The use of antidepressants in the treatment of chronic pain. A review of the current evidence

Shedding Light on Treatment Options for Coronary Vasomotor Disorders: A Systematic Review

PURPOSE

Coronary vasomotor dysfunction embraces two specific clinical entities: coronary (micro)vascular spasm and microvascular dysfunction. The clinical manifestations of these entities are respectively called vasospastic angina (VSA) and microvascular angina (MVA). Over the years, these diseases have become more and more prominent and several studies aimed to investigate the best diagnostic and therapeutic strategies. Patients with coronary vasomotor disorders are often undertreated due to the absence of evidence-based guidelines. The purpose of this overview is to illustrate the various therapeutic options available for the optimized management of these patients.

METHODS

A Medline search of full-text articles published in English from 1980 to April 2022 was performed. The main analyzed aspects of vasomotor disorders were treatment options. We also performed research on "Clinicaltrial.gov" for ongoing trials.

CONCLUSION

Coronary (micro)vascular spasm and microvascular dysfunction are clinical entities characterized by high prevalence and clinical representation. Several therapeutic strategies, both innovative and established, are available to optimize treatment and improve the quality of life of these patients.

HDAC6-selective inhibitors decrease nerve-injury and inflammation-associated mechanical hypersensitivity in mice

BACKGROUND

HDAC6 is a class IIB histone deacetylase expressed at many levels of the nociceptive pathway. This study tested the ability of novel and selective HDAC6 inhibitors to alleviate sensory hypersensitivity behaviors in mouse models of peripheral nerve injury and peripheral inflammation.

METHODS

We utilized the murine spared nerve injury (SNI) model for peripheral nerve injury and the Complete Freund's Adjuvant (CFA) model of peripheral inflammation. We applied the Von Frey assay to monitor mechanical allodynia.

RESULTS

Using the SNI model, we demonstrate that daily administration of the brain-penetrant HDAC6 inhibitor, ACY-738, abolishes mechanical allodynia in male and in female mice. Importantly, there is no tolerance to the antiallodynic actions of these compounds as they produce a consistent increase in Von Frey thresholds for several weeks. We observed a similar antiallodynic effect when utilizing the HDAC6 inhibitor, ACY-257, which shows limited brain expression when administered systemically. We also demonstrate that ACY-738 and ACY-257 attenuate mechanical allodynia in the CFA model of peripheral inflammation.

CONCLUSIONS

Overall, our findings suggest that inhibition of HDAC6 provides a promising therapeutic avenue for the alleviation of mechanical allodynia associated with peripheral nerve injury and peripheral inflammation.

Vers un élargissement des indications des antidépresseurs

Les données neurochimiques directes ou indirectes obtenues dans différentes affections du système nerveux central (SNC) constituent la base rationnelle de I'utilisation des médicaments dans des indications précises. Les antidépresseurs (AD) tricycliques agissant sur les principales amines du SNC trouvent ainsi des applications thérapeutiques variées en dehors de la dépression. L'arrivée de nouveaux AD au mécanisme d'action, soit plus cibé (la sérotonine), soit différent (IMAO) pose de nouveau cette question des indications psychiatriques et neurologiques, qui ne peut être résolue que par des essais méthodologiquement irréprochables. Une telle approche évitera d'ignorer pendant des années des effets thérapeutiques incontestables d'une molécule ancienne, tel que ce fut le cas de la clomipramine dans les troubles obsessifs-compulsifs.

Trends in antidepressant use among children and adolescents: a Scandinavian drug utilization study

OBJECTIVE

To compare antidepressant utilization in individuals aged 5-19 years from the Scandinavian countries.

METHODS

A population-based drug utilization study using publicly available data of antidepressant use from Denmark, Norway, and Sweden.

RESULTS

In the study period from 2007 to 2017, the proportion of antidepressant users increased markedly in Sweden (9.3-18.0/1000) compared to Norway (5.1-7.6/1000) and Denmark (9.3-7.5/1000). In 2017, the cumulated defined daily doses (DDD) of selective serotonin reuptake inhibitors were 5611/1000 inhabitants in Sweden, 2709/1000 in Denmark, and 1848/1000 in Norway. The use of 'other antidepressants' (ATC code N06AX) also increased in Sweden with a higher DDD in 2017 (497/1000) compared to Denmark (225/1000) and Norway (170/1000). The use of tricyclic antidepressants was generally low in 2017 with DDDs ranging between 30-42 per 1000. The proportion of antidepressant users was highest among 15- to 19-year-old individuals. Girls were more likely to receive treatment than boys, and the treated female/male ratios per 1000 were similar in Sweden (2.39), Denmark (2.44), and Norway (2.63).

CONCLUSION

Even in highly comparable healthcare systems like the Scandinavian countries', variation in antidepressant use is considerable. Swedish children and adolescents have a markedly higher and still increasing use of antidepressants compared to Danish and Norwegian peers.

Burning mouth syndrome

Objective

To review the clinical entity of primary burning mouth syndrome (BMS), its pathophysiological mechanisms, accurate new diagnostic methods and evidence-based treatment options, and to describe novel lines for future research regarding aetiology, pathophysiology, and new therapeutic strategies.

Description

Primary BMS is a chronic neuropathic intraoral pain condition that despite typical symptoms lacks clear clinical signs of neuropathic involvement. With advanced diagnostic methods, such as quantitative sensory testing of small somatosensory and taste afferents, neurophysiological recordings of the trigeminal system, and peripheral nerve blocks, most BMS patients can be classified into the peripheral or central type of neuropathic pain. These two types differ regarding pathophysiological mechanisms, efficacy of available treatments, and psychiatric comorbidity. The two types may overlap in individual patients. BMS is most frequent in postmenopausal women, with general population prevalence of around 1%. Treatment of BMS is difficult; best evidence exists for efficacy of topical and systemic clonazepam. Hormonal substitution, dopaminergic medications, and therapeutic non-invasive neuromodulation may provide efficient mechanism-based treatments for BMS in the future.

Conclusion

We present a novel comprehensive hypothesis of primary BMS, gathering the hormonal, neuropathic, and genetic factors presumably required in the genesis of the condition. This will aid in future research on pathophysiology and risk factors of BMS, and boost treatment trials taking into account individual mechanism profiles and subgroup-clusters.

Pharmacologic Treatment for Temporomandibular Disorders

Pharmacologic agents play an integral role in the overall management of temporomandibular joint disorder. The general dentist should be familiar with the different classes of drugs currently in use for dealing with this often complex medical/dental problem.

Effects of various pharmacological agents on the function of norepinephrine transporter

The norepinephrine transporter is selectively expressed in noradrenergic nerve terminals, where it can exert spatial and temporal control over the action of norepinephrine. The norepinephrine transporter mediates the termination of neurotransmission via the reuptake of norepinephrine released into the extracellular milieu. In the present brief review, we report our recent studies about the effects of various pharmacological agents such as fasudil, nicotine, pentazocine, ketamine and genistein on norepinephrine transporter function.

Pharmacological interventions for somatoform disorders in adults

BACKGROUND

Somatoform disorders are characterised by chronic, medically unexplained physical symptoms (MUPS). Although different medications are part of treatment routines for people with somatoform disorders in clinics and private practices, there exists no systematic review or meta-analysis on the efficacy and tolerability of these medications. We aimed to synthesise to improve optimal treatment decisions.

OBJECTIVES

To assess the effects of pharmacological interventions for somatoform disorders (specifically somatisation disorder, undifferentiated somatoform disorder, somatoform autonomic dysfunction, and pain disorder) in adults.

SEARCH METHODS

We searched the Cochrane Depression, Anxiety and Neurosis Review Group's Specialised Register (CCDANCTR) (to 17 January 2014). This register includes relevant randomised controlled trials (RCTs) from The Cochrane Library (all years), MEDLINE (1950 to date), EMBASE (1974 to date), and PsycINFO (1967 to date). To identify ongoing trials, we searched ClinicalTrials.gov, Current Controlled Trials metaRegister, the World Health Organization International Clinical Trials Registry Platform, and the Chinese Clinical Trials Registry. For grey literature, we searched ProQuest Dissertation & Theses Database, OpenGrey, and BIOSIS Previews. We handsearched conference proceedings and reference lists of potentially relevant papers and systematic reviews and contacted experts in the field.

SELECTION CRITERIA

We selected RCTs or cluster RCTs of pharmacological interventions versus placebo, treatment as usual, another medication, or a combination of different medications for somatoform disorders in adults. We included people fulfilling standardised diagnostic criteria for somatisation disorder, undifferentiated somatoform disorder, somatoform autonomic dysfunction, or somatoform pain disorder.

DATA COLLECTION AND ANALYSIS

One review author and one research assistant independently extracted data and assessed risk of bias. Primary outcomes included the severity of MUPS on a continuous measure, and acceptability of treatment.

MAIN RESULTS

We included 26 RCTs (33 reports), with 2159 participants, in the review. They examined the efficacy of different types of antidepressants, the combination of an antidepressant and an antipsychotic, antipsychotics alone, or natural products (NPs). The duration of the studies ranged between two and 12 weeks.One meta-analysis of placebo-controlled studies showed no clear evidence of a significant difference between tricyclic antidepressants (TCAs) and placebo for the outcome severity of MUPS (SMD -0.13; 95% CI -0.39 to 0.13; 2 studies, 239 participants; I(2) = 2%; low-quality evidence). For new-generation antidepressants (NGAs), there was very low-quality evidence showing they were effective in reducing the severity of MUPS (SMD -0.91; 95% CI -1.36 to -0.46; 3 studies, 243 participants; I(2) = 63%). For NPs there was low-quality evidence that they were effective in reducing the severity of MUPS (SMD -0.74; 95% CI -0.97 to -0.51; 2 studies, 322 participants; I(2) = 0%).One meta-analysis showed no clear evidence of a difference between TCAs and NGAs for severity of MUPS (SMD -0.16; 95% CI -0.55 to 0.23; 3 studies, 177 participants; I(2) = 42%; low-quality evidence). There was also no difference between NGAs and other NGAs for severity of MUPS (SMD -0.16; 95% CI -0.45 to 0.14; 4 studies, 182 participants; I(2) = 0%).Finally, one meta-analysis comparing selective serotonin reuptake inhibitors (SSRIs) with a combination of SSRIs and antipsychotics showed low-quality evidence in favour of combined treatment for severity of MUPS (SMD 0.77; 95% CI 0.32 to 1.22; 2 studies, 107 participants; I(2) = 23%).Differences regarding the acceptability of the treatment (rate of all-cause drop-outs) were neither found between NGAs and placebo (RR 1.01, 95% CI 0.64 to 1.61; 2 studies, 163 participants; I(2) = 0%; low-quality evidence) or NPs and placebo (RR 0.85, 95% CI 0.40 to 1.78; 3 studies, 506 participants; I(2) = 0%; low-quality evidence); nor between TCAs and other medication (RR 1.48, 95% CI 0.59 to 3.72; 8 studies, 556 participants; I(2) =14%; low-quality evidence); nor between antidepressants and the combination of an antidepressant and an antipsychotic (RR 0.80, 95% CI 0.25 to 2.52; 2 studies, 118 participants; I(2) = 0%; low-quality evidence). Percental attrition rates due to adverse effects were high in all antidepressant treatments (0% to 32%), but low for NPs (0% to 1.7%).The risk of bias was high in many domains across studies. Seventeen trials (65.4%) gave no information about random sequence generation and only two (7.7%) provided information about allocation concealment. Eighteen studies (69.2%) revealed a high or unclear risk in blinding participants and study personnel; 23 studies had high risk of bias relating to blinding assessors. For the comparison NGA versus placebo, there was relatively high imprecision and heterogeneity due to one outlier study. Although we identified 26 studies, each comparison only contained a few studies and small numbers of participants so the results were imprecise.

AUTHORS' CONCLUSIONS

The current review found very low-quality evidence for NGAs and low-quality evidence for NPs being effective in treating somatoform symptoms in adults when compared with placebo. There was some evidence that different classes of antidepressants did not differ in efficacy; however, this was limited and of low to very low quality. These results had serious shortcomings such as the high risk of bias, strong heterogeneity in the data, and small sample sizes. Furthermore, the significant effects of antidepressant treatment have to be balanced against the relatively high rates of adverse effects. Adverse effects produced by medication can have amplifying effects on symptom perceptions, particularly in people focusing on somatic symptoms without medical causes. We can only draw conclusions about short-term efficacy of the pharmacological interventions because no trial included follow-up assessments. For each of the comparisons where there were available data on acceptability rates (NGAs versus placebo, NPs versus placebo, TCAs versus other medication, and antidepressants versus a combination of an antidepressant and an antipsychotic), no clear differences between the intervention and comparator were found.Future high-quality research should be carried out to determine the effectiveness of medications other than antidepressants, to compare antidepressants more thoroughly, and to follow-up participants over longer periods (the longest follow up was just 12 weeks). Another idea for future research would be to include other outcomes such as functional impairment or dysfunctional behaviours and cognitions as well as the classical outcomes such as symptom severity, depression, or anxiety.

Relief of depression and pain improves daily functioning and quality of life in patients with major depressive disorder

OBJECTIVE

The objective of this study was to investigate the effects of depression relief and pain relief on the improvement in daily functioning and quality of life (QOL) for depressed patients receiving a 6-week treatment of fluoxetine.

METHOD

A total of 131 acutely ill inpatients with major depressive disorder (MDD) were enrolled to receive 20mg of fluoxetine daily for 6 weeks. Depression severity, pain severity, daily functioning, and health-related QOL were assessed at baseline and again at week 6. Depression severity, pain severity, and daily functioning were assessed using the 17-item Hamilton Depression Rating Scale, the Short-Form 36 (SF-36) Body Pain Index, and the Work and Social Adjustment Scale. Health-related QOL was assessed by three primary domains of the SF-36, including social functioning, vitality, and general health perceptions. Pearson's correlation and structural equation modeling were used to examine relationships among the study variables. Five models were proposed. In model 1, depression relief alone improved daily functioning and QOL. In model 2, pain relief alone improved daily functioning and QOL. In model 3, depression relief, mediated by pain relief, improved daily functioning and QOL. In model 4, pain relief, mediated by depression relief, improved daily functioning and QOL. In model 5, both depression relief and pain relief improved daily functioning and QOL.

RESULTS

One hundred and six patients completed all the measures at baseline and at week 6. Model 5 was the most fitted structural equation model (χ(2) = 8.62, df = 8, p = 0.376, GFI = 0.975, AGFI = 0.935, TLI = 0.992, CFI = 0.996, RMSEA = 0.027).

CONCLUSION

Interventions which relieve depression and pain improve daily functioning and QOL among patients with MDD. The proposed model can provide quantitative estimates of improvement in treating patients with MDD.

Pentazocine inhibits norepinephrine transporter function by reducing its surface expression in bovine adrenal medullary cells

(±)-Pentazocine (PTZ), a non-narcotic analgesic, is used for the clinical management of moderate to severe pain. To study the effect of PTZ on the descending noradrenergic inhibitory system, in the present study we examined the effect of [(3)H]norepinephrine (NE) uptake by cultured bovine adrenal medullary cells and human neuroblastoma SK-N-SH cells. (-)-PTZ and (+)-PTZ inhibited [(3)H]NE uptake by adrenal medullary cells in a concentration-dependent (3-100 μM) manner. Eadie-Hofstee analysis of [(3)H]NE uptake showed that both PTZs caused a significant decrease in the V(max) with little change in the apparent K(m), suggesting non-competitive inhibition. Nor-Binaltorphimine and BD-1047, κ-opioid and σ-receptor antagonists, respectively, did not affect the inhibition of [(3)H]NE uptake induced by (-)-PTZ and (+)-PTZ, respectively. PTZs suppressed specific [(3)H]nisoxetine binding to intact SK-N-SH cells, but not directly to the plasma membranes isolated from the bovine adrenal medulla. Scatchard analysis of [(3)H]nisoxetine binding to SK-N-SH cells revealed that PTZs reduced the B(max) without changing the apparent K(d). Western blot analysis showed a decrease in biotinylated cell-surface NE transporter (NET) expression after the treatment with (-)-PTZ. These findings suggest that PTZ inhibits the NET function by reducing the amount of NET in the cell surface membranes through an opioid and σ-receptor-independent pathway.

Four treatment strategies for complex regional pain syndrome type 1

Complex regional pain syndrome (CRPS) poses a dilemma for many clinicians due to its unknown etiology and largely unsuccessful treatment modalities. The purpose of this study was to compare the clinical results of 4 treatment modalities for CRPS type 1. A total of 59 patients were divided into 4 groups based on treatment modality: group A, an oral nonsteroidal anti-inflammatory drug (NSAID) (n=10); group B, oral gabapentin (n=12); group C, intravenous (IV) 10% mannitol and steroid (n=11); group D, a combination of IV 20% mannitol and steroid with oral gabapentin (n=26). The patients remained under medical supervision after discharge and were evaluated either once a month or once every 2 months until final follow-up at a mean of 8 months. Patients in group A showed improvement in pain level, finger range of motion, swelling, and grip strength, without statistical significance (P=.076, P=.062, P=.312, and P=.804, respectively). Patients in group B showed significant improvement in pain level (P<.001), and patients in group C showed improvement in pain, finger range of motion, and swelling (P=.127), which rendered functional impairment unchanged. In comparison, patients in group D showed recovery of grip strength and improvement in pain level, finger range of motion, and (P<.001, P=.016, P=.031, and P=.047, respectively). Based on these results, a protocol including a combination of IV 20% mannitol and steroid with oral gabapentin is an acceptable and effective treatment for CRPS type 1.

Painful peripheral neuropathies

BACKGROUND AND OBJECTIVES

Painful neuropathies are common and often difficult to treat. The objective of this report was to review the subject to facilitate diagnosis and pain relief.

CONTENTS

The classification, causes, type of fibers involved, manifestations, diagnosis, adjuvant tests, questionnaires used in the diagnosis, and treatment are described.

CONCLUSIONS

The subject is very broad and involves several causes and treatments that often should be combined to obtain adequate pain control.

Maternal buspirone protects against the adverse effects of in utero stress on emotional and pain-related behaviors in offspring

Previous investigations from our laboratory demonstrated that prenatal stress exacerbates inflammatory pain-related behavior in adult rats and that fetal serotonin (5-HT) is involved in this phenomenon. In the present study we test the hypothesis that injections of buspirone, a 5-HT1A agonist, to rat dams before restraint stress during the last week of pregnancy (between pregnant days 15 and 20) can improve the characteristics of emotional and inflammatory pain-related behaviors in the adult offspring. Buspirone was injected to dams between the 9 and 20 days of pregnancy, during restraint stress, five min before it. The depression-like behavior in the forced swim test, formalininduced pain and body weight were investigated in the adult offspring. Prenatal stress exacerbated the licking behavior, the index of formalin-induced pain, and increased the time of immobility, the index of depression-like behavior. Buspirone normalized the licking behavior and profoundly reduced the time of immobility, which indicates differences in the mechanisms of antinociceptive and antidepressant effects of buspirone. The present new findings demonstrate that adverse influences of prenatal stress on emotional and inflammatory pain-related behaviors can be prevented by using prenatal buspirone, which shows long-term anxiolytic, antidepressant and antinociceptive effects. The new fact of body weight decrease in buspirone+stress males is worth noting in the context of the important problem of body weight gain as a common side effect of treatment with antidepressant drugs.

Low-dose amitriptyline for treatment of persistent arm pain due to repetitive use

Amitriptyline is sometimes used to treat arm pain related to repetitive use, but rigorous evidence of its benefit is lacking. This randomized controlled trial investigated whether amitriptyline provided greater pain relief or improved arm function than a placebo pill in adults with arm pain associated with repetitive use that had persisted for at least 3 months. Participants (N=118) were randomly assigned to receive 25mg of amitriptyline or a placebo pill for 6 weeks. The primary outcome was intensity of pain (10-point numerical rating scale) and secondary outcomes were arm symptoms, arm function, grip strength, mood, and sleep. Assessments were done at baseline, 3 and 6 weeks of treatment, and 1 month after the treatment ended. Changes in arm pain were not statistically significant. However, the amitriptyline group improved more than the placebo group in arm function (p=0.023) and sense of well being (p=0.034). In a longitudinal analysis, the amitriptyline group's arm function score improved 0.45 points per week faster than placebo after adjusting for subject characteristics (p=0.015). At the treatment's midpoint, the amitriptyline group reported more "troublesome side-effects" than the placebo group (52.5% vs. 27.1%, p=0.005), but this difference decreased by the end of the treatment (30.5% vs. 22.0%, p=0.30). The most frequent side effect was drowsiness. In conclusion, this study found that low-dose amitriptyline did not significantly decrease arm pain among these participants but did significantly improve arm function and well being. Future research is needed to explore the effects of higher doses and longer duration of treatment.

Cardiac syndrome X: current concepts

Cardiac syndrome X is a heterogeneous entity, both clinically and pathophysiologically, encompassing a variety of pathogenic mechanisms. Management of this syndrome represents a major challenge to the treating physician. They often seek medical care because of recurring and disabling chest pain, which may imply repetitive and costly invasive and non-invasive investigations. A careful patient evaluation for underlying pathophysiologic mechanism and exclusion of other causes of chest pain along with attention to various psychological aspects is helpful in reducing the stress and suffering of these patients. This article reviews the available literature on the pathophysiology and current controversies surrounding the management of this difficult to treat condition.

Efficacy of tricyclic antidepressant therapy in adults with cyclic vomiting syndrome: a two-year follow-up study

AIM

To investigate the effects of prolonged tricyclic antidepressants (TCAs) therapy on the frequency and duration of episodes of cyclic vomiting syndrome (CVS) in adults, and the global assessment of clinical improvement and the number of emergency department (ED) visits and/or hospitalizations.

METHOD

An open labeled study was conducted in adult CVS patients treated with a TCA and followed for up to 2 years. Demographic data, TCA dosage, duration and frequency of CVS episodes, ED visits, and hospitalizations at baseline and during TCA therapy were recorded, and patients were monitored for any adverse events.

RESULTS

Forty-six patients initially met the inclusion criteria and 41 patients (22 male) with mean age of 35 years (range: 18 to 63 y) on TCA were able to be followed for 1 year and 23 were evaluated for 2 years. Mean age of onset of CVS symptoms was 26 years (range: 10 to 52 y) and mean age for making the diagnosis of CVS was 32 years (range: 15 to 63 y). The frequency and duration of an episode and ED visits related to CVS were all significantly reduced after both the first and second year of TCA therapy (P<0.05). Eighty-eight percent reported an improved clinical status by subjective global assessment. Mild side effects were reported in 34% not necessitating stoppage of the TCA.

CONCLUSIONS

Long-term TCA therapy significantly reduces the frequency and duration of CVS episodes, ED visits, and hospitalizations (P<0.05), and improves overall clinical well-being providing evidence that they are effective therapy for adult CVS.

