Glycopyrrolate Side Effects
Glycopyrrolate commonly causes anticholinergic side effects including dry mouth, urinary hesitancy/retention, blurred vision, mydriasis, cycloplegia, increased ocular tension, tachycardia, palpitations, decreased sweating, constipation, and bloating. 1
Common Side Effects
Glycopyrrolate is an anticholinergic medication that blocks muscarinic receptors, resulting in several predictable side effects:
Frequently Reported Side Effects
- Dry mouth (xerostomia) - most common side effect
- Urinary hesitancy and retention
- Visual disturbances:
- Blurred vision
- Photophobia due to mydriasis (pupil dilation)
- Cycloplegia (paralysis of ciliary muscle)
- Increased ocular tension
- Cardiovascular effects:
- Tachycardia
- Palpitations
- Decreased sweating
- Gastrointestinal effects:
- Loss of taste
- Constipation
- Bloated feeling
- Nausea
- Vomiting
- Neurological effects:
- Headache
- Nervousness
- Drowsiness
- Weakness
- Dizziness
- Insomnia 1
Serious Adverse Events
Post-marketing surveillance has identified several serious adverse events:
- Malignant hyperthermia
- Cardiac arrhythmias (including bradycardia, ventricular tachycardia, ventricular fibrillation)
- Cardiac arrest
- Hypertension and hypotension
- Seizures
- Respiratory arrest
- QTc interval prolongation (particularly when combined with anticholinesterase medications)
- Injection site reactions (pruritus, edema, erythema, pain) 1
Reduced CNS Side Effects
An important advantage of glycopyrrolate is its quaternary ammonium structure, which limits its ability to cross the blood-brain barrier compared to tertiary amine anticholinergics like atropine and scopolamine. This results in:
- Lower incidence of central nervous system side effects
- Potential benefit in patients with Parkinson's disease or other conditions with cognitive impairment 1, 2
Special Populations and Considerations
Pediatric Patients
In children with cerebral palsy and neurodevelopmental disabilities receiving glycopyrrolate for drooling:
- Side effects occur more frequently at higher doses
- Common side effects include dry mouth (9-41%), constipation (9-39%), and behavioral changes (18-36%) 3
- Side effects may lead to treatment discontinuation in approximately 28% of patients 4
Topical Formulations
When used as topical wipes (glycopyrronium tosylate):
- Overuse can lead to systemic anticholinergic effects including progressive myopia, dry mouth, anhidrosis, and urinary hesitancy 5
Precautions and Contraindications
Glycopyrrolate should be used with caution in patients with:
- Glaucoma (contraindicated)
- Prostatic hypertrophy
- Cognitive impairment (though less problematic than other anticholinergics) 6
Monitoring Recommendations
When initiating glycopyrrolate therapy:
- Start with lower doses and titrate based on response and side effects
- Monitor for anticholinergic side effects, particularly in vulnerable populations
- Be aware that effective doses can vary widely (0.01 to 0.82 mg/kg per day reported in pediatric studies) 4
- Consider discontinuation if side effects become intolerable despite dose adjustments
Glycopyrrolate's side effect profile, while significant, may be better tolerated than other anticholinergics in certain populations due to its limited central nervous system penetration. However, careful monitoring remains essential, particularly in pediatric patients and those with comorbidities.