Clinical experience with dual action antidepressants in different chronic pain syndromes

Management of Fibromyalgia: An Update

Fibromyalgia, a chronic pain condition marked by abnormal pain processing, impacts a significant part of the population, leading to reduced quality of life and function. Hallmark symptoms include widespread persistent pain, sleep disturbances, fatigue, cognitive dysfunction, and mood changes. Through this updated review, we aim to contribute to the evolving understanding and management of fibromyalgia, offering insights into the diverse tools available to improve the lives of those affected by this challenging condition. Management begins with educating patients to ultimately relieve them of unnecessary testing and provide reassurance. Treatment emphasizes a comprehensive approach, combining nonpharmacological interventions such as aforementioned education, exercise, and psychotherapy, alongside pharmacologic management-namely duloxetine, milnacipran, pregabalin, and amitriptyline-which have consistent benefits for a range of symptoms across the spectrum of fibromyalgia. Notably, drugs like nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are generally not recommended due to limited efficacy and associated risks. Lastly, a variety of other medications have shown promise, including NMDA-receptor antagonists, naltrexone, and cannabinoids; however, they should be used with caution due to a small amount of evidence and potential for adverse effects.

Tapentadol: A Review of Experimental Pharmacology Studies, Clinical Trials, and Recent Findings

Tapentadol is an analgesic compound that acts centrally to attenuate pain. Previous studies have shown that tapentadol has dual mechanisms of action as a mu-opioid receptor agonist and noradrenaline re-uptake inhibition. Therefore, tapentadol provides a great advantage over classic opioids in pain management from nociceptive to neuropathic. Cumulative evidence from in vitro data suggests that tapentadol effect of norepinephrine re-uptake could be a new target that overcomes other classic opioids in chronic neuropathic pain. Compared to tramadol and other opioids, tapentadol is associated with fewer adverse effects than tramadol. Tapentadol is a new alternative to treat acute, chronic, and neuropathic pain. Thus, this review article was focused on understanding the studies that led to the development of tapentadol as a novel analgesic drug and its advantages over conventional opioids. Thus, tapentadol is a good alternative with fewer adverse effects and is available for human use.

The epidemiology of antidepressant use in South Korea: Does short-term antidepressant use affect the relapse and recurrence of depressive episodes?

Background

The duration of antidepressant use affects the treatment of depression. Using the National Health Insurance database, which covers almost the entire national population, we verified the factors associated with the inadequate short-term use of initially prescribed antidepressants and their effects on the relapse and recurrence of depressive episodes.

Methods

There were 752,190 patients included who had been newly prescribed antidepressants in 2012 with the diagnosis of depressive disorder. They were followed-up until December 31, 2015. They were classified as short-term and long-term antidepressant users depending on whether they used a specific initial antidepressant for at least four weeks. Sociodemographic, clinical, and medical utilization factors affecting the duration of antidepressant use were investigated. We also identified whether the duration of antidepressant use affected the risk of relapse and recurrence, which was defined by the restarting of antidepressants.

Results

Initial antidepressants were taken for less than 28 days by 458,057 (60.84%) patients. Tricyclic antidepressants were used as the initial antidepressant more frequently than selective serotonin reuptake inhibitors (64.5% versus 19.3%). The type of initial antidepressant, polypharmacy, psychiatric and medical comorbidities, type of insurance coverage, and type of medical institution visited were associated with short-term use. Short-term use marginally increased the risk of relapse and recurrence of depressive episodes (Hazard ratio: 1.06, 95% confidence intervals 1.048–1.075).

Conclusions

Short-term antidepressant use is widespread in Korea, and assessment in various aspects are necessary to set proper treatment plans.

Comparative Effect of Collaborative Care, Pain Medication, and Duloxetine in the Treatment of Major Depressive Disorder and Comorbid (Sub)Chronic Pain: Results of an Exploratory Randomized, Placebo-Controlled, Multicenter Trial (CC:PAINDIP)

OBJECTIVE

Evidence exists for the efficacy of collaborative care (CC) for major depressive disorder (MDD), for the efficacy of the consequent use of pain medication against pain, and for the efficacy of duloxetine against both MDD and neuropathic pain. Their relative effectiveness in comorbid MDD and pain has never been established so far. This study explores the effectiveness of CC with pain medication and duloxetine, and CC with pain medication and placebo, compared with duloxetine alone, on depressive and pain symptoms. This study was prematurely terminated because of massive reorganizations and reimbursement changes in mental health care in the Netherlands during the study period and is therefore of exploratory nature.

METHODS

Three-armed, randomized, multicenter, placebo-controlled trial at three specialized mental health outpatient clinics with patients who screened positive for MDD. Interventions lasted 12 weeks. Pain medication was administered according to an algorithm that avoids opiate prescription as much as possible, where paracetamol, COX inhibitors, and pregabalin are offered as steps before opiates are considered. Patients who did not show up for three or more sessions were registered as non-compliant. Explorative, intention-to-treat and per protocol, multilevel regression analyses were performed. The trial is listed in the trial registration (http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1089; NTR number: NTR1089).

RESULTS

Sixty patients completed the study. Patients in all treatment groups reported significantly less depressive and pain symptoms after 12 weeks. CC with placebo condition showed the fastest decrease in depressive symptoms compared with the duloxetine alone group (b = -0.78; p = 0.01). Non-compliant patients (n = 31) did not improve over the 12-week period, in contrast to compliant patients (n = 29). Pain outcomes did not differ between the three groups.

CONCLUSION

In MDD and pain, patient's compliance and placebo effects are more important in attaining effect than choice of one of the treatments. Active pain management with COX inhibitors and pregabalin as alternatives to tramadol or other opiates might provide an attractive alternative to the current WHO pain ladder as it avoids opiate prescription as much as possible. The generalizability is limited due to the small sample size. Larger studies are needed.

Medication pain management in the elderly: unique and underutilized analgesic treatment options

BACKGROUND

By 2030, the US population of adults aged ≥65 years will increase by >80%, and these adults will account for nearly 20% of the US population. In this population, the decline of multiple physiologic processes and diseases collectively influence treatment options. Physiologic changes, drug-drug interactions resulting from polypharmacy, and drug-disease interactions combine to make elderly patients more sensitive to the adverse events (AEs) associated with medications, all of which must be considered in drug selection.

OBJECTIVE

This article focuses on select underutilized medication options for analgesia that may provide significant advantages in the elderly population above and beyond commonly prescribed conventional choices.

METHODS

We performed a complete review of the literature using the search terms pain management, elderly, opioids, NSAIDs, topical NSAIDs, levorphanol, buprenorphine transdermal, and tapentadol. Databases searched included PubMed, Google Scholar, Ovid, and Athens. Package inserts were utilized for approval dates, indications, and formulations available. We looked at reviews of agents to identify important studies for consideration that searches may have missed. Pharmacology and pharmacokinetic data were taken from randomized trials focusing in this area. Pivotal Phase III trials were utilized for discussion of clinical trial experience and to summarize efficacy and AEs. For purposes of validity, only peer-reviewed literature was included.

RESULTS

There were limited data that specifically outlined analgesic drug selection and highlighted safer alternatives for the elderly patient based on polypharmacy risks, end-organ deterioration, and/or drug choices that presented less risk. We focused on unique opioid alternatives: levorphanol, which offers several therapeutic advantages similar to methadone but without the pharmacokinetic and drug-interaction pitfalls associated with methadone; tapentadol, associated with significantly less gastrointestinal distress and constipation; and transdermal buprenorphine, an agonist/antagonist with less risk for the toxicities associated with conventional opioids and with compliance benefits. Topical NSAIDs are discussed as a viable therapeutic option. Specific attention to a more desirable tolerability profile, including avoidance of drug interactions, end-organ dysfunction, and gastrointestinal bleed with topical NSAID agents versus their oral counterparts is discussed, including the ability to achieve superior tissue levels for appropriately selected inflammatory conditions.

CONCLUSION

It is incumbent that providers consider these options as part of an analgesic armamentarium in an effort to maximize therapeutic benefit and minimize risks in the increasing elderly patient population.

Effectiveness and cost-effectiveness of transmural collaborative care with consultation letter (TCCCL) and duloxetine for major depressive disorder (MDD) and (sub)chronic pain in collaboration with primary care: design of a randomized placebo-controlled multi-Centre trial: TCC:PAINDIP

BACKGROUND

The comorbidity of pain and depression is associated with high disease burden for patients in terms of disability, wellbeing, and use of medical care. Patients with major and minor depression often present themselves with pain to a general practitioner and recognition of depression in such cases is low, but evolving. Also, physical symptoms, including pain, in major depressive disorder, predict a poorer response to treatment. A multi-faceted, patient-tailored treatment programme, like collaborative care, is promising. However, treatment of chronic pain conditions in depressive patients has, so far, received limited attention in research. Cost effectiveness of an integrated approach of pain in depressed patients has not been studied.

METHODS/DESIGN

This study is a placebo controlled double blind, three armed randomized multi centre trial. Patients with (sub)chronic pain and a depressive disorder are randomized to either a) collaborative care with duloxetine, b) collaborative care with placebo or c) duloxetine alone. 189 completers are needed to attain sufficient power to show a clinically significant effect of 0.6 SD on the primary outcome measures (PHQ-9 score). Data on depression, anxiety, mental and physical health, medication adherence, medication tolerability, quality of life, patient-doctor relationship, coping, health resource use and productivity will be collected at baseline and after three, six, nine and twelve months.

DISCUSSION

This study enables us to show the value of a closely monitored integrated treatment model above usual pharmacological treatment. Furthermore, a comparison with a placebo arm enables us to evaluate effectiveness of duloxetine in this population in a real life setting. Also, this study will provide evidence-based treatments and tools for their implementation in practice. This will facilitate generalization and implementation of results of this study. Moreover, patients included in this study are screened for pain symptoms, differentiating between nociceptive and neuropathic pain. Therefore, pain relief can be thoroughly evaluated.

TRIAL REGISTRATION

NTR1089.

Sensory neuromodulators in functional nausea and vomiting: predictors of response

BACKGROUND

Tricyclic antidepressants (TCAs) are known to benefit subjects with functional nausea and vomiting (FNV), but it is not known if alternate neuromodulators are also beneficial. We retrospectively evaluated outcomes and clinical predictors of response in FNV subjects treated with any neuromodulator, including TCAs.

METHODS

We identified 94 subjects (43.8±1.4 year, 79 F) with FNV (Rome III criteria) over a 12 year period, treated with neuromodulators and followed up for 8.5±1.1 months. Clinical presentation, demographics and gastric emptying study (GES) findings (when available) were extracted. Likert scales determined symptom severity at baseline and symptom response or remission at follow-up. Outcomes and predictors of response were evaluated using univariate and multivariate analyses.

RESULTS

At least moderate symptom improvement was reported by 72.3%, and 22.3% had symptom remission. Proportions achieving moderate improvement and remission, and mean outcome Likert scores were similar regardless of neuromodulator agent used or GES status. On univariate and multivariate logistic regression analysis, baseline symptom severity affected symptom response, and pain negatively impacted symptom remission to treatment (p≤0.04 for each); GES status failed to predict treatment response or remission.

CONCLUSIONS

Symptom improvement with neuromodulators may be seen in over two-thirds of subjects with FNV regardless of the specific agent administered. Response may be suboptimal in pain predominant presentations.

Implications of pain in generalized anxiety disorder: efficacy of duloxetine

OBJECTIVE

To conduct a post hoc evaluation of the prevalence of clinically significant pain and the efficacy of duloxetine in patients with generalized anxiety disorder (GAD) and concurrent pain.

METHOD

Data from two 9- to 10-week double-blind, placebo-controlled, randomized clinical trials of duloxetine (60 to 120 mg) in DSM-IV-defined GAD were analyzed (study 1 was conducted from July 2004 to September 2005; study 2 was conducted from August 2004 to June 2005). Efficacy was assessed with the Hamilton Rating Scale for Anxiety (HAM-A), visual analog scales (VAS) for pain, the Hospital Anxiety Depression Scale (HADS), the Clinical Global Impressions-Improvement of Illness (CGI-I) scale, the Patient Global Impressions-Improvement (PGI-I) scale, and the Sheehan Disability Scale (SDS) global functional impairment scale.

RESULTS

Of 840 patients randomly assigned to treatment, 61.3% (302 duloxetine, 213 placebo) had VAS scores ≥ 30 mm on at least 1 of the pain scales, indicating clinically significant pain. Among those patients with concurrent pain at baseline, change from baseline to endpoint in the HAM-A total score (42.9% change in mean scores for duloxetine, 31.4% for placebo), HADS anxiety scale (40.3% vs. 22.8%), HADS depression scale (36.1% vs. 20.5%), HAM-A psychic factor (45.9% vs. 29.9%), and SDS global functional improvement score (45.5% vs. 22.1%) was significantly (all p's < .001) greater for duloxetine compared with placebo. Improvement on the CGI-I (p = .003) and PGI-I (p < .001) was also significantly greater for duloxetine. Response (HAM-A total score decrease ≥ 50%) (49% vs. 29%) and remission (HAM-A total score ≤ 7 at endpoint) (29% vs. 18%) rates were significantly greater for duloxetine compared with placebo (p < .001 and p = .041, respectively). Duloxetine demonstrated statistically significantly greater reduction in pain on all 6 VAS pain scales (all p's < .001 except headaches with p < .002) (for duloxetine, percent change in means from baseline to endpoint ranged from 40.1% to 45.2% across the 6 VAS scales; for placebo, 22.0% to 26.3%).

CONCLUSION

Duloxetine, relative to placebo, improves anxiety symptoms, pain, and functional impairment among patients with GAD with concurrent clinically significant pain.

TRIAL REGISTRATION

clinicaltrials.gov Identifiers: NCT00122824 (study 1) and NCT00475969 (study 2).

The effects of serotonin/norepinephrine reuptake inhibitors and serotonin receptor agonist on morphine analgesia and tolerance in rats

Several studies have demonstrated that serotonergic and noradrenergic systems have important roles in morphine analgesia and tolerance. However, the exact mechanism underlying the development of morphine tolerance is not fully understood. The aim of this study was to investigate the possible role of serotonin/norepinephrine reuptake inhibitors (amitriptyline, venlafaxine) and serotonin receptor (5-HT(1A) and 5-HT(1B/1D)) agonist (dihydroergotamine) in morphine analgesia and tolerance in rats. To constitute morphine tolerance, animals received morphine (50 mg/kg; s.c.) once daily for 3 days. After the last dose of morphine was injected on day 4, morphine tolerance was evaluated. The analgesic effects of amitriptyline (20 mg/kg; i.p.), venlafaxine (20 mg/kg; s.c.), dihydroergotamine (100 μg/kg; i.v.) and morphine (5 mg/kg) were considered at 15- to 30-min intervals (0, 15, 30, 60, 90, and 120 min) by tail-flick and hot-plate analgesia tests. In this study, the data obtained suggested that amitriptyline and venlafaxine significantly increased the analgesic effect of morphine and attenuated the expression of morphine tolerance. However, dihydroergotamine significantly increased the analgesic effect of morphine but did not reduce the expression of morphine tolerance. In conclusion, we determined that co-administration of morphine with amitriptyline and venlafaxine increased the analgesic effects of morphine and attenuated the morphine analgesic tolerance.

In vivo electrophysiological and neurochemical effects of the selective 5-HT1A receptor agonist, F13640, at pre- and postsynaptic 5-HT1A receptors in the rat

RATIONALE

F13640 (befiradol) is a novel 5-HT(1A) receptor agonist with exceptional selectivity vs. other receptors and binding sites. It shows analgesic activity in animal models and is currently developed for human use.

OBJECTIVES

Given the potential dual role of the serotonergic system in pain, through the modulation of ascending signals in spinal cord and their emotional processing by corticolimbic areas, we examined the in vivo activity of F13640 at somatodendritic autoreceptors and postsynaptic 5-HT(1A) heteroreceptors in medial prefrontal cortex (mPFC).

METHODS

In vivo single unit recordings and intracerebral microdialysis in the rat.

RESULTS

F13640 reduced the activity of dorsal raphe serotonergic neurons at 0.2-18.2 μg kg(-1), i.v. (cumulative doses; ED(50) = 0.69 μg kg(-1), i.v.) and increased the discharge rate of 80% of mPFC pyramidal neurons in the same dose range (ED(50) = 0.62 μg kg(-1), i.v.). Both effects were reversed by the subsequent administration of the 5-HT(1A) receptor antagonist (±)WAY100635. In microdialysis studies, F13640 (0.04-0.63 mg kg(-1), i.p.) dose-dependently decreased extracellular 5-HT in the hippocampus and mPFC. Likewise, F13640 (0.01-2.5 mg kg(-1), i.p.) dose-dependently increased extracellular DA in mPFC, an effect dependent on the activation of postsynaptic 5-HT(1A) receptors in mPFC. Local perfusion of F13640 in mPFC (1-1,000 μM) also increased extracellular DA in a concentration-dependent manner. Both the systemic and local effects of F13640 were prevented by prior (±)WAY100635 administration.

CONCLUSIONS

These results indicate that, upon systemic administration, F13640 activates both 5-HT(1A) autoreceptors and postsynaptic 5-HT(1A) receptors in prefrontal cortex with a similar potency. Both activities are likely involved in the analgesic properties of the compound.

First-in-class, dual-action, 3,5-disubstituted indole derivatives having human nitric oxide synthase (nNOS) and norepinephrine reuptake inhibitory (NERI) activity for the treatment of neuropathic pain

A family of different 3,5-disubstituted indole derivatives having 6-membered rings were designed, synthesized, and demonstrated inhibition of human nitric oxide synthase (NOS) with norepinephrine reuptake inhibitory activity (NERI). The structure-activity relationship (SAR) within the cyclohexane ring showed the cis-isomers to be more potent for neuronal NOS and selective over endothelial NOS compared to their trans-counterparts. Compounds, such as cis-(+)-37, exhibited dual nNOS and NET inhibition (IC(50) of 0.56 and 1.0 μM, respectively) and excellent selectivity (88-fold and 12-fold) over eNOS and iNOS, respectively. The lead compound (cis-(+)-37) showed lack of any direct vasoconstriction or inhibition of ACh-mediated vasorelaxation in isolated human coronary arteries. Additionally, cis-(+)-37 was effective at reversing both allodynia and thermal hyperalgesia in a standard Chung (spinal nerve ligation) rat neuropathic pain model. Overall, the data suggest that cis-(+)-37 is a promising dual action development candidate having therapeutic potential for the treatment of neuropathic pain.

Usefulness of milnacipran in treating phantom limb pain

BACKGROUND

Amputation of an extremity often results in the sensation of a "phantom limb" where the patient feels that the limb that has been amputated is still present. This is frequently accompanied by "phantom limb pain". We report here the use of milnacipran, a serotonin and norepinephrine reuptake inhibitor, to treat phantom limb pain after amputation of injured or diseased limbs in three patients.

METHODS AND RESULTS

The severity of phantom pain before and during treatment was quantified using a visual analog scale. In one case, phantom limb pain responded partially to treatment with high doses of paroxetine, and then replacement with milnacipran further improved the pain relief and long-term full pain relief was achieved. In the two other cases, milnacipran was used as first-line treatment and phantom limb pain responded rapidly.

CONCLUSION

These results suggest that milnacipran administration may be useful in phantom limb pain, possibly as a first-line treatment.

Milnacipran dose-effect study in patients with burning mouth syndrome

OBJECTIVE

The object of this study was to evaluate the dose-dependent efficacy and tolerability of milnacipran in patients with burning mouth syndrome (BMS) with inadequate response at low doses.

METHODS

A 12-week open-label dose-escalation study was conducted in 56 female patients (aged 20-83 years, with a mean age of 60.8 years). The initial dosage of milnacipran was 30 mg/d, and the dosage was raised up to 60 mg and 90 mg/d every 4 weeks until an improvement of at least 50% reduction of visual analog scale was achieved.

RESULTS

The mean ± SD effective daily dose of milnacipran was 63.9 ±16.7 mg. The cumulative improvement rate for the daily dose of 30 mg was 28.6%, and this rate rose (50.8%-67.9%) as the daily dose was increased (from 60 to 90 mg, respectively). The cumulative proportion of responders was significantly greater, with maximal daily doses of 60 and 90 mg, compared with that of 30 mg (P < 0.05, χ test). Most adverse events appeared at the low dose, and there was little evidence for dose-dependence of adverse effects. No serious safety issues were observed.

CONCLUSION

From the result of this study, dose escalation of milnacipran for patients with burning mouth syndrome with inadequate response at low doses may be helpful if the 30-mg daily dose has been tolerated well.

Clinically Relevant Outcomes Based on Analysis of Pooled Data from 2 Trials of Duloxetine in Patients with Knee Osteoarthritis

Objective.

To determine response with duloxetine versus placebo in patients with osteoarthritis (OA) of the knee using the Outcome Measures in Rheumatoid Arthritis Clinical Trials-Osteoarthritis Research Society International (OMERACT-OARSI) responder index and other clinically relevant outcomes including minimal clinically important improvement (MCII) and patient acceptable symptom state (PASS) for pain and function.

Methods.

Data were pooled from two 13-week, randomized, double-blind, placebo-controlled trials comparing duloxetine 60 to 120 mg/day with placebo in patients with symptomatic OA of the knee. Treatment response was determined according to the OMERACT-OARSI responder index, ≥ 30% pain reduction, ≥ 50% pain reduction, and MCII and PASS for pain and function. (ClinicalTrials.gov identifiers NCT00433290 and NCT00408421)

Results.

Duloxetine-treated patients were 33% more likely to experience an OMERACT-OARSI response than placebo-treated patients [p < 0.001, number needed to treat (NNT) = 6]. A significantly greater percentage of duloxetine-treated patients, compared with placebo-treated patients, reported ≥ 30% improvement in pain from baseline to endpoint (p < 0.001, NNT = 5) and ≥ 50% improvement in pain relative to baseline (p < 0.001, NNT = 7). The duloxetine-treated patients were also more likely to fulfill MCII criteria for pain (p < 0.001, NNT = 6) and function (p < 0.001, NNT = 7), and to achieve PASS for pain (p < 0.001, NNT = 6) and function (p = 0.009, NNT = 9). More duloxetine-treated patients compared with placebo-treated patients experienced ≥ 1 treatment-emergent adverse event (p = 0.003, number needed to harm = 8).

Conclusion.

Significantly more patients receiving duloxetine than placebo achieved an OMERACT-OARSI response, improvements in pain and function exceeding the level accepted as MCII, and reached PASS. Results support the clinical relevance of outcomes of prior duloxetine studies in symptomatic OA of the knee.

Tapentadol extended-release for treatment of chronic pain: a review

Tapentadol is a centrally acting analgesic with a dual mechanism of action of mu receptor agonism and norepinephrine reuptake inhibition. Tapentadol immediate-release is approved by the US Food and Drug Administration for the management of moderate-to-severe acute pain. It was developed to decrease the intolerability issue associated with opioids. Tapentadol extended-release has a 12-hour duration of effect, and has recently been evaluated for pain in patients with chronic osteoarthritis, low back pain, and pain associated with diabetic peripheral neuropathy. Tapentadol extended-release was found to provide safe and highly effective analgesia for the treatment of chronic pain conditions, including moderate-to-severe chronic osteoarthritis pain and low back pain. Initial trials demonstrating efficacy in neuropathic pain suggest that tapentadol has comparable analgesic effectiveness and better gastrointestinal tolerability than opioid comparators, and demonstrates effectiveness in settings of inflammatory, somatic, and neuropathic pain. Gastrointestinal intolerance and central nervous system effects were the major adverse events noted. Tapentadol will need to be rigorously tested in chronic neuropathic pain, cancer-related pain, and cancer-related neuropathic pain.

Tapentadol: A Novel, Centrally Acting Analgesic for Moderate-to-Severe Acute Pain

Objective:

To review the role of tapentadol in the treatment of moderate-to-severe acute pain.

Data Sources:

Primary literature was retrieved by searching MEDLINE (1950–August Week 3, 2010), EMBASE (1980–Week 34, 2010), International Pharmaceutical Abstracts (1970-August 2010), and Google Scholar, A bibliographic review of published articles was also performed. Search terms included tapentadol, Nucynta, and acute pain.

Study Selection and Data Extraction:

Randomized controlled trials available in the English language that evaluated the efficacy and/or safety of tapentadol were included in this review.

Data Synthesis:

Tapentadol is a centrally acting analgesic that simultaneously activates μ-opioid receptors and inhibits the reuptake of norepinephrine in the central nervous system without affecting serotonin reuptake. We identified 6 randomized controlled trials that evaluated the use of tapentadol in over 3,000 adult patients in various acute pain models. Tapentadol was found to be superior to placebo for the management of moderate-to-severe acute pain and was found to be noninferior to oxycodone in the setting of post-bunionectomy pain and acute pain related to end-stage joint disease. Although the incidence of somnolence and dizziness was similar to that of oxycodone, tapentadol was less likely to cause nausea, vomiting, or constipation.

Conclusions:

Tapentadol is a novel analgesic with dual mechanisms of action that appears to be safe and effective for the management of moderate-to-severe acute pain. Future studies should focus on comparative efficacy as well as the role of tapentadol in chronic pain.

Literature mining for the discovery of hidden connections between drugs, genes and diseases

The scientific literature represents a rich source for retrieval of knowledge on associations between biomedical concepts such as genes, diseases and cellular processes. A commonly used method to establish relationships between biomedical concepts from literature is co-occurrence. Apart from its use in knowledge retrieval, the co-occurrence method is also well-suited to discover new, hidden relationships between biomedical concepts following a simple ABC-principle, in which A and C have no direct relationship, but are connected via shared B-intermediates. In this paper we describe CoPub Discovery, a tool that mines the literature for new relationships between biomedical concepts. Statistical analysis using ROC curves showed that CoPub Discovery performed well over a wide range of settings and keyword thesauri. We subsequently used CoPub Discovery to search for new relationships between genes, drugs, pathways and diseases. Several of the newly found relationships were validated using independent literature sources. In addition, new predicted relationships between compounds and cell proliferation were validated and confirmed experimentally in an in vitro cell proliferation assay. The results show that CoPub Discovery is able to identify novel associations between genes, drugs, pathways and diseases that have a high probability of being biologically valid. This makes CoPub Discovery a useful tool to unravel the mechanisms behind disease, to find novel drug targets, or to find novel applications for existing drugs.

The biomedical literature is an important source of knowledge on the function of genes and on the mechanisms by which these genes regulate cellular processes. Several text mining approaches have been developed to leverage this rich source of information by automatically extracting associations between concepts such as genes, diseases and drugs from a large body of text. Here, we describe a new method that extracts novel, not yet recognized associations between genes, diseases, drugs and cellular processes from the biomedical literature. Our method is built on the assumption that even if two concepts do not have a direct connection in literature, they may be functionally related if they are both connected to an overlapping set of concepts. Using this approach we predicted several novel connections between genes, diseases, drugs and pathways. Our results imply that our method is able to predict novel relationships from literature and, most importantly, that these newly identified relationships are biologically relevant. Our method can aid the drug discovery process where it can be used to find novel drug targets, increase insight in mode of action of a drug or find novel applications for known drugs.

Antidepressant treatment of neuropathic pain: looking for the mechanism

Neuropathic pain arises as a direct consequence of a lesion or disease affecting the somatosensory system. Among the recommended first-line treatments are antidepressant drugs – that is, molecules that were initially developed to treat other disorders of the nervous system. While their clinical efficacy against neuropathic pain was established more than 30 years ago, there is little information on the mechanism underlying their antidepressant action. However, understanding the therapeutic mechanism of these treatments could help to improve them, or even lead to new therapeutic approaches. In this article, we discuss the difficulties in conducting relevant preclinical research on neuropathic pain treatment with antidepressant drugs and we present the most recent findings on the putative mechanism, which highlight the role of β2-adrenoceptors and δ-opioid receptors.

Efficacy of milnacipran in the treatment of chronic pain syndromes

Abstract Eleven outpatients with chronic pain syndromes other than fibromyalgia were treated for 12 weeks with milnacipran, a novel serotonin noradrenaline reuptake inhibitor. The agent was administered at 50-150 mg/day, and the mean ± SD dose at 12 weeks or at the time drug treatment was stopped was 84.1 ± 32.2 mg/day. None of the patients met the DSM-IV criteria for a major depressive disorder. Abdominal, chest, back, arm, leg or glossal pain, or headache was involved. Pain was assessed clinically by means of a visual analog scale (VAS) before and 12 weeks after the start of milnacipran treatment, or at the time drug treatment was stopped. The mean ± SD decrease in VAS scores was 42.3 ± 31.6 (50.8 ± 49.2%). One patient discontinued treatment after 4 weeks because of nausea, whereas others tolerated the agent well. These results suggest that the use of milnacipran in patients with a variety of chronic pain syndromes is beneficial.

Desvenlafaxine: a new antidepressant or just another one?

Desvenlafaxine (DVS) is a serotonin-norepinephrine reuptake inhibitor (SNRI) with a different pharmacokinetic and pharmacodynamic profile to venlafaxine. It was approved in February 2008 by the United States Food and Drug Administration for the treatment of major depressive disorder (MDD) based on a number of randomized, placebo-controlled clinical trials demonstrating efficacy and safety for patients with MDD. Current evidence indicates that DVS has proven efficacy, acceptable safety and tolerability profiles, convenient once-daily dosing and minimal impact on cytochrome P450 enzyme system and adverse event-prone neuroreceptors. As with all monoamine-based antidepressants, DVS has mixed efficacy results from individual studies, unestablished dosing strategies and limited long-term data, and comparative efficacy/safety with other existing antidepressants should be further investigated. Preliminary evidence also suggests the clinical usefulness of DVS in the treatment of vasomotor symptoms of menopause, anxiety symptoms and painful physical symptoms, although only MDD is the approved indication.

Association between generalized anxiety levels and pain in a community sample: evidence for diagnostic specificity

BACKGROUND

It is unclear whether generalized anxiety disorder (GAD) has a specific relationship to pain syndromes, going beyond the established association of pain with anxiety syndromes in general.

METHODS

Mental disorders were assessed in a community sample (N=4181; 18-65 years) using the DSM-IV/M-CIDI. Several threshold definitions were used to define GAD and medically unexplained pain.

RESULTS

The association between pain and GAD (odds ratio, OR=5.8 pain symptoms; OR=16.0 pain disorder) is stronger than the association between pain and other anxiety disorders (OR=2.4 pain symptoms; OR=4.0 pain disorder). This association extends to subthreshold level definitions of GAD with some indication for a non-linear dose-response relationship. The GAD-pain link cannot sufficiently be explained by demographic factors, comorbid mental or physical disorders.

CONCLUSIONS

The association of pain and generalized anxiety is not artifactual. Compared to other anxiety syndromes, it appears to be stronger and more specific suggesting the need to explore clinical and public health implications.

The Efficacy and Safety of Milnacipran for Treatment of Fibromyalgia. A Randomized, Double-blind, Placebo-controlled Trial

Objective.

To evaluate the safety and efficacy of milnacipran, a dual norepinephrine and serotonin reuptake inhibitor, in the treatment of fibromyalgia (FM).

Methods.

A 27-week, randomized, double-blind, multicenter study compared milnacipran 100 and 200 mg/day with placebo in the treatment of 888 patients with FM. Two composite responder definitions were used to classify each patient’s individual response to therapy. “FM responders” concurrently satisfied response criteria for improvements in pain (visual analog scale 24-h morning recall), patient global impression of change (PGIC), and physical functioning (SF-36 Physical Component Summary); while “FM pain responders” concurrently satisfied response criteria for improvements in pain and PGIC.

Results.

At the primary endpoint, after 3-month stable dose treatment, a significantly higher percentage of milnacipran-treated patients met criteria as FM responders versus placebo (milnacipran 200 mg/day, p = 0.017; milnacipran 100 mg/day, p = 0.028). A significantly higher percentage of patients treated with milnacipran 200 mg/day also met criteria as FM pain responders versus placebo (p = 0.032). Significant pain reductions were observed after Week 1 with both milnacipran doses. At 15 weeks, milnacipran 200 mg/day led to significant improvements over placebo in pain (realtime, daily and weekly recall; all measures, p < 0.05), PGIC (p < 0.001), fatigue (p = 0.016), cognition (p = 0.025), and multiple SF-36 domains. Milnacipran was safe and well tolerated by the majority of patients during 27 weeks of treatment; nausea and headache were the most common adverse events.

Conclusion.

Milnacipran is safe and effective for the treatment of multiple symptoms of FM.

Role of serotonin 5-HT1A receptors in the antidepressant-like effect and the antinociceptive effect of venlafaxine in mice

The present study was undertaken to evaluate the potential role of 5-HT1A receptors in the antidepressant-like effect and antinociceptive effect of venlafaxine. With this aim, the effect of either a selective 5-HT1A receptor antagonist (WAY-100635; N-2-[4-(2-methoxyphenyl-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexane carboxamide) or a selective 5-HT1A receptor agonist (8-OH-DPAT; 8-hydroxy-2-(di-n-propylamine) tetralin hydrobromide) was investigated in mice in combination with venlafaxine by means of the forced swimming test, a paradigm aimed at screening potential antidepressants, and the hot-plate test, a phasic pain model. Surprisingly, the results showed that WAY-100635 produced a large decrease in the antidepressant-like effect of venlafaxine, while 8-OH-DPAT rendered effective a non-effective dose of this antidepressant. However, in the hot-plate test WAY-100635 significantly enhanced the antinociceptive effect of venlafaxine, whereas 8-OH-DPAT counteracted its antinociceptive effect. These findings show that 5-HT1A receptors play differing roles in modulating the antidepressant-like and antinociceptive effects of venlafaxine in the models investigated. The results imply that blockade of the 5-HT1A receptors in the forebrain will counteract the favourable (antidepressant-like) effect at raphe nuclei level, and consequently, the overall effect evidenced is an antagonism. This suggests a predominant role of 5-HT1A receptors located in the forebrain area for the antidepressant-like effect. In contrast, the antinociceptive effect of venlafaxine is probably potentiated due to the blockade of somatodendritic 5-HT1A receptors in the same raphe nuclei, facilitating the descending monoaminergic pain control system.

(–)-(1R,2R)-3-(3-Dimethylamino-1-ethyl-2-methyl-propyl)-phenol Hydrochloride (Tapentadol HCl): a Novel μ-Opioid Receptor Agonist/Norepinephrine Reuptake Inhibitor with Broad-Spectrum Analgesic Properties

(-)-(1R,2R)-3-(3-dimethylamino-1-ethyl-2-methyl-propyl)-phenol hydrochloride (tapentadol HCl) is a novel micro-opioid receptor (MOR) agonist (Ki = 0.1 microM; relative efficacy compared with morphine 88% in a [35S]guanosine 5'-3-O-(thio)triphosphate binding assay) and NE reuptake inhibitor (Ki = 0.5 microM for synaptosomal reuptake inhibition). In vivo intracerebral microdialysis showed that tapentadol, in contrast to morphine, produces large increases in extracellular levels of NE (+450% at 10 mg/kg i.p.). Tapentadol exhibited analgesic effects in a wide range of animal models of acute and chronic pain [hot plate, tail-flick, writhing, Randall-Selitto, mustard oil colitis, chronic constriction injury (CCI), and spinal nerve ligation (SNL)], with ED50 values ranging from 8.2 to 13 mg/kg after i.p. administration in rats. Despite a 50-fold lower binding affinity to MOR, the analgesic potency of tapentadol was only two to three times lower than that of morphine, suggesting that the dual mode of action of tapentadol may result in an opiate-sparing effect. A role of NE in the analgesic efficacy of tapentadol was directly demonstrated in the SNL model, where the analgesic effect of tapentadol was strongly reduced by the alpha2-adrenoceptor antagonist yohimbine but only moderately attenuated by the MOR antagonist naloxone, whereas the opposite was seen for morphine. Tolerance development to the analgesic effect of tapentadol in the CCI model was twice as slow as that of morphine. It is suggested that the broad analgesic profile of tapentadol and its relative resistance to tolerance development may be due to a dual mode of action consisting of both MOR activation and NE reuptake inhibition.