Evaluating the maintenance of effect of duloxetine in patients with diabetic peripheral neuropathic pain

BACKGROUND

To evaluate the maintenance of effect of duloxetine 60 mg QD over 26 weeks in patients with diabetic peripheral neuropathic pain (DPNP).

METHODS

Adult patients with DPNP and Brief Pain Inventory (BPI) 24-h average pain >or=4 were treated in this open-label study with duloxetine 60 mg QD for 8 weeks. Responders (>or=30% pain reduction) continued on duloxetine 60 mg QD (maintenance arm) for 26 weeks while non-responders had duloxetine increased to 120 mg QD (rescue arm). The primary outcome measure was the mean change from baseline (Week 8) to endpoint (Week 34) in BPI average pain in the maintenance arm. A number of secondary efficacy measures, as well as safety and tolerability, were assessed.

RESULTS

Two hundred and sixteen patients entered the study and their baseline BPI average pain was 5.9. Thirty-two patients (15%) discontinued during the acute phase. One hundred and fifteen (53%) patients were found to be responders to 60 mg dose and they entered the maintenance arm. During the maintenance period they reported a mean change of BPI average pain of 0.35, with 0.79 as the upper bound of the one-sided 97.5% CI, which was less than the pre-specified non-inferiority margin of 1.5 (p < 0.001). Non-responders, upon dose increase to 120 mg QD, reported a statistically significant pain reduction. Total of 119 patients completed either arm of the study. Twenty patients experienced 27 serious adverse events including one death.

CONCLUSION

In this open-label study, the effect of duloxetine 60 mg QD in patients with DPNP was maintained over 6-month period.

Antidepressant use in painful rheumatic conditions

This article reviews the pharmacologic and clinical evidence supporting the use of antidepressant drugs for treating painful rheumatologic conditions. Clinical studies have shown that tricyclic antidepressants, even at low doses, have analgesic effects in rheumatologic conditions equivalent to those of serotonin and noradrenalin reuptake inhibitors, but are less well tolerated. Selective serotonin reuptake inhibitors may also have analgesic effects, but higher doses are required to achieve analgesia in conditions such as fibromyalgia and low back pain. Antidepressant drugs may be useful in painful rheumatologic conditions, but in some studies the analgesic effects of antidepressants may be associated with functional impairment, sleep disorders, and fatigue. Further studies are required to determine antidepressants' analgesic mechanism of action and the specific role they should play in the management of chronic painful rheumatologic conditions.

Effects of amitriptyline on gastric sensorimotor function and postprandial symptoms in healthy individuals: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Low-dose tricyclic antidepressants have been used to treat chronic somatic and gastrointestinal pain disorders, including refractory functional dyspepsia. However, there are only limited data on the effects of these drugs on upper gastrointestinal function.

AIM

To compare the effects of two doses of amitriptyline (AMT) and placebo on gastric accommodation, emptying, satiation, and postprandial symptoms in healthy volunteers.

METHODS

Using a parallel-group, double-blind, placebo-controlled design, 41 healthy volunteers were randomized to AMT 25 mg, AMT 50 mg, or placebo for 2 wk. During the final 3 days of therapy, the following end points were assessed: fasting and postprandial gastric volumes, 2- and 4-h gastric emptying, time and volume to maximum satiation using a nutrient drink test, and postprandial symptoms 30 min later using 10-cm visual analog scales. AMT and metabolite levels were measured.

RESULTS

AMT slowed gastric emptying at 2 h (median 75% for placebo, 57% for AMT 25 mg, 67% for AMT 50 mg; P= 0.037) and 4 h (median 98% for placebo, 96% for AMT 25 mg, 92% for AMT 50 mg; P= 0.003). AMT did not affect gastric volumes or satiation volume, but it did reduce nausea scores at 30 min in a dose-dependent manner (median 2.1 for placebo, 0.9 for AMT 25 mg, and 0.0 for AMT 50 mg; P= 0.009).

CONCLUSION

In healthy volunteers, AMT slows gastric emptying of solids, but it does not significantly affect gastric volumes or satiation. AMT reduces nausea after challenge with a high calorie liquid load.

Is there any evidence to support the use of anti-depressants in painful rheumatological conditions? Systematic review of pharmacological and clinical studies

The aim of this study was to review the evidence supporting the use of anti-depressants in painful rheumatological conditions. A systematic review of papers published between 1966 and 2007, in five European languages, on anti-depressants in rheumatological conditions was performed. Papers were scored using Jadad method and analgesic ES was calculated. We selected 78 clinical studies and 12 meta-analyses, from 140 papers. The strongest evidence of an analgesic effect of anti-depressants has been obtained for fibromyalgia. A weak analgesic effect is observed for chronic low back pain, with an efficacy level close to that of analgesics. In RA and AS, there is no analgesic effect of anti-depressants, but these drugs may help to manage fatigue and sleep disorders. There is no clear evidence of an analgesic effect inOA, but studies have poor methodological quality. Analgesic effects of anti-depressants are independent of their anti-depressant effects. Tricyclic anti-depressants (TCAs), even at low doses, have analgesic effects equivalent to those of serotonin and noradrenalin reuptake inhibitors (SNRIs), but are less well tolerated. Selective serotonin reuptake inhibitors (SSRIs) have modest analgesic effects, but higher doses are required to achieve analgesia. Anti-depressant drugs, particularly TCAs and SNRIs, have analgesic effects in chronic rheumatic painful states in which analgesics and NSAIDs are not very efficient, such as fibromyalgia and chronic low back pain. In inflammatory rheumatic diseases, anti-depressants may be useful for managing fatigue and sleep disorders. Further studies are required to compare anti-depressants with other analgesics in the management of chronic painful rheumatological conditions.

Antinociception occurs with a reversal in alpha 2-adrenoceptor regulation of TNF production by peripheral monocytes/macrophages from pro- to anti-inflammatory

Tumor necrosis factor-alpha (TNF) plays a role in neuropathic pain. During neuropathic pain development in the chronic constriction injury model, elevated TNF levels in the brain occur in association with enhanced alpha 2-adrenoceptor inhibition of norepinephrine release. alpha 2-Adrenoceptors are also located on peripheral macrophage where they normally function as pro-inflammatory, since they increase the production of the cytokine TNF, a proximal mediator of inflammation. How the central increase in TNF affects peripheral alpha 2-adrenoceptor function was investigated. Male, Sprague-Dawley rats had four loose ligatures placed around the right sciatic nerve. Thermal hyperalgesia was determined by comparing hind paw withdrawal latencies between chronic constriction injury and sham-operated rats. Chronic constriction injury increased TNF immunoreactivity at the lesion and the hippocampus. Amitriptyline, an antidepressant that is used as an analgesic, was intraperitoneally administered (10 mg/kg) starting simultaneous with ligature placement (day-0) or at days-4 or -6 post-surgery. Amitriptyline treatment initiated at day-0 or day-4 post-ligature placement alleviated hyperalgesia. When initiated at day-0, amitriptyline prevented increased TNF immunoreactivity in the hippocampus and at the lesion. A peripheral inflammatory response, macrophage production of TNF, was also assessed in the current study. Lipopolysaccharide (LPS)-stimulated production of TNF by whole blood cells and peritoneal macrophages was determined following activation of the alpha 2-adrenoceptor in vitro. alpha 2-Adrenoceptor regulation of TNF production from peripheral immune-effector cells reversed from potentiation in controls to inhibition in chronic constriction injured rats. This effect is accelerated with amitriptyline treatment initiated at day-0 or day-4 post-ligature placement. Amitriptyline treatment initiated day-6 post-ligature placement did not alleviate hyperalgesia and prevented the switch from potentiation to inhibition in alpha 2-adrenoceptor regulation of TNF production. Recombinant rat TNF i.c.v. microinfusion reproduces the response of peripheral macrophages from rats with chronic constriction injury. A reversal in peripheral alpha 2-adrenoceptor regulation of TNF production from pro- to anti-inflammatory is associated with effective alleviation of thermal hyperalgesia. Thus, alpha 2-adrenoceptor regulation of peripheral TNF production may serve as a potential biomarker to evaluate therapeutic regimens.

