ABSTRACT
Retigabine [D23129; N‐(2‐amino‐4‐(4‐fluorobenzylamino)‐phenyl)carbamic acid ethyl ester] is an antiepileptic drug with a recently described novel mechanism of action that involves opening of neuronal KV7.2–7.5 (formerly KCNQ2‐5) voltage‐activated K+ channels. These channels (primarily KV7.2/7.3) enable generation of the M‐current, a subthreshold K+ current that serves to stabilize the membrane potential and control neuronal excitability. In this regard, retigabine has been shown to have a broad‐spectrum of activity in animal models of electrically‐induced (amygdala‐kindling, maximal electroshock) and chemically‐induced (pentylenetetrazole, picrotoxin, NMDA) epileptic seizures. These encouraging results suggest that retigabine may also prove useful in the treatment of other diseases associated with neuronal hyperexcitability. Neuropathic pain conditions are characterized by pathological changes in sensory pathways, which favor action potential generation and enhanced pain transmission. Although sometimes difficult to treat with conventional analgesics, antiepileptics can relieve some symptoms of neuropathic pain. A number of recent studies have reported that retigabine can relieve pain‐like behaviors (hyperalgesia and allodynia) in animal models of neuropathic pain. Neuronal activation within several key structures within the CNS can also be observed in various animal models of anxiety. Moreover, amygdala‐kindled rats, which have a lowered threshold for neuronal activation, also display enhanced anxiety‐like responses. Retigabine dose‐dependently reduces unconditioned anxiety‐like behaviors when assessed in the mouse marble burying test and zero maze. Early clinical studies have indicated that retigabine is rapidly absorbed and distributed, and is resistant to first pass metabolism. Tolerability is good in humans when titrated up to its therapeutic dose range (600‐1200 mg/day). No tolerance, dependence or withdrawal potential has been reported, although adverse effects can include mild dizziness, headache, nausea and somnolence. Thus, retigabine may prove to be useful in the treatment of a diverse range of disease states in which neuronal hyperexcitability is a common underlying factor.
Keywords: Anxiety, Epilepsy, KCNQ – KV7 channel, M‐current, Pain
Full Text
The Full Text of this article is available as a PDF (166.7 KB).
REFERENCES
- 1. Adamec RE, Morgan HD. The effect of kindling of different nuclei in the left and right amygdala on anxiety in the rat. Physiol Behav 1994;55:1–12. [DOI] [PubMed] [Google Scholar]
- 2. Anisman H, Kelly O, Hayley S, et al. Acoustic startle and fear‐potentiated startle in rats selectively bred for fast and slow kindling rates: Relation to monoamine activity. Eur J Neurosci 2000;12:4405–4416. [DOI] [PubMed] [Google Scholar]
- 3. Armand V, Rundfeldt C, Heinemann U. Effects of retigabine (D‐23129) on different patterns of epileptiform activity induced by 4‐aminopyridine in rat entorhinal cortex hippocampal slices. Naunyn Schmiedebergs Arch Pharmacol 1999;359:33–39. [DOI] [PubMed] [Google Scholar]
- 4. Backonja M. Anticonvulsants and antiarrhythmics in the treatment of neuropathic pain syndromes In: Hansson PT, et al., Eds. Neuropathic pain: Pathophysiology and treatment. IASP Press; 2001:185–201. [Google Scholar]
- 5. Bartolomeil F, Guye M, Wendling F, et al. Fear, anger and compulsive behavior during seizure: Involvement of large scale fronto‐temporal neural networks. Epileptic Disord 2002;4:235–241. [PubMed] [Google Scholar]
