Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neuropathic pain is a persistent pain condition that develops secondary to nerve injury. The two most common types of peripheral neuropathic pain are post-herpetic neuralgia (PHN) and painful diabetic neuropathy (PDN). Amitriptyline, nortriptyline, desipramine and imipramine are TCAs that have been shown to be effective for the symptomatic relief of PHN and PDN. Serotonin noradrenaline reuptake inhibitors (SNRIs) such as venlafaxine and duloxetine have been shown to be very promising for the treatment of PDN with fewer adverse effects than TCAs. Selective serotonin reuptake inhibitors (SSRIs) were shown in a number of studies to have some efficacy in relieving PDN-related pain, yet other studies of the SSRIs have demonstrated conflicting outcomes. Most of the older antiepileptic studies were performed in patients with PDN; consequently, little is known about the efficacy of these drugs in patients with PHN. Carbamazepine, phenytoin and valproic acid were shown to be effective in ameliorating PDN-related pain. Other antiepileptic agents, including lamotrigine, oxcarbazepine and topiramate, have demonstrated some beneficial effects for the treatment of PDN, although they were also found to be ineffective in some PDN studies. alpha2delta Ligands such as gabapentin and pregabalin have been proven to be effective for the treatment of PHN and PDN in a number of large placebo-controlled trials. These drugs are useful not only in relieving pain but also in improving quality of life. Although the use of opioids for the treatment of neuropathic pain is controversial, a number of studies support the efficacy and safety of opioids in the treatment of neuropathic pain. Of these, oxycodone and tramadol have been shown to be superior to placebo for the treatment of PHN and PDN. A number of small studies have shown that dextromethorphan was effective in patients with PDN but not in patients with PHN. Topical agents such as lidocaine 5% patches and topical capsaicin are useful in ameliorating pain in patients with PHN but these agents are unsatisfactory for use as a sole agent. Although a number of drug treatments are available for the symptomatic relief of neuropathic pain symptoms, these agents do not provide satisfactory relief in all patients. For these patients, other treatment alternatives such as combination drug therapy that produces pain relief via distinctly different mechanisms may be successful. The purpose of this review is to compare the efficacy and limitations of currently available pharmacological treatments for the symptomatic relief of PHN and PDN, and to discuss the potential of combination therapy in PHN and PDN.
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PMID:An update on the pharmacological management of post-herpetic neuralgia and painful diabetic neuropathy. 1839 10

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.
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PMID:Antinociception occurs with a reversal in alpha 2-adrenoceptor regulation of TNF production by peripheral monocytes/macrophages from pro- to anti-inflammatory. 1851 87

Amitriptyline is used to treat neuropathic pain in humans. It produces antinociception in several animal models of pain, and this effect is blocked by methylxanthine adenosine receptor antagonists which implicates adenosine it its actions. Here, the antinociceptive effect of amitriptyline, and the ability of caffeine to reverse it, were examined using the formalin test (a model of persistent pain) in wild type mice and mice lacking the adenosine A(1) receptor (A1R). Amitriptyline produced dose-related suppression of flinching in wild type mice following both systemic and intraplantar drug administration; both of these effects were unaltered in A1R -/- mice. Following systemic administration, caffeine reversed the systemic effect of amitriptyline in wild type, but not A1R -/- mice; -/+ mice exhibited an intermediate effect. Intraplantar administration of caffeine also reversed the effect of intraplantar amitriptyline in A1R +/+, but not in -/- or +/- mice. These results indicate that adenosine A(1) receptors are not required in order for amitriptyline to cause antinociception in mice, but they are required to see caffeine reversal of this antinociceptive effect. When A1Rs are present, actions of amitriptyline may, however, partly depend on A1Rs.
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PMID:Caffeine reverses antinociception by amitriptyline in wild type mice but not in those lacking adenosine A1 receptors. 1856 97

In the present study, the characteristics of the sleep features of amitriptyline, mexiletine, and N-(4-tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropyradine-1(2H)-carbox-amide (BCTC) were studied. Electrodes were chronically implanted into the frontal cortex and the dorsal neck muscles of rats for electroencephalogram (EEG) and electromyogram (EMG) measurements, respectively. EEG and EMG were recorded with an electroencephalograph, and SleepSign ver. 2.0. was used for sleep-wake state analysis. Recordings were performed from 11:00 to 17:00. Amitriptyline caused significant decreases in sleep latency and total wake time and an increase in total non-rapid eye movement (non-REM) sleep time. Mexiletine caused a significant decrease in sleep latency, but no significant effect was observed in total wake time and total non-REM sleep time. On the other hand, BCTC, which is an antagonist of transient receptor potential vaniloid 1 (TRPV1), showed no significant effect on sleep latency, total wake time, total non-REM sleep time, and total REM sleep time. From these results, it can be concluded that a TRPV1 antagonist may become a useful drug for neuropathic pain without sedative side effects in the daytime, different from amitriptyline and mexiletine.
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PMID:Studies on somnolence in the daytime caused by drugs used for neuropathic pain. 1858 20

The objective of this study was to assess the efficacy and safety of amitriptyline as a treatment of FM. A comprehensive computerized search in Medline (Pubmed), EMBASE and The Cochrane Library was performed. Randomized controlled trials (RCTs) comparing amitriptyline vs placebo in adult patients suffering from FM were identified, the methodological quality was assessed and the results of the main outcomes were evaluated. Ten RCTs were identified. Large clinical variability and statistical heterogeneity precluded quantitative meta-analysis. Overall, the study quality was moderate to high. Amitriptyline 25 mg/day (six RCTs) demonstrated a therapeutic response compared with placebo in the domains of pain, sleep, fatigue and overall patient and investigator impression. This benefit was generally seen at 6-8 weeks of treatment but no effect was noted at 12 weeks. Amitriptyline 50 mg/day (four RCTs) did not demonstrate a therapeutic effect compared with placebo. Neither dose of amitriptyline had an effect on tender points count. No clear statements on adverse events with amitriptyline can be made due to inconsistencies in data among the studies. A definitive clinical recommendation regarding the efficacy of amitriptyline for FM symptoms cannot be made. There is some evidence to support the short-term efficacy of amitriptyline 25 mg/day in FM. There is no evidence to support the efficacy of amitriptyline at higher doses or for periods >8 weeks. More stringent RCTs with longer follow-up periods are required to determine the long-term efficacy and safety of the amitriptyline and define its role in the multidisciplinary management of FM.
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PMID:Amitriptyline in the treatment of fibromyalgia: a systematic review of its efficacy. 1898 12

Amitriptyline is a tricyclic antidepressant, considered the treatment of choice for different types of chronic pain, including chronic myofascial pain. Its antinociceptive property is independent of its antidepressant effect. Although its analgesic mechanism is not precisely known, it is believed that the serotonin reuptake inhibition in the central nervous system plays a fundamental role in pain control. Although this medication is widely used in the prevention of chronic tension-type headache, few studies have investigated the efficacy of this treatment and the published results are contradictory. The objective of this article was to review the literature published on the use of amitriptyline in the prophylactic treatment of chronic tension-type headache, considering the level of scientific evidence of the different studies using the SORT criteria. From this review, 5 articles of evidence level 1, and another 5 articles of evidence level 2 were selected. Following analysis of the 10 studies, and in function of their scientific quality, a level A recommendation was made in favor of using amitriptyline in the treatment of chronic tension-type headache.
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PMID:Use of amitriptyline for the treatment of chronic tension-type headache. Review of the literature. 1875 1

Migraine is common, underdiagnosed, and frequently inadequately treated in the general population. Nausea and vomiting are common reasons for patients to be referred for symptom control. Nausea can be the most prominent feature of migraine; the International Classification of Headache Disorders (ICHD) recognizes cyclical vomiting syndrome as a migraine variant in children, and there is increasing evidence for a similar entity in adults. We present three patients with troublesome nausea uncontrolled by conventional antiemetic therapy. On questioning, all three had other symptoms suggestive of migraine, and two had a family history. Their symptoms settled with the use of various antimigraine therapies. Amitriptyline appears to be particularly useful. A therapeutic trial of prophylaxis may be indicated for patients whose nausea and vomiting may be attributed to migraine.
J Pain Symptom Manage 2009 May
PMID:Migraine as a cause of persistent nausea or vomiting in palliative care: a case series. 1904 Dec 19

