Is Myrbetriq Contraindicated for Glaucoma?
No, Myrbetriq (mirabegron) is not contraindicated in patients with glaucoma. Unlike anticholinergic medications used for overactive bladder, mirabegron is a beta-3 adrenergic agonist that does not affect pupil size or intraocular pressure and can be safely used in patients with either open-angle or angle-closure glaucoma 1, 2.
Mechanism and Safety Profile
- Mirabegron works by stimulating beta-3 adrenergic receptors in the detrusor muscle of the bladder, causing relaxation and increased bladder capacity 1.
- A randomized, double-masked, placebo-controlled study specifically evaluated ocular safety in 321 healthy volunteers receiving supratherapeutic doses of mirabegron 100 mg daily for 8 weeks 2.
- The mean change in intraocular pressure from baseline to day 56 was -0.3 mmHg for mirabegron versus -0.2 mmHg for placebo, with a difference of only -0.1 mmHg (95% CI: -0.4 to 0.3) 2.
- No treatment-emergent adverse events of glaucoma were reported, and no subjects discontinued due to increased intraocular pressure 2.
- Mirabegron does not affect voiding urodynamic parameters, and the overall change in post-void residual is small 1.
Contrast with Anticholinergic Medications
- Muscarinic receptor antagonists (antimuscarinics) used for overactive bladder are contraindicated in patients with narrow-angle glaucoma unless approved by the treating ophthalmologist 1.
- Anticholinergics cause angle closure through pupillary dilation in patients with pre-existing anatomically narrow angles, bunching peripheral iris tissue into the angle 3, 4.
- This mechanism is particularly dangerous in hyperopic, older phakic patients with shallow anterior chambers 3.
- Several drug classes including anticholinergics, antihistamines, and antidepressants have been reported to induce or precipitate acute angle-closure glaucoma 4, 5.
Clinical Advantages of Mirabegron in Glaucoma Patients
- Mirabegron is well tolerated in elderly patients and those with multiple comorbidities 1.
- The most frequent adverse effects are hypertension, urinary tract infections, headache, and nasopharyngitis—not ocular complications 1.
- The only cardiovascular contraindication is severe uncontrolled hypertension 1.
- Mirabegron provides an important alternative for patients with overactive bladder who have glaucoma and cannot safely use anticholinergic medications 6.
Important Caveats
- While mirabegron is safe for glaucoma patients, it is contraindicated in patients with severe uncontrolled hypertension 1.
- Long-term data on efficacy and safety of mirabegron in men of any age with lower urinary tract symptoms are not yet available 1.
- Clinicians should still monitor blood pressure regularly in patients taking mirabegron, as hypertension is a known adverse effect 1.