The effect of short-term, low-dose tricyclic and tetracyclic antidepressant treatment on satiation, postnutrient load gastrointestinal symptoms and gastric emptying: a double-blind, randomized, placebo-controlled trial

Antidepressants are commonly prescribed for patients with functional dyspepsia. However, the effect of tricyclic antidepressants on satiation and gastric emptying remains unclear, and there are no data for tetracyclic compounds. To compare the effects of nortriptyline (maximum dose: 50 mg daily) and mirtazapine (30 mg daily) vs placebo on gastric emptying, gastric satiation and postprandial symptoms after a nutrient load in healthy volunteers. Randomized, double-blind, placebo-controlled study evaluated gastric function before and after 14 days of nortriptyline (n = 13), mirtazapine (n = 13), or placebo (n = 14) in healthy volunteers. Validated methods were used to study gastric emptying ((13)C-octanoate) and satiation postnutrient drink test. The three arms were comparable with regard to age, gender, body mass index and hospital anxiety/depression scale. There were no statistically significant effects of mirtazapine or nortriptyline on gastric emptying compared to placebo (P = 0.34). Maximum tolerated volume was similar on drug and placebo (P = 0.56). Aggregate symptom score 30 min postmaximum tolerated volume after nutrient drink challenge on placebo was 132 (+/-21), vs 165 (+/-21) on mirtazapine, and 126 (+/-21) on nortriptyline 50 mg respectively (P = 0.28). Tricyclic and tetracyclic antidepressant agents do not appear to have significant effects on gastric motor or satiation postnutrient challenge in healthy individuals at the doses tested.

Antidepressants for neuropathic pain

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 3, 2005 of The Cochrane Library. For many years antidepressant drugs have been used to manage neuropathic pain, and are often the first choice treatment. It is not clear, however, which antidepressant is more effective, what role the newer antidepressants can play in treating neuropathic pain, and what adverse effects are experienced by patients.

OBJECTIVES

To determine the analgesic effectiveness and safety of antidepressant drugs in neuropathic pain.

SEARCH STRATEGY

Randomised controlled trials (RCTs) of antidepressants in neuropathic pain were identified in MEDLINE (1966 to Oct 2005); EMBASE (1980 to Oct 2005); the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, Issue 3, 2005; and the Cochrane Pain, Palliative and Supportive Care Trials Register (May 2002). Additional reports were identified from the reference list of the retrieved papers, and by contacting investigators.

SELECTION CRITERIA

RCTs reporting the analgesic effects of antidepressant drugs in adult patients, with subjective assessment of pain of neuropathic origin. Studies that included patients with chronic headache and migraine were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors agreed the included studies, extracted data, and assessed methodological quality independently. Sixty one trials of 20 antidepressants were considered eligible (3293 participants) for inclusion. Relative Risk (RR) and Number-Needed-to-Treat (NNTs) were calculated from dichotomous data for effectiveness and adverse effects. This update includes 11 additional studies (778 participants).

MAIN RESULTS

Sixty one RCTs were included in total. Tricyclic antidepressants (TCAs) are effective and have an NNT of 3.6 (95% CI 3 to 4.5) RR 2.1 (95% CI 1.8 to 2.5) for the achievement of at least moderate pain relief. There is limited evidence for the effectiveness of the newer SSRIs but no studies of SNRIs were found. Venlafaxine (three studies) has an NNT of 3.1 (95% CI 2.2 to 5.1) RR 2.2 (95% CI 1.5 to 3.1). There were insufficient data to assess effectiveness for other antidepressants such as St Johns Wort and L-tryptophan. For diabetic neuropathy the NNT for effectiveness was 1.3 (95% CI 1.2 to 1.5) RR 12.4 (95% CI 5.2 to 29.2) (five studies); for postherpetic neuralgia 2.7 (95% CI 2 to 4.1), RR 2.2 (95% CI 1.6 to 3.1) (four studies). There was evidence that TCAs are not effective in HIV-related neuropathies. The number needed to harm (NNH) for major adverse effects defined as an event leading to withdrawal from a study was 28 (95% CI 17.6 to 68.9) for amitriptyline and 16.2 (95% CI 8 to 436) for venlafaxine. The NNH for minor adverse effects was 6 (95% CI 4.2 to 10.7) for amitriptyline and 9.6 (95% CI 3.5 to 13) for venlafaxine.

AUTHORS' CONCLUSIONS

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.

Burning Mouth Syndrome: Will Better Understanding Yield Better Management?

"Burning mouth syndrome" (BMS) refers to a chronic orofacial pain disorder usually unaccompanied by mucosal lesions or other clinical signs of organic disease. BMS is typically characterized by a continuous, spontaneous, and often intense burning sensation as if the mouth or tongue were scalded or on fire. Burning mouth syndrome is a relatively common condition. The estimated prevalence of BMS reported in recent studies ranges between 0.7 and 4.6% of the general population. About 1.3 million American adults, mostly women in the postmenopausal period, are afflicted with BMS. The etiology of this disorder is poorly understood even though new evidence for a possible neuropathic pathogenesis of idiopathic BMS is emerging. Burning mouth syndrome may present as an idiopathic condition (primary BMS type) distinct from the symptom of oral burning that can potentially arise from various local or systemic abnormalities (secondary BMS type), including nutritional deficiencies, hormonal changes associated with menopause, local oral infections, denture-related lesions, xerostomia, hypersensitivity reactions, medications, and systemic diseases including diabetes mellitus. In more than a third of patients, multiple, concurrent causes of BMS may be identified. It is important to note that the diagnosis of BMS should be established only after all other possible causes have been ruled out. Professional delay in diagnosing, referring, and appropriately managing of BMS patients occurs frequently. Treatment should be tailored to each patient and it is recommended to practice the treatment in a multidisciplinary facility. This article discusses our current understanding of the etiology and pathogenesis of BMS. The authors have tried to emphasize new pharmacological approaches to manage this challenging disorder.

Medical management of cervical spondylosis

Medical management is often the initial management of cervical spondylitic syndromes, including radiculopathy, myelopathy, and neck pain. This includes pharmacological and rehabilitation treatment. Prospective studies comparing the efficacy of surgical versus medical management are lacking. The indications and efficacy of pharmacological and rehabilitative treatments are reviewed. The use of anti-inflammatory drugs, muscle relaxants, analgesics, antidepressants, anticonvulsants, steroids, facet joint ablation, and physical therapy are reviewed. A rationale for the medical management of acute neck pain, chronic neck pain, radiculopathy, and myelopathy is presented.

Sodium channel blockade may contribute to the analgesic efficacy of antidepressants

Sodium channel blockers such as lidocaine, lamotrigine, and carbamazepine can be effective in the treatment of neuropathic pain. Though not approved for neuropathic pain indications, tricyclic antidepressants are often considered first-line treatment for conditions such as post-herpetic neuralgia and diabetic neuropathy. Several tricyclic antidepressants have been shown to block peripheral nerve sodium channels, which may contribute to their antihyperalgesic efficacy. In this study, we compared the sodium channel-blocking potency of a number of antidepressants, including tricyclic antidepressants and selective serotonin reuptake inhibitors. All compounds tested inhibited Na(V)1.7 in a state- and use-dependent manner, with affinities for the inactivated state ranging from 0.24 micromol/L for amitriptyline to 11.6 micromol/L for zimelidine. The tricyclic antidepressants were more potent blockers of Na(V)1.7. Moreover, IC(50)s for block of the inactivated state for amitriptyline, nortriptyline, imipramine, desipramine, and maprotiline were in the range of therapeutic plasma concentrations for both the treatment of depression as well as neuropathic pain. By contrast, fluoxetine, paroxetine, mianserine, and zimelidine had IC(50)s for Na(V)1.7 outside their therapeutic concentration ranges and generally were not efficacious against post-herpetic neuralgia or diabetic neuropathy. These results suggest that block of peripheral nerve sodium channels may contribute to the antihyperalgesic efficacy of certain antidepressants.

