorder.

Efficacy of duloxetine and selective serotonin reuptake inhibitors: comparisons as assessed by remission rates in patients with major depressive disorder.

It has been proposed that serotonin and norepinephrine reuptake inhibitors (SNRIs) may result in higher remission rates of major depressive disorder than therapy with selective serotonin reuptake inhibitors (SSRIs). To test this hypothesis, a meta-analysis of individual patient data (N = 1833) was performed for the complete set of 6 phase II/III studies that compared duloxetine (fixed doses; range, 40-120 mg/d) with 2 SSRIs (paroxetine or fluoxetine; 20 mg/d) in outpatients with major depressive disorder. Remission was defined as an end point score of less than or equal to 7 on the 17-item Hamilton Rating Scale for Depression (HAMD17); alternate outcome criteria were also examined, as were remission rates among the 1044 patients with moderate-to-severe depression (HAMD17 total score greater than or equal to 19). The HAMD17 remission rates were 40.3% (351/871), 38.3% (162/423), and 28.4% (144/507) for duloxetine, the 2 SSRIs, and placebo, respectively. Both active treatments were superior to placebo; the difference between duloxetine and SSRIs was not statistically significant. Similar findings were observed for alternate outcomes. Duloxetine therapy was significantly more effective than therapy with the 2 SSRIs for patients with more severe depression, with remission rates of 35.9% (183/510) versus 28.6% (70/245) (P = 0.046). A secondary analysis of dose-response relationships indicated that this advantage was not attributable to the studies using higher doses of duloxetine. Thus, whereas duloxetine and the 2 SSRIs were comparably efficacious overall, therapy with the serotonin and norepinephrine reuptake inhibitor resulted in a significantly higher remission rate among patients with moderate-to-severe depression.

Clinical evidence for serotonin and norepinephrine reuptake inhibition of duloxetine.

Most antidepressants in clinical use are believed to function by enhancing neurotransmission of serotonin [5-hydroxytryptamine (5-HT)] and/or norepinephrine (NE) via inhibition of neurotransmitter reuptake. Agents that affect reuptake of both 5-HT and NE (serotonin-norepinephrine reuptake inhibitors) have been postulated to offer greater efficacy for the treatment of major depressive disorder (MDD). These dual-acting agents also display a broader spectrum of action, including efficacy for MDD and associated painful physical symptoms, diabetic peripheral neuropathic pain, generalized anxiety disorder, and fibromyalgia syndrome. Substantial preclinical evidence shows that duloxetine, an approved drug for the treatment of MDD, generalized anxiety disorder, and the management of diabetic peripheral neuropathic pain, inhibits reuptake of both 5-HT and NE. This paper reviews clinical and neurochemical evidence of duloxetines effects on 5-HT and NE reuptake inhibition. The clinical evidence supporting duloxetines effects on NE reuptake inhibition includes indirect measures such as altered excretion of NE metabolites, cardiovascular effects, and treatment-emergent adverse event profiles similar to those for other drugs believed to act through the inhibition of NE reuptake. In summary, the data presented in this report provide clinical evidence of a mechanism for duloxetine involving both 5-HT and NE reuptake inhibition in humans and are consistent with preclinical evidence for 5-HT/NE reuptake inhibition.

Efficacy and safety of the α4β2 neuronal nicotinic receptor agonist ABT-894 in patients with diabetic peripheral neuropathic pain

TOC summary In 2 well‐controlled phase 2 clinical trials, the selective α4β2 neuronal nicotinic receptor agonist ABT‐894 was found to be ineffective in treating patients with diabetic neuropathic pain. Abstract Preclinical and clinical studies suggest that neuronal nicotinic receptor (NNR) agonists may be a novel and effective therapy for numerous painful conditions. Analgesic efficacy and safety of the highly selective α4β2 NNR agonist ABT‐894 was evaluated in 2 separate randomized, double‐blind, multicenter, placebo‐controlled clinical trials in patients with diabetic peripheral neuropathic pain (DPNP). Study 1 (280 patients randomized) tested 1, 2, and 4 mg ABT‐894 twice daily compared with placebo and 60 mg duloxetine once per day over 8 weeks of treatment. Study 2 (124 patients randomized) tested 6 mg ABT‐894 twice daily vs placebo for 8 weeks. The primary efficacy outcome measure in both studies was the weekly mean of the 24‐hour average pain score recorded in each patient’s diary. In both trials, none of the ABT‐894 dose groups showed efficacy compared with placebo, whereas duloxetine achieved a statistically significant improvement over placebo in Study 1. All dose levels of ABT‐894 were well tolerated, and no significant safety issues were identified. These results are in contrast to the outcome of a previously reported study of DPNP using the less selective α4β2 NNR agonist ABT‐594, which demonstrated efficacy compared with placebo, albeit with significant tolerability limitations. The failure of the highly selective α4β2 NNR agonist ABT‐894 indicates that it may not be possible to define a therapeutic index for this mechanism or that selectively targeting α4β2 NNRs may not be a viable approach to treating neuropathic pain.

