Vetdrugs 2.0Butylscopolamine bromide, also called hyoscine butylbromide or N-butylscopolammonium bromide, is a short-acting peripheral antimuscarinic antispasmodic. It is used chiefly in horses for painful gastrointestinal spasm and to facilitate selected examinations. It can also briefly relieve vagally mediated bronchoconstriction.
Its quaternary ammonium structure limits penetration into the central nervous system, distinguishing it from more centrally active related compounds. The clinical effect is temporary smooth-muscle relaxation and reduced parasympathetic activity, not correction of every cause of colic or a direct general analgesic effect.
Group
Antimuscarinic antispasmodic
Mechanism of Action
Butylscopolamine competitively blocks muscarinic receptors at peripheral parasympathetic effector sites. In gastrointestinal smooth muscle, reduced acetylcholine signaling decreases spasm and motility and reduces secretory activity. Relief of spasm can reduce associated pain even though the drug does not function as a conventional opioid or NSAID.
Muscarinic blockade can also relax the rectum and relieve bronchial smooth-muscle constriction when vagal signaling is contributing. Cardiac muscarinic blockade can increase heart rate, so a transient rate change after administration is partly pharmacologic rather than necessarily evidence of a change in the underlying colic.
Poor blood–brain barrier penetration limits central anticholinergic effects. Rapid clearance produces a brief response, which can assist an examination or relieve spasm while the cause is assessed. It does not remove an obstruction, reverse strangulation or provide prolonged anti-inflammatory treatment.
Dose Rates
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Spasmodic colic | 0.3 mg/kg | IV | Once | Administer slowly; also used to reduce spasm during rectal examination. |
| Bronchoconstriction | 0.3 mg/kg | IV | Once | |
| Esophageal obstruction adjunct | Reference only | IV | Butylscopolamine bromide 0.3 mg/kg IV once with oxytocin 0.11–0.22 IU/kg IV once. Avoid oxytocin in pregnant mares and substantially reduce or avoid its use in other mares. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Calf scour antispasmodic adjunct | 0.4 mg/kg | IM | Once | Calves only; the specific 20 mg/mL hyoscine butylbromide product supports IM use. Provide oral rehydration and other indicated therapy; this is symptomatic treatment, not a replacement for fluid correction. |
Indications
- Short-term relief of pain associated with spasmodic or flatulent colic in horses.
- Relief of smooth-muscle spasm accompanying selected intestinal impactions.
- Rectal relaxation and reduction of straining to facilitate equine rectal examination.
- Rapid, short-lived relief of bronchoconstriction in selected horses with equine asthma.
- Selected antispasmodic adjunctive applications, including esophageal obstruction or calf-scour management.
Contraindications
- Use cautiously where further reduction in gastrointestinal motility is undesirable.
- Paralytic ileus or impaction with ileus; equine glaucoma.
- The cited equine product lacks established safety in nursing foals or pregnant/lactating mares.
- For the cited horses-and-calves product, do not use in foals younger than six weeks; pregnancy use is not recommended.
Interactions
- Opposes cholinergic or prokinetic therapy, including metoclopramide.
- Atropine and other anticholinergics can add to tachycardia and intestinal hypomotility.
Adverse effects
- Transient tachycardia
- Dry mucous membranes and reduced secretion
- Mydriasis
- Reduced gut motility
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Butylscopolamine Bromide (N-Butylscopolammonium Bromide) 20 mg/mL injection | Injection | 20 mg / mL | IV |
| Buscopan 20 mg/mL injection for horses and calves Hyoscine butylbromide salt basis. Horses: IV only; calves: IM only. Species-specific permitted routes must be respected; a route list alone does not make equine IM dosing appropriate. | Injection | 20 mg / mL | IV, IM |
Monitoring and Administration
Monitor heart rate, gut sounds and fecal output. Give slowly intravenously; onset is usually within 2 minutes and effects last less than 2 hours.
Transient drug-induced tachycardia makes heart rate unreliable as a pain indicator for approximately 30 minutes after administration. Persistent colic despite treatment warrants reassessment for a surgical lesion.
Buscopan Compositum is not plain Buscopan: the described combination contains metamizole 500 mg/mL and hyoscine butylbromide 4 mg/mL. Its dose cannot be inferred from the single-active 20 mg/mL injection.