QT Interval Effects of Dupixent and Simbrinza
Neither Dupixent (dupilumab) nor Simbrinza (brinzolamide/brimonidine) prolong the QT interval, and both can be used safely in patients with cardiac risk factors or pre-existing QT prolongation.
Dupixent (Dupilumab) and QT Interval
Dupilumab does not appear on any major cardiology society lists of QT-prolonging medications, including the comprehensive catalogs from the American College of Cardiology, American Heart Association, Heart Rhythm Society, or European Society of Cardiology 1, 2, 3.
The extensive guideline reviews of QT-prolonging drugs—which systematically catalog antiarrhythmics, antibiotics (macrolides, fluoroquinolones), antifungals, antimalarials, antipsychotics, antiemetics, and other high-risk agents—make no mention of dupilumab or any biologic immunomodulator as causing QT prolongation 1, 2, 3.
Dupilumab is a monoclonal antibody targeting IL-4 receptor alpha and has no known mechanism for blocking cardiac ion channels (hERG/IKr potassium channels or Nav1.5 sodium channels) that mediate drug-induced QT prolongation 3.
Simbrinza (Brinzolamide/Brimonidine) and QT Interval
Simbrinza, a fixed-combination ophthalmic suspension containing brinzolamide 1% and brimonidine 0.2%, is not listed among QT-prolonging medications in any major cardiac guideline 1, 2, 3.
The most common adverse effects of Simbrinza are local ocular reactions—blurred vision, eye irritation, and dysgeusia (abnormal taste)—with no cardiac arrhythmias or QT prolongation reported in clinical trials 4, 5.
Topical ophthalmic administration results in minimal systemic absorption, further reducing any theoretical cardiac risk 6. Plasma concentrations of brimonidine after Simbrinza administration are approximately 0.8-fold lower than after single-drug brimonidine formulation 6.
Phase III randomized trials evaluating Simbrinza over 3-6 months documented no unexpected safety findings or cardiac adverse events, with the tolerability profile consistent with its individual components 4, 5.
Clinical Implications
No baseline ECG, cardiac monitoring, or electrolyte surveillance is required when prescribing either dupilumab or Simbrinza, even in patients with known cardiac disease or prolonged QTc 1, 2, 3.
These medications can be safely combined with other QT-prolonging drugs without creating additive cardiac risk, unlike the exponential risk seen when combining multiple true QT-prolonging agents 1, 3.
Simbrinza represents the first available fixed-combination glaucoma medication without a β-blocker, making it particularly valuable for patients with cardiac comorbidities (bradycardia, heart failure, conduction abnormalities) where β-adrenergic antagonists are contraindicated 5, 7.
Medications That Actually Prolong QT
For context, the medications that do require QT monitoring include macrolide antibiotics (erythromycin, azithromycin, clarithromycin), fluoroquinolones (moxifloxacin > levofloxacin > ciprofloxacin), antipsychotics (haloperidol, thioridazine, pimozide), antiemetics (ondansetron, domperidone, metoclopramide), Class IA and III antiarrhythmics, azole antifungals, antimalarials, and methadone 1, 2, 3.