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Wiener J, Hsieh J, McIntyre A, Teasell R. Effectiveness of 4-Aminopyridine for the Management of Spasticity in Spinal Cord Injury: A Systematic Review. Top Spinal Cord Inj Rehabil 2018; 24:353-362. [PMID: 30459498 DOI: 10.1310/sci17-00048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Background: Spasticity is a common secondary complication of spinal cord injury (SCI), which can severely impact functional independence and quality of life. 4-Aminopyridine (4-AP) is a potassium channel blocker that has been studied as an intervention for spasticity in individuals with SCI. Objective: To conduct a systematic review of the available evidence regarding the effectiveness of 4-AP for the management of spasticity in individuals with SCI. Methods: A comprehensive literature search was conducted on five electronic databases for articles published in English up to January 2017. Studies were included if (1) the sample size was three or more subjects, (2) the population was ≥50% SCI, (3) the subjects were ≥18 years old, (4) the treatment was 4-AP via any route, and (5) spasticity was assessed before and after the intervention. Subject characteristics, study design, intervention protocol, assessment methods, side effects, adverse events, and outcomes were extracted from selected studies. Randomized controlled trials (RCTs) were evaluated for methodological quality using the Physiotherapy Evidence Database (PEDro) tool. Levels of evidence were assigned using a modified Sackett scale. Results: Nine studies met inclusion criteria with a pooled sample size of 591 subjects. Six studies were RCTs (PEDro = 6-10, Level 1 evidence) and three studies were pre-post tests (Level 4 evidence). There was a wide range in duration, severity, and level of SCI across subjects. Oral 4-AP was investigated in five studies; one study reported significant improvements on the Ashworth Scale (AS), while the remaining four studies found no improvement. Three studies found no significant improvements on the Spasm Frequency Scale. Intravenous 4-AP was investigated in three studies; no significant improvements were found on the AS or in the Reflex Score. Intrathecal 4-AP was investigated in one study, which did not find significant improvements on the AS. Conclusion: There is weak evidence supporting the effectiveness of 4-AP in reducing spasticity post SCI. Future research should utilize contemporary measures of spasticity and address methodological limitations such as small sample sizes.
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Affiliation(s)
- Joshua Wiener
- Lawson Health Research Institute, Parkwood Institute, London, Ontario, Canada
| | - Jane Hsieh
- Lawson Health Research Institute, Parkwood Institute, London, Ontario, Canada
| | - Amanda McIntyre
- Lawson Health Research Institute, Parkwood Institute, London, Ontario, Canada
| | - Robert Teasell
- Lawson Health Research Institute, Parkwood Institute, London, Ontario, Canada.,St. Joseph's Health Care, Parkwood Institute, London, Ontario, Canada.,Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
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2
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Page JC, Park J, Chen Z, Cao P, Shi R. Parallel Evaluation of Two Potassium Channel Blockers in Restoring Conduction in Mechanical Spinal Cord Injury in Rat. J Neurotrauma 2018; 35:1057-1068. [PMID: 29228863 DOI: 10.1089/neu.2017.5297] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Myelin damage is a hallmark of spinal cord injury (SCI), and potassium channel blocker (PCB) is proven effective to restore axonal conduction and regain neurological function. Aiming to improve this therapy beyond the U.S. Food and Drug Administration-approved 4-aminopyridine (4-AP), we have developed multiple new PCBs, with 4-aminopyridine-3-methanol (4-AP-3-MeOH) being the most potent and effective. The current study evaluated two PCBs, 4-AP-3-MeOH and 4-AP, in parallel in both ex vivo and in vivo rat mechanical SCI models. Specifically, 4-AP-3-MeOH induced significantly greater augmentation of axonal conduction than 4-AP in both acute and chronic injury. 4-AP-3-MeOH had no negative influence on the electrical responsiveness of rescued axons whereas 4-AP-recruited axons displayed a reduced ability to follow multiple stimuli. In addition, 4-AP-3-MeOH can be applied intraperitoneally at a dose that is at least 5 times higher (5 mg/kg) than that of 4-AP (1 mg/kg) in vivo. Further, 5 mg/kg of 4-AP-3-MeOH significantly improved motor function whereas both 4-AP-3-MeOH (1 and 5 mg/kg) and, to a lesser degree, 4-AP (1 mg/kg) alleviated neuropathic pain-like behavior when applied in rats 2 weeks post-SCI. Based on these and other findings, we conclude that 4-AP-3-MeOH appears to be more advantageous over 4-AP in restoring axonal conduction because of the combination of its higher efficacy in enhancing the amplitude of compound action potential, lesser negative effect on axonal responsiveness to multiple stimuli, and wider therapeutic range in both ex vivo and in vivo application. As a result, 4-AP-3-MeOH has emerged as a strong alternative to 4-AP that can complement the effectiveness, and even partially overcome the shortcomings, of 4-AP in the treatment of neurotrauma and degenerative diseases where myelin damage is implicated.
