Venlafaxine versus imipramine in painful polyneuropathy: a randomized, controlled trial. Venlafaxine extended release in the treatment of painful diabetic neuropathy: a double-blind, placebo-controlled study. Venlafaxine in neuropathic pain following treatment of breast cancer. Venlafaxine in the treatment of atypical facial pain: a randomized controlled trial. Treatment response in antidepressant-naïve postherpetic neuralgia patients: double-blind, randomized trial. The effect of venlafaxine on ongoing and experimentally induced pain in neuropathic pain patients: a double blind, placebo controlled study. Opioids versus antidepressants in postherpetic neuralgia: a randomized, placebo-controlled trial. A randomized, within-patient, cross-over, placebo-controlled trial on the efficacy and tolerability of the tricyclic antidepressants chlorimipramine and nortriptyline in central pain. Efficient assessment of neuropathic pain drugs in patients with small fiber sensory neuropathies.
Tricyclic antidepressants (TCA) are often used in the treatment of painful polyneuropathy. Venlafaxine is a serotonin and weak noradrenaline reuptake inhibitor antidepressant with a different profile of other pharmacologic actions from those of TCA.
                To test if venlafaxine would relieve painful polyneuropathy and compare its possible efficacy with that of the TCA imipramine.
                The study design was randomized, double blind, and placebo controlled, with a three-way crossover. Forty patients were assigned to one of the treatment sequences, and 29 completed all three study periods. The daily doses were venlafaxine 225 mg and imipramine 150 mg. During the three treatment periods, each of 4 weeks' duration, patients rated pain paroxysms, constant pain, and touch- and pressure-evoked pain by use of 0- to 10-point numeric rating scales.
                The sum of the individual pain scores during treatment week 4 was lower on venlafaxine (80% of baseline score; p = 0.006) and imipramine (77%; p = 0.001) than on placebo (100%) and did not show any statistical difference between venlafaxine and imipramine (p = 0.44). The individual pain scores for pain paroxysms, constant pain, and pressure-evoked pain showed a similar pattern, whereas touch-evoked pain was uncommon and was not altered by any of the drugs. Numbers needed to treat to obtain one patient with moderate or better pain relief were 5.2 for venlafaxine and 2.7 for imipramine.
                Venlafaxine relieves pain in polyneuropathy and may be as effective as imipramine. To evaluate the efficacy and safety of 6 weeks of venlafaxine extended-release (ER) (75 mg and 150-225 mg) treatment in patients with painful diabetic neuropathy. This multicenter, double-blind, randomized, placebo-controlled study included 244 adult outpatients with metabolically stable type 1 or 2 diabetes with painful diabetic neuropathy. Primary efficacy measures were scores on the daily 100 mm Visual Analog Pain Intensity (VAS-PI) and Pain Relief (VAS-PR) scales. Secondary efficacy measures included the Clinical Global Impressions-Severity of Illness and the Clinical Global Impressions-Improvement, Patient Global Rating of Pain Relief, and percentage of patients achieving 50% reduction in pain intensity. Baseline pain intensity was 68.7 mm (moderately severe). At week 6, the percentage reduction from baseline in VAS-PI was 27% (placebo), 32% (75 mg), and 50% (150-225 mg; P < 0.001 vs placebo). Mean VAS-PR scores in the 150-225 mg group were significantly greater than placebo at week 6 (44 vs 60 mm; P < 0.001). The number needed to treat (NNT) for 50% pain intensity reduction with venlafaxine ER 150-225 mg was 4.5 at week 6. Nausea and somnolence were the most common treatment-emergent adverse events. Seven patients on venlafaxine had clinically important ECG changes during treatment. Venlafaxine ER appears effective and safe in relieving pain associated with diabetic neuropathy. NNT values for higher dose venlafaxine ER are comparable to those of tricyclic antidepressants and the anticonvulsant gabapentin. Amitriptyline effectively relieves neuropathic pain following treatment of breast cancer. However, adverse effects are a major problem. Venlafaxine has no anticholinergic effects and could have a better compliance. The aim of the study was to evaluate the effectiveness of venlafaxine in neuropathic pain. The study was a randomized, double-blind, crossover comparison of venlafaxine and inactive placebo. The study lasted 10 weeks. The number of tablets (18.75 mg) taken daily was increased by one at a 1 week interval. Pain intensity and pain relief were registered daily by a diary and by a questionnaire and a computer program (Painscreen) on each visit. Adverse effects were evaluated with the diaries and a 10-item list on each visit. Also, anxiety and depression were measured on each visit. Venous blood samples were collected before the treatment and at 4 weeks for the determination of the serum levels of venlafaxine and its three metabolites. Thirteen patients were analysed. The average daily pain intensity as reported in the diary (primary outcome) was not significantly reduced by venlafaxine compared with placebo. However, the average pain relief (diary) and the maximum pain intensity (retrospective assessment by the computer program) were significantly lower with venlafaxine compared with placebo. Anxiety and depression were not affected. Adverse effects did not show significant differences between treatments. The two poor responders had low venlafaxine concentrations whereas the two slow hydroxylizers had high venlafaxine concentrations and excellent pain relief. Thus, higher doses could be used in order to improve pain relief.
