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Affiliation(s)
| | - Carlotta Viti
- Department of Molecular Medicine, University of Padova, Bologna, Italy
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Abstract
It is evident that chronic pain can modify the excitability of central nervous system which imposes a specific challenge for the management and for the development of new analgesics. The central manifestations can be difficult to quantify using standard clinical examination procedures, but quantitative sensory testing (QST) may help to quantify the degree and extend of the central reorganization and effect of pharmacological interventions. Furthermore, QST may help in optimizing the development programs for new drugs.Specific translational mechanistic QST tools have been developed to quantify different aspects of central sensitization in pain patients such as threshold ratios, provoked hyperalgesia/allodynia, temporal summation (wind-up like pain), after sensation, spatial summation, reflex receptive fields, descending pain modulation, offset analgesia, and referred pain areas. As most of the drug development programs in the area of pain management have not been very successful, the pharmaceutical industry has started to utilize the complementary knowledge obtained from QST profiling. Linking patients QST profile with drug efficacy profile may provide the fundamentals for developing individualized, targeted pain management programs in the future. Linking QST-assessed pain mechanisms with treatment outcome provides new valuable information in drug development and for optimizing the management regimes for chronic pain.
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Affiliation(s)
- Lars Arendt-Nielsen
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, School of Medicine, Aalborg University, Fredrik Bajers Vej 7-D3, 9220, Aalborg, Denmark,
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3
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McKeown A, Gewandter JS, McDermott MP, Pawlowski JR, Poli JJ, Rothstein D, Farrar JT, Gilron I, Katz NP, Lin AH, Rappaport BA, Rowbotham MC, Turk DC, Dworkin RH, Smith SM. Reporting of sample size calculations in analgesic clinical trials: ACTTION systematic review. J Pain 2014; 16:199-206.e1-7. [PMID: 25481494 DOI: 10.1016/j.jpain.2014.11.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 11/10/2014] [Accepted: 11/13/2014] [Indexed: 11/29/2022]
Abstract
UNLABELLED Sample size calculations determine the number of participants required to have sufficiently high power to detect a given treatment effect. In this review, we examined the reporting quality of sample size calculations in 172 publications of double-blind randomized controlled trials of noninvasive pharmacologic or interventional (ie, invasive) pain treatments published in European Journal of Pain, Journal of Pain, and Pain from January 2006 through June 2013. Sixty-five percent of publications reported a sample size calculation but only 38% provided all elements required to replicate the calculated sample size. In publications reporting at least 1 element, 54% provided a justification for the treatment effect used to calculate sample size, and 24% of studies with continuous outcome variables justified the variability estimate. Publications of clinical pain condition trials reported a sample size calculation more frequently than experimental pain model trials (77% vs 33%, P < .001) but did not differ in the frequency of reporting all required elements. No significant differences in reporting of any or all elements were detected between publications of trials with industry and nonindustry sponsorship. Twenty-eight percent included a discrepancy between the reported number of planned and randomized participants. This study suggests that sample size calculation reporting in analgesic trial publications is usually incomplete. Investigators should provide detailed accounts of sample size calculations in publications of clinical trials of pain treatments, which is necessary for reporting transparency and communication of pre-trial design decisions. PERSPECTIVE In this systematic review of analgesic clinical trials, sample size calculations and the required elements (eg, treatment effect to be detected; power level) were incompletely reported. A lack of transparency regarding sample size calculations may raise questions about the appropriateness of the calculated sample size.
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Affiliation(s)
- Andrew McKeown
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Jennifer S Gewandter
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Michael P McDermott
- Department of Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York; Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York; Department of Center for Human Experimental Therapeutics, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Joseph R Pawlowski
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Joseph J Poli
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Daniel Rothstein
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - John T Farrar
- University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ian Gilron
- Queen's University, Kingston, Ontario, Canada
| | - Nathaniel P Katz
- Analgesic Solutions, Natick, Massachusetts; Department of Anesthesiology, Tufts University, Boston, Massachusetts
| | - Allison H Lin
- Center for Drug Evaluation and Research, United States Food and Drug Administration, Silver Spring, Maryland
| | - Bob A Rappaport
- Center for Drug Evaluation and Research, United States Food and Drug Administration, Silver Spring, Maryland
| | | | - Dennis C Turk
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington
| | - Robert H Dworkin
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York; Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York; Department of Center for Human Experimental Therapeutics, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Shannon M Smith
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York.