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Affiliation(s)
- Jessica C Page
- 1 Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University , West Lafayette, Indiana
| | - Jonghyuck Park
- 2 Weldon School of Biomedical Engineering, Purdue University , West Lafayette, Indiana
| | - Zhe Chen
- 3 Department of Orthopedics, Rui-Jin Hospital, School of Medicine, Shanghai Jiao-tong University , Institute of Trauma and Orthopedics, Shanghai, China
| | - Peng Cao
- 3 Department of Orthopedics, Rui-Jin Hospital, School of Medicine, Shanghai Jiao-tong University , Institute of Trauma and Orthopedics, Shanghai, China
| | - Riyi Shi
- 1 Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University , West Lafayette, Indiana.,2 Weldon School of Biomedical Engineering, Purdue University , West Lafayette, Indiana
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3
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Moore SA, Granger N, Olby NJ, Spitzbarth I, Jeffery ND, Tipold A, Nout-Lomas YS, da Costa RC, Stein VM, Noble-Haeusslein LJ, Blight AR, Grossman RG, Basso DM, Levine JM. Targeting Translational Successes through CANSORT-SCI: Using Pet Dogs To Identify Effective Treatments for Spinal Cord Injury. J Neurotrauma 2017; 34:2007-2018. [PMID: 28230415 DOI: 10.1089/neu.2016.4745] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Translation of therapeutic interventions for spinal cord injury (SCI) from laboratory to clinic has been historically challenging, highlighting the need for robust models of injury that more closely mirror the human condition. The high prevalence of acute, naturally occurring SCI in pet dogs provides a unique opportunity to evaluate expeditiously promising interventions in a population of animals that receive diagnoses and treatment clinically in a manner similar to persons with SCI, while adhering to National Institutes of Health guidelines for scientific rigor and transparent reporting. In addition, pet dogs with chronic paralysis are often maintained long-term by their owners, offering a similarly unique population for study of chronic SCI. Despite this, only a small number of studies have used the clinical dog model of SCI. The Canine Spinal Cord Injury Consortium (CANSORT-SCI) was recently established by a group of veterinarians and basic science researchers to promote the value of the canine clinical model of SCI. The CANSORT-SCI group held an inaugural meeting November 20 and 21, 2015 to evaluate opportunities and challenges to the use of pet dogs in SCI research. Key challenges identified included lack of familiarity with the model among nonveterinary scientists and questions about how and where in the translational process the canine clinical model would be most valuable. In light of these, we review the natural history, outcome, and available assessment tools associated with canine clinical SCI with emphasis on their relevance to human SCI and the translational process.
