A case of torsades de pointes induced by severe QT prolongation after an overdose of eperisone and triazolam in a patient receiving nifedipine.
BACKGROUND
Eperisone hydrochloride is a centrally acting muscle relaxant, and triazolam is a short-acting benzodiazepine. Although commonly prescribed, cardiotoxicity induced by a single overdose of either drug is comparatively rare. A patient receiving nifedipine developed torsades de pointes (TdP) because of prolongation of the corrected QT (QTc) interval after an overdose of eperisone hydrochloride and triazolam.


METHODS
A 60-year-old man receiving nifedipine was admitted in a comatose condition 3 h after ingesting 5,000 mg of eperisone and 2.5 mg of triazolam. Electrocardiogram showed sinus rhythm with prolongation of the QTc interval (820 ms). The serum electrolyte levels were as follows: potassium, 3.8 mEq/L; magnesium, 2.4 mg/dL. The serum drug concentrations were high: eperisone, 15,360 ng/mL; triazolam, 110.8 ng/mL. A temporary cardiac pacemaker was implanted immediately after the development of TdP, 11 h after the ingestion. The serum triazolam concentration normalized on day 2. The QTc interval and eperisone concentration normalized on day 6.


CONCLUSIONS
Eperisone and triazolam overdose can cause life-threatening cardiotoxicity. Electrocardiographic monitoring and serial determination of QTc interval are likely the best way to observe these patients and evaluate the risk of cardiotoxicity.
Yamagiwa
Takeshi
T
Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa, Japan. yamagiwa@is.icc.u-tokai.ac.jp
Amino
Mari
M
Morita
Seiji
S
Yamamoto
Rie
R
Saito
Takeshi
T
Inokuchi
Sadaki
S
D014151:Anti-Anxiety Agents / Q000493:pharmacokinetics / Q000506:poisoning; D002121:Calcium Channel Blockers / Q000009:adverse effects; D003128:Coma / Q000139:chemically induced; D004347:Drug Interactions; D062787:Drug Overdose; D004562:Electrocardiography; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D009125:Muscle Relaxants, Central / Q000493:pharmacokinetics / Q000506:poisoning; D009543:Nifedipine / Q000009:adverse effects; D011427:Propiophenones / Q000493:pharmacokinetics / Q000506:poisoning*; D016171:Torsades de Pointes / Q000139:chemically induced*; D014229:Triazolam / Q000493:pharmacokinetics / Q000506:poisoning*
D014151:Anti-Anxiety Agents; D002121:Calcium Channel Blockers; D009125:Muscle Relaxants, Central; D011427:Propiophenones; D014229:Triazolam; C030848:eperisone; D009543:Nifedipine