                Copyright 2002 European Federation of Chapters of the International Association for the Study of Pain To study in a randomized placebo-controlled design the efficacy of the antidepressant venlafaxine, a serotonin and a weak noradrenaline reuptake inhibitor, in the treatment of atypical facial pain (AFP).
                The study was a randomized, double-blind, crossover comparison of venlafaxine and a placebo. It consisted of 2 treatment periods, each of 4 weeks' duration, separated by a 2-week washout period. Thirty patients suffering from chronic pain who had been diagnosed with AFP after a thorough clinical examination were recruited. Pain intensity and pain relief were registered at 6 visits. Anxiety, depression, and adverse effects were recorded. Venous blood samples were collected at the end of each treatment period for the determination of serum levels of venlafaxine and its metabolites.
                Twenty patients completed the trial. Eight patients discontinued because of adverse effects and 2 patients were excluded because of noncompliance. Two patients completed the trial but were excluded from the analysis because they experienced no pain at the baseline visit. There was no significant difference in pain intensity reduction between the maximum tolerated dose of venlafaxine (75 mg in most cases) and the placebo. Pain relief was significantly greater with venlafaxine than with the placebo treatment. Significantly more escape medication was consumed during the placebo period compared with the venlafaxine period. No significant correlation was found between the serum concentration of the drug and the response to treatment. Anxiety and depression scores did not differ between venlafaxine and placebo treatment. Adverse effects were equally common during both treatments.
                Venlafaxine was only modestly effective in the treatment of AFP. In 47 patients with postherpetic neuralgia (PHN) who had never had an adequate trial of any antidepressant, we performed a randomized, double-blind, parallel design trial comparing desipramine, amitriptyline, and fluoxetine. Patients were titrated to a maximum of 150 mg/day for desipramine and amitriptyline and 60 mg/day for fluoxetine over a 3-week period and then treated for an additional 3 weeks before tapering off study medication. A total of 38 subjects (81%) completed the entire trial. The modified intent-to-treat analysis of percent change in daily diary pain intensity scores showed no significant differences among the 3 drugs (ANOVA P = .120). Desipramine produced the greatest reduction in pain intensity (47%), followed by amitriptyline (38%) and fluoxetine (35%). Clinically meaningful pain relief (moderate or better) was significantly more likely with desipramine (12/15 patients) than with amitriptyline (9/17) or fluoxetine (5/15); chi(2)P = 0.036). The 11 subjects using opioids at study entry had smaller reductions in pain than those not using concomitant opioids. The fluoxetine group had the highest noncompletion rate (33%), with 1 subject hospitalized for hyponatremia. Although the magnitude of pain reduction and the category pain relief rating was not significantly different among the 3 drugs, the tricyclics desipramine and amitriptyline were well tolerated and provided clinically meaningful pain relief in 53% to 80% of subjects.
                Few clinical trials focus on patients who are naïve to an entire class of medication. In this randomized blinded trial, the tricyclic antidepressants desipramine and amitriptyline were compared to the serotonin-selective antidepressant fluoxetine. All 3 drugs reduced PHN pain, with desipramine providing satisfactory relief in 80% of those treated. The aim of this randomized double blind placebo controlled study was to investigate the effectiveness and the safety of venlafaxine XR 75 and 150 mg on ongoing pain and on quantitative sensory tests in 60 patients with neuropathic pain for 8 weeks.
                Evaluation parameters consisted of ongoing pain intensity (VAS), patient satisfaction, side effects, global efficacy and tolerance. Quantitative sensory measurements taken from the affected area before and after the drug treatment included pin-prick hyperalgesia, allodynia, detection and pain thresholds to electrical and heat stimuli, temporal summation of repetitive electrical and heat stimuli.
                A total of 55 patients completed the study. VAS scores decreased significantly compared to the baseline measurements in all groups. There was no significant difference between the groups regarding pain intensity and escape medication. The areas of allodynia and pin-prick hyperalgesia decreased significantly in venlafaxine groups compared to the placebo. There was no significant difference between the groups regarding the detection thresholds (electrical and heat). The pain threshold and the summation threshold to electrical stimuli and the summation threshold to heat stimuli increased significantly following treatment in both venlafaxine groups. In addition, the degree of the temporal summation to electrical and heat stimuli decreased significantly following treatment in both venlafaxine groups compared to the placebo.