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Tompkins DA, Smith MT, Bigelow GE, Moaddel R, Venkata SL, Strain EC. The effect of repeated intramuscular alfentanil injections on experimental pain and abuse liability indices in healthy males. Clin J Pain 2014; 30:36-45. [PMID: 23446076 DOI: 10.1097/AJP.0b013e3182851758] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Opioid-induced hyperalgesia (OIH), increased sensitivity to noxious stimuli after repeated opioid exposures, has been demonstrated in preclinical studies. However, there is no accepted, prospective model of OIH after repeated opioid exposures currently available in humans. This study assessed a potential prospective OIH model. METHODS Double-blind intramuscular injections of a short-acting opioid (alfentanil 15 mcg/kg; N=8) were compared to active placebo (diphenhydramine 25 mg; N=3) on cold and pressure pain testing and standard abuse liability measures in eight 10-hour sessions (1 injection/session) over 4 to 5 weeks in healthy, pain-free males. Decreases from session baseline pain threshold (PThr) and tolerance (PTol) were calculated to represent hyperalgesia, and were assessed both within and across sessions. RESULTS Mean decreases in cold PTol were seen in the alfentanil group at 180 minutes (-3.8 s, ±26.5) and 480 minutes (-1.63 s, ±31.5) after drug administration. There was a trend for differences between conditions on cold PThr hyperalgesia but not for pressure PThr. Alfentanil participants had greater mean ratings on Liking and High visual analog scales at peak effects (30 min), but these scores did not change across sessions. DISCUSSION Repeated alfentanil exposures over 4 to 5 weeks resulted in within session decreases in cold pain tolerance from baseline but these differences were not substantially different from diphenhydramine controls. The results did not support the phenomenon of OIH in this model, although definitive conclusions regarding the existence of OIH in humans likely requires a larger sample size or an alternative model.
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Olesen AE, Andresen T, Staahl C, Drewes AM. Human experimental pain models for assessing the therapeutic efficacy of analgesic drugs. Pharmacol Rev 2012; 64:722-79. [PMID: 22722894 DOI: 10.1124/pr.111.005447] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Pain models in animals have shown low predictivity for analgesic efficacy in humans, and clinical studies are often very confounded, blurring the evaluation. Human experimental pain models may therefore help to evaluate mechanisms and effect of analgesics and bridge findings from basic studies to the clinic. The present review outlines the concept and limitations of human experimental pain models and addresses analgesic efficacy in healthy volunteers and patients. Experimental models to evoke pain and hyperalgesia are available for most tissues. In healthy volunteers, the effect of acetaminophen is difficult to detect unless neurophysiological methods are used, whereas the effect of nonsteroidal anti-inflammatory drugs could be detected in most models. Anticonvulsants and antidepressants are sensitive in several models, particularly in models inducing hyperalgesia. For opioids, tonic pain with high intensity is attenuated more than short-lasting pain and nonpainful sensations. Fewer studies were performed in patients. In general, the sensitivity to analgesics is better in patients than in healthy volunteers, but the lower number of studies may bias the results. Experimental models have variable reliability, and validity shall be interpreted with caution. Models including deep, tonic pain and hyperalgesia are better to predict the effects of analgesics. Assessment with neurophysiologic methods and imaging is valuable as a supplement to psychophysical methods and can increase sensitivity. The models need to be designed with careful consideration of pharmacological mechanisms and pharmacokinetics of analgesics. Knowledge obtained from this review can help design experimental pain studies for new compounds entering phase I and II clinical trials.
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Affiliation(s)
- Anne Estrup Olesen
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg Hospital, Mølleparkvej 4, 9000 Aalborg, Denmark.
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Arendt-Nielsen L, Hoeck HC. Optimizing the early phase development of new analgesics by human pain biomarkers. Expert Rev Neurother 2011; 11:1631-1651. [DOI: 10.1586/ern.11.147] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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Rubin TK, Henderson LA, Macefield VG. Changes in the Spatiotemporal Expression of Local and Referred Pain Following Repeated Intramuscular Injections of Hypertonic Saline: A Longitudinal Study. The Journal of Pain 2010; 11:737-45. [DOI: 10.1016/j.jpain.2009.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 10/17/2009] [Accepted: 11/09/2009] [Indexed: 11/30/2022]
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Staahl C, Olesen AE, Andresen T, Arendt-Nielsen L, Drewes AM. Assessing analgesic actions of opioids by experimental pain models in healthy volunteers - an updated review. Br J Clin Pharmacol 2009; 68:149-68. [PMID: 19694733 PMCID: PMC2767277 DOI: 10.1111/j.1365-2125.2009.03456.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Accepted: 04/02/2009] [Indexed: 11/30/2022] Open
Abstract
AIM Experimental pain models may help to evaluate the mechanisms of action of analgesics and target the clinical indications for their use. This review addresses how the efficacy of opioids can be assessed in human volunteers using experimental pain models. The drawback with the different study designs is also discussed. METHOD A literature search was completed for randomized controlled studies which included human experimental pain models, healthy volunteers and opioids. RESULTS Opioids with a strong affinity for the micro-opioid receptor decreased the sensation in a variety of experimental pain modalities, but strong tonic pain was attenuated more than short lasting pain and non-painful sensations. The effects of opioids with weaker affinity for the micro-opioid receptor were detected by a more narrow range of pain models, and the assessment methods needed to be more sensitive. CONCLUSION The way the pain is induced, assessed and summarized is very important for the sensitivity of the pain models. This review gives an overview of how different opioids perform in experimental pain models. Generally experimental pain models need to be designed with careful consideration of pharmacological mechanisms and pharmacokinetics of analgesics. This knowledge can aid the decisions needed to be taken when designing experimental pain studies for compounds entering phase 1 clinical trials.
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Affiliation(s)
- Camilla Staahl
- Center for Sensory-Motor Interactions, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7, Aalborg 9000, Denmark.
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Rubin TK, Gandevia SC, Henderson LA, Macefield VG. Effects of intramuscular anesthesia on the expression of primary and referred pain induced by intramuscular injection of hypertonic saline. J Pain 2009; 10:829-35. [PMID: 19380258 DOI: 10.1016/j.jpain.2009.01.327] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 01/13/2009] [Accepted: 01/31/2009] [Indexed: 11/30/2022]
Abstract
UNLABELLED Intramuscular injection of hypertonic saline produces pain in the belly of the injected muscle (primary pain) and, often, pain that projects distally (referred pain). While it is known that referred pain can be induced during complete sensory block of the distal site, there is little evidence as to whether the perception of referred pain depends on ongoing input from the primary stimulus. We assessed whether blocking the noxious input following the induction of pain blocks the primary but not the referred pain. A cannula was inserted into the tibialis anterior muscle in 15 subjects (8 male, 7 female). In a quasi-random crossover design conducted over 2 experimental sessions, each subject received a bolus intramuscular injection of .5 mL of 5% hypertonic saline, followed 90 seconds later by either: A) A second bolus injection or; B) An injection of 2 mL lignocaine through the same cannula. Protocol A was followed 60 seconds later by either a sham injection or an injection of lignocaine, while protocol B was followed 60 seconds later by either a sham injection or an injection of hypertonic saline. Subjects mapped the areas of primary and referred pain, and rated the intensities at these sites every 30 seconds until the cessation of pain. In all subjects, the area and intensity of primary pain rapidly disappeared within 7.5 minutes of intramuscular lignocaine injection (P < .02 relative to the nonanesthesia condition). With the exception of 2 subjects, in whom the referred pain continued in the absence of primary pain, the referred pain declined in parallel with local pain: the mean total pain intensity declined by 74% in both regions. We conclude that the maintenance of referred muscle pain usually depends on ongoing noxious inputs from the site of primary muscle pain. PERSPECTIVE Referred pain is a significant clinical problem, and commonly occurs with pain originating in muscle but not from skin. It is important to know the primary source of the pain so that treatment can be directed to this site rather to the site of referral.