Mice lacking central serotonergic neurons show enhanced inflammatory pain and an impaired analgesic response to antidepressant drugs

A large body of literature has implicated serotonin [5-hydroxytryptamine (5-HT)] in descending modulation of nociceptive transmission. Here, we have studied the pain behavior of Lmx1b conditional knock-out mice (Lmx1b(f/f/p)), which lack 5-HT neurons in the CNS. Lmx1b(f/f/p) mutant mice showed normal thermal and visceral pain responses but were less sensitive to mechanical stimuli and exhibited enhanced inflammatory pain compared with their littermate control mice. Importantly, the analgesic effect of several antidepressant drugs, including selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and tricyclic antidepressants, was either abolished or greatly attenuated in Lmx1b(f/f/p) mice. Moreover, in the acute versus persistent pain settings, the analgesic actions of the SNRI duloxetine and the SSRI fluoxetine were differentially affected. Together, our results provide in vivo genetic evidence demonstrating that although the predominant role of the central 5-HT system in inflammatory pain is inhibitory, its role in acute mechanical pain is facilitatory. The findings that the analgesic effects of various antidepressant drugs are differentially dependent on the central 5-HT system should help us to understand the mechanism of the analgesic action of different classes of antidepressants in the management of persistent pain.

Medication use in a female orofacial pain population

OBJECTIVE

This study compared, both quantitatively and qualitatively, the self-reported medication usage between an adult female orofacial pain population and a comparison group.

STUDY DESIGN

Eighty-seven subjects from both an orofacial pain center (OPC) and undergraduate dental clinic (UDC) completed a standardized medical history questionnaire. Both groups had a similar distribution with regard to age. The number of medications and medication categories were compared between the two groups. Statistical analysis used the Student t-test, Fisher's exact tests, Pearson's chi2 tests, and calculated odds ratios.

RESULTS

The number of pain and non-pain medications, and the number of medication categories endorsed by OPC subjects was significantly higher compared with the UDC group.

CONCLUSION

Adult female orofacial pain subjects report greater overall and higher rate of medication use, which was not limited to only the analgesic/narcotic categories, than the comparison group.

The burden of severe depression: a review of diagnostic challenges and treatment alternatives

Among the factors making recognition of severe depression problematic for clinicians are the heterogeneous nature of the condition, lack of standardized definitions, and concomitant comorbidities that confound differential diagnosis of symptoms. The spectrum of severity in depressive disorders is extraordinarily broad, and severity assessment is comprised of several metrics including symptom intensity, diagnostic subtypes, suicidality risk, and hospitalization status. The overall diagnosis is achieved through consideration of symptom types and severities together with the degree of functional impairment as assessed by the psychiatric interview. It is likely that no single fundamental neurobiological defect underlies severe depression. The chronicity and heterogeneity of this disorder lead to frequent clinic visits and a longer course of treatment; therefore, successful approaches may require an arsenal of treatments with numerous mechanisms of action. The categories of drugs used to treat severe depression are detailed herein, as are several non-pharmacologic options including a number of experimental treatments. Pharmacotherapies include tricyclic antidepressants, selective serotonin reuptake inhibitors, atypical antidepressants such as serotonin-norepinephrine reuptake inhibitors and monoamine oxidase inhibitors, and combination and augmentation therapies. Drugs within each class are not equivalent, and efficacy may vary with symptom severity. Patient adherence makes tolerability another critical consideration in antidepressant choice. The role of non-pharmacological treatments such as electroconvulsive therapy, vagus nerve stimulation, transcranial magnetic stimulation, and deep brain stimulation remain active avenues of investigation. Improved knowledge and treatment approaches for severe depression are necessary to facilitate remission, the ideal treatment goal.

Management of musculoskeletal pain

Chronic musculoskeletal pain is a major public health problem affecting about one third of the adult population. Pain is often present without any specific findings in the musculoskeletal system and a strictly biomedical approach could be inadequate. A biopsychosocial model could give a better understanding of symptoms and new targets for management. Identification of risk factors for chronicity is important for prevention and early intervention. The cornerstones in management of chronic non-specific, and often widespread, musculoskeletal pain are non-pharmacological. Physical exercise and cognitive behavioral therapy, ideally in combination, are first line treatments in e.g. chronic low back pain and fibromyalgia. Analgesics are useful when there is a specific nociceptive component, but are often of limited usefulness in non-specific or chronic widespread pain (including fibromyalgia). Antidepressants and anticonvulsants could be of value in some patients but there is a need for more knowledge in order to give general recommendations.

Japanese experience with milnacipran, the first serotonin and norepinephrine reuptake inhibitor in Japan

Milnacipran is a serotonin and norepinephrine reuptake inhibitor (SNRI), with a balanced potency for the inhibition of the reuptake of the two monoamines. In this, it contrasts with venlafaxine and duloxetine which, while possessing a dual action, have a selectivity of the order of 30-fold and 10-fold respectively for the reuptake of serotonin. Milnacipran has mainly been launched in countries where the selective serotonin reuptake inhibitors (SSRIs) and venlafaxine had been established for several years. As such it has attracted relative little interest from clinician investigators as a research tool. Japan, however, represents a unique situation because in 1999 milnacipran was launched within months of the first SSRI and is still the only SNRI in Japan together with only two SSRIs (a third has just been introduced). This has led to a large number of investigative clinical studies, many of which give interesting insights into the potential of milnacipran in the treatment of depression and of other disorders. This article reviews these Japanese studies with milnacipran.

Uncovering molecular elements of brain-body communication during development and treatment of neuropathic pain

Integral to neuropathic pain is a reciprocal interaction between tumor necrosis factor-alpha (TNF) production and the alpha(2)-adrenergic receptor response, offering an attractive therapeutic target. The effects of varying levels of brain TNF on alpha(2)-adrenergic regulation of cyclic AMP (cAMP) production in the hippocampus and sciatic nerve were investigated during the development and amitriptyline treatment of chronic pain. Increased levels of TNF during the development of chronic pain transform alpha(2)-adrenergic inhibition of cAMP production in the brain to potentiation. While alpha(2)-adrenergic receptors regulate TNF production, they also affect descending noradrenergic pathways. Increases in levels of TNF in the brain deeply impact peripheral inflammation through regulating alpha(2)-adrenergic receptors, offering insight into brain-body interactions during neuropathic pain. Amitriptyline as an analgesic inhibits pain-induced increases in brain-associated TNF and transforms peripheral alpha(2)-adrenergic receptors. The dynamic equilibrium between TNF levels and alpha(2)-adrenergic functioning is uniquely altered during development and treatment of neuropathic pain. Proper manipulations of this interaction offer efficacious treatment of neuropathic pain.

Functional interaction between α2-adrenoceptors, μ- and κ-opioid receptors in the guinea pig myenteric plexus: Effect of chronic desipramine treatment

The existence of a functional interplay between alpha(2)-adrenoceptor and opioid receptor inhibitory pathways modulating neurotransmitter release has been demonstrated in the enteric nervous system by development of sensitivity changes to alpha(2)-adrenoceptor, mu- and kappa-opioid receptor agents on enteric cholinergic neurons after chronic sympathetic denervation. In the present study, to further examine this hypothesis we evaluated whether manipulation of alpha(2)-adrenoceptor pathways by chronic treatment with the antidepressant drug, desipramine (10 mg/kg i.p. daily, for 21 days), could entail changes in enteric mu- and kappa-opioid receptor pathways in the myenteric plexus of the guinea pig distal colon. In this region, subsensitivity to the inhibitory effect of both UK14,304 and U69,593, respectively alpha(2A)-adrenoceptor and kappa-opioid receptor agonist, on the peristaltic reflex developed after chronic desipramine treatment. On opposite, in these experimental conditions, supersensitivity developed to the inhibitory effect of [D-Ala, N-Me-Phe4-Gly-ol5]-enkephalin (DAMGO), mu-opioid receptor agonist, on propulsion velocity. Immunoreactive expression levels of alpha(2A)-adrenoceptors, mu- and kappa-opioid receptors significantly decreased in the myenteric plexus of the guinea pig colon after chronic desipramine treatment. In these experimental conditions, mRNA levels of alpha(2A)-adrenoceptors, mu- and kappa-opioid receptors significantly increased, excluding a direct involvement of transcription mechanisms in the regulation of receptor expression. Levels of G protein-coupled receptor kinase 2/3 and of inhibitory G(i/o) proteins were significantly reduced in the myenteric plexus after chronic treatment with desipramine. Such changes might represent possible molecular mechanisms involved in the development of subsensitivity to UK14,304 and U69,593 on the efficiency of peristalsis. Alternative molecular mechanisms, including a higher efficiency in the coupling between receptor activation and downstream intracellular effector systems, possibly independent from inhibitory G(i/o) proteins, may be accounted for the development of supersensitivity to DAMGO. Increased sensitivity to the mu-opioid agonist might compensate for the development of alpha(2A)-adrenoceptor and kappa-opioid receptor subsensitivity. On the whole, the present data further strengthen the concept that, manipulation of alpha(2)-adrenergic inhibitory receptor pathways in the enteric nervous system entails changes in opioid inhibitory receptor pathways, which might be involved in maintaining homeostasis as suggested for mu-opioid, but not for kappa-opioid receptors.

Antidepressants in the treatment of fibromyalgia

Fibromyalgia syndrome is a chronic disease of widespread and debilitating pain whose cause is unknown and whose risk factors are poorly understood. It is often comorbid with rheumatoid and other pain disorders as well as psychiatric disorders such as anxiety and depression. Although they are not officially approved for this indication, antiepileptics and antidepressants are often used to treat fibromyalgia. The tricyclic antidepressants (TCAs), particularly amitriptyline, are among the most common treatment strategies. Because of the poor tolerability of the tricyclics, the newer antidepressants have been widely tested in fibromyalgia. The selective serotonin reuptake inhibitors (SSRIs) and the reversible monoamine oxidase inhibitors do not seem to be particularly helpful. The serotonin and norepinephrine reuptake inhibitors (SNRIs), duloxetine and milnacipran, on the other hand, have been shown in placebo-controlled trials to offer significant relief to patients suffering from fibromyalgia. Although no direct comparative studies have been performed, these compounds appear to be as effective as the TCAs but much better tolerated. The effectiveness of the SNRIs as well as other dual acting antidepressants, such as mirtazapine, but not the SSRIs, implies that a dysfunction of both serotonin and norepinephrine neurotransmission probably exists in fibromyalgia. The effectiveness of antidepressants appears to be independent of their effect on comorbid depression.

Antidepressants enhance the antinociceptive effects of carbamazepine in the acetic acid-induced writhing test in mice

Some antidepressants, as well as antiepileptics, are effective for treating pain of varying etiology. The present study was designed to characterize the antinociceptive effects of imipramine, a tricyclic antidepressant, fluvoxamine, a selective serotonin reuptake inhibitor, milnacipran, a serotonin noradrenaline reuptake inhibitor, and carbamazepine, an antiepileptic drug, using the acetic acid-induced writhing test in mice. Imipramine (1.25-10 mg/kg, i.p.), fluvoxamine (5-40 mg/kg, i.p.) and milnacipran (2.5-20 mg/kg, i.p.) all dose-dependently and significantly reduced the number of writhes induced by the injection of acetic acid (0.8% (v/v)), although the maximal effect of milnacipran was weaker than those of imipramine and fluvoxamine. Similarly, carbamazepine (5-20 mg/kg, i.p.) also showed a dose-dependent and significant antinociceptive effect. In combination studies, the co-administration of a sub-effective dose of carbamazepine (5 mg/kg, i.p.) with imipramine (1.25 and 2.5 mg/kg, i.p.), fluvoxamine (10 mg/kg, i.p.) or milnacipran (1.25 and 2.5 mg/kg, i.p.) significantly reduced the number of writhes. Additionally, the hole-board test revealed that the medications with significant antinociceptive effects barely produced changes in motor activity that could possibly affect writhing behavior. Thus, the present study demonstrated that the antinociceptive effect of carbamazepine is enhanced by combination with imipramine, fluvoxamine and milnacipran. Therefore, the combined therapy using antidepressants and carbamazepine may be useful clinically for the control of pain.

Treatment of phantom bite syndrome with milnacipran - a case series

Phantom bite syndrome is characterized by an uncomfortable sensation mainly affecting corrected dentition in which no abnormality is clinically detectable. Despite repeated failures of dental surgery, sufferers persist in seeking bite correction from a succession of dentists. The etiology-pathogenesis of phantom bite is unknown but some consider the syndrome to be a psychosomatic disorder. Seven patients with this syndrome were treated with the serotonin and norepinephrine reuptake inhibitor milnacipran for 4 weeks. One patient withdrew after 2 weeks because he was feeling "well". At the end of the study, 5 of the 6 patients completing the study reported significant improvements, with a mean decrease in occlusal discomfort of 55.3%, as indicated by a visual analogue scale. This result appeared to be independent of any antidepressant effect. Only minor and transient side-effects were observed. It is suggested that milnacipran may be a helpful treatment for phantom bite but this needs to be confirmed by further and longer term studies.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

Pharmacological profile of the "triple" monoamine neurotransmitter uptake inhibitor, DOV 102,677

1. The molecular and behavioral pharmacology of DOV 102,677 is characterized. 2. This characterization was performed using radioligand binding and neurotransmitter uptake assays targeting the monoamine neurotransmitter receptors. In addition, the effects of DOV 102,677 on extracellular neurotransmitter levels were investigated using in vivo microdialysis. Finally, the effects of DOV 102,677 in the forced swim test, locomotor function, and response to prepulse inhibition was investigated.3. DOV 102,677 is a novel, "triple" uptake inhibitor that suppresses [(3)H]dopamine (DA), [(3)H]norepinephrine (NE) and [(3)H]serotonin (5-HT) uptake by recombinant human transporters with IC(50) values of 129, 103 and 133 nM, respectively. Radioligand binding to the dopamine (DAT), norepinephrine (NET), and serotonin (SERT) transporters is inhibited with k (i) values of 222, 1030, and 740 nM, respectively. DOV 102,677 (20 mg/kg IP) increased extracellular levels of DA and 5-HT in the prefrontal cortex to 320 and 280% above baseline 100 min after administration. DA levels were stably increased for the duration (240 min) of the study, but serotonin levels declined to baseline by 200 min after administration. NE levels increased linearly to a maximum of 348% at 240 min post-dosing. Consistent with these increases in NE levels, the density of beta-adrenoceptors was selectively decreased in the cortex of rats treated with DOV 102,677 (20 mg/kg per day, PO, 35 days). 4. DOV 102,677 dose-dependently reduced the amount of time spent immobile by rats in the forced swim test, a model predictive of antidepressant activity, with a minimum effective dose (MED) of 20 mg/kg and a maximal efficacy comparable to imipramine. This decrease in immobility time did not appear to result from increased motor activity. Further, DOV 102,677 was as effective as methylphenidate in reducing the amplitude of the startle response in juvenile mice, without notably altering motor activity. 5. In summary, DOV 102,677 is an orally active, "balanced" inhibitor of DAT, NET and SERT with therapeutic versatility in treating neuropsychiatric disorders beyond depression.

Depression and pain: an overview

BACKGROUND

Depression and pain are both burdensome ailments that affect a major proportion of the population. It is evident that depression and pain frequently coexist, with treatment and outcome implications.

OBJECTIVE

To review the literature on the nature, prevalence and co-morbidity of depression and pain, the biological and psychological mechanisms involved and treatment options, thus presenting a broad overview of the current information available.

METHODS

Relevant sources were identified from PubMed and Medline databases using a combination of keywords including depression, pain, prevalence, co-morbidity, biological and psychological mechanisms, serotonin (5-HT), norepinephrine (NE), hypothalamic-pituitary-adrenal (HPA) axis, amygdala, functional magnetic resonance imaging (fMRI), antidepressant and psychological therapy.

RESULTS

It is evident from the research that depression and pain are common co-morbidities. Pain as a physical symptom of depression affects approximately 65% of patients, leading to less favourable outcomes and greater health care utilization. Moreover, depression is a common feature in chronic pain patients and can affect pain threshold and tolerance. Evidence from biological and psychological studies has revealed mechanisms that link chronic pain to depression. Several classes of anti-depressants and psychological interventions have been used successfully in the treatment of somatic symptoms of depression and for a variety of pain syndromes.

CONCLUSIONS

Pain and depression are linked by overlapping phenomenology, neurobiology and therapy. They are mutually interacting, and the interaction has significant treatment and outcome implications.

Functional abdominal pain syndrome

Functional abdominal pain syndrome (FAPS) differs from the other functional bowel disorders; it is less common, symptoms largely are unrelated to food intake and defecation, and it has higher comorbidity with psychiatric disorders. The etiology and pathophysiology are incompletely understood. Because FAPS likely represents a heterogeneous group of disorders, peripheral neuropathic pain mechanisms, alterations in endogenous pain modulation systems, or both may be involved in any one patient. The diagnosis of FAPS is made on the basis of positive symptom criteria and a longstanding history of symptoms; in the absence of alarm symptoms, an extensive diagnostic evaluation is not required. Management is based on a therapeutic physician-patient relationship and empirical treatment algorithms using various classes of centrally acting drugs, including antidepressants and anticonvulsants. The choice, dose, and combination of drugs are influenced by psychiatric comorbidities. Psychological treatment options include psychotherapy, relaxation techniques, and hypnosis. Refractory FAPS patients may benefit from a multidisciplinary pain clinic approach.

Effects of venlafaxine and desipramine on heroin-induced conditioned place preference in the rat

Venlafaxine, an antidepressant with serotonin and noradrenaline reuptake inhibiting properties, has been reported to reduce acquisition (but not maintenance) of heroin intravenous self-administration (IVSA) in rats. The present study investigated whether this phase-dependent effect is due to an antidepressant-induced attenuation of the rewarding effect of heroin, as assessed in the conditioned place preference (CPP) paradigm. In order to study the effects of venlafaxine and the tricyclic antidepressant desipramine on acquisition and expression of heroin CPP, both compounds were administered prior to the conditioning sessions (together with heroin), or prior to the expression test after conditioning, respectively. As clinical evidence indicates that antidepressants require repeated administration for full efficacy, additional experiments were performed in which both antidepressants were administered for 2 weeks prior to conditioning, or for 1 week prior to the expression test, respectively. When tested alone, heroin [0.05-3.16 mg/kg intraperitoneally (i.p.)] produced a dose-dependent CPP, whereas the antidepressants (1-21.5 mg/kg i.p.) produced neither a CPP nor a conditioned place aversion (CPA). For both antidepressants (10 mg/kg i.p.), neither acute nor repeated pretreatment affected acquisition or expression of heroin (0.5 mg/kg) CPP. Thus, the present study does not support the hypothesis that the previously observed attenuation of acquisition of heroin IVSA by venlafaxine is due to an antidepressant-induced attenuation of the rewarding effect of heroin. It is conceivable, however, that the rewarding effect of the 0.5 mg/kg dose of heroin was too pronounced to be susceptible to modulation by antidepressants. Alternatively, the modulation of acquisition of heroin IVSA in the previous study may be related to mechanisms that cannot be modelled with the CPP paradigm.

Serotonin noradrenaline reuptake inhibitors: New hope for the treatment of chronic pain

Depression and painful symptoms occur frequently together. Over 75% of depressed patients report painful symptoms such as headache, stomach pain, neck and back pain as well as non-specific generalized pain. In addition, World Health Organization data have shown that primary care patients with chronic pain have a four fold greater risk of becoming depressed than pain-free patients. Increasingly, pain is considered as an integral symptom of depression and there evidence to suggest that pain and depression may arise from a common neurobiological dysfunction. Serotonergic cell bodies, in the raphe nucleus, and noradrenergic cell bodies in the locus coeruleus send projections to various parts of the brain, where they are involved in the control of mood, movement, cognitive functioning and emotions. In addition both serotonergic and noradrenergic neurons project to the spinal cord. These descending pathways serve to inhibit input from the intestines, skeletal muscles and other sensory inputs. Usually, these inhibitory effects are modest, but in times of stress, in the interest of the survival of the individual, they can completely inhibit the input from painful stimuli. A dysfunction of the serotonergic and noradrenergic neurons can thus affect both the ascending and descending pathways resulting in the psychological symptoms of depression and somatic pain symptoms such as chronic pain, fibromyalgia, non-cardiac chest pain, or irritable bowel syndrome. In view of this, it is not surprising that tricyclic antidepressants have been a standard treatment of chronic pain for many years. In contrast and in spite of their improved tolerance, selective serotonin reuptake inhibitors do not appear to be particularly effective in the treatment of pain. Recently, a number of open and controlled trials with selective serotonin and noradrenaline reuptake inhibitors such as venlafaxine, milnacipran and duloxetine, suggest that these compounds may be more effective in relieving pain than selective inhibitors of serotonin reuptake. Wherever valid comparisons have been made the newer dual action drugs appear to be as effective as the tricyclic and considerably better tolerated. Dual action antidepressants may thus soon become the new standard treatment of chronic pain whether it is associated with depression or not. In addition, these agents may also have a role in modulating neurogenesis and other neuroplastic changes in the central nervous system, thereby leading to more complete recovery in patients suffering from the symptoms of depression or chronic pain.