Glycopyrrolate is a synthetic, quaternary ammonium antimuscarinic agent. It acts as a competitive antagonist at peripheral muscarinic acetylcholine receptors, particularly M1, M2, and M3 subtypes. Its quaternary structure limits its passage across the blood-brain barrier and lipid membranes, resulting in predominantly peripheral effects with minimal central nervous system (CNS) side effects. It is used primarily to reduce gastric acid secretion and gastrointestinal motility. In the Indian context, it is a key component in pre-anesthetic medication and for managing peptic ulcer disease and other GI hypermotility disorders.
Adult: Oral: 1 to 2 mg (i.e., 5 to 10 tablets of 0.2mg) two to three times daily. Typical regimen is 1 mg three times a day and 2 mg at bedtime. Pre-anesthetic: 0.004 mg/kg IM, 30-60 minutes before procedure.
Note: Take orally with a full glass of water, 30 minutes to 1 hour before meals and at bedtime for optimal acid suppression. Do not crush or chew. For pre-anesthetic use, administer IM deep into a large muscle mass.
Glycopyrrolate competitively blocks the action of acetylcholine at postganglionic muscarinic receptors in smooth muscle, cardiac muscle, exocrine glands, and the sinoatrial and atrioventricular nodes. This inhibition reduces secretions (salivary, bronchial, gastric, sweat) and decreases gastrointestinal motility and tone.
Pregnancy: Category B (US FDA). Animal studies show no risk, but no adequate, well-controlled studies in pregnant women. Use only if clearly needed, weighing benefits against risks. May reduce uterine tone during labor.
Driving: May cause blurred vision, dizziness, or drowsiness. Patients should be cautioned against driving or operating machinery until their response is known.
| Other Anticholinergics (e.g., Atropine, Dicyclomine, TCAs, Antihistamines) | Additive anticholinergic side effects (dry mouth, constipation, urinary retention, confusion). | Major |
| Potassium Chloride (wax-matrix formulations) | Increased risk of GI mucosal lesions/ulceration due to reduced motility. | Major |
| Metoclopramide | Mutual antagonism of effects on GI motility. | Moderate |
| Digoxin | Increased serum digoxin levels due to decreased GI motility and enhanced absorption. | Moderate |
| Amantadine, Antipsychotics (e.g., Phenothiazines) | Enhanced anticholinergic side effects and risk of psychosis. | Moderate |
| Opioid Analgesics | Severe constipation, risk of paralytic ileus; additive CNS depression. | Major |
| Antacids | May reduce absorption of glycopyrrolate; administer at least 1 hour apart. | Minor |
Same composition (Glycopyrrolate (0.2mg)), different brands: