Effects of a single oral dose of desipramine on postoperative morphine analgesia

Opioid Use in the Postoperative Arena: Global Reduction in Opioids After Surgery Through Enhanced Recovery and Gynecologic Surgery

Enhanced recovery programs aim to reduce surgical stress to improve the patient perioperative experience. Through a combination of multimodal analgesia and maintaining a physiological state, postoperative recovery is improved. Many analgesic adjuncts are available that improve postoperative pain control and limit opioid analgesia requirements. Adjuncts are often used in combination, but different interventions may be incorporated for patient-specific and procedure-specific needs. Postoperative pain control can be optimized by continuing nonopioid adjuncts, and prescribing opioid analgesia to address breakthrough pain. Prescribing practices should balance optimizing pain relief, minimizing the risk of chronic pain, while limiting the potential for opioid misuse.

Antidepressant Drugs for Postsurgical Pain: Current Status and Future Directions

Current treatments for postsurgical pain are often inadequate and adverse effects are substantial such that residual pain and/or side effects impair recovery. The recognition of analgesic efficacy with antidepressant drugs for chronic pain suggests the potential for efficacy in acute postsurgical pain. As reviewed here, current evidence suggests that approximately half of previous trials suggest efficacy of various antidepressants for acute postoperative pain. However, most trials are older with deficiencies including: lack of designation of a primary outcome, no assessment of movement-evoked pain, small size and limited safety assessment. Only one of three trials addressing prevention of chronic postsurgical pain suggested any efficacy; however, the evidence base for this indication is limited. Thus, current evidence does not yet support routine use of any one specific antidepressant for treatment of acute, or prevention of chronic, postsurgical pain. However, limitations in available trials are such that one cannot yet rule out the possibility that one or more antidepressant drugs may provide benefit in specific populations. Therefore, future larger trials should explore optimal dosing and duration of antidepressant treatment, procedure specificity, safety evaluation, and assessment of movement-evoked pain.

Antidepressant drugs for prevention of acute and chronic postsurgical pain: early evidence and recommended future directions

BACKGROUND

This review evaluates trials of antidepressants for acute and chronic postsurgical pain.

METHODS

Trials were systematically identified using predefined inclusion and exclusion criteria. Extracted data included the following: pain at rest and with movement, adverse effects, and other outcomes.

RESULTS

Fifteen studies (985 participants) of early postoperative pain evaluated amitriptyline (three trials), bicifadine (two trials), desipramine (three trials), duloxetine (one trial), fluoxetine (one trial), fluradoline (one trial), tryptophan (four trials), and venlafaxine (one trial). Three studies (565 participants) of chronic postoperative pain prevention evaluated duloxetine (one trial), escitalopram (one trial), and venlafaxine (one trial). Heterogeneity because of differences in drug, dosing regimen, outcomes, and/or surgical procedure precluded any meta-analyses. Superiority to placebo was reported in 8 of 15 trials for early pain reduction and 1 of 3 trials for chronic pain reduction. The majority of positive trials did not report sufficient data to estimate treatment effect sizes. Many studies had inadequate size, safety evaluation/reporting, procedure specificity, and movement-evoked pain assessment.

CONCLUSIONS

There is currently insufficient evidence to support the clinical use of antidepressants-beyond controlled investigations-for treatment of acute, or prevention of chronic, postoperative pain. Multiple positive trials suggest the therapeutic potential of antidepressants, which need to be replicated. Other nontrial evidence suggests potential safety concerns of perioperative antidepressant use. Future studies are needed to better define the risk-benefit ratio of antidepressants in postoperative pain management. Higher-quality trials should optimize dosing, timing and duration of antidepressant treatment, trial size, patient selection, safety evaluation and reporting, procedure specificity, and assessment of movement-evoked pain relevant to postoperative functional recovery.

Perioperative interventions to reduce chronic postsurgical pain

Approximately 10% of patients following a variety of surgeries develop chronic postsurgical pain. Reducing chronic postoperative pain is especially important to reconstructive surgeons because common operations such as breast and limb reconstruction have even higher risk for developing chronic postsurgical pain. Animal studies of posttraumatic nerve injury pain demonstrate that there is a critical time frame before and immediately after nerve injury in which specific interventions can reduce the incidence and intensity of chronic neuropathic pain behaviors-so called "preventative analgesia." In animal models, perineural local anesthetic, systemic intravenous local anesthetic, perineural clonidine, systemic gabapentin, systemic tricyclic antidepressants, and minocycline have each been shown to reduce pain behaviors days to weeks after treatment. The translation of this work to humans also suggests that brief perioperative interventions may protect patients from developing new chronic postsurgical pain. Recent clinical trial data show that there is an opportunity during the perioperative period to dramatically reduce the incidence and severity of chronic postsurgical pain. The surgeon, working with the anesthesiologist, has the ability to modify both early and chronic postoperative pain by implementing an evidence-based preventative analgesia plan.

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.

Combination drug therapy for chronic pain: a call for more clinical studies

Chronic pain is a debilitating clinical condition associated with a variety of disease entities including diabetic neuropathy, postherpetic neuralgia, low back pathology, fibromyalgia, and neurological disorders. For many general practitioners and specialists, managing chronic pain has become a daunting challenge. As a modality of multidisciplinary chronic pain management, medications are often prescribed in combinations, an approach referred to as combination drug therapy (CDT). However, many medications for pain therapy, including antidepressants and opioid analgesics, have significant side effects that can compound when used in combination and impact the effectiveness of CDT. To date, clinical practice of CDT for chronic pain has been based largely on clinical experiences. In this article, we will focus on (1) the scientific basis and rationales for CDT, (2) current clinical data on CDT, and (3) the need for more clinical studies to establish a framework for the use of CDT.

PERSPECTIVE

More preclinical, clinical, and translational studies are needed to improve the efficacy of combination drug therapy that is an integral part of a comprehensive approach to the management of chronic pain.

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.

Identification of discrete sites of action of chronic treatment with desipramine in a model of neuropathic pain

Tricyclic antidepressants (TCAs) are an important analgesic treatment for neuropathic pain, though the neural substrates mediating these effects are poorly understood. We have used an integrative approach combining behavioural pharmacology with functional magnetic resonance imaging (fMRI) to investigate the effects of chronic treatment with the TCA desipramine, on touch-evoked pain (mechanical allodynia) and brain regional activity in the selective spinal nerve ligation (SNL) model of neuropathic pain. SNL and sham-operated rats received once daily i.p. administration of 10 mg/kg DMI, or saline, for 14 days. Withdrawal responses to the application of a normally non-noxious (10 g) stimulus were recorded in SNL and sham-operated rats over this period. On the final day of the study, SNL and sham-operated rats received a final challenge dose of DMI (10 mg/kg i.p.) during fMRI scanning. Chronic administration of desipramine (DMI) significantly attenuated mechancial allodynia in SNL rats. DMI challenge in chronic DMI-treated neuropathic rats produced significantly greater activation of the deep mesencephalic nucleus, primary somatosensory cortex, insular cortex, medial globus pallidus, inferior colliculus, perirhinal cortex and cerebellum compared to sham-operated rats and saline controls. By contrast, the spatial pattern of brain regional activation by chronic DMI treatment in sham controls encompassed a number of other areas including those associated with learning and memory processes. These novel findings identify key brain regions implicated in the analgesic and mood altering effects associated with chronic treatment with DMI.

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.

A randomized, double-blind, 8-week crossover study of once-daily controlled-release tramadol versus immediate-release tramadol taken as needed for chronic noncancer pain

OBJECTIVE

The purpose of this study was to evaluate the efficacy of controlled-release (CR) tramadol and immediate-release (IR) tramadol in patients with moderate or greater intensity chronic noncancer pain.

