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Iseki M, Yamamoto T, Ogawa Y, Majima Y, Abe Y, Watanabe D, Amaya F, Hasegawa T, Inafuku K, Kosugi T, Nomura Y, Deguchi T, Hamada T, Shimizu K, Arai S, Takahashi M, Hamada I, Ishikawa Y, Kawashima M. Efficacy and safety of intravenous fosphenytoin for patients with acute herpes zoster-associated pain: A placebo-controlled randomized trial. J Dermatol 2024; 51:234-242. [PMID: 38149403 DOI: 10.1111/1346-8138.17054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 12/28/2023]
Abstract
Acute zoster-associated pain develops in most patients with herpes zoster. Nonopioid analgesics are usually used to treat acute zoster-associated pain but are frequently ineffective. We administered intravenous fosphenytoin, the prodrug of phenytoin, to patients with acute zoster-associated pain to examine its analgesic efficacy and safety. At 13 medical institutions in Japan, we conducted a phase II, double-blind, placebo-controlled, randomized trial of intravenous fosphenytoin in Japanese inpatients with acute zoster-associated pain for whom nonopioid analgesics had shown an insufficient analgesic effect. The patients were randomly assigned (1:1:1) to receive a single intravenous dose of fosphenytoin at 18 mg/kg (high dose), a single intravenous dose of fosphenytoin at 12 mg/kg (low dose), or placebo. The primary endpoint was the mean change per hour (slope) in the numerical rating scale score from the baseline score until 120 min after dosing. Seventeen patients were randomly assigned to the low-dose fosphenytoin group (n = 6, median age 62.5 years, range 39-75 years), high-dose fosphenytoin group (n = 5, median age 69.0 years, range 22-75 years), and placebo group (n = 5, median age 52.0 years, range 38-72 years). One patient was excluded because of investigational drug dilution failure. This study was discontinued because of the influences of coronavirus disease 2019. The slope was significantly lower in the high- and low-dose fosphenytoin groups than in the placebo group (P < 0.001 and P = 0.016, respectively). Responsiveness to intravenous fosphenytoin (≥2-point reduction in the numerical rating scale score from baseline to 120 min after dosing) was inferred at plasma total phenytoin concentrations of 10-15 μg/mL. Treatment-emergent adverse events caused no safety concerns in the clinical setting and intravenous fosphenytoin was well tolerated. Intravenous fosphenytoin appears to be an effective and promising alternative treatment for acute zoster-associated pain. Trial Registration: ClinicalTrials.gov NCT04139330.
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Affiliation(s)
- Masako Iseki
- Department of Anesthesiology and Pain Medicine, Juntendo University Faculty of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Takenobu Yamamoto
- Department of Dermatology, Kawasaki Medical School General Medical Center, Okayama, Okayama, Japan
| | - Youichi Ogawa
- Department of Dermatology, Faculty of Medicine, University of Yamanashi, Chuo, Yamanashi, Japan
| | - Yuta Majima
- Department of Dermatology, Shizuoka City Shizuoka Hospital, Shizuoka, Shizuoka, Japan
| | - Yoichiro Abe
- Department of Pain Clinic, NTT Medical Center Tokyo, Shinagawa, Tokyo, Japan
| | - Daisuke Watanabe
- Department of Dermatology, Aichi Medical University School of Medicine, Nagakute, Aichi, Japan
| | - Fumimasa Amaya
- Department of Pain Management and Palliative Care Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Toshio Hasegawa
- Department of Dermatology and Allergology, Juntendo University Shizuoka Hospital, Izunokuni, Shizuoka, Japan
| | - Kazuhiro Inafuku
- Department of Dermatology, Kimitsu Chuo Hospital, Kisarazu, Chiba, Japan
| | - Toshifumi Kosugi
- Department of Palliative Care, Saga-Ken Medical Centre Koseikan, Saga, Japan
| | - Yukiko Nomura
- Department of Dermatology, KKR Sapporo Medical Center, Sapporo, Hokkaido, Japan
| | - Tokiko Deguchi
- Division of Dermatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Toshihisa Hamada
- Department of Dermatology, Takamatsu Red Cross Hospital, Takamatsu, Kagawa, Japan
| | | | - Saori Arai
- Nobelpharma Co., Ltd., Chuo-ku, Tokyo, Japan
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Kocot-Kępska M, Pawlik K, Ciapała K, Makuch W, Zajączkowska R, Dobrogowski J, Przeklasa-Muszyńska A, Mika J. Phenytoin Decreases Pain-like Behaviors and Improves Opioid Analgesia in a Rat Model of Neuropathic Pain. Brain Sci 2023; 13:858. [PMID: 37371338 DOI: 10.3390/brainsci13060858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/18/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