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Affiliation(s)
- Sarah A Moore
- 1 Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine , Columbus Ohio.,2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI)
| | - Nicolas Granger
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,3 Faculty of Health Sciences, University of Bristol , Langford, North Somerset, United Kingdom
| | - Natasha J Olby
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,4 Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University , Raleigh, North Carolina.,5 Comparative Medicine Institute, North Carolina State University , Raleigh, North Carolina
| | - Ingo Spitzbarth
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,6 Department of Pathology, University of Veterinary Medicine , Hannover, Germany .,7 Center for Systems Neuroscience , Hannover, Germany
| | - Nick D Jeffery
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,8 Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University , College Station, Texas
| | - Andrea Tipold
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,7 Center for Systems Neuroscience , Hannover, Germany.,9 Department of Small Animal Medicine and Surgery, University of Veterinary Medicine , Hannover, Germany
| | - Yvette S Nout-Lomas
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,10 College of Veterinary Medicine and Biomedical Sciences, Colorado State University , Fort Collins, Colorado
| | - Ronaldo C da Costa
- 1 Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine , Columbus Ohio.,2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI)
| | - Veronika M Stein
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,11 Department of Clinical Veterinary Sciences, University of Bern , Bern, Switzerland
| | - Linda J Noble-Haeusslein
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,12 Departments of Physical Therapy and Rehabilitation Sciences and Neurological Surgery, University of California , San Francisco, San Francisco, California
| | - Andrew R Blight
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,13 Acorda Therapeutics, Inc. Ardsley, New York
| | - Robert G Grossman
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,14 Department of Neurosurgery, Houston Methodist Neurological Institute , Houston, Texas
| | - D Michele Basso
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,15 School of Health and Rehabilitation Sciences, The Ohio State University , Columbus, Ohio
| | - Jonathan M Levine
- 2 The Canine Spinal Cord Injury Consortium (CANSORT-SCI).,8 Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University , College Station, Texas
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4
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Yan R, Page JC, Shi R. Acrolein-mediated conduction loss is partially restored by K⁺ channel blockers. J Neurophysiol 2015; 115:701-10. [PMID: 26581866 DOI: 10.1152/jn.00467.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 11/18/2015] [Indexed: 11/22/2022] Open
Abstract
Acrolein-mediated myelin damage is thought to be a critical mechanism leading to conduction failure following neurotrauma and neurodegenerative diseases. The exposure and activation of juxtaparanodal voltage-gated K(+) channels due to myelin damage leads to conduction block, and K(+) channel blockers have long been studied as a means for restoring axonal conduction in spinal cord injury (SCI) and multiple sclerosis (MS). In this study, we have found that 100 μM K(+) channel blockers 4-aminopyridine-3-methanol (4-AP-3-MeOH), and to a lesser degree 4-aminopyridine (4-AP), can significantly restore compound action potential (CAP) conduction in spinal cord tissue following acrolein-mediated myelin damage using a well-established ex vivo SCI model. In addition, 4-AP-3-MeOH can effectively restore CAP conduction in acrolein-damaged axons with a range of concentrations from 0.1 to 100 μM. We have also shown that while both compounds at 100 μM showed no preference of small- and large-caliber axons when restoring CAP conduction, 4-AP-3-MeOH, unlike 4-AP, is able to augment CAP amplitude while causing little change in axonal responsiveness measured in refractory periods and response to repetitive stimuli. In a prior study, we show that 4-AP-3-MeOH was able to functionally rescue mechanically injured axons. In this investigation, we conclude that 4-AP-3-MeOH is an effective K(+) channel blocker in restoring axonal conduction following both primary (physical) and secondary (chemical) insults. These findings also suggest that 4-AP-3-MeOH is a viable alternative of 4-AP for treating myelin damage and improving function following central nervous system trauma and neurodegenerative diseases.
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Affiliation(s)
- Rui Yan
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana; and
| | - Jessica C Page
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana; and
| | - Riyi Shi
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana; and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
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5
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Shi R, Sun W. Potassium channel blockers as an effective treatment to restore impulse conduction in injured axons. Neurosci Bull 2011; 27:36-44. [PMID: 21270902 DOI: 10.1007/s12264-011-1048-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Most axons in the vertebral central nervous system are myelinated by oligodendrocytes. Myelin protects and insulates neuronal processes, enabling the fast, saltatory conduction unique to myelinated axons. Myelin disruption resulting from trauma and biochemical reaction is a common pathological event in spinal cord injury and chronic neurodegenerative diseases. Myelin damage-induced axonal conduction block is considered to be a significant contributor to the devastating neurological deficits resulting from trauma and illness. Potassium channels are believed to play an important role in axonal conduction failure in spinal cord injury and multiple sclerosis. Myelin damage has been shown to unmask potassium channels, creating aberrant potassium currents that inhibit conduction. Potassium channel blockade reduces this ionic leakage and improves conduction. The present review was mainly focused on the development of this technique of restoring axonal conduction and neurological function of demyelinated axons. The drug 4-aminopyridine has recently shown clinical success in treating multiple sclerosis symptoms. Further translational research has also identified several novel potassium channel blockers that may prove effective in restoring axonal conduction.
