Hyoscine butylbromide is a quaternary ammonium antimuscarinic, antispasmodic agent. It is a semi-synthetic derivative of scopolamine (hyoscine) with a butylbromide group, which limits its passage across the blood-brain barrier, making it predominantly peripherally acting. It is a potent, competitive antagonist at muscarinic (M1, M2, M3) receptors located on smooth muscle cells of the gastrointestinal, biliary, and genitourinary tracts. Its primary therapeutic effect is the relief of smooth muscle spasm and associated pain, making it a cornerstone for managing abdominal colic in the Indian clinical setting.
Adult: Oral: 20mg to 40mg, 3-4 times daily. Maximum: 120mg/day. Parenteral (IV/IM): 20mg, repeated after 30 minutes if necessary. Maximum parenteral dose: 100mg/day.
Note: Tablets should be swallowed whole with a glass of water, preferably before meals. Can be taken with or without food. For acute colic, the first dose can be taken at the onset of pain. Do not crush or chew. For IV administration, inject slowly over at least 1 minute.
Hyoscine butylbromide competitively and reversibly blocks the action of acetylcholine at postganglionic muscarinic receptors (M1, M2, M3) on smooth muscle cells of hollow visceral organs. This blockade inhibits the parasympathetic nervous system's stimulatory effects, leading to relaxation of smooth muscle tone and reduction of spasmodic contractions. It has a direct spasmolytic effect on smooth muscle, independent of its anticholinergic action, contributing to its efficacy.
Pregnancy: Category C: Animal reproduction studies have shown an adverse effect, but there are no adequate and well-controlled studies in humans. Use only if the potential benefit justifies the potential risk to the fetus. Should be avoided, especially in the first trimester, unless absolutely necessary.
Driving: May cause dizziness, blurred vision, or drowsiness. Patients should be cautioned about operating machinery or driving until they know how the drug affects them.
| Other Anticholinergics (e.g., Atropine, Dicyclomine, Tricyclic Antidepressants, Antihistamines) | Additive anticholinergic side effects (dry mouth, constipation, urinary retention, tachycardia, confusion). | Major |
| Metoclopramide, Domperidone | Pharmacological antagonism; hyoscine reduces GI motility, while prokinetics increase it, reducing efficacy of both. | Moderate |
| Potassium Chloride (wax-matrix tablets) | Anticholinergics slow GI transit, increasing risk of GI mucosal injury from KCl. | Moderate |
| Digoxin | Reduced GI motility may increase bioavailability of digoxin, potentially leading to toxicity. | Moderate |
| Levodopa | Reduced gastric emptying may increase degradation of levodopa in the stomach, decreasing its absorption and efficacy. | Moderate |
| Alcohol, CNS Depressants (Benzodiazepines, Opioids) | Additive sedative effect, increased risk of dizziness and drowsiness. | Moderate |
Same composition (Hyoscine butylbromide (20mg)), different brands: