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Whitehead MC, Hoppes SM, Musser JMB, Perkins JL, Lepiz ML. The Use of Alfaxalone in Quaker Parrots ( Myiopsitta monachus). J Avian Med Surg 2020; 33:340-348. [PMID: 31833302 DOI: 10.1647/2018-393] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Alfaxalone is a neurosteroid anesthetic that acts on gamma-aminobutyric acid alpha-receptors. The objective of this study was to evaluate the clinical safety and efficacy of alfaxalone (Alfaxan CD). Due to observed hyperexcitability in the subject animals when alfaxalone was the only drug used during the initial trials, premedication with midazolam was also evaluated during the final study. Ten adult Quaker parrots (Myiopsitta monachus) were assigned to 3 groups: 1) low-dose alfaxalone 10 mg/kg (LD), 2) high-dose alfaxalone 25 mg/kg (HD), and 3) alfaxalone 10 mg/ kg with midazolam 1 mg/kg premedication (AM), administered intramuscularly. Induction time, sedation quality, duration of action, and vital parameters, including heart rate, respiratory rate, and temperature, were recorded. All protocols achieved adequate sedation; however, muscle tremors and hyperexcitation were variable. The LD group had a significantly longer mean ± SD induction time (13.5 ± 4.5 minutes) as compared to the HD (6.0 ± 1.3 minutes, P = .002) and AM (6.5 ± 2.9 minutes, P = .006) groups, while recovery time was significantly longer in the HD group (86.2 ± 13.4 minutes) than the LD group (44.4 ± 10.8 minutes, P < .001). Midazolam premedication resulted in reduction of both muscle tremors and hyperexcitation associated with alfaxalone administration, but the recovery time was significantly longer (103.5 ± 15.1 minutes, P < .001) than for the LD group. Alfaxalone as a sole agent resulted in muscle tremors and hyperexcitation during induction, which was attenuated by premedication with midazolam. Further investigation is warranted to characterize the effects of alfaxalone and drugs used to premedicate Quaker parrots.
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Affiliation(s)
- Michelle C Whitehead
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4474, USA
| | - Sharman M Hoppes
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4474, USA
| | - Jeffrey M B Musser
- Department of Veterinary Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA
| | - Jennifer L Perkins
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4474, USA
| | - Mauricio L Lepiz
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4474, USA
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Sedative effects of two doses of alfaxalone in combination with methadone and a low dose of dexmedetomidine in healthy Beagles. Vet Anaesth Analg 2020; 47:463-471. [PMID: 32507717 DOI: 10.1016/j.vaa.2019.12.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 11/11/2019] [Accepted: 12/02/2019] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To evaluate the sedative effects of two doses of alfaxalone when added to a combination of dexmedetomidine and methadone injected intramuscularly (IM) in healthy Beagles. STUDY DESIGN Randomized, blinded, crossover, experimental study. ANIMALS A group of six adult Beagles. METHODS Dogs were sedated on three different occasions with IM dexmedetomidine (3 μg kg-1) and methadone (0.3 mg kg-1) combined with two doses of alfaxalone (0.5 and 1 mg kg-1; A0.5 and A1, respectively) or saline (A0). Quality of sedation, response to tail clamping and rectal temperature were recorded at baseline, 5, 15, 25, 35 and 45 minutes. Pulse and respiratory rates, oxygen saturation of haemoglobin (SpO2) and noninvasive blood pressure (NIBP) were recorded every 5 minutes. Onset of sedation and duration of recumbency, response to venous catheterization and recovery quality were assessed. Physiological variables (analysis of variance) were analysed between treatments and within treatments compared with baseline (Student t test). Nonparametric data were analysed using Friedman and Cochran's Q tests. Significance was p < 0.05. RESULTS Sedation scores were significantly higher when alfaxalone was co-administered (area under the curve; p = 0.024, A0.5; p = 0.019, A1), with no differences between doses. Onset of sedation was similar, but duration of recumbency was longer in A0.5 than in A0 [median (minimum-maximum), 43 (35-54) versus 30 (20-47) minutes, p = 0.018], but not in A1. Response to venous catheterization and tail clamping, and quality of recovery (acceptable) presented no differences between treatments. A decrease in all physiological variables (compared with baseline) was observed, except for NIBP, with no differences between treatments. All dogs required oxygen supplementation due to reduced SpO2. CONCLUSIONS AND CLINICAL RELEVANCE Adding alfaxalone to methadone and dexmedetomidine enhanced sedation and duration of recumbency. Although cardiopulmonary depression was limited, oxygen supplementation is advisable.
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Lin WL, Lee MS, Wong CS, Chan SM, Lai HC, Wu ZF, Lu CH. Effects of intraoperative propofol-based total intravenous anesthesia on postoperative pain in spine surgery: Comparison with desflurane anesthesia - a randomised trial. Medicine (Baltimore) 2019; 98:e15074. [PMID: 30921241 PMCID: PMC6456101 DOI: 10.1097/md.0000000000015074] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND As reported, patients experience less postoperative pain after propofol-based total intravenous anesthesia (TIVA). In the present study, we investigated the postoperative analgesic effects between propofol-based TIVA and desflurane anesthesia after spine surgery. METHODS Sixty patients were included who received (surgical time >180 minutes) lumbar spine surgery. Patients were randomly assigned to receive either TIVA (with target-controlled infusion) with propofol/fentanyl-based anesthesia (TIVA group) or desflurane/fentanyl-based anesthesia (DES group), titrated to maintain Bispectral Index values between 45 and 55. All patients received patient-controlled analgesia (PCA) with fentanyl for postoperative pain relief. Numeric pain rating scale (NRS) pain scores, postoperative fentanyl consumption, postoperative rescue tramadol use, and fentanyl-related side effects were recorded. RESULTS The TIVA group patients reported lower NRS pain scores during coughing on postoperative day 1 but not day 2 and 3 (P = .002, P = .133, P = .161, respectively). Less fentanyl consumption was observed on postoperative days 1 and 2, but not on day 3 (375 μg vs 485 μg, P = .032, 414 μg vs 572 μg, P = .033, and 421 μg vs 479 μg, P = .209, respectively), less cumulative fentanyl consumption at postoperative 48 hours (790 μg vs 1057 μg, P = .004) and 72 hours (1210 μg vs 1536 μg, P = .004), and total fentanyl consumption (1393 μg vs 1704 μg, P = .007) when compared with the DES group. No difference was found in rescue tramadol use and fentanyl-related side effects. CONCLUSION Patients anesthetized with propofol-based TIVA reported less pain during coughing and consumed less daily and total PCA fentanyl after lumbar spine surgery.