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Affiliation(s)
- Riyi Shi
- Department of Basic Medical Sciences, School of Veterinary Medicine, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
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6
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Liu WM, Wu JY, Li FC, Chen QX. Ion channel blockers and spinal cord injury. J Neurosci Res 2011; 89:791-801. [PMID: 21394757 DOI: 10.1002/jnr.22602] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 12/11/2010] [Accepted: 12/19/2010] [Indexed: 12/23/2022]
Abstract
The activation of a delayed secondary cascade of unsatisfactory cellular and molecular responses after a primary mechanical insult to the spinal cord causes the progressive degeneration of this structure. Disturbance of ionic homeostasis is part of the secondary injury process and plays an integral role in the early stage of spinal cord injury (SCI). The secondary pathology of SCI is complex and involves disturbance of the homeostasis of K(+) , Na(+) , and Ca(2+) . The effect of ion channel blockers on chronic SCI has also been proved. In this Mini-Review, we provide a comprehensive summary of the effects of ion channel blockers on the natural responses after SCI. Combination therapy is based on the roles of ions and disturbance of their homeostasis in SCI. The effects of ion channel blockers suggest that they have potential in the treatment of SCI, although the complexity of their effects shows that further knowledge is needed before they can be applied clinically.
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Affiliation(s)
- Wang-Mi Liu
- Department of Orthopedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
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7
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Sun W, Smith D, Fu Y, Cheng JX, Bryn S, Borgens R, Shi R. Novel Potassium Channel Blocker, 4-AP-3-MeOH, Inhibits Fast Potassium Channels and Restores Axonal Conduction in Injured Guinea Pig Spinal Cord White Matter. J Neurophysiol 2010; 103:469-78. [DOI: 10.1152/jn.00154.2009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We have demonstrated that 4-aminopyridine-3-methanol (4-AP-3-MeOH), a 4-aminopyridine derivative, significantly restores axonal conduction in stretched spinal cord white-matter strips and shows no preference in restoring large and small axons. This compound is 10 times more potent when compared with 4-AP and other derivatives in restoring axonal conduction. Unlike 4-AP, 4-AP-3-MeOH can restore axonal conduction without changing axonal electrophysiological properties. In addition, we also have confirmed that 4-AP-3-MeOH is indeed an effective blocker of IA based on patch-clamp studies using guinea pig dorsal root ganglia cells. Furthermore, we have also provided the critical evidence to confirm the unmasking of potassium channels following mechanical injury. Taken together, our data further supports and implicates the role of potassium channels in conduction loss and its therapeutic value as an effective target for intervention to restore function in spinal cord trauma. Furthermore, due to its high potency and possible low side effect of impacting electrophysiological properties, 4-AP-3-MeOH is perhaps the optimal choice in reversing conduction block in spinal cord injury compared with other derivatives previously reported from this group.
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Affiliation(s)
- Wenjing Sun
- Department of Basic Medical Sciences, Center for Paralysis Research
| | - Daniel Smith
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana
| | - Yan Fu
- Weldon School of Biomedical Engineering; and
| | | | - Steven Bryn
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana
| | - Richard Borgens
- Department of Basic Medical Sciences, Center for Paralysis Research
- Weldon School of Biomedical Engineering; and
| | - Riyi Shi
- Department of Basic Medical Sciences, Center for Paralysis Research
- Weldon School of Biomedical Engineering; and
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8
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Namur S, González-de la Parra M, Castañeda-Hernández G. Quantification of 4-aminopyridine in plasma by capillary electrophoresis with electrokinetic injection. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 878:290-4. [PMID: 19962357 DOI: 10.1016/j.jchromb.2009.11.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 11/10/2009] [Accepted: 11/15/2009] [Indexed: 11/29/2022]
Abstract
A rapid and sensitive CE method for the determination of 4-aminopyridine in human plasma using 3,4-diaminopyridine as an internal standard was developed and validated. The analytes were extracted from 0.5-mL aliquots of human plasma by liquid-liquid extraction, using 8 mL of ethyl ether, and injected electrokinetically into capillary electrophoresis equipment. The instrumental conditions were obtained and optimized by Design of Experiments (DOE--factorial and response surface model), having as factors: separation voltage, ionic strength (buffer concentration), pH and temperature. The response variables were migration time, resolution, tailing factor and drug peak area. After obtaining mathematically predicted values for the response variables with best factors combinations, these were reproduced experimentally in good agreement with predicted values. In addition to optimal separation conditions obtained by Design of Experiments, sensitivity was improved using electrokinetic injection at 10 kV for 10 s, and a capillary with 50 cm effective length and 100 microm I.D. The final instrumental conditions were voltage at 19 kV, capillary temperature at 15 degrees C, wavelength at 254 nm, and phosphate buffer 100 mM, pH 2.5 as the background electrolyte. This assay was linear over a concentration range of 2.5-80 ng/mL with a lower limit of quantification of 2.5 ng/mL. The relative standard deviation for the assay precision was <7% and the accuracy was >95%. This method was successfully applied to the quantification of 4-aminopyridine (4-AP) in plasma samples from patients with spinal cord injury.