- 6. Biervert C, Schroeder BC, Kubisch C, et al. A potassium channel mutation in neonatal human epilepsy. Science 1998;279:403–406. [DOI] [PubMed] [Google Scholar]
- 7. Blackburn‐Munro G. Pain‐like behaviours in animals: How human are they Trends Pharmacol Sci 2004;6:299–305. [DOI] [PubMed] [Google Scholar]
- 8. Blackburn‐Munro G, Skaaning Jensen B. The anticonvulsant retigabine attenuates nociceptive behaviours in animal models of persistent and neuropathic pain. Eur J Pharmacol 2003;460:109–116. [DOI] [PubMed] [Google Scholar]
- 9. Brown BS, Yu SP. Modulation and genetic identification of the M channel. Prog Biophys Mol Biol 2000;73:135–166. [DOI] [PubMed] [Google Scholar]
- 10. Chang BS, Lowenstein DH. Epilepsy. N Engl J Med 2003;349:1257–1266. [DOI] [PubMed] [Google Scholar]
- 11. Davis M. Animal models of anxiety based on classical conditioning: The conditioned emotional response (CER) and the fear‐potentiated startle effect. Pharmacol Ther 1990;47:147–165. [DOI] [PubMed] [Google Scholar]
- 12. Davis M. The role of the amygdala in fear and anxiety. Annu Rev Neurosci 1992;15:353–375. [DOI] [PubMed] [Google Scholar]
- 13. Dedek K, Kunath B, Kananura C, Reuner U, Jentsch TJ, Steinlein OK. Myokymia and neonatal epilepsy caused by a mutation in the voltage sensor of the KCNQ2 K+ channel. Proc Natl Acad Sci USA 2001;98:12272–12277. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14. Dennison Z, Teskey GC, Cain DP. Persistence of kindling: Effect of partial kindling, retention interval, kindling site, and stimulation parameters. Epilepsy Res 1995;21:171–182. [DOI] [PubMed] [Google Scholar]
- 15. De Sarro G, Di Paola ED, Conte G, Pasculli MP, De Sarro A. Influence of retigabine on the anticonvulsant activity of some antiepileptic drugs against audiogenic seizures in DBA/2 mice. Naunyn Schmiedebergs Arch Pharmacol 2001;363:330–336. [DOI] [PubMed] [Google Scholar]
- 16. Devaux JJ, Kleopa KA, Cooper EC, Scherer SS. KCNQ2 is a nodal K+ channel. J Neurosci 2004;24:1236–1244. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17. Dieter, H‐R , Engel J, Kutscher B, Polymeropoulos E, Szelenyi S, Nickel B. EP 0 554 543 B1, 1996.
- 18. Dost R, Rostock A, Rundfeldt C. The anti‐hyperalgesic activity of retigabine is mediated by KCNQ potassium channel activation. Naunyn Schmiedebergs Arch Pharmacol 2004;369:382–390. [DOI] [PubMed] [Google Scholar]
- 19. Dost R, Rundfeldt C. The anticonvulsant retigabine potently suppresses epileptiform discharges in the low Ca++ and low Mg++ model in the hippocampal slice preparation. Epilepsy Res 2000;38:53–66. [DOI] [PubMed] [Google Scholar]
- 20. Dupuis DS, Schroder RL, Jespersen T, et al. Activation of KCNQ5 channels stably expressed in HEK293 cells by BMS‐204352. Eur J Pharmacol 2002;437:129–137. [DOI] [PubMed] [Google Scholar]
- 21. Dworkin RH, Backonja M, Rowbotham MC, et al. Advances in neuropathic pain: Diagnosis, mechanisms, and treatment recommendations. Arch Neurol 2003;60:1524–1534. [DOI] [PubMed] [Google Scholar]
- 22. Ferron GM, Paul J, Fruncillo R, et al. Multiple‐dose, linear, dose‐proportional pharmacokinetics of retigabine in healthy volunteers. J Clin Pharmacol 2002;42:175–182. [DOI] [PubMed] [Google Scholar]
- 23. Friedel HA, Fitton A. Flupirtine. A review of its pharmacological properties, and therapeutic efficacy in pain states. Drugs 1993;45:548–569. [DOI] [PubMed] [Google Scholar]
- 24. Ferron GM, Patat A, Parks V, Rolan P, Troy SM. Lack of pharmacokinetic interaction between retigabine and phenobarbitone at steady‐state in healthy subjects. Br J Clin Pharmacol 2003;56:39–45. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25. Geller I, Seifter J. The effects of meprobamate, barbiturate, D‐amphetamine and promazine on experimentally‐induced conflict in the rat. Psychopharmacologia 1960;1:482–492. [Google Scholar]