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Affiliation(s)
- Wei-Lin Lin
- Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center
| | | | - Chih-Shung Wong
- Department of Anesthesiology, Cathay General Hospital, Taipei
| | - Shun-Ming Chan
- Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center
| | - Hou-Chuan Lai
- Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center
| | - Zhi-Fu Wu
- Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center
- Department of Anesthesiology, Chi Mei Medical Center, Tainan, Taiwan, Republic of China
| | - Chueng-He Lu
- Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center
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Bennell PM, Whittem T, Tudor E. A controlled randomized clinical trial to assess postoperative analgesia after thiopental-isoflurane anaesthesia or total intravenous anaesthesia with alfaxalone in dogs. J Vet Pharmacol Ther 2019; 42:268-277. [PMID: 30666663 DOI: 10.1111/jvp.12740] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 11/25/2018] [Accepted: 11/26/2018] [Indexed: 11/26/2022]
Abstract
Alfaxalone, a synthetic neuroactive steroid, has been attributed with properties including sedation, anaesthesia and analgesia. The clinical relevance of any analgesic properties of alfaxalone has not been demonstrated. This study was a prospective, blinded, randomized, negative control clinical trial in 65 healthy dogs presented for ovariohysterectomy. Anaesthesia was induced and maintained, for Group 1 (TIVA) dogs (n = 30) with intravenous alfaxalone alone and for Group 2 dogs (n = 35) with thiopental followed by isoflurane in 100% oxygen inhalation. After ovariohysterectomy, quantitative measures of pain or nociception were recorded at 15 min intervals for 4 hr using three independent scoring systems, a composite measure pain scale (CMPS), von Frey threshold testing and measures of fentanyl rescue analgesia. The mean CMPS scores of Group 2 (THIO/ISO) dogs remained higher than Group 1 (TIVA) dogs from 15 to 135 min post-surgery but this difference was not statistically significant. There were no significant differences between groups in the proportions of dogs requiring rescue fentanyl analgesia, the total fentanyl dose used or the time to first fentanyl dose. The Von Frey threshold testing was found to be unsuitable for measurement of pain in this experimental model. When administered as total intravenous anaesthesia, alfaxalone did not provide analgesia in the postoperative period.
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Affiliation(s)
- Paula M Bennell
- Melbourne Veterinary School, University of Melbourne, Parkville, Victoria, Australia
| | - Ted Whittem
- Melbourne Veterinary School, University of Melbourne, Parkville, Victoria, Australia
| | - Elizabeth Tudor
- Melbourne Veterinary School, University of Melbourne, Parkville, Victoria, Australia
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Italiano M, Robinson R. Effect of benzodiazepines on the dose of alfaxalone needed for endotracheal intubation in healthy dogs. Vet Anaesth Analg 2018; 45:720-728. [DOI: 10.1016/j.vaa.2018.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 04/08/2018] [Accepted: 06/12/2018] [Indexed: 11/30/2022]
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ALFAXALONE ANESTHESIA IN THE BENGALESE FINCH (LONCHURA DOMESTICA). J Zoo Wildl Med 2017; 48:1146-1153. [DOI: 10.1638/2016-0300r.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Fernández-Parra R, Donnelly TM, Pignon C, Noirault A, Zilberstein L. Immersıon Anesthesia with Alfaxalone in a Goldfısh ( Carassius auratus ). J Exot Pet Med 2017. [DOI: 10.1053/j.jepm.2017.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Bertrand HGMJ, Sandersen C, Murray J, Flecknell PA. A combination of alfaxalone, medetomidine and midazolam for the chemical immobilization of Rhesus macaque (Macaca mulatta): Preliminary results. J Med Primatol 2017; 46:332-336. [PMID: 28940590 DOI: 10.1111/jmp.12315] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2017] [Indexed: 01/15/2023]
Abstract
BACKGROUND Chemical immobilization of non-human primates can be required to perform scientific or veterinary procedure with different invasiveness degrees. This preliminary study was undertaken to assess the clinical effects of a combination of alfaxalone, medetomidine and midazolam (AMM). METHODS Seven rhesus macaques were chemically immobilized, for invasive veterinary procedures, with alfaxan 2 mg kg-1 , medetomidine 20 μg kg-1 and midazolam 0.3 mg kg-1 injected subcutaneously. RESULTS The alfaxalone combination induced surgical anaesthesia, with a complete absence of response to noxious stimuli, for at least 20 minutes. The total duration of anaesthesia was 56 ± 7 minutes, and the administration of atipamezole, to partially reverse the combination effects, did not appear to alter the depth of anaesthesia. CONCLUSION In conclusion, the AMM combination produced rapid onset general anaesthesia, following subcutaneous administration of a relatively low volume (0.28 mL/kg) of injectate.
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Affiliation(s)
- Henri G M J Bertrand
- Comparative Biology Centre, Newcastle University, Newcastle upon Tyne, UK.,Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
| | - Charlotte Sandersen
- Faculty of Veterinary Medicine, Veterinary Anesthesia Department, University of Liege, Liege, Belgium
| | - Jennifer Murray
- Comparative Biology Centre, Newcastle University, Newcastle upon Tyne, UK
| | - Paul A Flecknell
- Comparative Biology Centre, Newcastle University, Newcastle upon Tyne, UK.,Institute of Neurosciences, Newcastle University, Newcastle upon Tyne, UK
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Bennett RC, Salla KM, Raekallio MR, Scheinin M, Vainio OM. Effects of the α2-adrenoceptor agonist medetomidine on the distribution and clearance of alfaxalone during coadministration by constant rate infusion in dogs. Am J Vet Res 2017; 78:956-964. [DOI: 10.2460/ajvr.78.8.956] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Kalchofner Guerrero KS, Reichler IM, Schwarz A, Jud RS, Hässig M, Bettschart-Wolfensberger R. Alfaxalone or ketamine-medetomidine in cats undergoing ovariohysterectomy: a comparison of intra-operative parameters and post-operative pain. Vet Anaesth Analg 2014; 41:644-53. [DOI: 10.1111/vaa.12157] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 07/26/2013] [Indexed: 11/29/2022]
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Hansen LL, Bertelsen MF. Assessment of the effects of intramuscular administration of alfaxalone with and without medetomidine in Horsfield's tortoises (Agrionemys horsfieldii). Vet Anaesth Analg 2013; 40:e68-75. [PMID: 23672199 DOI: 10.1111/vaa.12045] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 02/12/2013] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To characterise four different intramuscular (IM) anaesthetic protocols, two with alfaxalone and two with alfaxalone in combination with medetomidine in terrestrial tortoises. STUDY DESIGN Blinded, randomized, cross-over experimental study. ANIMALS Nine healthy adult male Horsfield's tortoises (Agrionemys horsfieldii). METHODS Each tortoise was randomly assigned to one of four different protocols: 1) 10 mg kg(-1) alfaxalone; 2) 10 mg kg(-1) alfaxalone + 0.10 mg kg(-1) medetomidine; 3) 20 mg kg(-1) alfaxalone; and 4) 20 mg kg(-1) alfaxalone + 0.05 mg kg(-1) medetomidine. During the experiment, the following variables were recorded: heart rate; respiratory rate; peripheral nociceptive responses; muscle strength; ability to intubate; palpebral, corneal and tap reflexes; and cloacal temperature. RESULTS Protocols 1 and 2 resulted in moderate sedation with no analgesia, and moderate to deep sedation with minimal analgesia, respectively. Protocols 3 and 4 resulted in deep sedation or anaesthesia with variable analgesic effect; these two protocols had the longest total anaesthetic time and allowed intubation in 6/9 and 8/9 tortoises respectively. The total anaesthesia/sedation time produced by alfaxalone was significantly increased (p < 0.05) by the addition of medetomidine. There were no significant differences regarding time to plateau phase and duration of plateau phase. Baseline heart rate of 53 ± 6 beats minute(-1) decreased significantly (p < 0.05) with all protocols, and was lower (p < 0.05) in protocols 3 and 4. Heart rate increased after atipamezole administration, but the increase was transient. In two tortoises, extreme bradycardia with no cardiac activity for 10 minutes was observed with protocols 3 and 4. CONCLUSION AND CLINICAL RELEVANCE Alfaxalone 10 and 20 mg kg(-1) IM can be used for sedation for non-painful procedures. Alfaxalone in combination with medetomidine can be used for deeper sedation or anaesthesia, but the observed respiratory and cardiovascular depression may limit its use.