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Affiliation(s)
- Salvador Namur
- Fundación Liomont A.C. Privada Jesús del Monte 77, Cuajimalpa, 05000, México D.F., Mexico.
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9
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OLBY NJ, SMITH DT, HUMPHREY J, SPINAPOLICE K, PARKE N, MEHTA PM, DISE D, PAPICH M. Pharmacokinetics of 4-aminopyridine derivatives in dogs. J Vet Pharmacol Ther 2009; 32:485-91. [DOI: 10.1111/j.1365-2885.2009.01072.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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McBride JM, Smith DT, Byrn SR, Borgens RB, Shi R. 4-Aminopyridine derivatives enhance impulse conduction in guinea-pig spinal cord following traumatic injury. Neuroscience 2007; 148:44-52. [PMID: 17629412 DOI: 10.1016/j.neuroscience.2007.05.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 05/24/2007] [Accepted: 05/30/2007] [Indexed: 11/22/2022]
Abstract
4-Aminopyridine (4-AP), a potassium channel blocker, is capable of restoring conduction in the injured spinal cord. However, the maximal tolerated level of 4-AP in humans is 100 times lower than the optimal dose in in vitro animal studies due to its substantially negative side effects. As an initial step toward the goal of identifying alternative potassium channel blockers with a similar ability of enhancing conduction and with fewer side effects, we have synthesized structurally distinct pyridine-based blockers. Using isolated guinea-pig spinal cord white matter and a double sucrose gap recording device, we have found three pyridine derivatives, N-(4-pyridyl)-methyl carbamate (100 microM), N-(4-pyridyl)-ethyl carbamate (100 microM), and N-(4-pyridyl)-tertbutyl (10 microM) can significantly enhance conduction in spinal cord white matter following stretch. Similar to 4-AP, the derivatives did not preferentially enhance conduction based on axonal caliber. Unlike 4-AP, the derivatives did not change the overall electrical responsiveness of axons to multiple stimuli, indicating the axons recruited by the derivatives conducted in a manner similar to healthy axons. These results demonstrate the ability of novel constructs to serve as an alternative to 4-AP for the purpose of reversing conduction deficits.
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Affiliation(s)
- J M McBride
- Department of Basic Medical Sciences, Center for Paralysis Research, Purdue University, 408 South University Street, West Lafayette, IN 47907, USA
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11
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Abstract
Fampridine-SR is a sustained-release tablet form of the K(+) channel-blocking compound 4-aminopyridine that has been shown to restore conduction in focally demyelinated axons, to enhance synaptic transmission in many types of neurons and to potentiate muscle contraction. The present review describes the mechanism of action and chemistry of Fampridine-SR, its pharmacokinetics and safety, and the outcomes of clinical trials of its safety and efficacy for enhancing neuromuscular function in patients with multiple sclerosis or spinal cord injury. Randomized clinical trials completed to date indicate that this form of K(+) channel blockade may be useful for the improvement of walking ability in patients with multiple sclerosis.
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Affiliation(s)
- Keith C Hayes
- The University of Western Ontario, Department of Physical Medicine & Rehabilitation, London, Ontario, Canada.
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12
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Lammertse D, Tuszynski MH, Steeves JD, Curt A, Fawcett JW, Rask C, Ditunno JF, Fehlings MG, Guest JD, Ellaway PH, Kleitman N, Blight AR, Dobkin BH, Grossman R, Katoh H, Privat A, Kalichman M. Guidelines for the conduct of clinical trials for spinal cord injury as developed by the ICCP panel: clinical trial design. Spinal Cord 2006; 45:232-42. [PMID: 17179970 PMCID: PMC4106695 DOI: 10.1038/sj.sc.3102010] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The International Campaign for Cures of Spinal Cord Injury Paralysis established a panel tasked with reviewing the methodology for clinical trials for spinal cord injury (SCI), and making recommendations on the conduct of future trials. This is the fourth of four papers. Here, we examine the phases of a clinical trial program, the elements, types, and protocols for valid clinical trial design. The most rigorous and valid SCI clinical trial would be a prospective double-blind randomized control trial utilizing appropriate placebo control subjects. However, in specific situations, it is recognized that other trial procedures may have to be considered. We review the strengths and limitations of the various types of clinical trials with specific reference to SCI. It is imperative that the design and conduct of SCI clinical trials should meet appropriate standards of scientific inquiry to insure that meaningful conclusions about efficacy and safety can be achieved and that the interests of trial subjects are protected. We propose these clinical trials guidelines for use by the SCI clinical research community.