METHODS

A total of 122 patients underwent washout from all opioids 2 to 7 days before randomization to 1 of 2 groups: active CR tramadol 200 mg every morning plus placebo IR tramadol 50 mg every 4 to 6 hours PRN rescue, or placebo CR tramadol 200 mg every morning plus active IR tramadol 50 mg every 4 to 6 hours PRN rescue. After 2 weeks, the doses were increased to CR tramadol 400 mg or placebo and IR tramadol 100 mg every 4 to 6 hours PRN or placebo, as rescue. After 4 weeks in the first phase, patients crossed over to the alternative treatment for another 4 weeks. Pain intensity (100-mm visual analog scale [VAS] and 5-point ordinal scales) was assessed twice daily in diaries. Pain intensity, Pain and Disability Index (PDI; 0-10 ordinal scale), Pain and Sleep Questionnaire (100-mm VAS), and analgesic effectiveness (7-point ordinal scale) were assessed at biweekly clinic visits.

RESULTS

Sixty-five patients (35 men, 30 women) completed the study. Mean (SD) age was 56.5 (12.7) years; mean (SD) weight was 82.0 (18.5) kg. Daily diary pain intensity (mean [SD]) was significantly lower in the CR tramadol group than in the IR tramadol group in the last 2 weeks of each phase (completers: VAS, 29.9 [20.5] vs 36.2 [20.4] mm, P < 0.001; ordinal scale, 1.41 [0.7] vs 1.64 [0.6], P < 0.001; intent-to-treat [ITT] population: VAS, 32.5 [22.9] vs 38.6 [21.2] mm, P < 0.003; ordinal scale, 1.50 [0.8] vs 1.72 [0.7], P < 0.002). The overall pain intensity scores from the daily diary were also significantly better with CR tramadol for both the completers and ITT. Similar results were obtained on the biweekly VAS pain intensity questionnaire. No differences were found between treatments in total PDI or overall Pain and Sleep scores in either population. For the completers, both patients and investigators rated effectiveness higher for CR tramadol than for IR tramadol (P < 0.004 and P < 0.008 for patients and investigators, respectively).

CONCLUSION

This study reports significant improvement in pain intensity with CR tramadol as compared with IR tramadol.

Systematic overview of drug interactions with antidepressant medications

OBJECTIVE

Antidepressants are commonly used drugs with potential for numerous drug interactions. This study aims to systematically review the literature on drug interactions with antidepressants.

METHODS

We searched MEDLINE (1966 to November 2003) and EMBASE (1980 to 2003), using the heading drug interactions combined with individual antidepressant names. We restricted searches to English-language articles and human studies. We screened drug interaction texts and review articles for relevant studies. We included articles reporting original human data on drug interactions with antidepressants commonly used in North America. Articles were independently evaluated by 2 reviewers on clinical effect, clinical significance, and quality of evidence. Discrepancies were resolved by consensus.

RESULTS

There were 904 eligible interactions, involving 9509 patients, for a total of 598 summary interactions. Of these, 439 (73%) demonstrated an interaction, 148 (25%) had no effect, and 11 (2%) had conflicting evidence. For 510 interactions (85%), the quality of evidence was poor. It was fair for 67 (11%) interactions and good for 10 (2%) interactions. There were no interactions with excellent quality of evidence. There were 145 (24%) interactions of major clinical significance. These were predominantly hypertensive emergencies and serotonin syndrome. Most interacting drugs had central nervous system (CNS) activity. As expected, monoamine oxidase inhibitors (MAOIs) appear to be the most problematic family in terms of potential for serious drug interactions.

CONCLUSIONS

Drug interactions with antidepressants are an important cause for concern, but this concern is based primarily on poor evidence. We recommend caution when combining antidepressants with other CNS drugs, particularly when coadministering MAOIs with other substances.