- 26. Gutman GA, Chandy KG, Adelman JP, et al. International Union of Pharmacology. XLI. Compendium of voltage‐gated ion channels: potassium channels. Pharmacol Rev 2003;55:583–586. [DOI] [PubMed] [Google Scholar]
- 27. Hadley JK, Passmore GM, Tatulian L, et al. Stoichiometry of expressed KCNQ2/KCNQ3 potassium channels and subunit composition of native ganglionic M channels deduced from block by tetraethylammonium. J Neurosci 2003;23:5012–5019. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28. Hempel R, Schupke H, McNeilly PJ, et al. Metabolism of retigabine (D‐23129), a novel anticonvulsant. Drug Metab Dispos 1999;27:613–622. [PubMed] [Google Scholar]
- 29. Hermann R, Ferron GM, Erb K, et al. Effects of age and sex on the disposition of retigabine. Clin Pharmacol Ther 2003;73:61–70. [DOI] [PubMed] [Google Scholar]
- 30. Hermann R, Knebel NG, Neibch G, Richards L, Borlak J, Locher M. Pharmacokinetic interaction between retigabine and lamotrigine in healthy subjects. Eur J Clin Pharmacol 2003;58:795–802. [DOI] [PubMed] [Google Scholar]
- 31. Hetka R, Rundfeldt C, Heinemann U, Schmitz D. Retigabine strongly reduces repetitive firing in rat entorhinal cortex. Eur J Pharmacol 1999;386:165–171. [DOI] [PubMed] [Google Scholar]
- 32. Hiller A, Nguyen N, Strassburg CP, et al. Retigabine N‐glucuronidation and its potential role in enterohepatic circulation. Drug Metab Dispos 1999;27:605–612. [PubMed] [Google Scholar]
- 33. Ishikawa K, Tanaka M, Black JA, Waxman SG. Changes in expression of voltage‐gated potassium channels in dorsal root ganglion neurons following axotomy. Muscle Nerve 1999;22:502–507. [DOI] [PubMed] [Google Scholar]
- 34. Jentsch TJ. Neuronal KCNQ potassium channels: Physiology and role in disease. Nat Rev Neurosci 2000;1:21–30. [DOI] [PubMed] [Google Scholar]
- 35. Kapetanovic IM, Yonekawa WD, Kupferberg HJ. The effects of D‐23129, a new experimental anticonvulsant drug, on neurotransmitter amino acids in the rat hippocampus in vitro. Epilepsy Res 1995;22:167–173. [DOI] [PubMed] [Google Scholar]
- 36. Knebel NG, Grieb S, Leisenheimer S, Locher M. Determination of retigabine and its acetyl metabolite in biological matrices by on‐line solid‐phase extraction (column switching) liquid chromatography with tandem mass spectrometry. J Chromatogr B Biomed Sci Appl 2000;748:97–111. [DOI] [PubMed] [Google Scholar]
- 37. LeDoux J. The emotional brain, fear, and the amygdala. Cell Mol Neurobiol 2003;23:727–738. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 38. Loscher W. Animal models of drug‐resistant epilepsy. Novartis Found Symp 2002;243:149–159. [PubMed] [Google Scholar]
- 39. Luben V, Muller H, Lobisch M, Worz R. Treatment of tumor pain with flupirtine. Results of a double‐blind study versus tramadol. Fortschr Med 1994;112:282–286. [PubMed] [Google Scholar]
- 40. Main MJ, Cryan JE, Dupere JR, Cox B, Clare JJ, Burbidge SA. Modulation of KCNQ2/3 potassium channels by the novel anticonvulsant retigabine. Mol Pharmacol 2000;58:253–262. [DOI] [PubMed] [Google Scholar]
- 41. Marrion NV. Control of M‐current. Annu Rev Physiol 1997;59:483–504. [DOI] [PubMed] [Google Scholar]
- 42. Matsuda S, Peng H, Yoshimura H et al. Persistent c‐fos expression in the brains of mice with chronic social stress. Neurosci Res 1996;26:157–170. [PubMed] [Google Scholar]
- 43. Meisel P, Landgraf K‐F, Schäfer J, et al. US Patent 5,914,425, 1999.
- 44. Millan MJ. The neurobiology and control of anxious states. Prog Neurobiol 2003;70:83–244. [DOI] [PubMed] [Google Scholar]
- 45. Mineka S, Zinbarg R. Conditioning and ethological models of anxiety disorders: Stress‐in‐dynamic‐context anxiety models. Nebr Symp Motiv 1996;43:135–210. [PubMed] [Google Scholar]
- 46. Mohapel P, McIntyre DC. Amygdala kindling‐resistant (SLOW) or ‐prone (FAST) rat strains show differential fear responses. Behav Neurosci 1998;112:1402–1413. [DOI] [PubMed] [Google Scholar]
- 47. Muzina DJ, El‐Sayegh S, Calabrese JR. Antiepileptic drugs in psychiatry‐focus on randomized controlled trial. Epilepsy Res 2002;50:195–202. [DOI] [PubMed] [Google Scholar]
- 48. McMahon FG, Arndt WF Jr, Newton JJ, Montgomery PA, Perhach JL. Clinical experience with flupirtine in the U.S. Postgrad Med J 1987;63(Suppl 3):81–85. [PubMed] [Google Scholar]
- 49. McNeilly PJ, Torchin CD, Anderson LW, Kapetanovic IM, Kupferberg JH, Strong JM. In vitro glucuronidation of D‐23129, a new anticonvulsant, by human liver microsomes and liver slices. Xenobiotica 1997;27:431–441. [DOI] [PubMed] [Google Scholar]
- 50. Nielsen AN, Mathiesen C, Blackburn‐Munro G. Pharmacological characterisation of acid‐induced muscle allodynia in rats. Eur J Pharmacol 2004;487:93–103. [DOI] [PubMed] [Google Scholar]
- 51. Njung'e K, Handley SL. Evaluation of marble‐burying behavior as a model of anxiety. Pharmacol Biochem Behav 1991;38:63–67. [DOI] [PubMed] [Google Scholar]
- 52. Pare D, Collins DR. Neuronal correlates of fear in the lateral amygdala: Multiple extracellular recordings in conscious cats. J Neurosci 2000;20:2701–2710. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 53. Pascoe JP, Kapp BS. Electrophysiological characteristics of amygdaloid central nucleus neurons in the awake rabbit. Brain Res Bull 1985;14:331–338. [DOI] [PubMed] [Google Scholar]
- 54. Passmore GM, Selyanko AA, Mistry M, et al. KCNQ/M currents in sensory neurons: Significance for pain therapy. J Neurosci 2003;23:7227–7236. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 55. Petersen EN, Lassen JB. A water lick conflict paradigm using drug experienced rats. Psychopharmacology 1981;75:236–239. [DOI] [PubMed] [Google Scholar]
- 56. Quirk GJ, Gehlert DR. Inhibition of the amygdala: Key to pathological states Ann NY Acad Sci 2003;985:263–272. [DOI] [PubMed] [Google Scholar]
- 57. Quirk GJ, Repa C, LeDoux JE. Fear conditioning enhances short‐latency auditory responses of lateral amygdala neurons: Parallel recordings in the freely behaving rat. Neuron 1995;15:1029–1039. [DOI] [PubMed] [Google Scholar]
- 58. Rasband MN, Park EW, Vanderah TW, Lai J, Porreca F, Trimmer JS. Distinct potassium channels on painsensing neurons. Proc Natl Acad Sci USA 2001;23:13373–13378. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 59. Rauch SL, Shin LM, Wright CI. Neuroimaging studies of amygdala function in anxiety disorders. Ann NY Acad Sci 2003;985:389–410. [DOI] [PubMed] [Google Scholar]
- 60. Ringe JD, Miethe D, Pittrow D, Wegscheider K. Analgesic efficacy of flupirtine in primary care of patients with osteoporosis related pain. A multivariate analysis. Arzneimittelforschung 2003;53:496–502. [DOI] [PubMed] [Google Scholar]
- 61. Rivera‐Arconada I, Martinez‐Gomez J, Lopez‐Garcia JA. M‐current modulators alter rat spinal nociceptive transmission: An electrophysiological study in vitro. Neuropharmacology 2004;46:598–606. [DOI] [PubMed] [Google Scholar]
- 62. Rogawski, M. A. KCNQ2/KCNQ3 K+ channels and the molecular pathogenesis of epilepsy: Implications for therapy. Trends Neurosci 2000;23:393–398. [DOI] [PubMed] [Google Scholar]
- 63. Rogawski MA, Loscher W. The neurobiology of antiepileptic drugs. Nat Rev Neurosci 2004;5:553–564. [DOI] [PubMed] [Google Scholar]