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13
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McBride JM, Smith DT, Byrn SR, Borgens RB, Shi R. Dose responses of three 4-aminopyridine derivatives on axonal conduction in spinal cord trauma. Eur J Pharm Sci 2006; 27:237-42. [PMID: 16297607 DOI: 10.1016/j.ejps.2005.10.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Revised: 09/07/2005] [Accepted: 10/08/2005] [Indexed: 11/25/2022]
Abstract
To explore novel treatments for enhancing conduction through traumatically injured spinal cord we have synthesized structurally distinct pyridine based compounds; N-(4-pyridyl) methyl carbamate, N-(4-pyridyl) ethyl carbamate, and N-(4-pyridyl) t-butyl carbamate. With the use of a double sucrose gap-recording chamber we perform a dose-response assay to examine the effects of these compounds on axonal conduction following an in vitro stretch injury. The tested compounds significantly enhanced axonal conduction to the stretch injured cord at 1 microM, a dose that coincides with the clinically relevant dose of potassium channel blocker 4-aminopyridine (4-AP). Methyl carbamate enhanced conduction maximally at 100 microM. This is also the most effective concentration of 4-AP in vitro. The other compounds ethyl carbamate and t-butyl carbamate enhanced conduction maximally at lower concentrations of 10 and 1 microM. At higher concentrations each of these compounds continued to increased CAP amplitude, however not significantly. Additionally, two of the compounds ethyl and t-butyl carbamate appear to have negative effects on CAP amplitude when administered at or beyond 100 microM. These compounds demonstrate the possibility that derivatives of 4-AP can retain the ability to increase axonal conduction in the injured spinal cord.
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Affiliation(s)
- Jennifer M McBride
- Department of Basic Medical Sciences, Center for Paralysis Research, Purdue University, West Lafayette, IN 47907, USA
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14
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Abstract
Clinicians and scientists in the field of spinal cord injury research and medicine are poised to begin translating promising new experimental findings into treatments for people. Advances in experimental regeneration research have led to several transplantation strategies that promote axonal regrowth and partial functional recovery in animal models of injury. In this review, we summarize current knowledge regarding various invasive experimental treatments that have been or are now being applied clinically. Various questions about the timeliness, safety, and benefits of the procedures are under discussion within the spinal cord injury (SCI) research community. We also describe guidelines for carrying out optimal clinical trials and efforts to establish specific international guidelines to translate preclinical treatment strategies into clinical trials in SCI. The clinical trial process and the role that clinical professionals have in advising individuals regarding participation in experimental procedures also is discussed.
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Affiliation(s)
- Maria J Amador
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL, USA.
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15
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Abstract
4-Aminopyridine (4-AP or fampridine) is a potassium channel-blocking agent that has been shown to restore conduction in focally demyelinated axons. A sustained-release matrix tablet form of 4-AP (fampridine-SR) is currently undergoing multicenter clinical trials in patients with multiple sclerosis or chronic spinal cord injury. This review describes the pharmacology and mechanisms of action of 4-AP, its pharmacokinetics in human subjects, and the outcomes of clinical trials employing either immediate-release or sustained-release formulations of the drug. The randomized clinical trials that have been completed to date indicate that K+ channel blockade may prove to be a useful strategy for ameliorating central conduction deficits due to demyelination. Diverse neurological gains have been reported for both motor and sensory domains. At the present time, however, the clinical trials have not provided sufficiently robust or definitive evidence of efficacy to gain regulatory approval for the symptomatic management of patients with either multiple sclerosis or spinal cord injury.
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Affiliation(s)
- Keith C Hayes
- Department of Physical Medicine & Rehabilitation, The University of Western Ontario, London, Ontario, Canada.
