Cardiol J
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Methadone is increasingly prescribed for chronic pain, yet the associated mortality appears to be rising disproportionately relative to other opioid analgesics. We review the available evidence on methadone-associated mortality, and explore potential pharmacokinetic and pharmacodynamic explanations for its greater apparent lethality. While methadone shares properties of central nervous system and respiratory depression with other opioids, methadone is unique as a potent blocker of the delayed rectifier potassium ion channel (IKr). ⋯ Predicting an individual's propensity for methadone-induced TdP is difficult at present given the inherent limitations of the QT interval as a risk-stratifier combined with the multifactorial nature of the arrhythmia. Consensus recommendations have recently been published to mitigate the risk of TdP until further studies better define the arrhythmia risk factors for methadone. Studies are needed to provide insights into the clinical covariates most likely to result in methadone-associated arrhythmia and to assess the feasibility of current risk mitigation strategies.
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Digoxin remains one of the most frequently prescribed drugs in the management of atrial fibrillation. The main indications for digoxin in atrial fibrillation are restoration of sinus rhythm, prevention of recurrence and slowing of the ventricular rate. ⋯ In addition, recent reports suggest increased mortality in patients with atrial fibrillation without heart failure taking digoxin. The aim of this article is to review the role of digoxin in atrial fibrillation without heart failure.