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.
Pain 2010 Apr
PMID:Low-dose amitriptyline for treatment of persistent arm pain due to repetitive use. 2017 54

Opioids have been discovered to have Toll-like receptor (TLR) activity, beyond actions at classical opioid receptors. This raises the question whether other pharmacotherapies for pain control may also possess TLR activity, contributing to or opposing their clinical effects. We document that tricyclics can alter TLR4 and TLR2 signaling. In silico simulations revealed that several tricyclics docked to the same binding pocket on the TLR accessory protein, myeloid differentiation protein 2 (MD-2), as do opioids. Eight tricyclics were tested for effects on TLR4 signaling in HEK293 cells over-expressing human TLR4. Six exhibited mild (desipramine), moderate (mianserin, cyclobenzaprine, imiprimine, ketotifen) or strong (amitriptyline) TLR4 inhibition, and no TLR4 activation. In contrast, carbamazepine and oxcarbazepine exhibited mild and strong TLR4 activation, respectively, and no TLR4 inhibition. Amitriptyline but not carbamazepine also significantly inhibited TLR2 signaling in a comparable cell line. Live imaging of TLR4 activation in RAW264.7 cells and TLR4-dependent interleukin-1 release from BV-2 microglia revealed that amitriptyline blocked TLR4 signaling. Lastly, tricyclics with no (carbamazepine), moderate (cyclobenzeprine), and strong (amitriptyline) TLR4 inhibition were tested intrathecally (rats) and amitriptyline tested systemically in wildtype and knockout mice (TLR4 or MyD88). While tricyclics had no effect on basal pain responsivity, they potentiated morphine analgesia in rank-order with their potency as TLR4 inhibitors. This occurred in a TLR4/MyD88-dependent manner as no potentiation of morphine analgesia by amitriptyline occurred in these knockout mice. This suggests that TLR2 and TLR4 inhibition, possibly by interactions with MD2, contributes to effects of tricyclics in vivo. These studies provide converging lines of evidence that several tricyclics or their active metabolites may exert their biological actions, in part, via modulation of TLR4 and TLR2 signaling and suggest that inhibition of TLR4 and TLR2 signaling may potentially contribute to the efficacy of tricyclics in treating chronic pain and enhancing the analgesic efficacy of opioids.
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PMID:Evidence that tricyclic small molecules may possess toll-like receptor and myeloid differentiation protein 2 activity. 2038 91

Amitriptyline (AMI) is widely used for migraine prophylaxis, but its mechanism is undetermined. Cortical spreading depression (CSD), reflected by alterations in calcium, sodium, and Na(+)-K(+)ATP channels, has been implicated in migraine and as a headache trigger. Evidences indicate that mutations in sodium and calcium channels are involved in migraine. Sodium channels are critical for the electrical excitability of sensory neurons and play a key role in pain sensation by controlling afferent impulse discharge. To investigate the mechanism underlying AMI effectiveness for migraine prophylaxis, we studied the effects of AMI on voltage-gated sodium channels in cultured rat cortical neurons by the whole-cell patch clamp recording and real-time reverse transcription polymerase chain reaction (RT-PCR). We found that AMI blocked sodium channel current (I(Na)) in a concentration-dependent, not voltage-dependent manner. AMI also altered the activation and steady-state inactivation of I(Na) toward hyperpolarization. Results of real-time RT-PCR indicated that AMI inhibited the expression for sodium channels in a concentration-dependent manner; inhibition of expression of the Na(V)1.1 and Na(V)1.6 sodium channels was more than that of Na(V)1.2. From these results, we speculate that AMI may reduce CSD by inhibiting I(Na) and mRNA expression of sodium channels. This may contribute to strategies for migraine prophylaxis.
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PMID:Amitriptyline inhibits currents and decreases the mRNA expression of voltage-gated sodium channels in cultured rat cortical neurons. 2039 37


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