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Affiliation(s)
- Lone L Hansen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg C, Denmark
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Takechi K, Carstens MI, Klein AH, Carstens E. The antinociceptive and antihyperalgesic effects of topical propofol on dorsal horn neurons in the rat. Anesth Analg 2013; 116:932-8. [PMID: 23337417 DOI: 10.1213/ane.0b013e31827f560d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Propofol (2,6-diisopropylphenol) is an IV anesthetic used for general anesthesia. Recent evidence suggests that propofol-anesthetized patients experience less postoperative pain, and that propofol has analgesic properties when applied topically. We presently investigated the antinociceptive effects of topical propofol using behavioral and single-unit electrophysiological methods in rats. METHODS In behavioral experiments with rats, we assessed the effect of topical hindpaw application of propofol (1%-25%) on heat and mechanically evoked paw withdrawals. In electrophysiological experiments, we recorded from lumbar dorsal horn wide dynamic range (WDR)-type neurons in pentobarbital-anesthetized rats. We assessed the effect of topical application of propofol to the ipsilateral hindpaw on neuronal responses elicited by noxious heat, cold, and mechanical stimuli. We additionally tested whether propofol blocks heat sensitization of paw withdrawals and WDR neuronal responses induced by topical application of allyl isothiocyanate (AITC; mustard oil). RESULTS Topical application of propofol (1%-25%) significantly increased the mean latency of the thermally evoked hindpaw withdrawal reflex on the treated (but not opposite) side in a concentration-dependent manner, with no effect on mechanically evoked hindpaw withdrawal thresholds. Propofol also prevented shortening of paw withdrawal latency induced by AITC. In electrophysiological experiments, topical application of 10% and 25% propofol, but not 1% propofol or vehicle (10% intralipid), to the ipsilateral hindpaw significantly attenuated the magnitude of responses of WDR neurons to noxious heating of glabrous hindpaw skin with no significant change in thermal thresholds. Maximal suppression of noxious heat-evoked responses was achieved 15 minutes after application followed by recovery to the pre-propofol baseline by 30 minutes. Responses to skin cooling or graded mechanical stimuli were not significantly affected by any concentration of propofol. Topical application of AITC enhanced the noxious heat-evoked response of dorsal horn neurons. This enhancement of heat-evoked responses was attenuated when 10% propofol was applied topically after application of AITC. CONCLUSIONS The results indicate that topical propofol inhibits responses of WDR neurons to noxious heat consistent with analgesia, and reduced AITC sensitization of WDR neurons consistent with an antihyperalgesic effect. These results are consistent with clinical studies demonstrating reduced postoperative pain in surgical patients anesthetized with propofol. The mechanism of analgesic action of topical propofol is not clear, but may involve desensitization of TRPV1 or TRPA1 receptors expressed in peripheral nociceptive nerve endings, engagement of endocannabinoids, or activation of peripheral γ-aminobutyric acid A receptors.
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Affiliation(s)
- Kenichi Takechi
- Department of Anesthesiology and Resuscitology, Ehime University Medical School, Matsuyama, Japan
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Oral opioid analgesics vs. spinal steroid injections in the treatment of low back pain syndromes. Am J Phys Med Rehabil 2012; 91:162-76. [PMID: 22037559 DOI: 10.1097/phm.0b013e318238a028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The aim of this study was to examine the outcomes related to analgesia, function, mortality, and adverse effects of oral opioid analgesics and spinal steroid injections on low back pain syndromes. DESIGN Databases including Medline, EMBASE, PubMed, and Cochrane Library were searched in September 2009 using combinations of terms related to spinal pain and its treatment. A systematic review was performed of randomized controlled trials that enrolled patients with low back pain syndromes and that evaluated patient outcomes after intervention using either oral opioids or spinal steroid injections. RESULTS Eight high-quality and ten moderate-quality randomized controlled trials were identified. One high-quality study on oral opioid therapy showed significant improvements in pain relief and patient function. Those on spinal steroid injections had a decreased Visual Analog Scale pain score by 7.18 (95% confidence interval, 2.21-12.1) points more than the control group at 1 mo or less and by 0.429 (95% confidence interval, -4.41 to 5.27) points at 1-3 mos. At more than 6 mos, there was no significant benefit: 0.930 (95% confidence interval, -5.03 to 6.89). Spinal steroids decreased the Oswestry Disability Index by 3.53 (95% confidence interval, 0.480-6.57) at 1 mo or less, by -0.281 (95% confidence interval, -3.18 to 2.62) at 1-3 mos, by -11.0 (95% confidence interval, -14.8 to -7.16) at 3-6 mos, and by -0.205 (95% confidence interval, -3.50 to 3.09) compared with the control group at 6 mos or more, suggesting that there was improvement in function. All-cause mortality was low in our analysis of patients attending specialty clinics. It was difficult to assess the adverse effects of opioid therapy because they influenced up to 28% of patients to withdraw from the original studies. In terms of spinal steroid injections, headache appeared to be the most common adverse effect. However, there was no significantly increased risk of headaches associated with spinal steroids compared with control injections: odds ratio, 1.29 (95% confidence interval, 0.69-2.39). CONCLUSIONS Oral opioid therapy may be helpful for the treatment of low back pain, but it is unclear from the high-quality literature whether there are limitations from adverse effects. Spinal steroid injections are beneficial for low back pain and disability in the short-term. The high dropout rates caused by insufficient pain relief and adverse effects suggest that opioids may not be as effective as spinal steroid injections. There is more high-quality literature to support the use of spinal steroid injections compared with oral opioids in this condition.
