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).