PERSPECTIVE

Tricyclic antidepressants are often considered first-line treatment for neuropathic pain. Some tricyclic antidepressants block sodium channels, which may contribute to their antihyperalgesic efficacy. In the current study, we compared the potency of peripheral sodium channel blockade for several tricyclic antidepressants and selective serotonin reuptake inhibitors with their therapeutic efficacy.

Duloxetine for patients with diabetic peripheral neuropathic pain: a 6-month open-label safety study

OBJECTIVE

Duloxetine is a relatively balanced and potent reuptake inhibitor of both serotonin and norepinephrine. Because these neurotransmitters play a role in pain inhibition, duloxetine was considered a possible treatment for diabetic peripheral neuropathic pain (DPNP). This study assessed the 6-month safety and tolerability of duloxetine in patients with DPNP; evaluation of efficacy was a secondary objective.

DESIGN

In this 28-week, open-label study, in the clinical setting, 449 patients with DPNP were randomized (3:1) to receive duloxetine 60 mg twice daily (BID) (N = 334) or duloxetine 120 mg once daily (QD) (N = 115). Comprehensive safety evaluations including laboratory analyses and electrocardiograms were performed for all patients. Efficacy measures included the Brief Pain Inventory (BPI) and Clinical Global Impression of Severity (CGI-S) scales.

RESULTS

Protocol completion rates were 63.8% and 62.6% for the 60 mg BID and 120 mg QD groups, respectively (P = 0.823). Discontinuations were primarily due to adverse events, 20.1% for 60 mg BID and 27.0% for 120 mg QD (P = 0.149). Heart rate increased slightly in both treatment groups (P </= 0.02 in both groups). Systolic blood pressure was unaffected, while diastolic blood pressure decreased slightly in the 120 mg QD group (P = 0.04). Sustained elevation in blood pressure was reported for 18 (5.5%) patients in the 60 mg BID group and six (5.4%) in the 120 mg QD group. Duloxetine treatment was not associated with significant QTc prolongation. There was significant improvement at endpoint on all subscales of the BPI and CGI-S (P < 0.001 in both groups).

CONCLUSIONS

In this study, duloxetine 60 mg BID and 120 mg QD were safely administered and well tolerated in patients with DPNP for up to 28 weeks. There were few differences in safety or tolerability between the two dosages. At both doses, duloxetine provided clinically significant pain relief.

Pain and psychiatry: a critical analysis and pharmacological review

Pain is one of the most difficult medical problems to diagnose and treat and can be a common symptom of several psychiatric disorders. Pain-related issues are heterogeneous and often underestimated or misinterpreted, with the result that psychiatric interventions, which might have been beneficial from the outset, are often delayed or requested only as a last measure. Several problems arise from the definition, classification and assessment of pain, when documented according to the different scales which are commonly used, since these attempt to cover a multitude of analytical requirements, without really succeeding. An area of constant debate regards the connection between pain and various psychiatric disorders, and the difficulty in the classification of pain disorders within the currently existing framework. The pharmacological treatment of pain is complex and implies a variety of different compounds, from opioids to psychotropic medications like antidepressants and anticonvulsivants.

This paper explores the mutual and reciprocal influence between pain and psychiatric disorders reviewing the latest developments in the definition, assessment and treatment of pain, with special emphasis on the impact of pain on psychiatric disorders (and vice versa), and on the use of psychotropic drugs in the treatment of pain syndromes.

Sensory neuropathic cough: a common and treatable cause of chronic cough

OBJECTIVE

To describe our experience with chronic sensory neuropathic cough and its response to amitriptyline in a first group of patients.

STUDY DESIGN AND SETTING

A prospective cohort of patients is described in detail. Each was referred to an academic laryngological practice after extensive prior negative workup for cough and failure to respond to various treatments. Each of these patients was treated with amitriptyline and asked to report the effect on the cough at fixed intervals by means of telephone interviews.

RESULTS

A first cohort of 12 consecutive patients with a chronic, nonproductive cough that lasted between 2 months and 20 years, with no (formerly) discernible cause is described. Purely clinical criteria of inclusion and exclusion are proposed. All patients had at least 40% reduction of self-reported symptoms, with most describing between 75% to 100% short-term relief.

CONCLUSION

Sensory neuropathic cough can be diagnosed clinically in patients with chronic idiopathic cough. A trial of amitriptyline 10 mg or of other anti-neuralgia type medications may be helpful. Longer term and controlled trials are warranted to validate this entity and prove efficacy of neurologic medication in chronic sensory neuropathic cough.

EBM RATING

C-4.

Sleep quality and the role of sleep medications for veterans with chronic pain

OBJECTIVE

The purpose of this study was to investigate the nature of sleep problems in veterans presenting to a pain clinic, factors that predict likelihood of being prescribed a sleep medication, types of medications prescribed, and the relationships between sleep medication use and sleep quality, pain, and depression.

DESIGN/SETTING/PATIENTS

Participants were 201 consecutive patients referred to a Veterans Affairs outpatient pain clinic. They were administered the Pittsburgh Sleep Quality Index, Multidimensional Pain Inventory, and Beck Depression Inventory at intake and 2-month follow-up. Sleep and opioid medication prescriptions were also monitored.

RESULTS

Pain severity did not predict global sleep quality; global sleep quality was not predictive of pain severity. Greater depression predicted both more severe pain and more sleep impairment. Having previously been prescribed such medications was the only significant predictor of being prescribed a sleep medication at the time of the 2-month assessment. For the 45% of participants on sleep medications, these medications were not associated with any significant change in pain factors or depression. However, sleep medication use was associated with worse global sleep quality, sleep duration, and sleep efficiency. Opioid prescription was not a significant predictor of sleep factors, pain-related variables, or depression symptoms.

DISCUSSION

Results suggest depression may contribute more significantly to sleep problems than pain-related variables in this population. The data suggest the need for controlled, prospective studies of sleep medication to further investigate the impact of sleep medications on sleep components in patients with chronic pain.

Cardiac syndrome X in women: the role of oestrogen deficiency

Cardiac syndrome X (CSX), defined as typical exertional chest pain, a positive response to stress testing, and normal coronary arteriograms, encompasses different pathogenic subgroups. Both cardiac and non-cardiac mechanisms have been suggested to play a pathogenic role, and it has been shown that the syndrome is associated with myocardial ischaemia in at least a proportion of patients. Radionuclide myocardial perfusion defects, coronary sinus oxygen saturation abnormalities and pH changes, myocardial lactate production and stress-induced alterations of cardiac high energy phosphate have been reported in CSX patients, suggesting an ischaemic origin for their symptoms. Microvascular abnormalities often caused by endothelial dysfunction appear to be responsible for myocardial ischaemia in these patients. CSX is more prevalent in women than in men, and the majority of women with CSX are peri- or post-menopausal. Thus oestrogen deficiency has been suggested to have a pathogenic role in CSX. Additional factors such as abnormal pain perception may also contribute to the genesis of chest pain in patients with angina and normal coronary angiograms. The management of this syndrome is difficult because of the heterogeneity of pathogenic mechanisms and uncertainties as to its origin. This article discusses the problem of CSX in women, the potential pathogenic role of oestrogen deficiency, and practical clinical management.