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Rodríguez JM, Muñoz-Rascón P, Navarrete-Calvo R, Gómez-Villamandos RJ, Domínguez Pérez JM, Fernández Sarmiento JA, Quirós Carmona S, Granados Machuca MM. Comparison of the cardiopulmonary parameters after induction of anaesthesia with alphaxalone or etomidate in dogs. Vet Anaesth Analg 2012; 39:357-65. [PMID: 22405410 DOI: 10.1111/j.1467-2995.2011.00695.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To compare the cardiorespiratory effects and quality of induction of and recovery from anaesthesia following etomidate or alphaxalone-HPCD IV. STUDY DESIGN Randomized 'blinded' cross-over study. Twenty-four hours was allowed between phases. ANIMALS Eight healthy adult Beagles (four male, four female). METHODS Dogs were anaesthetized with sevoflurane for instrumentation, then allowed to awake. They then received etomidate (treatment E) or alphaxalone-HPCD (treatment A) intravenously to effect. Heart rate (HR), body temperature, invasive arterial pressures (AP), systemic vascular resistance index (SVRI), stroke volume index, cardiac index (CI), contractility, respiratory rate, central venous pressure, and capnometry were obtained before anaesthetic induction (baseline), 30 seconds and 1 minute after induction, after intubation, one minute after intubation, and for every 5 minutes afterwards until the dog began to swallow and the trachea was extubated. Arterial bloods were taken for analyses before induction, after intubation and every 10 minutes thereafter. The dogs breathed room air. The quality of induction of and recovery from anaesthesia were scored categorically. Statistical analyses used anova for repeated measures, paired t-tests or Wilcoxon signed rank-test as relevant. Significance was set at p < 0.05. RESULTS The induction doses required were (mean ± SD) 2.91 ± 0.41 mg kg(-1) and 4.15 ± 0.7 mg kg(-1) for treatment E and A respectively. No significant changes in cardiovascular parameters were observed with treatment E. Treatment A resulted in statistically significant increases in HR and CI and reductions of APs and SVRI. Time to extubation was longer with treatment A (25 ± 7 minutes) than with treatment E (17 ± 4 minutes). Dogs became hypoxic with both treatments. The quality of induction and recovery were excellent with treatment A, but significantly less satisfactory with treatment E (recovery score, treatment E median 1, range 0-2; treatment A median 0, range 0-1). CONCLUSIONS AND CLINICAL RELEVANCE Alphaxalone-HPCD caused significant tachycardia and increase in CI, and statistically (but not clinically) significant decreases in APs and SVRI. Etomidate caused no statistically significant cardiovascular changes. Quality of recovery was better with alfaxalone-HPCD. Both agents caused short-lived hypoxia, and oxygen supplementation is advisable.
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Kilts JD, Tupler LA, Keefe FJ, Payne VM, Hamer RM, Naylor JC, Calnaido RP, Morey RA, Strauss JL, Parke G, Massing MW, Youssef NA, Shampine LJ, Marx CE. Neurosteroids and self-reported pain in veterans who served in the U.S. Military after September 11, 2001. PAIN MEDICINE 2010; 11:1469-76. [PMID: 20735755 DOI: 10.1111/j.1526-4637.2010.00927.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Nearly half of Operation Enduring Freedom/Operation Iraqi Freedom veterans experience continued pain post-deployment. Several investigations report analgesic effects of allopregnanolone and other neurosteroids in animal models, but few data are currently available focusing on neurosteroids in clinical populations. Allopregnanolone positively modulates GABA(A) receptors and demonstrates pronounced analgesic and anxiolytic effects in rodents, yet studies examining the relationship between pain and allopregnanolone in humans are limited. We thus hypothesized that endogenous allopregnanolone and other neurosteroid levels may be negatively correlated with self-reported pain symptoms in humans. DESIGN We determined serum neurosteroid levels by gas chromatography/mass spectrometry (allopregnanolone, pregnenolone) or radioimmunoassay (dehydroepiandrosterone [DHEA], progesterone, DHEA sulfate [DHEAS]) in 90 male veterans who served in the U.S. military after September 11, 2001. Self-reported pain symptoms were assessed in four areas (low back pain, chest pain, muscle soreness, headache). Stepwise linear regression analyses were conducted to investigate the relationship between pain assessments and neurosteroids, with the inclusion of smoking, alcohol use, age, and history of traumatic brain injury as covariates. SETTING Durham VA Medical Center. RESULTS Allopregnanolone levels were inversely associated with low back pain (P=0.044) and chest pain (P=0.013), and DHEA levels were inversely associated with muscle soreness (P=0.024). DHEAS levels were positively associated with chest pain (P=0.001). Additionally, there was a positive association between traumatic brain injury and muscle soreness (P=0.002). CONCLUSIONS Neurosteroids may be relevant to the pathophysiology of self-reported pain symptoms in this veteran cohort, and could represent future pharmacological targets for pain disorders.
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Affiliation(s)
- Jason D Kilts
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27705, USA
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Murison PJ, Taboada FM. Effect of propofol and alfaxalone on pain after ovariohysterectomy in cats. Vet Rec 2010; 166:334-5. [DOI: 10.1136/vr.b4788] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- P. J. Murison
- University of Bristol; Division of Companion Animal Studies; Langford House Langford, Bristol BS40 5DU
| | - F. M. Taboada
- University of Bristol; Division of Companion Animal Studies; Langford House Langford, Bristol BS40 5DU
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Muir W, Lerche P, Wiese A, Nelson L, Pasloske K, Whittem T. The cardiorespiratory and anesthetic effects of clinical and supraclinical doses of alfaxalone in cats. Vet Anaesth Analg 2009; 36:42-54. [DOI: 10.1111/j.1467-2995.2008.00428.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Pogatzki-Zahn EM, Zahn PK, Brennan TJ. Postoperative pain--clinical implications of basic research. Best Pract Res Clin Anaesthesiol 2007; 21:3-13. [PMID: 17489216 DOI: 10.1016/j.bpa.2006.11.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Postoperative incisional pain is a unique and common form of acute pain. Although ample evidence indicates that an efficeous postoperative pain treatment reduces patient morbidity and patient outcome, recent studies demonstrate that about 50-70% of patients experience moderate to severe pain after surgery indicating that postoperative pain remains poorly treated. Perhaps important reasons for this quandary are distinct mechanisms of incisional nociception compared to other pain conditions limiting our regimen to drugs designed for other clinical pain problems. Another reason might be the lack of an in depth knowledge about the pathophysiology and neuropharmacology of postoperative pain. Basic research offers important insights in the mechanisms of postsurgical incisional pain and the translation of experimental results into clinical practice will have important implications on the improvement of new multimodal treatment regimens based postoperative pain mechanisms. In the present review, recent developments in experimental postsurgical incisional pain research will be described and their possible relevance for clinical practice discussed.
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Affiliation(s)
- Esther M Pogatzki-Zahn
- Department of Anesthesiology and Intensive Care Medicine, University of Muenster, Albert Schweitzer Str. 33, 48149 Muenster, Germany.
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WHITTEM T. KN01 Anaesthesia and analgesia at the central GABA Areceptor. J Vet Pharmacol Ther 2006. [DOI: 10.1111/j.1365-2885.2006.00759_1.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ferré PJ, Pasloske K, Whittem T, Ranasinghe MG, Li Q, Lefebvre HP. Plasma pharmacokinetics of alfaxalone in dogs after an intravenous bolus of Alfaxan-CD RTU. Vet Anaesth Analg 2006; 33:229-36. [PMID: 16764587 DOI: 10.1111/j.1467-2995.2005.00264.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To determine the pharmacokinetic parameters of alfaxalone in dogs after the intravenous (IV) administration of clinical and supra-clinical doses of a 2-hydroxypropyl-beta-cyclodextrin (HPCD) alfaxalone formulation (Alfaxan-CD RTU). EXPERIMENTAL DESIGN Prospective two-period crossover design. Animals Eight (four male and four female) young adult healthy Beagle dogs. Methods The steroid anaesthetic alfaxalone was administered IV at two doses in a crossover design (2 and 10 mg kg(-1)) with a washout period of 21 days. Blood samples were collected before and up to 8 hours after dosing. Plasma concentrations of alfaxalone were assayed using a liquid chromatograph/mass selective detector technique and analyzed to estimate the main pharmacokinetic parameters by noncompartmental analysis. Results were expressed as mean +/- SD. RESULTS The mean duration of anaesthesia from endotracheal intubation to extubation was 6.4 +/- 2.9 and 26.2 +/- 7.5 minutes, for the 2 and 10 mg kg(-1) doses, respectively. The plasma clearance of alfaxalone for the 2 and 10 mg kg(-1) doses differed statistically at 59.4 +/- 12.9 and 52.9 +/- 12.8 mL kg(-1) minute(-1), respectively (p = 0.008) but this difference was deemed clinically unimportant; the harmonic mean plasma terminal half-lives (t(1/2)) were 24.0 +/- 1.9 and 37.4 +/- 1.6 minutes respectively. The volume of distribution was between 2 and 3 L kg(-1) and did not differ between the two doses. No sex effect was observed. CONCLUSIONS AND CLINICAL RELEVANCE Alfaxalone, as an HPCD formulation (Alfaxan-CD RTU) administered in the dog provides rapid and smooth induction of anaesthesia, satisfactory conditions for endotracheal intubation and a short duration of anaesthesia. There was no clinically significant modification of the pharmacokinetic parameters between sexes and between the clinical (2 mg kg(-1)) and supra-clinical (10 mg kg(-1)) doses.
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Affiliation(s)
- Pierre J Ferré
- UMR 181 Physiopathologie et Toxicologie Expérimentales INRA-ENVT, France
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Gilron I. Review article: The role of anticonvulsant drugs in postoperative pain management: a bench-to-bedside perspective. Can J Anaesth 2006; 53:562-71. [PMID: 16738290 DOI: 10.1007/bf03021846] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Anticonvulsant drugs are effective in the treatment of chronic neuropathic pain but were not, until recently, thought to be useful in more acute conditions such as postoperative pain. However, similar to nerve injury, surgical tissue injury is known to produce neuroplastic changes leading to spinal sensitization and the expression of stimulus-evoked hyperalgesia and allodynia. Pharmacological effects of anticonvulsant drugs which may be important in the modulation of these postoperative neural changes include suppression of sodium channel, calcium channel and glutamate receptor activity at peripheral, spinal and supraspinal sites. The purpose of this article is to review preclinical evidence and clinical trial data describing the efficacy and safety of anticonvulsant drugs in the setting of postoperative pain management. SOURCE A Medline search was performed to retrieve available literature on the basic and clinical pharmacology of anticonvulsant drugs as they pertain to postoperative pain management. PRINCIPAL FINDINGS Numerous laboratory studies have described analgesic effects of different anticonvulsant drugs in experimental pain models. Furthermore, several recent clinical trials have shown that anticonvulsants may reduce spontaneous and movement-evoked pain, as well as decrease opioid requirements postoperatively. Some early findings suggest further that anticonvulsant drugs may alleviate postoperative anxiety, accelerate postoperative functional recovery and reduce chronic postsurgical pain. CONCLUSION Given the incomplete efficacy of currently available non-opioid analgesics, and the identified benefits of opioid sparing, anticonvulsant medications may be useful adjuncts for postoperative analgesia. Further research in this field is warranted.
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Affiliation(s)
- Ian Gilron
- Department of Anesthesiology, Kingston General Hospital, Queen's University, Kingston, Ontario, Canada.
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Petrenko AB, Yamakura T, Askalany AR, Kohno T, Sakimura K, Baba H. Effects of ketamine on acute somatic nociception in wild-type and N-methyl-d-aspartate (NMDA) receptor ɛ1 subunit knockout mice. Neuropharmacology 2006; 50:741-7. [PMID: 16427663 DOI: 10.1016/j.neuropharm.2005.11.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 11/14/2005] [Accepted: 11/29/2005] [Indexed: 10/25/2022]
Abstract
Although the properties of ketamine appear to be well characterized, there is a lot of ambiguity in the literature regarding its analgesic effects. After careful selection of proper experimental conditions and drug doses, we systematically characterized the effects of systemic ketamine on acute somatic nociception in mice and examined the role of the NMDA receptor epsilon1 subunit in mediating its analgesia. Intraperitoneal administration of ketamine was not analgesic in any of the phasic pain assays (thermal, mechanical, electrical) applied to C57BL/6 (wild-type) and NMDA receptor epsilon1 subunit knockout (mutant) mice. Surprisingly, rather than being analgesic for thermal nociception, ketamine showed pronociceptive properties in case of low-intensity heat stimulation in wild-type mice. In the formalin test (tonic pain), ketamine significantly reduced phase 2 nociceptive behavior in both wild-type and mutant mice. These data indicate that in wild-type mice ketamine has no analgesic effect on phasic pain in normal somatic tissues, but alleviates tonic pain after inflammation. Such analgesic spectrum of ketamine can be fully explained by its NMDA receptor antagonist properties. The results for the mutant mice suggest that the epsilon1 subunit of the NMDA receptor does not mediate the analgesic effects of ketamine in tonic pain.