Neuropathic pain remains a clinical challenge due to its complex and not yet fully understood pathomechanism, which result in limited analgesic effectiveness of the management offered, particularly for patients with acute, refractory neuropathic pain states. In addition to the introduction of several modern therapeutic approaches, such as neuromodulation or novel anti-neuropathic drugs, significant efforts have been made in the repurposing of well-known substances such as phenytoin. Although its main mechanism of action occurs at sodium channels in excitable and non-excitable cells and is well documented, how the drug affects the disturbed neuropathic interactions at the spinal cord level and how it influences morphine-induced analgesia have not been clarified, both being crucial from a clinical perspective. We demonstrated that single and repeated systemic administrations of phenytoin decreased tactile and thermal hypersensitivity in an animal model of neuropathic pain. Importantly, we observed an increase in the antinociceptive effect on thermal stimuli with repeated administrations of phenytoin. This is the first study to report that phenytoin improves morphine-induced antinociceptive effects and influences microglia/macrophage activity at the spinal cord and dorsal root ganglion levels in a neuropathic pain model. Our findings support the hypothesis that phenytoin may represent an effective strategy for neuropathic pain management in clinical practice, particularly when combination with opioids is needed.
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Affiliation(s)
- Magdalena Kocot-Kępska
- Department of Pain Research and Treatment, Jagiellonian University Medical College, 31-501 Krakow, Poland
| | - Katarzyna Pawlik
- Department of Pain Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, 31-343 Krakow, Poland
| | - Katarzyna Ciapała
- Department of Pain Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, 31-343 Krakow, Poland
| | - Wioletta Makuch
- Department of Pain Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, 31-343 Krakow, Poland
| | - Renata Zajączkowska
- Department of Interdisciplinary Intensive Care, Jagiellonian University Medical College, 30-688 Krakow, Poland
| | - Jan Dobrogowski
- Department of Pain Research and Treatment, Jagiellonian University Medical College, 31-501 Krakow, Poland
| | - Anna Przeklasa-Muszyńska
- Department of Pain Research and Treatment, Jagiellonian University Medical College, 31-501 Krakow, Poland
| | - Joanna Mika
- Department of Pain Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, 31-343 Krakow, Poland
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Ou M, Chen J, Yang S, Xiao L, Xiong D, Wu S. Rodent models of postherpetic neuralgia: How far have we reached? Front Immunol 2023; 14:1026269. [PMID: 37020565 PMCID: PMC10067614 DOI: 10.3389/fimmu.2023.1026269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 02/22/2023] [Indexed: 04/07/2023] Open
Abstract
Background Induced by varicella zoster virus (VZV), postherpetic neuralgia (PHN) is one of the common complications of herpes zoster (HZ) with refractory pain. Animal models play pivotal roles in disclosing the pain mechanisms and developing effective treatments. However, only a few rodent models focus on the VZV-associated pain and PHN. Objective To summarize the establishment and characteristics of popular PHN rodent models, thus offer bases for the selection and improvement of PHN models. Design In this review, we retrospect two promising PHN rodent models, VZV-induced PHN model and HSV1-induced PHN model in terms of pain-related evaluations, their contributions to PHN pathogenesis and pharmacology. Results Significant difference of two PHN models is the probability of virus proliferation; 2) Most commonly used pain evaluation of PHN model is mechanical allodynia, but pain-induced anxiety and other behaviours are worth noting; 3) From current PHN models, pain mechanisms involve changes in virus gene and host gene expression, neuroimmune-glia interactions and ion channels; 4) antiviral drugs and classical analgesics serve more on the acute stage of herpetic pain. Conclusions Different PHN models assessed by various pain evaluations combine to fulfil more comprehensive understanding of PHN.
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Affiliation(s)
- Mingxi Ou
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, China
- Department of Chemistry, University of Science and Technology of China, Hefei, China
| | - Jiamin Chen
- Teaching and Research Group of Biology, Vanke Bilingual School (VBS), Shenzhen, China
| | - Shaomin Yang
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, China
| | - Lizu Xiao
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, China
| | - Donglin Xiong
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, China
| | - Songbin Wu
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, China
- *Correspondence: Songbin Wu,
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