The effect of mirtazapine in patients with chronic pain and concomitant depression

OBJECTIVE

To evaluate the safety, tolerability and efficacy of mirtazapine in patients with the primary diagnosis of chronic pain and concomitant depression in an open post-marketing surveillance study.

RESEARCH DESIGN AND METHODS

594 patients with a primary diagnosis of at least one chronic pain syndrome (minimum duration of 3 months) and the diagnosis of concomitant depression, appropriately made by a neurologist or psychiatrist, were recruited at psychiatric and/or neurological outpatient facilities throughout Germany. The primary efficacy parameter was pain at baseline and endpoint using a patient self-assessment scale. Secondary analyses were performed at baseline, week 1 (day 7 +/- 2), week 4 (day 28 +/- 4) and at endpoint (day 42 +/- 4 or early termination) and included safety and tolerability assessments. Investigators rated the severity of different potential co-morbidities (including depression) with a four-step rating scale (not present, mild, moderate, severe).

RESULTS

594 patients were enrolled and treated with mirtazapine (mean daily dose of 34.5 +/- 10.4 mg at study endpoint). A statistically significant (p < 0.0001; one sample sign test) reduction of pain from baseline to endpoint was found for the overall population. The percentage of patients free of pain or with only moderate pain increased significantly, irrespective of patients' age or pain syndromes. Furthermore, we found a substantial improvement from baseline to endpoint regarding co-morbidities such as sleep disturbance, irritability and exhaustion. The number of adverse events was low (<7%; n = 37), with fatigue (n = 13) and weight gain (n = 11) occurring most frequently. No previously-unknown side effects occurred. One hundred and six patients (18%) discontinued mirtazapine during the study. The main reason was lack of efficacy (6%, n = 33), which may be a reflection of sub-optimal response to the anti-depressant or analgesic effect of the drug, but no appropriate rating scale was used to clarify this question. Only a small number of patients stopped the drug due to adverse events (3%; n = 15). At study endpoint, the majority of physicians and patients rated the overall efficacy and tolerability of mirtazapine as good or very good. Most patients (80%) continued the therapy after 6 weeks.

CONCLUSIONS

Despite the limitations of an open observational study, our findings suggest that mirtazapine is a safe and well-tolerated drug for use in daily clinical practice. It still remains unclear whether the reduction of pain, the enhancement of the depressed mood or the combination of both effects led to these results. Nevertheless, our data point to a potential beneficial effect of mirtazapine in the treatment of patients with pain and concomitant depression. However, more systematic research, including placebo-controlled studies, and further empirical testing are necessary.

Antidepressants for neuropathic pain

BACKGROUND

For many years antidepressant drugs have been used to manage neuropathic pain, and are often the first choice treatment. It is not clear, however, which antidepressant is more effective, what role the newer antidepressants can play in treating neuropathic pain, and what adverse effects are experienced by patients.

OBJECTIVES

To determine the analgesic effectiveness and safety of antidepressant drugs in neuropathic pain. Migraine and headache studies were not considered.

SEARCH STRATEGY

Randomised trials of antidepressants in neuropathic pain were identified in MEDLINE (1966 to Dec 2003); EMBASE (1980 to Dec 2003); the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2004, Issue 1; and the Cochrane Pain, Palliative and Supportive Care Trials Register (May 2002). Additional reports were identified from the reference list of the retrieved papers, and by contacting investigators.

SELECTION CRITERIA

Randomised trials reporting the analgesic effects of antidepressant drugs in adult patients, with subjective assessment of pain of neuropathic origin. Studies that included patients with chronic headache and migraine were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers agreed the included studies, extracted data, and assessed methodological quality independently. Fifty trials of 19 antidepressants were considered eligible (2515 patients) for inclusion. Relative Risk (RR) estimates and Number-Needed-to-Treat (NNTs) were calculated from dichotomous data for effectiveness and adverse effects.

MAIN RESULTS

Tricyclic antidepressants (TCAs) are effective treatments for the treatment of neuropathic pain. Amitriptyline has an NNT of 2 (95%CI 1.7 to 2.5) RR 4.1(95%CI 2.9-5.9) for the achievement of at least moderate pain relief. There is limited evidence for the effectiveness of the newer selective serotonin reuptake inhibitor antidepressant drugs (SSRIs). There were insufficient data for an assessment of evidence of effectiveness for other antidepressants such as St Johns Wort, venlafaxine and L-tryptophan. For diabetic neuropathy the NNT for effectiveness was 1.3 (95%CI 1.2 to 1.5) RR 12.4(95%CI 5.2-29.2) (five studies); for postherpetic neuralgia 2.2 (95%CI 1.7 to 3.1), RR 4.8(95%CI 2.5-9.5)(three studies). There was evidence that TCAs are not effective in HIV-related neuropathies. The number needed to harm(NNH) for major adverse effects defined as an event leading to withdrawal from a study was 16 (95%CI: 10-45). The NNH for minor adverse effects was 4.6 (95%CI 3.3-6.7)

AUTHORS' CONCLUSIONS

Antidepressants are effective for a variety of neuropathic pains. The best evidence available is for amitriptyline. There are only limited data for the effectiveness of SSRIs. It is not possible to identify the most effective antidepressant until more studies of SSRIs are conducted.

HS014, a selective melanocortin-4 (MC4) receptor antagonist, modulates the behavioral effects of morphine in mice

RATIONALE

Melanocortin and opioid systems regulate feeding as well as other behaviors; however, the relationship between the two systems is not yet defined. Since agonist-induced stimulation of melanocortin receptors blocks the behavioral effects of mu opioid receptor agonists, and melanocortin-4 (MC4) receptors and mu opioid receptors share a similar anatomical distribution in the central nervous system, MC4 receptor blockade may increase opioid responsiveness.

OBJECTIVES

The goal of this study was to test the hypothesis that blockade of MC4 receptors increases the behavioral effects of morphine.

METHODS

The effects of HS014 (0.0032, 0.032, and 1 nmol, i.c.v.), a selective MC4 antagonist, on morphine-induced (3.2, 10, and 32 mg/kg, i.p.) locomotor activity (measured in the open field for 15 min) and antinociception (measured in the hot plate at 55 degrees C) were assessed in C57Bl/6 mice. In addition, the effects of morphine were evaluated in A(y) mice, a genetic model for MC4 receptor blockade.

RESULTS

The dose-effect curve of morphine for locomotor activity was shifted downwards in C57Bl/6 mice pretreated with HS014 and in A(y) mice. The dose-effect curve of morphine for antinociception was shifted two- and threefold to the left in C57Bl/6 mice pretreated with HS014 and in A(y) mice, respectively.

CONCLUSIONS

These results indicate that blockade of MC4 receptors increases the antinociceptive effects of morphine without changing the potency of morphine for locomotor activity, suggesting that MC4 receptor antagonists may be candidate drugs that can be clinically used for the treatment of pain.

Guidelines for the use of antidepressants in painful rheumatic conditions

OBJECTIVES

Antidepressants are widely used to treat painful chronic rheumatic conditions but, contrary to neuropathic conditions, little is known about their true analgesic properties and value in these situations. Our group, which focuses on pain in rheumatology, aimed to develop recommendations for the use of antidepressants in rheumatology, based on evidence-based review of published data and expert opinion.

METHOD

We identified relevant drugs and conditions and searched Medline, Embase and Pascal (1966-2003) for relevant publications in a number of European languages. We scored each study for quality, and used an expert consensus approach to formulate recommendations.

