Glycopyrrolate

Robinul

Quaternary ammonium muscarinic antagonist / antisialagogue

Competitive antagonist at peripheral muscarinic acetylcholine receptors. Quaternary structure → does NOT cross blood-brain barrier (unlike atropine, scopolamine) → no CNS effects. Primary anesthesia uses: (1) prevent muscarinic effects of anticholinesterases during NMB reversal; (2) reduce secretions before fiberoptic/awake intubation.

Indications

•Pair with neostigmine (reversal of NMB) to prevent muscarinic effects (bradycardia, secretions, bronchospasm)
•Antisialagogue before awake fiberoptic intubation
•Treat intraoperative bradycardia (vagal-mediated)
•Reduce secretions in upper airway/dental procedures

Dosing

Context	Adult	Pediatric
With neostigmine (reversal)	0.01 mg/kg IV (or ~0.2 mg per 1 mg neostigmine ratio)	0.01 mg/kg IV
Bradycardia treatment	0.1–0.4 mg IV	0.004–0.01 mg/kg IV
Antisialagogue (pre-AFOI)	0.2–0.4 mg IM 30 min preop OR 0.2 mg IV	0.004–0.01 mg/kg IM

Pharmacokinetics

Onset 1–3 min IV (peak 30–60 min IM). Duration ~6 h antisialagogue effect; ~2–3 h cardiac effect. Renal excretion. T½ ~30–60 min initial distribution, longer terminal.

Hemodynamic effects

↑HR (anticholinergic), often modestly less tachycardic than atropine. Minimal direct BP effect. Onset on HR within 1–3 min IV.

Respiratory effects

Mild bronchodilation. Reduces salivary + tracheobronchial secretions.

Side effects

!Tachycardia (avoid in CAD with active ischemia, severe AS — increases O₂ demand)
!Dry mouth (intended)
!Urinary retention (elderly males with BPH)
!Increased intraocular pressure (avoid in narrow-angle glaucoma)
!Constipation (rare from single dose)

Contraindications

×Narrow-angle glaucoma
×Bladder outlet obstruction
×Severe ulcerative colitis
×Myasthenia gravis (paradoxical effect)

Clinical pearls

★PREFERRED over atropine for NMB reversal because of slower, more sustained onset matching neostigmine kinetics → fewer transient bradycardic episodes.
★Quaternary structure means no central anticholinergic syndrome (vs scopolamine, atropine) — safe choice in elderly to avoid delirium.
★Antisialagogue effect peaks at 30 min IM — give preop in pre-anesthesia area for awake fiberoptic.
★Ratio with neostigmine: 0.2 mg glyco per 1 mg neostigmine (1:5 ratio by mass). Given simultaneously to match HR effect (neo causes bradycardia, glyco prevents).
★If using sugammadex instead of neostigmine: NO glycopyrrolate needed (sugammadex has no muscarinic effects).

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