Psychotropic combinations and cardiac risk
Psychiatry Evidence Base simulator, for healthcare professionals
Many psychotropic drugs prolong the QT interval, and they are often combined. In a European hospital pharmacovigilance database, after the 2011 letters to prescribers, nearly one in three inpatients treated for a major depressive episode with citalopram or escitalopram also received another QT-prolonging psychotropic, even though the European product information contraindicates these combinations (de Bardeci et al., 2023). This simulator checks a prescription against the French interaction guide (ANSM), product labelling and the literature, and takes the patient’s risk factors into account. It does not replace an ECG or a cardiologist’s opinion.
Source
ANSM (French medicines agency) drug interaction guide, last updated September 2023 and no longer maintained; available until 15 June 2027. It mainly flags combinations of drugs classed as torsadogenic, and is the least restrictive of the sources.
Prescription to check
Somatic co-medication: is the patient also taking…?
Each category is assessed drug by drug, from the labelling of 49 somatic drugs and the ANSM guide. Potassium-lowering drugs, acid suppressants and heart-rate-lowering drugs also count as risk factors (PEB convention).
Patient risk factors
ECG QT: enter the QT or QTc
Fridericia corrects for heart rate better than Bazett, which overestimates QTc at fast heart rates (Vandenberk et al., 2016). Reference points: 450 ms or more in men, 470 ms or more in women (RISQ-PATH thresholds, Vandael et al., 2017); above 500 ms, the risk of torsades is two to three times higher, based on congenital long QT data (Drew et al., 2010).
Vigilance level
This indicator is a clinical support tool designed by PEB. It crosses drug burden with risk factors, based on product labelling and the literature; its thresholds are clinical reference points proposed by PEB, not values from a published study. It does not estimate a probability of torsades de pointes and does not change the regulatory level of each pair, shown below.
QT and torsades de pointes: pairs
Conduction, Brugada, bradycardia and other alerts
QT ruler
Mean published effects, measured in controlled studies. They are orders of magnitude: they do not add up across drugs, and variation between patients is much wider. The ruler does not predict the patient’s QTc on treatment.
Documents to print
Two documents filled in with the prescription entered, to display then print. They are created on your device; patient and prescriber details are completed by hand, and nothing is transmitted.
The five levels
PEB synthesis: level of evidence
PEB critical reading of the literature, on an evidence scale separate from the regulatory levels. Demonstrated: dose-related QT prolongation in a controlled study, above 10 ms at therapeutic doses, and torsades reported in pharmacovigilance (agencies, reporting databases, SmPC, published cases). Suggested: prolongation in some studies or published cases, or a positive result only at a supratherapeutic dose. Theoretical: laboratory data or class warning only. Insufficient data: no controlled study able to exclude a 10 ms effect, and no reports found. No QT risk found: both drugs have a negative QT study (thorough QT study or placebo-controlled trial). For a pair: the lower level of the two drugs when both have a signal, theoretical if only one has a signal; in both cases, at least suggested if an interaction increases the exposure of a drug that has a signal. A drug that increases another drug’s exposure does not take a grade of its own from that drug’s effects: the interaction is handled by the pair rule. The own effect of a drug taken at an authorised dose, whose exposure is increased by an interaction, counts toward its grade. The grade measures the strength of evidence for QT prolongation, not the size of the risk: a drug with a strong pharmacovigilance signal may remain suggested for lack of a controlled study at therapeutic doses. Exposures recorded in a series of torsades de pointes without attribution to the drug (Swedish cohort of Danielsson 2020, Lazzerini 2018 series), like cases after overdose or misuse, are given for information, without evidential weight. Review in progress: drug not yet reviewed. The PEB synthesis line appears only for pairs with at least one regulatory signal.
Tool for healthcare professionals. It does not replace an ECG or a cardiologist’s opinion. Privacy: everything you enter stays on your device. Nothing is sent, stored or transmitted over the internet, and everything is cleared when you close the page. Sources: French public medicines database and EMA product information, read on 26 and 27 September 2026; ANSM guide, September 2023.
Further reading, external resources: CredibleMeds, BrugadaDrugs.org.