What is the QTc (corrected QT interval) cutoff for metoclopramide (Reglan)?

QTc Cutoff for Metoclopramide

Metoclopramide should be discontinued or dose-reduced if the QTc reaches >500 ms or increases by >60 ms from baseline. 1

Critical QTc Thresholds

The following QTc values require action when prescribing metoclopramide:

• QTc >500 ms: Discontinue metoclopramide and continue monitoring until the drug washes out and QTc is documented to be decreasing 1
• QTc increase >60 ms from baseline: Discontinue or reduce dose 1
• QTc 450-500 ms: Consider this a "grey zone" requiring heightened vigilance and risk factor optimization 1

Baseline QTc Monitoring Protocol

Before initiating metoclopramide therapy:

• Obtain baseline ECG to establish the patient's QTc, particularly in those with cardiac risk factors 1
• Document normal upper limits: QTc <450 ms in men, <460 ms in women 1, 2
• Measure QTc at baseline, then every 8-12 hours if the patient has Class I indication for QT monitoring 1
• Repeat QTc measurement before and after dose increases 1

Risk Factors Requiring Enhanced Monitoring

Metoclopramide poses higher risk in patients with:

• Female sex (women have inherently longer QTc intervals) 1
• Hypokalemia or other electrolyte disturbances (maintain potassium >4 mM/L) 1
• Bradycardia 1
• Concomitant QT-prolonging medications 1
• Structural heart disease or baseline QT prolongation 1
• Age >65 years 1
• Congestive heart failure 1

Clinical Context

While metoclopramide is not listed among the most frequent QT-prolonging drugs in the guidelines 1, it has been documented to cause QTc prolongation in clinical practice 3. The European Heart Journal guidelines provide Class I evidence (Level C) that any drug with QT-prolonging potential should be discontinued when QTc reaches >500 ms or increases >60 ms from baseline 1.

Measurement Considerations

• Use Fridericia's formula for QTc correction when possible, as Bazett's formula overcorrects at higher heart rates (>80 bpm) and may produce artificially elevated values 1, 4
• Measure in leads II, V3, or V5, using the longest value 2
• Document the correction formula used to ensure consistency in serial measurements 1

Management Algorithm

1. Pre-treatment: Check baseline ECG and electrolytes 1
2. If QTc <450 ms (men) or <460 ms (women): Proceed with metoclopramide, optimize risk factors 1, 2
3. If QTc 450-500 ms: Consider alternative antiemetic; if metoclopramide necessary, monitor closely and eliminate other risk factors 1
4. If QTc >500 ms or increase >60 ms: Discontinue metoclopramide immediately 1
5. During treatment: Avoid concomitant QT-prolonging drugs, maintain normal potassium levels, monitor for bradycardia 1