Related Experiment Video
Updated: Aug 15, 2026
08:28
Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus
Published on: April 5, 2011
Effects of methadone on QT-interval dispersion
Mori J Krantz1, Christopher M Lowery, Bridget A Martell
1Department of Medicine, Denver Health Medical Center, Denver, Colorado 80204, USA. Mkrantz@dhha.org
Pharmacotherapy
|October 20, 2005
Summary
Methadone modestly increased QT-interval dispersion and rate-corrected QT (QTc) interval in patients undergoing treatment. This effect, indicating heterogeneous cardiac repolarization, was less pronounced than with antiarrhythmic drugs.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Electrophysiology
Background:
- Opioid medications, including methadone, are widely used for pain management and opioid maintenance therapy.
- Concerns exist regarding potential cardiac side effects of methadone, particularly its impact on cardiac repolarization.
- QT interval dispersion is a measure of repolarization heterogeneity, which can be associated with an increased risk of arrhythmias.
Purpose of the Study:
- To investigate the effect of methadone therapy on QT interval dispersion.
- To assess changes in rate-corrected QT (QTc) interval in patients receiving methadone.
- To identify factors associated with increased QT dispersion during methadone treatment.
Main Methods:
- A prospective, single-center cohort study was conducted.
- 118 patients newly admitted for methadone maintenance therapy were enrolled.
- Electrocardiograms (ECGs) were obtained at baseline and 6 months, with manual interpretation by blinded investigators.
Main Results:
- Methadone therapy significantly increased mean QT dispersion from 32.9 msec at baseline to 42.4 msec at 6 months (p<0.0001).
- Rate-corrected QT (QTc) interval also increased significantly by 14.1 msec (p<0.0001).
- Concomitant antidepressant therapy was associated with a greater increase in QT dispersion.
Conclusions:
- Methadone therapy leads to a modest increase in both QTc interval and QT dispersion.
- The observed increase in QT dispersion suggests heterogeneous cardiac repolarization.
- The cardiac repolarization effects of methadone appear less significant compared to those of antiarrhythmic drugs.
Related Concept Videos
01:12Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers
Class III antiarrhythmic drugs are a group of medications that can prolong action potentials in the heart. They achieve this by blocking potassium channels or enhancing inward currents from sodium channels. However, these drugs have a unique property of "reverse use-dependence," which is most pronounced at slower heart rates and can lead to torsades de pointes—a specific type of arrhythmia. However, it is essential to note that excessive QT interval prolongation—a measure of the heart's...
01:26Therapeutic Drug Monitoring: Drug Analysis Methods
Therapeutic Drug Monitoring (TDM) is a clinical practice that measures specific drug levels in a patient's blood or body tissues to tailor drug therapy effectively. This monitoring is critical for managing drugs with narrow therapeutic indices like digoxin and phenytoin, ensuring they are both safe and effective. For instance, monitoring theophylline levels in asthma patients involves precision and sensitivity to adjust doses according to individual responses to therapy, ensuring efficacy and...
01:14Pharmacokinetic–Pharmacodynamic Relationship: Duration of Dose-Effect Relationship
For drugs producing a quantal response, onset occurs when plasma concentration reaches a minimum effective level (Cmin). The drug's action duration depends on how long the plasma concentration remains above Cmin.Two primary factors influence this duration: dose size and the rate of drug removal from the action site. Both depend on the drug's redistribution to poorly perfused tissues and elimination processes. A larger dose promotes rapid onset and prolongs the effect's duration.Consider a...
01:15Pharmacodynamic Models: Linear Concentration–Effect Model
The linear concentration–effect model, underpinned by the principle that pharmacological effect (E) is directly proportional to plasma drug concentration (C), emerges as a pivotal simplification of the Emax model for conditions where C is significantly less than EC50. This model portrays a linear trajectory of the concentration–effect relationship when drug levels are markedly below the EC50 threshold.Despite its inherent assumption of continuous effect augmentation with increasing drug...
01:29Therapeutic Drug Monitoring: Affecting Factors
Therapeutic Drug Monitoring (TDM) is the clinical practice of measuring specific drug levels in a patient's blood or body tissues to manage and optimize therapy. TDM is crucial for drugs with narrow therapeutic windows, like warfarin and phenytoin, where incorrect doses can lead to treatment failure or severe side effects. This monitoring ensures the dosage administered is within a safe and effective range. The factors affecting therapeutic drug monitoring include:Patient-Specific Factors:a.
01:02Noncompartmental Analysis: Mean Transit, Absorption and Dissolution Time
When drugs are administered extravascularly, a comprehensive evaluation through noncompartmental analysis becomes imperative. This analytical approach considers various parameters that play a crucial role in understanding the pharmacokinetics of these drugs.
One of the key parameters is the mean transit time (MTT), which refers to the total duration required for drug molecules to transit through the body. MTT is determined by calculating the ratio of the area under the moment curve to the area...
One of the key parameters is the mean transit time (MTT), which refers to the total duration required for drug molecules to transit through the body. MTT is determined by calculating the ratio of the area under the moment curve to the area...