glycopyrrolate
Robinul, Robinul Forte

Available forms
Available by prescription only
Injection: 0.2 mg/ml in 1-ml, 2-ml, 5-ml, 20-ml vials
Tablets: 1 mg, 2 mg

Indications and dosages
 Blockade of cholinergic effects of anticholinesterase drugs used to reverse neuromuscular blockade. Adults and children: 0.2 mg I.V. for each 1 mg neostigmine or 5 mg of pyridostigmine. May be given I.V. without dilution or may be added to dextrose injection and infused.
 Preoperatively to diminish secretions and block cardiac vagal reflexes. Adults and children older than age 2: 0.004 mg/kg of body weight given I.M. 30 to 60 minutes before anesthesia.
 Adjunctive therapy in peptic ulcers and other GI disorders. Adults: 1 to 2 mg P.O. t.i.d. or 0.1 mg to 0.2 mg I.M. or IV q 4 hours t.i.d. to q.i.d. Individualize dosage.

Pharmacodynamics
Anticholinergic action: Glycopyrrolate inhibits muscarinic actions of acetylcholine on autonomic effectors innervated by postganglionic cholinergic nerves. This action blocks adverse muscarinic effects of anticholinesterase agents used to reverse curariform-induced neuromuscular blockade. Glycopyrrolate decreases secretions and GI motility by the same mechanism. Glycopyrrolate blocks cardiac vagal reflexes by blocking vagal inhibition of the SA node.

Pharmacokinetics
Absorption: Poorly absorbed from GI tract (10% to 25%) after oral administration.
Distribution: Rapidly distributed. Because it’s a quaternary amine, drug doesn’t cross the blood-brain barrier or enter the CNS.
Metabolism: Exact metabolic fate is unknown.
Excretion: Small amount of drug is eliminated in urine as unchanged drug and metabolites. Drug is mostly excreted unchanged in feces or bile.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug and in those with glaucoma, obstructive uropathy, obstructive disease of the GI tract, myasthenia gravis, paralytic ileus, intestinal atony, unstable CV status in acute hemorrhage, severe ulcerative colitis, or toxic megacolon.
  Use cautiously in patients with autonomic neuropathy, hyperthyroidism, coronary artery disease, arrhythmias, heart failure, hypertension, hiatal hernia, hepatic or renal disease, and ulcerative colitis. Also use cautiously in hot or humid conditions where drug-induced heatstroke may occur.

Interactions
Drug-drug. Amantadine, antihistamines, antiparkinsonians, disopyramide, glutethimide, meperidine, phenothiazines, procainamide, quinidine, tricyclic antidepressants: Causes additive adverse effects. Avoid use together.
Antacids: Decreases oral absorption of anticholinergics. Give glycopyrrolate at least 1 hour before antacids.
Ketoconazole, levodopa: Decreases GI absorption. Separate administration times by 2 to 3 hours.
Oral potassium supplements, especially wax-matrix formulations: Increases risk of potassium-induced GI ulcerations. Use cautiously.
Slowly dissolving digoxin tablets: May yield higher serum digoxin levels when administered with anticholinergics. Use cautiously; dose adjustment may be needed.

Adverse reactions
CNS: weakness, nervousness, insomnia, drowsiness, dizziness, headache, confusion or excitement (in elderly patients), fever.
CV: palpitations, tachycardia.
EENT: dilated pupils, blurred vision, photophobia, increased intraocular pressure.
GI: constipation, dry mouth, nausea, loss of taste, abdominal distension, vomiting, epigastric distress.
GU: urinary hesitancy, urine retention, impotence.
Skin: urticaria, decreased sweating or anhidrosis, other dermal manifestations.
Other: allergic reactions (anaphylaxis).

Effects on lab test results
None reported.

Overdose and treatment
Overdose causes such peripheral effects as dilated, nonreactive pupils; blurred vision; flushed, hot, dry skin; dryness of mucous membranes; dysphagia; decreased or absent bowel sounds; urine retention; hyperthermia; tachycardia; hypertension; and increased respiration.
 Treatment is primarily symptomatic and supportive, as needed. If patient is alert, induce emesis (or use gastric lavage) and follow with a saline cathartic and activated charcoal to prevent further drug absorption. In severe life-threatening cases, physostigmine may be administered to block antimuscarinic effects of glycopyrrolate. Give fluids, as needed, to treat shock. If urine retention occurs, catheterization may be needed.

Special considerations
• Even slight overdose can lead to toxicity.
• For immediate treatment of bradycardia, some clinicians prefer atropine over glycopyrrolate.
• Don’t mix glycopyrrolate with I.V. solutions containing sodium chloride or bicarbonate.
• Drug may be administered with neostigmine or physostigmine in same syringe.
• Drug is incompatible with thiopental, methohexital, secobarbital, pentobarbital, chloramphenicol, dimenhydrinate, and diazepam.
• Monitor patient for CNS effects and for urinary hesitancy or urine retention.
Breast-feeding patients
• Drug may appear in breast milk, possibly resulting in infant toxicity. Breast-feeding women should avoid this drug.
• Drug may decrease milk production.
Pediatric patients
• Drug isn’t recommended for peptic ulcer in children younger than age 12.
• Manufacturer recommends that drug not be used in neonates younger than age 1 month because glycopyrrolate injection contains benzyl alcohol.
Geriatric patients
• Administer glycopyrrolate cautiously to elderly patients, even though it may be the preferred anticholinergic in these patients.

Patient education
• Instruct patient to take oral drug 30 to 60 minutes before meals.
• Warn patient to avoid activities that require alertness until CNS effects of drug are known.
• Advise patient to report signs of urinary hesitancy or urine retention.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use