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16
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DeForge D, Nymark J, Lemaire E, Gardner S, Hunt M, Martel L, Curran D, Barbeau H. Effect of 4-aminopyridine on gait in ambulatory spinal cord injuries: a double-blind, placebo-controlled, crossover trial. Spinal Cord 2004; 42:674-85. [PMID: 15356676 DOI: 10.1038/sj.sc.3101653] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
UNLABELLED Animal and human research have shown that the drug 4-aminopyridine (4-AP) may improve gait in spinal cord lesions by enhancing nerve transmission to affected muscles. STUDY DESIGN Prospective, randomized, double-blind, placebo-controlled, crossover trial. OBJECTIVES To determine the efficacy of 4-AP in improving lower limb muscle strength and biomechanical gait patterns of chronic spinal cord injuries (SCI). SETTING The Rehabilitation Centre (Ottawa, Canada). METHODS In all, 15 chronic, ambulatory SCI persons were randomized to an initial 2 weeks of 40 mg/day, oral medication of either placebo or immediate-release, 4-AP and subsequently crossed over to the alternate medication for the following 2 weeks. Evaluations were conducted at baseline (before starting 4-AP or placebo medication), 2 weeks, and 4 weeks. Measures included dynamometer lower limb isometric muscle force and biomechanical gait measures including temporal-spatial parameters, electromyographic activation patterns, joint kinematics and kinetics. Subjective impressions of the drug by the participants were obtained from an exit survey. RESULTS Despite some positive comments from subjects, statistical and clinical analyses showed no within-subject differences between placebo and 4-AP measures of lower limb muscle force and objective gait analyses (ANOVA statistic P>0.05). CONCLUSION Results demonstrated the importance of placebo-controlled trials and quantitative outcome measures for the evaluation of 4-AP aimed to enhance gait for chronic, ambulatory SCI persons. Energy expenditure measures and mood may relate more to subjective comments and is suggested for future investigations.
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Affiliation(s)
- D DeForge
- Division of Physical Medicine and Rehabilitation, University of Ottawa, Ottawa, Ontario, Canada
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Jensen JM, Shi R. Effects of 4-aminopyridine on stretched mammalian spinal cord: the role of potassium channels in axonal conduction. J Neurophysiol 2003; 90:2334-40. [PMID: 12853442 DOI: 10.1152/jn.00868.2002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Axonal conduction deficit is a major contributor to various degrees of disability after spinal cord injury. 4-aminopyridine (4-AP), a potassium channel blocker, has been shown to restore some conduction and improve neurological function in both animal and human studies. Using a double sucrose-gap recording device, we have examined the effects of 4-AP on isolated guinea pig spinal cord white matter after stretch injury. At a concentration of 100 microM, 4-AP increased the amplitude of the compound action potential by 100% while 1 microM 4-AP increased it by 43%, a larger response than seen following compression injury. The length of affected tissue is suggested as a potential explanation of this differential sensitivity to 4-AP. Plastic sections taken from the injury site revealed severe myelin damage, especially in the paranodal area, which may also partially explain why 4-AP has more effect on conduction after stretch injury than compression. In addition, we have shown that while enhancing conductivity in some axons, 4-AP significantly reduced the overall responsiveness to multiple stimuli, as evidenced by increase of the refractory period in response to dual stimuli and the decreased ability to follow repetitive stimuli. This increased refractoriness may be largely attributed to residual deficits in fibers newly recruited by 4-AP treatment.
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Affiliation(s)
- Jennifer M Jensen
- Department of Basic Medical Sciences, Center for Paralysis Research, Purdue University, West Lafayette, Indiana 47907, USA
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18
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Abstract
Programmed cell death or apoptosis is broadly responsible for the normal homeostatic removal of cells and has been increasingly implicated in mediating pathological cell loss in many disease states. As the molecular mechanisms of apoptosis have been extensively investigated a critical role for ionic homeostasis in apoptosis has been recently endorsed. In contrast to the ionic mechanism of necrosis that involves Ca(2+) influx and intracellular Ca(2+) accumulation, compelling evidence now indicates that excessive K(+) efflux and intracellular K(+) depletion are key early steps in apoptosis. Physiological concentration of intracellular K(+) acts as a repressor of apoptotic effectors. A huge loss of cellular K(+), likely a common event in apoptosis of many cell types, may serve as a disaster signal allowing the execution of the suicide program by activating key events in the apoptotic cascade including caspase cleavage, cytochrome c release, and endonuclease activation. The pro-apoptotic disruption of K(+) homeostasis can be mediated by over-activated K(+) channels or ionotropic glutamate receptor channels, and most likely, accompanied by reduced K(+) uptake due to dysfunction of Na(+), K(+)-ATPase. Recent studies indicate that, in addition to the K(+) channels in the plasma membrane, mitochondrial K(+) channels and K(+) homeostasis also play important roles in apoptosis. Investigations on the K(+) regulation of apoptosis have provided a more comprehensive understanding of the apoptotic mechanism and may afford novel therapeutic strategies for apoptosis-related diseases.