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Affiliation(s)
- Andrey B Petrenko
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, Asahimachi 1-757, Niigata 951-8510, Japan
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Pathirathna S, Todorovic SM, Covey DF, Jevtovic-Todorovic V. 5alpha-reduced neuroactive steroids alleviate thermal and mechanical hyperalgesia in rats with neuropathic pain. Pain 2006; 117:326-339. [PMID: 16150542 DOI: 10.1016/j.pain.2005.06.019] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Revised: 06/15/2005] [Accepted: 06/20/2005] [Indexed: 11/30/2022]
Abstract
5alpha-reduced neuroactive steroids with selective modulatory action in vitro on T or combined modulatory action on T and GABA(A) currents present in peripheral sensory neurons have been shown to induce potent peripheral analgesia in vivo in intact animals. Although the role of T and GABA(A) currents in pathophysiology of neuropathic pain (NPP) is not established, it appears that blockade of T currents and/or potentiation of GABA(A) currents could be beneficial in the management of NPP. To study the potential usefulness of 5alpha-reduced neuroactive steroids in alleviating NPP, we selected two newly synthesized steroids-ECN and CDNC24-with a selective blocking effect on T currents and a selective potentiating effect on GABA(A) currents, respectively, and commercial analogs-alphaxalone and 3alpha5alphaP-with the effects on both ion channels. We used a sciatic nerve ligation model to induce thermal and mechanical hyperalgesia in adult rats and tested peripheral thermal and mechanical nociception following local injection of neuroactive steroids into the peripheral receptive fields of a ligated hind paw. We found that 5alpha-reduced neuroactive steroids alleviate thermal and mechanical hyperalgesia in NPP rats. ECN and CDNC24 were more selective in alleviating thermal nociception in NPP than in sham animals when compared to 3alpha5alphaP and alphaxalone although the anti-nociceptive effect induced by 3alpha5alphaP and alphaxalone was more profound. CDNC24 was most selective since it had very minimal anti-nociceptive effect in sham animals but a very profound anti-nociceptive effect in NPP animals suggesting that, under pathological conditions, peripheral GABA(A) receptors might be an attractive therapeutic target.
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Affiliation(s)
- S Pathirathna
- Department of Anesthesiology, University of Virginia Health System, P.O. Box 800710, Charlottesville, VA 22908, USA Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Pathirathna S, Brimelow BC, Jagodic MM, Krishnan K, Jiang X, Zorumski CF, Mennerick S, Covey DF, Todorovic SM, Jevtovic-Todorovic V. New evidence that both T-type calcium channels and GABAA channels are responsible for the potent peripheral analgesic effects of 5α-reduced neuroactive steroids. Pain 2005; 114:429-443. [PMID: 15777868 DOI: 10.1016/j.pain.2005.01.009] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Revised: 11/05/2004] [Accepted: 01/14/2005] [Indexed: 11/24/2022]
Abstract
Neurosteroids are potent blockers of neuronal low-voltage activated (T-type) Ca(2+) channels and potentiators of GABA(A) ligand-gated channels, but their effects in peripheral pain pathways have not been studied previously. To investigate potential analgesic effects and the ion channels involved, we tested the ability of locally injected 5alpha-reduced neurosteroids to modulate peripheral thermal nociception to radiant heat in adult rats in vivo and to modulate GABA(A) and T-type Ca(2+) channels in vitro. The steroid anesthetic alphaxalone (ALPX), the endogenous neurosteroid allopregnanolone (3alpha5alphaP), and a related compound ((3alpha,5alpha,17beta)-3-hydroxyandrostane-17-carbonitrile, (ACN)), induced potent, dose-dependent, enantioselective anti-nociception in vivo and modulation of both T-type Ca(2+) currents and GABA(A)-mediated currents in vitro. Analgesic effects of ALPX were incompletely antagonized by co-injections of the GABA(A) receptor antagonist bicuculline. The neurosteroid analogue ((3alpha,5alpha)-3-hydroxy-13,24-cyclo-18,21-dinorchol-22-en-24-ol (CDNC24), a compound with GABAergic but not T-type activity, was not analgesic. However, (3beta,5alpha,17beta)-17-hydroxyestrane-3-carbonitrile (ECN)), which has effects on T-type channels but not on GABA(A) receptors, also induced potent enantioselective peripheral anti-nociception. ECN increased pain thresholds less than ALPX, 3alpha5alphaP and ACN. However, when an ineffective dose of CDNC24 was combined with ECN, anti-nociceptive activity was greatly enhanced, and this effect was bicuculline-sensitive. These results strongly suggest that GABA(A) channels do not contribute to baseline pain transmission, but they can enhance anti-nociception mediated by blockade of T-type Ca(2+) channels. In conclusion, we demonstrate that potent peripheral analgesia induced by 5alpha-reduced neurosteroid is mediated in part by effects on T-type Ca(2+) channels. Our results also reveal a role of GABA-gated ion channels in peripheral nociceptive signaling.
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Affiliation(s)
- Sriyani Pathirathna
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St Louis, MO, USA Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA
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Lake APJ. Balanced anaesthesia 2005: Avoiding the Transition from Acute to Chronic Pain. SOUTHERN AFRICAN JOURNAL OF ANAESTHESIA AND ANALGESIA 2005. [DOI: 10.1080/22201173.2005.10872384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Abstract
OBJECTIVE To validate IV subhypnotic propofol, a gamma-aminobutyric acid A (GABA-A) agonist, as a diagnostic test for central pain. METHODS The efficacy of systemic propofol (0.2 mg/kg IV bolus) was evaluated in a double-blind, placebo-controlled and crossover fashion on both spontaneous ongoing pain and allodynia in 44 patients with chronic central pain of both brain and cord origin. RESULTS Propofol was significantly superior to the placebo (Intralipid, Kabi Pharmacia) in reducing the intensity of spontaneous ongoing pain for up to 1 hour after the injection: 24 of 44 patients (55%) receiving propofol showed a significant reduction in spontaneous pain, whereas only 6 patients showed this after the placebo. Propofol also significantly reduced the intensity of both mechanical and cold allodynia. In a few cases, only the evoked components were abolished but not the spontaneous pain. In general, the side effects were minimal and consisted mainly of transitory burning upon injection of both propofol and placebo and slight lightheadedness in a few cases. CONCLUSIONS Systemic propofol induces analgesic effects on all studied components of central pain and highlights the key role of GABA modulation in central pain.