Duloxetine in the long-term management of diabetic peripheral neuropathic pain: An open-label, 52-week extension of a randomized controlled clinical trial

BACKGROUND Duloxetine hydrochloride, a selective serotonin (5-HT) and norepinephrine (NE) reuptake inhibitor, is relatively balanced in its affinity for both 5-HT and NE reuptake inhibition and is the first US Food and Drug Administration-approved prescription drug for the management of diabetic peripheral neuropathic pain (DPNP). OBJECTIVES The aim of this study was to determine whether management of DPNP with duloxetine interferes with the treatment of diabetes. It also examined the tolerability of long-term exposure to duloxetine with regard to the progression of diabetic complications, and assessed the impact of DPNP management with duloxetine versus routine care. METHODS This was a 52-week, multicenter, re-randomized, open-label extension of a parallel, double-blind, randomized, placebo-controlled, acute (12-week) study. Patients who completed the duloxetine or placebo acute treatment period were randomly reassigned in a 2:1 ratio to treatment with duloxetine 60 mg BID or routine care for an additional 52 weeks. The study included male and female outpatients aged ≥18 years with a diagnosis of DPNP caused by type 1 or type 2 diabetes. Over the course of the 52-week study, visits were scheduled on the following weeks (of the extension phase of the study): 1 (via phone only), 2, 4, 8, 12, 20, 28, 40, and 52. Tolerability was assessed by review and analyses of discontinuation rates, adverse events (AEs), laboratory data, vital signs, electrocardiographic results, concomitant medications, and diabetic complications. Treatment-emergent AEs (TEAEs) were defined as AEs that appeared during therapy (were not present at baseline) or were exacerbated during treatment. Data on AEs and concomitant medications were collected at every visit. Data on blood pressure, heart rate, and significant hypoglycemic events were collected at every visit starting from week 2. Fasting clinical chemistry and electrolyte group laboratory assessments were done at every visit, starting from week 4. Electrocardiographic data was collected at weeks 4 and 52, and glycosylated hemoglobin and lipid profile data were collected at weeks 20 and 52. Hematology and urinalysis laboratory assessments and diabetic complication assessments were done at week 52. All safety data was assessed in cases of early discontinuation. Treatment differences on quality of life (QOL) were compared using the Short Form-36 Health Status Survey (SF-36) and the EQ-5D instrument of the European Health-Related Quality of Life Measures. This was assessed at the last visit or at early discontinuation. RESULTS The open-label extension-phase study included 337 patients (duloxetine, n = 222; routine care, n = 115). For the duloxetine group, mean age was 60.2 years, 61.3% were male, and 78.4% were white. For the routine-care group, mean age was 58.9 years, 60.0% were male, and 74.8% were white. Mean weight was 95.3 kg for both groups. None of the TEAEs occurred significantly more often in the duloxetine-treated group than in the routine-care-treated group. No TEAEs were reported by >10% of patients in the duloxetine group. The TEAEs reported by >10% of patients in the routine-care group included dizziness (11.3%), somnolence (13.0%), headache (10.4%), and vomiting (10.4%). No significant differences were found between treatment groups in the occurrence of serious AEs or in the number of patients discontinuing because of AEs. Duloxetine was significantly better than routine care on the bodily pain subscale of the SF-36 (mean change: 1.5 vs -4.1; P= 0.021) and on the EQ-5D (mean change: -0.00 vs -0.09; P = 0.001). CONCLUSIONS Over 52 weeks of follow-up, treatment of these diabetic patients with duloxetine for peripheral neuropathic pain was associated with outcomes similar to, or significantly better than, that of routine care on most measures of tolerability, diabetic complications, and QOL.