RESULTS

We identified 77 studies and 12 meta-analyses and literature review on the use of antidepressant to treat painful rheumatological conditions. Forty-nine of these clinical studies were considered valid and were used to develop the recommendations. When evidence was lacking we based recommendations on our clinical experience.

CONCLUSIONS

These recommendations for the treatment of painful rheumatological conditions with antidepressants were developed using evidence-based and expert consensus approaches and are the first of their kind in this field. Our review of the literature highlights the need for further, well-designed clinical studies of the use of antidepressants to treat painful rheumatological conditions.

Clinical response to tricyclic antidepressants in functional bowel disorders is not related to dosage

BACKGROUND

As shown in the per protocol analysis of a recent randomized, controlled trial, when tolerated, Desipramine (DES) is effective over placebo (PLA) in treating moderate-to-severe functional bowel disorders (FBD). Clinical experience suggests that the benefit from tricyclic antidepressants (TCA) in FBD can be achieved at doses lower than those used to treat major depression. Within psychiatry, when using higher dosage of TCAs, plasma levels can be used to adjust daily dosage to optimize a treatment response. However, in FBD, it is not known whether plasma levels at the lower dosage are similarly related to a clinical response.

AIM

To determine in treating FBD, whether DES blood levels or dose taken can predict a clinical response.

METHODS

As part of a study of 12 wk of antidepressant and psychological treatment in 431 patients with FBD at UNC and U of Toronto, we studied those participants who completed treatment (per protocol analysis) taking DES (N = 97, dose 50-150 mg/day) or pill placebo (PLA) (N = 55 1-3 pills/day). The primary outcome measure was defined as a composite score (Satisfaction with Treatment, McGill Pain Questionnaire, Global Well-being, and IBS-QOL). The composite score was correlated with: (i) DES plasma levels at week 6, and (ii) number of pills taken over the duration of the 12-wk treatment period. In addition, we also compared DES dose with DES plasma levels.

RESULTS

There was a modest correlation between mean DES dose at weeks 5 and 6 and DES blood level at week 6 (R = 0.2 p < 0.07). However, there were no significant correlations between the composite score either with DES dose or with DES blood levels.

CONCLUSIONS

Detectable blood levels of DES are associated with a clinical response in FBD. However, with dosages up to 150 mg, there is no relationship between total dose or plasma level and the clinical response.

Duloxetine: A Dual Serotonin-Norepinephrine Reuptake Inhibitor for Treatment of Major Depressive Disorder

The burden of mental illness has been underestimated worldwide. Depression was the fourth leading cause of disease burden in the world in 1990 and is projected to be the second leading cause of disability by 2020. It is a leading cause of morbidity and mortality in the United States, costing billions of dollars annually in direct and indirect medical costs and losses in productivity. Patients with major depressive disorder (MDD) may experience both psychological and medical complaints, including somatic sensations or pain. Some antidepressants have been shown to treat chronic pain syndromes, but despite the variety of antidepressants available in the United States, only 65-70% of patients respond to initial antidepressant treatment. Treatments are limited by delayed onset of antidepressant effects, side effects, partial response, and treatment resistance. Duloxetine, approved by the U.S. Food and Drug Administration for the treatment of MDD, is a reuptake inhibitor at serotonergic and noradrenergic neurons and appears to have low affinity for other neurotransmitter systems. In clinical trials, duloxetine was effective for the treatment of MDD and was well tolerated. Further study is needed to compare its efficacy with that of other antidepressants, to clarify effects on somatic symptoms, and to assess potential adverse cardiovascular and sexual side effects. Duloxetine is also approved for the management of diabetic peripheral neuropathic pain and is under investigation for the treatment of stress urinary incontinence in women.

Adverse reactions related to drugs for headache treatment: clinical impact

OBJECTIVE

To assess the clinical impact of adverse reactions related to drugs for primary headache treatment.

METHODS

We examined the adverse reactions to 360 medications prescribed by the specialists of the Headache Centre of the University of Modena and Reggio Emilia to 256 consecutive outpatients (214 female, 42 male; mean age: 38.88 +/- 14.06 years; range 10-72 years). Adverse reactions were reported by patients during scheduled follow-up visits, classified by specialists and reassessed by a clinical pharmacologist.

RESULTS

Adverse reactions with a causal relationship classified as definite/probable/possible were 202 (56%): 62% (80/129) were due to acute treatments and 53% (122/231) to prophylactic treatments (chi2 test, P = 0.115 ns). More than 90% of the adverse reactions were of limited intensity [mild (58%) or moderate (36%)]. Only 5% were severe, and two reactions (1%) were serious. The most affected apparatus was the nervous system (41%). Of these adverse reactions, 43% caused the discontinuance of the treatment, especially of prophylaxis (54%). Patients evaluated 70% of the medications as effective, but, at the same time, they considered most of the adverse reactions (69%) unacceptable.

CONCLUSION

Adverse reactions related to headache medications have a strong impact on patients' management, even if their real intensity and severity are usually very limited. Drugs for headache treatment are still far from being ideal drugs. To prevent the discontinuance of effective medications, the physician, prior to prescribing, should assess, together with the patient, the acceptability of the more common adverse drug reactions.

Cardiac syndrome X. Diagnosis, pathogenesis and management

Patients with cardiac syndrome X (typical chest pain and normal coronary arteriograms) represent a heterogeneous syndrome, which encompasses different pathogenic mechanisms. Although symptoms in most patients with cardiac syndrome X are non-cardiac, a sizable proportion of them have angina pectoris due to transient myocardial ischemia. Thus radionuclide myocardial perfusion defects, coronary sinus oxygen saturation abnormalities and pH changes, myocardial lactate production and stress-induced alterations of cardiac high energy phosphate suggest an ischemic origin of symptoms in at least a proportion of patients with cardiac syndrome X. Microvascular abnormalities, caused by endothelial dysfunction, appear to be responsible for myocardial ischemia in patients with cardiac syndrome X. Endothelial dysfunction is likely to be multifactorial in these patients and it is conceivable that risk factors such as hypertension, hypercholesterolemia, diabetes mellitus and smoking can contribute to its development. Most patients with cardiac syndrome X are postmenopausal women and estrogen deficiency has been therefore proposed as a pathogenic factor in female patients. Additional factors such as abnormal pain perception may contribute to the pathogenesis of chest pain in patients with angina pectoris and normal coronary angiograms. Although prognosis is good regarding survival, patients with cardiac syndrome X have an impaired quality of life. Management of this syndrome represents a major challenge to the treating physician. Understanding the mechanism underlying the condition is of vital importance for patient management. Thus diagnostic tests should aim at identifying the cause of the symptoms in the individual patient, i.e. myocardial ischemia, increased pain perception, abnormalities of adrenergic tone, non-cardiac mechanisms, etc. Moreover, it is important to bear in mind that treatment of cardiac syndrome X should be mainly directed towards improving quality of life, as prognosis is usually good in these patients. Conventional antianginal agents such nitrates, calcium channel antagonists, beta-adrenoceptor antagonists and nicorandil are effective particularly in patients in whom chest pain and ECG changes are clearly suggestive of myocardial ischemia and in those with objective documentation of ischemia. Angiotensin-converting enzyme inhibitors have been shown to be useful in syndrome X patients with increased adrenergic tone, borderline systemic hypertension, and those with documented endothelial dysfunction. Analgesic interventions of different sorts have been proposed based on the hypothesis that somatic and visceral perception of pain is altered in cardiac syndrome X patients. Pharmacological agents such as imipramine and aminophylline, and neural electrical stimulation techniques have been assessed in recent years with encouraging results. Psychological treatment, particularly cognitive therapy, appears to be useful in defined patient subsets. Relaxation techniques such as transcendental meditation have been successfully used in small studies and shown to improve not only chest pain but also exercise-induced ST segment changes. Reports indicate that these techniques improve quality of life.