- 64. Rogawski MA, Loscher W. The neurobiology of antiepileptic drugs for the treatment of nonepileptic conditions. Nat Med 2004;10:685–692. [DOI] [PubMed] [Google Scholar]
- 65. Rosen JB, Hamerman E, Sitcoske M, et al. Hyperexcitability: Exaggerated fear‐potentiated startle produced by partial amygdala kindling. Behav Neurosci 1996;110:43–50. [DOI] [PubMed] [Google Scholar]
- 66. Rostock A, Tober C, Rundfeldt C, et al. D‐23129: A new anticonvulsant with a broad spectrum activity in animal models of epileptic seizures. Epilepsy Res 1996;23:211–223. [DOI] [PubMed] [Google Scholar]
- 67. Rundfeldt C. The new anticonvulsant retigabine (D‐23129) acts as an opener of K+ channels in neuronal cells. Eur J Pharmacol 1997;336:243–249. [DOI] [PubMed] [Google Scholar]
- 68. Rundfeldt C. Characterization of the K+ channel opening effect of the anticonvulsant retigabine in PC12 cells. Epilepsy Res 1999;35:99–107. [DOI] [PubMed] [Google Scholar]
- 69. Rundfeldt C, Netzer R. Investigations into the mechanism of action of the new anticonvulsant retigabine. Interaction with GABAergic and glutamatergic neurotransmission and with voltage gated ion channels. Arzneimittelforschung 2000;50:1063–1070. [DOI] [PubMed] [Google Scholar]
- 70. Rundfeldt C, Netzer R. The novel anticonvulsant retigabine activates M‐currents in Chinese hamster ovarycells transfected with human KCNQ2/3 subunits. Neurosci Lett 2000;282:73–76. [DOI] [PubMed] [Google Scholar]
- 71. Saganich MJ, Machado E, Rudy B. Differential expression of genes encoding subthreshold‐operating voltage‐gated K+ channels in brain. J Neurosci 2001;21:4609–4624. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 72. Sajdyk TJ, Shekhar A. Excitatory amino acid receptor antagonists block the cardiovascular and anxiety responses elicited by gamma‐aminobutyric acidA receptor blockade in the basolateral amygdala of rats. J Pharmacol Exp Ther 1997;283:969–977. [PubMed] [Google Scholar]
- 73. Sajdyk TJ, Shekhar A. Excitatory amino acid receptors in the basolateral amygdala regulate anxiety responses in the social interaction test. Brain Res 1997;764:262–264. [DOI] [PubMed] [Google Scholar]
- 74. Sanders SK, Morzorati SL, Shekhar A. Priming of experimental anxiety by repeated subthreshold GABA blockade in the rat amygdala. Brain Res 1995;699:250–259. [DOI] [PubMed] [Google Scholar]
- 75. Savonenko A, Filipkowski RK, Werka T et al. Defensive conditioning‐related functional heterogeneity among nuclei of the rat amygdala revealed by c‐Fos mapping. Neuroscience 1999;94:723–733. [DOI] [PubMed] [Google Scholar]
- 76. Scheef W. Analgesic efficacy and safety of oral flupirtine in the treatment of cancer pain. Postgrad Med J 1987;63(Suppl 3):67–70. [PubMed] [Google Scholar]
- 77. Schroder RL, Jespersen T, Christophersen P, Strobaek D, Jensen BS, Olesen SP. KCNQ4 channel activation by BMS‐204352 and retigabine. Neuropharmacology 2001;40:888–898.Erratum in: Neuropharmacology 2003;44:553. [DOI] [PubMed] [Google Scholar]
- 78. Schroeder BC, Kubisch C, Stein V, Jentsch TJ. Moderate loss of function of cyclic‐AMP‐modulated KCNQ2/KCNQ3 K+ channels causes epilepsy. Nature 1998;396:687–690. [DOI] [PubMed] [Google Scholar]
- 79. Shepherd JK, Grewal SS, Fletcher A, et al. Behavioural and pharmacological characterisation of the elevated “zero‐maze” as an animal model of anxiety. Psychopharmacology 1994;116:56–64. [DOI] [PubMed] [Google Scholar]
- 80. Sindrup SH, Jensen TS. Antidepressants in the treatment of neuropathic pain In: Hansson PT, et al., Eds. Neuropathic pain: Pathophysiology and treatment. IASP Press; 2001:169–183. [Google Scholar]
- 81. Singh NA, Charlier C, Stauffer D, et al. A novel potassium channel gene, KCNQ2, is mutated in an inherited epilepsy of newborns. Nat Genet 1998;18:25–29. [DOI] [PubMed] [Google Scholar]