                The study showed significant effect of venlafaxine in the manifestations of hyperalgesia and temporal summation, but not on the ongoing pain intensity. Furthermore, the quantitative sensory tests provided complementing information to the clinical measures. Tricyclic antidepressants (TCA) provide less than satisfactory pain relief for postherpetic neuralgia (PHN), and the role of opioids is controversial.
                To compare the analgesic and cognitive effects of opioids with those of TCA and placebo in the treatment of PHN.
                Seventy-six patients with PHN were randomized in a double-blind, placebo-controlled, crossover trial. Each subject was scheduled to undergo three treatment periods (opioid, TCA, and placebo), approximately 8 weeks' duration each. Doses were titrated to maximal relief or intolerable side effects. The primary outcome measures were pain intensity (0 to 10 scale), pain relief (0 to 100%), and cognitive function. Analyses included patients who provided any pain ratings after having received at least a single dose of a study medication.
                Fifty patients completed two periods, and 44 patients completed all three. Mean daily maintenance doses were morphine 91 mg or methadone 15 mg and nortriptyline 89 mg or desipramine 63 mg. Opioids and TCA reduced pain (1.9 and 1.4) more than placebo (0.2; p < 0.001), with no appreciable effect on any cognitive measure. The trend favoring opioids over TCA fell short of significance (p = 0.06), and reduction in pain with opioids did not correlate with that following TCA. Treatment with opioids and TCA resulted in greater pain relief (38 and 32%) compared with placebo (11%; p < 0.001). More patients completing all three treatments preferred opioids (54%) than TCA (30%; p = 0.02).
                Opioids effectively treat PHN without impairing cognition. Opioids and TCA act via independent mechanisms and with varied individual effect. Antidepressant drugs are increasingly used in the management of chronic pain. They are mainly prescribed for cancer-related pain and central pain, e.g. phantom or stump pain, post-herpetic neuropathy. However, no controlled clinical trials have validated their in either pathology. Thus, physicians still do not know whether antidepressants are really effective and which might be best. It is still debated whether the effect of antidepressants in the management of chronic pain is limited to the amelioration of frequently concomitant depression or extends to pain itself. To verify both the analgesic effect of tricyclic antidepressants, and the possible relationship between their antidepressant effect and the relief of central pain, we carried out a randomized, within-patient (cross-over) placebo-controlled study in patients suffering from central pain. The results clearly indicate the better analgesic effect of tricyclic antidepressants over placebo (p less than 0.0001). Within the antidepressants tested, chlorimipramine, a blocker of serotonin reuptake, is significantly more effective (p less than 0.0001) than notriptyline, a blocker of noradrenaline reuptake. Finally, the antinociceptive effect is independent of the effects of the two drugs on the symptoms of depression. We sought to develop an enrichment crossover study design that would allow us to efficiently evaluate and compare promising candidate neuropathic pain drugs. We evaluated the efficacy of gabapentin or tramadol vs. active placebo (diphenhydramine) in subjects with biopsy-proven painful idiopathic small fiber neuropathy (SFN) who were self-reported gabapentin responders. Eligible subjects entered two single blind run-in phases. In the first phase (Period A), subjects were treated with single blinded gabapentin at their prestudy dose followed by a second run-in phase (Period B) in which they were treated with diphenhydramine active placebo. Subjects with >or=3 pain and a >or=30% increase in pain intensity in Period B compared to Period A were then randomized to a double-blind three period cross over trial of gabapentin at pre study dosage, tramadol 50mg QID and diphenhydramine 50mgqhs. Of the 59 subjects enrolled, 41 subjects were excluded: Twenty-three had an insufficient rise in pain intensity in Period B; eight had skin biopsies that did not confirm SFN. Eighteen subjects were randomized into the double-blind, crossover phase. There was a significant treatment effect of gabapentin vs. diphenhydramine (p=0.001) and tramadol vs. diphenhydramine (p=0.018) by the before-bed daily pain score averaged over the final 7 days of each treatment period. We conclude that gabapentin and tramadol were effective in the treatment of painful SFN and that this experimental enrichment paradigm is attractive to screen potential neuropathic pain compounds for efficacy in proof-of-concept studies.
This update has provided additional confirmation on the effectiveness of antidepressants for neuropathic pain and has provided new information on another antidepressant - venlafaxine. There is still limited evidence for the role of SSRIs. Whether antidepressants prevent the development of neuropathic pain (pre-emptive use) is still unclear. Both TCAs and venlafaxine have NNTs of approximately three. This means that for approximately every three patients with neuropathic pain who are treated with either of these antidepressants, one will get at least moderate pain relief. There is evidence to suggest that other antidepressants may be effective but numbers of participants are insufficient to calculate robust NNTs. SSRIs are generally better tolerated by patients and more high quality studies are required.