Qbrexza - Drug Monograph

Introduction

Qbrexza (glycopyrronium) is a topical anticholinergic medication approved by the FDA in 2018 for the treatment of primary axillary hyperhidrosis. It represents the first prescription cloth-based topical treatment for this condition, offering a novel delivery system for patients struggling with excessive underarm sweating.

Mechanism of Action

Qbrexza contains glycopyrronium, a quaternary ammonium anticholinergic compound that acts as a competitive inhibitor of muscarinic acetylcholine receptors. By blocking these receptors in the sweat glands, it reduces the stimulation of eccrine sweat glands, thereby decreasing sweat production. The topical formulation allows for localized action with minimal systemic absorption.

Indications

• Primary axillary hyperhidrosis (excessive underarm sweating) in patients aged 9 years and older

Dosage and Administration

• Standard dosing: One cloth to each axilla once daily
• Application: Use dry hands to remove cloth from pouch. Wipe entire cloth on one underarm once, then use a new cloth for the other underarm
• Timing: Apply at bedtime to dry, intact skin
• Special populations: No dosage adjustment required for renal or hepatic impairment
• Pediatric use: Approved for patients 9 years and older
• Geriatric use: No specific recommendations

Pharmacokinetics

• Absorption: Minimal systemic absorption (mean Cmax 60.4 pg/mL after single dose)
• Distribution: Quaternary ammonium structure limits CNS penetration
• Metabolism: Undergoes minimal hepatic metabolism
• Elimination: Primarily excreted unchanged in urine and feces
• Half-life: Approximately 3 hours

Contraindications

• Hypersensitivity to glycopyrronium or any component of the formulation
• Patients with glaucoma
• Patients with urinary retention

Warnings and Precautions

• Anticholinergic effects: May cause blurred vision, dizziness, or drowsiness
• New-onset urinary retention: Monitor for urinary symptoms
• Ocular exposure: Avoid contact with eyes. Wash hands after application
• Systemic effects: Possible anticholinergic systemic effects even with topical administration
• Pregnancy: Category C - Use only if potential benefit justifies potential risk
• Lactation: Exercise caution when administering to nursing women

Drug Interactions

• Other anticholinergic medications (additive effects)
• Medications that cause dry mouth or constipation
• Drugs that prolong QT interval (theoretical risk)
• CYP450 interactions unlikely due to minimal metabolism

Adverse Effects

• Dry mouth (17%)
• Mydriasis (dilated pupils) (9%)
• Blurred vision (5%)
• Urinary retention (5%)
• Erythema at application site (3%)
• Dry throat (2%)

• Severe allergic reactions
• Acute urinary retention requiring catheterization
• Angle-closure glaucoma
• Severe constipation

Monitoring Parameters

• Sweat reduction efficacy and patient satisfaction
• Visual changes or eye discomfort
• Urinary function and symptoms of retention
• Signs of anticholinergic effects
• Skin reactions at application site
• Hydration status in patients experiencing dry mouth

Patient Education

• Apply to clean, dry underarms at bedtime
• Wash hands thoroughly after application
• Avoid contact with eyes, nose, and mouth
• Allow treated areas to dry completely before covering with clothing
• Use exactly as prescribed - do not use more than once daily
• Discard used cloths properly after single use
• Report any vision changes, difficulty urinating, or severe skin irritation
• Store at room temperature (20-25°C)
• Keep out of reach of children and pets

References

1. US Food and Drug Administration. (2018). Qbrexza prescribing information. 2. Glaser DA, et al. (2019). Efficacy and safety of glycopyrronium cloth in patients with primary axillary hyperhidrosis. Journal of the American Academy of Dermatology, 80(5), 1283-1289. 3. Pariser DM, et al. (2019). Long-term efficacy and safety of glycopyrronium cloth in primary axillary hyperhidrosis. Dermatologic Therapy, 32(1), e12776. 4. Lexicomp Online. (2023). Glycopyrronium topical monograph. 5. ClinicalTrials.gov. (2017). Phase 3 study of glycopyrronium cloth in primary axillary hyperhidrosis (ATMOS-1 and ATMOS-2).