title: Serum concentration of eperisone hydrochloride correlates with QT interval.
abstract: BACKGROUND
  Eperisone hydrochloride is a centrally acting muscle relaxant prescribed for muscle stiffness that acts by depressing the activities of α and γ efferent neurons in the spinal cord and supraspinal structures. Although a case of eperisone-induced severe QT prolongation had been reported, the relationship between serum eperisone concentration and QT interval remains obscure.
  
  
  OBJECTIVE
  The aim of this study was to investigate the relationship between serum eperisone concentration and QT interval.
  
  
  METHODS
  Four patients who overdosed on eperisone were admitted to our hospital between January 2010 and December 2011. We took simultaneous serial measurements of serum eperisone concentration and QT interval in the intensive care unit. In total, 22 measurement points were plotted for these patients. We analyzed the correlation between the serum eperisone concentration and corrected QT (QTc) interval.
  
  
  RESULTS
  Three men and one woman (mean age, 50 years) overdosed on eperisone with an average dose of 3087.5 mg (therapeutic dose, 150 mg/day). The mean QTc interval at arrival was 592 ms (range, 444-825 ms), and the mean serum eperisone concentration at arrival was 1257.5 ng/mL (range, 14.5-4120.0 ng/mL). The correlation coefficient was 0.833 between serum eperisone concentration and QTc interval (P < .001).
  
  
  CONCLUSIONS
  Serum eperisone concentration correlates with QTc interval in patients who overdose on eperisone.
authors.affiliation: Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Kanagawa, Japan. Electronic address: yamagiwa@is.icc.u-tokai.ac.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamagiwa
authors.affiliation: Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Morita
authors.affiliation: Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Kanagawa, Japan; Department of Cardiology, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Amino
authors.affiliation: Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Miura
authors.affiliation: Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Saito
authors.affiliation: Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: Sadaki
authors.initials: S
authors.lastname: Inokuchi
mesh_terms: D000293:Adolescent; D000368:Aged; D062787:Drug Overdose / Q000097:blood / Q000150:complications / Q000503:physiopathology; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009125:Muscle Relaxants, Central / Q000009:adverse effects / Q000097:blood*; D011427:Propiophenones / Q000009:adverse effects / Q000097:blood*; D012189:Retrospective Studies
chemical_list: D009125:Muscle Relaxants, Central; D011427:Propiophenones; C030848:eperisone