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Affiliation(s)
- Shan Ping Yu
- Department of Pharmaceutical Sciences, School of Pharmacy, Medical University of South Carolina, 280 Calhoun Street, PO Box 250140, Charleston, SC 29425, USA.
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Wang XQ, Xiao AY, Yang A, LaRose L, Wei L, Yu SP. Block of Na+,K+-ATPase and induction of hybrid death by 4-aminopyridine in cultured cortical neurons. J Pharmacol Exp Ther 2003; 305:502-6. [PMID: 12606650 DOI: 10.1124/jpet.102.045013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
K(+) channel blockers such as 4-aminopyridine (4-AP) can be toxic to neurons; the cellular mechanism underlying the toxicity, however, is obscure. In cultured mouse cortical neurons, we tested the hypothesis that the toxic effect of 4-AP might result from inhibiting the Na(+),K(+)-ATPase (Na(+),K(+)-pump) and thereafter induction of a hybrid death of concomitant apoptosis and necrosis. The Na(+),K(+)-pump activity, monitored as whole-cell membrane currents, was markedly blocked by 4-AP in concentration- and voltage-dependent manners in low millimolar ranges. At similar concentrations, 4-AP induced a neuronal death sensitive to attenuation by the caspase inhibitor Z-VAD-FMK (Z-Val-Ala-Asp(OMe)-fluoromethyl ketone) or Ca(2+) chelator BAPTA-AM (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester). Electron microscopy confirmed hybrid ultrastructural features of coexisting apoptotic and necrotic components in same cells. We suggest that 4-AP is a potent antagonist of the Na(+),K(+)-ATPase and an inducer of the hybrid death of central neurons.
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Affiliation(s)
- Xue Qing Wang
- Center for the Study of Nervous System Injury and Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
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20
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Hayes KC, Katz MA, Devane JG, Hsieh JTC, Wolfe DL, Potter PJ, Blight AR. Pharmacokinetics of an immediate-release oral formulation of Fampridine (4-aminopyridine) in normal subjects and patients with spinal cord injury. J Clin Pharmacol 2003; 43:379-85. [PMID: 12723458 DOI: 10.1177/0091270003251388] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Plasma concentration profiles of the K+ channel-blocking compound Fampridine were obtained from (1) control subjects (n = 6) following oral administration of doses of 10, 15, 20, and 25 mg and (2) patients with spinal cord injury (SCI) (n = 11) following a single oral dose of 10 mg of an immediate-release formulation. Plasma concentrations were determined using a reversed-phase ion-pair high-performance liquid chromatography (HPLC) assay with ultraviolet light detection employing liquid extraction. The drug was rapidly absorbed with a tmax approximately 1 hour for both groups; tmax was independent of dose. Cmax and AUC0-infinity were linearly related to dose, and t 1/2 was 3 to 4 hours for both groups. There were no obvious differences in the (10-mg) plasma concentration profiles between control subjects and SCI patients. The drug was well tolerated, with only mild and transient side effects of light-headedness, dysesthesias, and dizziness.
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Affiliation(s)
- K C Hayes
- Department of Physical Medicine and Rehabilitation, University of Western Ontario, Program of Rehabilitation and Geriatric Care, Lawson Health Research Institute, St. Joseph's Health Care London, London, Ontario, Canada
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21
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Abstract
BACKGROUND Intrathecal drug delivery has been used clinically since the 1970's. Significant clinical advances have been made combining new technology with pharmacology and surgery. Continuous infusion of medication for both analgesia and spasticity has become a part of the armamentarium for specialists in these areas. Significant recent advances in technology promise further enhancements and improvements for intrathecal therapy. METHODS A review of the literature combined with 20 years personal experience with intrathecal drug delivery. FINDINGS/DISCUSSION Intrathecal therapy has established a role in the treatment of malignant pain, benign pain and severe spasticity. Significant literature and the current state of practice in the United States are reviewed. Recent therapeutic enhancements are discussed, and a wish list of future technological enhancements presented.
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Affiliation(s)
- M S Turner
- Pediatric Neurosurgery, Indianapolis Neurosurgical Group, Inc., IN, USA.
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