Major
citalopram × Omeprazole
SSRI (selective serotonin reuptake inhibitor)×Proton pump inhibitors
Mechanism
Omeprazole is a potent CYP2C19 inhibitor, the main citalopram metabolic route. Citalopram plasma levels rise by 40–50%. The FDA capped citalopram at 20 mg/day with CYP2C19 inhibitors in 2012 because of dose-dependent QT risk.
Symptoms
QT prolongation on ECG. Clinically: dizziness, syncope, palpitations. Severe cases progress to polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
Cap citalopram at 20 mg/day when combined. Alternative PPIs without CYP2C19 effect: pantoprazole or rabeprazole.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.