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Affiliation(s)
- S Canavero
- Turin Advanced Neuromodulation Group, Turin, Italy.
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Munglani R, Erdmann A. Advances in the Management of Spinal Pain and Radiofrequency Techniques. Pain 2003. [DOI: 10.1201/9780203911259.ch14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Horishita T, Minami K, Yanagihara N, Shiraishi M, Okamoto T, Shiga Y, Ueno S, Shigematsu A. Alphaxalone, a neurosteroid anesthetic, inhibits norepinephrine transporter function in cultured bovine adrenal medullary cells. Anesth Analg 2002; 95:1661-6, table of contents. [PMID: 12456434 DOI: 10.1097/00000539-200212000-00034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
UNLABELLED We studied the effects of alphaxalone, a neurosteroid anesthetic, on norepinephrine transporter (NET) function in cultured bovine adrenal medullary cells and the effect of a bolus injection of alphaxalone on blood pressure and serum norepinephrine (NE) levels in anesthetized rats. Alphaxalone (10-100 micro M) inhibited the desipramine-sensitive uptake of [(3)H]-NE by bovine adrenal medullary cells in a concentration-dependent manner. Eadie-Hofstee analysis of [(3)H]-NE uptake showed that alphaxalone increased the apparent Michaelis constant without altering the maximal velocity, indicating that inhibition occurred via competition for the NET. Alphaxalone inhibited the specific binding of [(3)H]-desipramine to plasma membranes isolated from bovine adrenal medulla. Scatchard analysis of [(3)H]-desipramine binding revealed that alphaxalone increased the apparent dissociation constant for binding without altering maximal binding, indicating competitive inhibition. Bolus IV administration of alphaxalone had little effect on blood pressure but slightly, and significantly, increased the serum NE levels in anesthetized rats. These findings suggest that alphaxalone competitively inhibits NET function by interfering with both desipramine binding and NE recognition on the NET in adrenal medullary cells and probably in sympathetic neurons. IMPLICATIONS Alphaxalone inhibited the desipramine-sensitive uptake of [(3)H]-norepinephrine (NE) by interfering with desipramine binding in bovine adrenal medullary cells. A bolus IV administration of alphaxalone slightly and significantly increased the serum NE levels in anesthetized rats. These findings suggest that alphaxalone competitively inhibits NE transporter function probably in sympathetic neurons.
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Affiliation(s)
- Takafumi Horishita
- Department of Anesthesiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan
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Monks DA, Arciszewska G, Watson NV. Estrogen-inducible progesterone receptors in the rat lumbar spinal cord: regulation by ovarian steroids and fluctuation across the estrous cycle. Horm Behav 2001; 40:490-6. [PMID: 11716578 DOI: 10.1006/hbeh.2001.1717] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ovarian hormones influence the physiology of the spinal cord through incompletely understood cellular mechanisms. To date, there has been little compelling evidence for progesterone receptors in spinal cord neurons. Using two antibodies specific for progesterone receptors in an immunohistochemical investigation, we now report the presence of estrogen-inducible progesterone receptors in the spinal cord. Estrogen-inducible progesterone receptors were observed in the neurons of lamina X and the interomedialateral cell column, which are also known to express estrogen receptors. Estrogen-inducible progesterone receptors similar to those observed in females were also apparent in lamina X and interomediolateral cell column neurons in the spinal cords of males treated with estradiol. Furthermore, the density of progesterone receptors in lamina X was observed to fluctuate across the estrous cycle in female rats, with the highest progesterone receptor expression levels occurring late in proestrus, following the estradiol surge and coincident with high circulating progesterone levels. The lowest progesterone receptor expression levels were observed late in estrus following the progesterone surge. Together, these results demonstrate that estrogen-sensitive progestin targets exist in the spinal cord, and their possible role in the nervous control of reproduction and ovarian steroid modulation of nociception is discussed.
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Affiliation(s)
- D A Monks
- Department of Psychology, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada
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Nadeson R, Goodchild CS. Antinociceptive properties of neurosteroids II. Experiments with Saffan and its components alphaxalone and alphadolone to reveal separation of anaesthetic and antinociceptive effects and the involvement of spinal cord GABA(A) receptors. Pain 2000; 88:31-39. [PMID: 11098097 DOI: 10.1016/s0304-3959(00)00300-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Studies have shown that the steroid anaesthetic alphaxalone positively modulates gamma-aminobutyric acid (GABA) receptors in vitro. It has also been reported that positive modulation of GABA(A) receptors in the rat spinal cord can produce antinociception in vivo. This present study looks at the interaction of an intraperitoneal injection (i.p.) of the steroid anaesthetic combination Saffan (alphaxalone 9 mg/ml, alphadolone acetate 3 mg/ml) with GABA(A) receptors in the spinal cord. Full recovery from anaesthesia induced by Saffan 2 ml/kg i.p., as assessed by the rotarod test, occurred after 28.78 +/- 0.86 min. Residual antinociceptive effects were assessed by application of electrical current at two skin sites (neck and tail) and also tail withdrawal from noxious heat. Residual antinociception was observed at both skin sites assessed by the electrical test but not when assessed by noxious heat. The antinociceptive effects in the tail but not the neck were suppressed by intrathecal administration of GABA(A) antagonists (bicuculline and SR-95531). In a separate group of experiments alphaxalone and alphadolone were given i.p. individually at the same doses that were given when formulated in Saffan. Alphaxalone produced sedative and anaesthetic effects with no antinociception. Alphadolone caused no sedation but it did cause antinociceptive effects equal in magnitude to those produced by Saffan. We conclude that Saffan produces antinociception in rats when given i.p. by an interaction with spinal GABA(A) receptors. Furthermore, this antinociception is due to the alphadolone content of the neurosteroid anaesthetic and not the alphaxalone.
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Affiliation(s)
- R Nadeson
- Department of Anaesthesia, Monash University, Level 5, Block E, Monash Medical Centre, 246 Clayton Road, Clayton, Victoria 3168, Australia
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Pan B, Castro-Lopes JM, Coimbra A. Central afferent pathways conveying nociceptive input to the hypothalamic paraventricular nucleus as revealed by a combination of retrograde labeling and c-fos activation. J Comp Neurol 1999. [DOI: 10.1002/(sici)1096-9861(19991011)413:1<129::aid-cne9>3.0.co;2-q] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Gilron I, Quirion R, Coderre TJ. Pre- Versus Postformalin Effects of Ketamine or Large-Dose Alfentanil in the Rat. Anesth Analg 1999. [DOI: 10.1213/00000539-199907000-00022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Gilron I, Quirion R, Coderre TJ. Pre- versus postformalin effects of ketamine or large-dose alfentanil in the rat: discordance between pain behavior and spinal Fos-like immunoreactivity. Anesth Analg 1999; 89:128-35. [PMID: 10389790 DOI: 10.1097/00000539-199907000-00022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
UNLABELLED The purpose of this animal investigation was to compare behavioral responses with spinal Fos-like immunoreactivity (FLI) after pre-versus postformalin administration of anesthetic doses of IV ketamine or alfentanil. Preformalin and postformalin injection (1.5% subcutaneously) treatment groups included IV saline control (1.5 mL/kg), ketamine (10 mg/kg), and alfentanil (170 microg/kg). In the behavioral study group, nociceptive behavior was evaluated 15-60 min after hindpaw formalin injection. In the spinal FLI study group, rats were perfused 2 h postformalin, and spinal cords were dissected, sliced at 30 microm, and processed by immunoperoxidase staining with an antibody against the Fos protein. Quantification and determination of the laminar distribution of Fos-labeled nuclei were performed at the L4-5 spinal level ipsilateral to formalin injection. Ketamine produced a selective preemptive analgesic effect in behavioral formalin experiments, yet failed to suppress spinal FLI. In contrast, alfentanil failed to demonstrate a selective preemptive analgesia in behavioral experiments, but did produce preemptive suppression of spinal FLI. Together with previous data from our laboratory, we conclude that behavioral analgesia and spinal Fos expression may be uncoupled under certain circumstances. IMPLICATIONS In this study, we compared pain reduction produced by IV drugs (ketamine or alfentanil) with the ability to prevent injury-induced spinal cord changes. We measured pain behavior and spinal Fos protein after rats received ketamine or alfentanil before versus after formalin injection. Fos inhibition patterns did not clearly correlate with pain reduction, providing further evidence that Fos inhibition is not always predictive of behavioral analgesia.
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Affiliation(s)
- I Gilron
- Pain Research Clinic, Pain and Neurosensory Mechanisms Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Gilron I, Quirion R, Coderre TJ. Pre- Versus Postinjury Effects of Intravenous GABAergic Anesthetics on Formalin-Induced Fos Immunoreactivity in the Rat Spinal Cord. Anesth Analg 1999. [DOI: 10.1213/00000539-199902000-00036] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Gilron I, Quirion R, Coderre TJ. Pre- versus postinjury effects of intravenous GABAergic anesthetics on formalin-induced Fos immunoreactivity in the rat spinal cord. Anesth Analg 1999; 88:414-20. [PMID: 9972767 DOI: 10.1097/00000539-199902000-00036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
UNLABELLED We evaluated the suppression of spinal Fos-like immunoreactivity (FLI) by i.v. anesthetics in the rat formalin model. Preformalin injection (1.5% subcutaneously) treatment groups included i.v. saline controls and three i.v. GABAergic anesthetic groups (pentobarbital 20 mg/kg, propofol 10 mg/kg, or alphaxalone 1.5 mg/kg; n = 12 per group). After perfusion 2 h postformalin, spinal cords were dissected, sliced at 30 microm, and processed by immunoperoxidase staining with an antibody against the Fos protein. Quantification and determination of the laminar distribution of Fos-labeled nuclei were performed at the L4-5 spinal level ipsilateral to formalin injection. Drug groups demonstrating FLI suppression were comparatively studied in a 5-min postformalin treatment group. Pentobarbital pretreatment failed to suppress FLI. However, significant reductions (percent decrease) of FLI were observed with propofol (63%) and alphaxalone (30%) compared with saline controls. Pre- versus postformalin comparison studies showed that propofol, but not alphaxalone, suppressed FLI more effectively when given preformalin. Given the observed inconsistencies between this study of Fos expression and our previous behavioral study, it is questionable whether anesthetic modulation of noxious stimulus-induced FLI parallels that of behavioral responses. IMPLICATIONS In this study, we examined whether i.v. general anesthetics (propofol, alphaxalone, and pentobarbital) prevent injury-induced spinal cord changes. We measured spinal Fos protein after rats received anesthetics before versus after a formalin injection. Fos inhibition patterns were inconsistent with behavioral studies of these anesthetics, suggesting that Fos inhibition does not always correlate with behavioral analgesia.
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Affiliation(s)
- I Gilron
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Todorovic SM, Prakriya M, Nakashima YM, Nilsson KR, Han M, Zorumski CF, Covey DF, Lingle CJ. Enantioselective blockade of T-type Ca2+ current in adult rat sensory neurons by a steroid that lacks gamma-aminobutyric acid-modulatory activity. Mol Pharmacol 1998; 54:918-27. [PMID: 9804627 DOI: 10.1124/mol.54.5.918] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A number of steroids seem to have anesthetic effects resulting primarily from their ability to potentiate currents gated by gamma-aminobutyric acidA (GABAA) receptor activation. One such compound is (3alpha,5alpha, 17beta)-3-hydroxyandrostane-17-carbonitrile [(+)-ACN]. We were interested in whether carbonitrile substitution at other ring positions might result in other pharmacological consequences. Here we examine effects of (3beta,5alpha, 17beta)-17-hydroxyestrane-3-carbonitrile [(+)-ECN] on GABAA receptors and Ca2+ channels. In contrast to (+)-ACN, (+)-ECN does not potentiate GABAA-receptor activated currents, nor does it directly gate GABAA-receptor mediated currents. However, both steroids produce an enantioselective reduction of T-type current. (+)-ECN blocked T current with an IC50 value of 0.3 microM with a maximal block of 41%. (+)-ACN produced a partial block of T current (44% maximal block) with an IC50 value of 0.4 microM. Block of T current showed mild use- and voltage-dependence. The (-)-ECN enantiomer was about 33 times less potent than (+)-ECN, with an IC50 value of 10 microM and an amount of maximal block comparable to (+)-ECN. (+)-ECN was less effective at blocking high-voltage-activated Ca2+ current in DRG neurons (IC50 value of 9. 3 microM with maximal block of about 27%) and hippocampal neurons. (+)-ECN (10 microM) had minimal effects on voltage-gated sodium and potassium currents in rat chromaffin cells. The results identify a steroid with no effects on GABAA receptors that produces a partial inhibition of T-type Ca2+ current with reasonably high affinity and selectivity. Further study of steroid actions on T currents may lead to even more selective and potent agents.
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Affiliation(s)
- S M Todorovic
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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