- 82. Stables JP, Bertram E, Dudek FE, et al. Therapy discovery for pharmacoresistant epilepsy and for disease‐modifying therapeutics: Summary of the NIH/NINDS/AES models II workshop. Epilepsia 2003;44:1472–1478. [DOI] [PubMed] [Google Scholar]
- 83. Strassburg CP, Strassburg A, Kneip S. Developmental aspects of human hepatic drug glucuronidation in young children and adults. Gut 2002;50:259–265. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 84. Straub H, Kohling R, Hohling J et al. Effects of retigabine on rhythmic synchronous activity of human neocortical slices. Epilepsy Res 2001;44:155–165. [DOI] [PubMed] [Google Scholar]
- 85. Sullivan GM, Apergis J, Gorman JM et al. Rodent doxapram model of panic: Behavioral effects and c‐Fos immunoreactivity in the amygdala. Biol Psychiatry 2003;53:863–870. [DOI] [PubMed] [Google Scholar]
- 86. Tatulian L, Brown DA. Effect of the KCNQ potassium channel opener retigabine on single KCNQ2/3 channels expressed in CHO cells. J Physiol 2003;549:57–63. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 87. Tatulian L, Delmas P, Abogadie FC, Brown DA. Activation of expressed KCNQ potassium currents and native neuronal M‐type potassium currents by the anti‐convulsant drug retigabine. J Neurosci 2001;21:5535–5545. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 88. Tober C, Rostock A, Rundfeldt C, Bartsch R. D‐23129: A potent anticonvulsant in the amygdala kindling model of complex partial seizures. Eur J Pharmacol 1996;303:163–169. [DOI] [PubMed] [Google Scholar]
- 89. Vogel JR, Beer B, Clody DE. A simple and reliable conflict procedure for testing anti‐anxiety agents. Psychopharmacologia 1971;21:1–7. [DOI] [PubMed] [Google Scholar]
- 90. Wang HS, Pan Z, Shi W, et al. KCNQ2 and KCNQ3 potassium channel subunits: Molecular correlates of the M‐channel. Science 1998;282:1890–1893. [DOI] [PubMed] [Google Scholar]
- 91. Waxman SG. The molecular pathophysiology of pain: Abnormal expression of sodium channel genes and its contributions to hyperexcitability of primary sensory neurons. Pain 1999;6(Suppl):S133–140. [DOI] [PubMed] [Google Scholar]
- 92. Wickenden AD, Rigdon GC, McNaughton‐Smith GA, Gross MF. US Patent 6,326,385 B1;2001.
- 93. Wickenden AD, Roeloffs R, McNaughton‐Smith G, Rigdon GC. KCNQ potassium channels: Drug targets for the treatment of epilepsy and pain. Expert Opin Ther Patents 2004;14:457–469. [Google Scholar]
- 94. Wickenden AD, Yu W, Zou A, Jegla T, Wagoner PK. Retigabine, a novel anti‐convulsant, enhances activation of KCNQ2/Q3 potassium channels. Mol Pharmacol 2000;58:591–600. [DOI] [PubMed] [Google Scholar]
- 95. Wickenden AD, Zou A, Wagoner PK, Jegla T. Characterization of KCNQ5/Q3 potassium channels expressed in mammalian cells. Br J Pharmacol 2001;132:381–384. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 96. Woolf CJ, Salter MW. Neuronal plasticity: Increasing the gain in pain. Science 2000;288:1765–1769. [DOI] [PubMed] [Google Scholar]
- 97. Worz R. Flupirtine in chronic myofacial pain conditions. Fortschr Med 1991;109:158–160. [PubMed] [Google Scholar]
- 98. Worz R, Bolten W, Heller B, Krainick JU, Pergande G. Flupirtine in comparison with chlormezanone in chronic musculoskeletal back pain. Results of a multicenter randomized double‐blind study. Fortschr Med 1996;114:500–504. [PubMed] [Google Scholar]
- 99. Yonekawa WD, Kapetanovic IM, Kupferberg HJ. The effects of anticonvulsant agents on 4‐aminopyridine induced epileptiform activity in rat hippocampus in vitro. Epilepsy Res 1995;20:137–150. [DOI] [PubMed] [Google Scholar]
- 100. Yus‐Najera E, Munoz A, Salvador N, et al. Localization of KCNQ5 in the normal and epileptic human temporal neocortex and hippocampal formation. Neuroscience 2003;120:353–364. [DOI] [PubMed] [Google Scholar]
