Causality assessment · Contested: signal not confirmed by large randomized trials

Loperamide and QT prolongation: is the FAERS signal real?

n=274 co-reports · PRR 3.6 · ROR 3.6

A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.

Contested: signal not confirmed by large randomized trials

Loperamide ↔ QT prolongation

n=274 co-reports · PRR 3.6 · ROR 3.6

Loperamide is an over-the-counter opioid-receptor agonist for diarrhoea; at high doses it blocks cardiac sodium and potassium channels, prolonging the QT interval and causing torsades de pointes (274 co-reports, PRR 3.6), which triggered an FDA warning. The QT signal is thus dose-dependent and confined to supratherapeutic abuse rather than normal use, so it does not represent a hazard at labelled doses.

Regulatory basis: loperamide labelling — FDA 2016 warning on cardiac arrhythmias with high doses; QT-prolongation literature.

Bradford Hill viewpoint	Status	Note
Temporality (necessary)	met	QT prolongation with high doses
Strength	met	PRR 3.6, modest
Consistency	met	Reproduced across case series
Specificity	met	Specific to high-dose use
Biological gradient	met	Dose-dependent
Plausibility	met	Sodium/potassium-channel blockade
Coherence	met	Fits the pharmacology
Experiment	n/a	Not a trial endpoint
Analogy	met	Analogous to other QT-prolonging drugs

This table is this page's own qualitative read of the literature cited above, not an automated or citation-gated assessment — see the note at the bottom of this page.

✓ Trial evidence found — E7 TCR T Cells for Human Papillomavirus-Associated Cancers (NCT02858310)

Adverse event	Phase I:Dose Escalation Cohort; Arm 1:Phase I:DoseLevel 1: 1 x 10^9 E7 T-Cell Receptor (TCR) Cells (n=3) · Phase I: Dose Escalation Cohort; Arm 1: Phase I; Dose Level 2: 1 x 10^10 E7 T-Cell Receptor Cells (n=3) · Phase I: Dose Escalation Cohort; Arm 1: Phase I; Dose Level 3: 1 x 10^11 E7 Cells (n=6) · Phase II Cohort; Arm 2: Phase II: 1 x 10^11 E7 Cells (n=18)
Activated partial thromboplastin time prolonged	0/3	0/3	0/6	1/18
Investigations - Other, specify: Prolonged QTcB interval (EKG)	0/3	0/3	0/6	1/18

Post-marketing signal terms appear in this trial's posted adverse-event tables; per-arm counts shown as affected/at-risk. View on ClinicalTrials.gov →