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Affiliation(s)
- Troy K Rubin
- Prince of Wales Medical Research Institute, Sydney NSW, Australia
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Abstract
Visual analogue scales are commonly used to measure the intensity of sensations, and their validity and reliability have been reported. However, biases similar to those found in visual line bisection have not been investigated. 23 right-handed and 19 left-handed participants, with a mean age of 30.1 yr., marked three points on a visual analogue scale representing imagined pain, using both the left and right hands, corresponding to 1/4, 1/2, and 3/4 of the way across the scale. In keeping with visual line bisection literature, both right- and left-handed participants marked the scale with the left hand significantly leftward of the point marked with the right hand, thereby underreporting the intensity. Right-handed participants marked 1/4 significantly leftward and 3/4 significantly rightward of veridical points, thereby underreporting and overreporting, respectively, the intensity. However, left-handed participants did not display this bias and consistently erred leftward for 1/4, 1/2, and 3/4 positions, underreporting intensity. These findings were explained in terms of hemispheric specialisation and activation for a manual response to a visuospatial task, with the conclusion that scoring the visual analogue scale to millimetre accuracy is subject to a potential confound of these factors.
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Affiliation(s)
- Jacqui G McKechnie
- Department of Psychology, Glasgow Caledonian University, Cowcaddens Rd., Glasgow G4 0BA, UK.
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McKECHNIE JACQUIG. HAND AND HAND PREFERENCES IN USE OF A VISUAL ANALOGUE SCALE. Percept Mot Skills 2008. [DOI: 10.2466/pms.107.7.643-650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract
This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, United States.
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Olesen AE, Staahl C, Ali Z, Drewes AM, Arendt-Nielsen L. Effects of Paracetamol Combined with Dextromethorphan in Human Experimental Muscle and Skin Pain. Basic Clin Pharmacol Toxicol 2007; 101:172-6. [PMID: 17697036 DOI: 10.1111/j.1742-7843.2007.00095.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
By combining drugs with different mechanisms of action, synergistic effects may be achieved. The aim of the present experimental pain study was to combine paracetamol with dextromethorphan for synergistic effects. Furthermore, the reproducibility of the pain assessment methods was evaluated. Eighteen volunteers completed all periods in a three-way cross-over study. Pain stimuli were assessed at baseline and 1, 2 and 3 hr after dosing. The aim was to compare the pain-alleviating effect of 1 g paracetamol, 1 g paracetamol plus 30 mg dextromethorphan and placebo in response to a number of different stimuli in a human experimental volunteer model of skin and muscle pain. Repeated electrical stimulation of skin and muscle (temporal summation) modelled central integration and intramuscular hypertonic saline mimicked musculoskeletal pain. The method provided statistically stable pain recordings between repetitions on the same day and between days (all P > 0.05). Between repetitions on the same day, all tests were reproducible within the participants (intra-class correlation > 0.60). Between days all tests, except muscular pain pressure threshold, were reproducible within the participants (intra-class correlation > 0.60). There were no statistical differences (all P > 0.05) between paracetamol compared to placebo, and between the effect of paracetamol and dextromethorphan compared to placebo. The acute pain models were not sufficiently sensitive to detect an analgesic effect of paracetamol or the combination with dextromethorphan. The selected dose of dextromethorphan was low as the aim was to use commonly used doses, and a higher dose of dextromethorphan is most likely needed to attenuate the selected pain measures.
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Affiliation(s)
- Anne Estrup Olesen
- Center for Visceral Biomechanichs and Pain, Department of Medical Gastroenterology, University Hospital Aalborg, Aalborg, Denmark.
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