N-butylscopolammonium bromide
Also known as: Buscapina · Buscopan Compositum · butylscopolamine bromide · hyoscine butylbromide · hyoscine N-butylbromide · scopolamini butylbromidum · hyoscini butylbromidum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Control of abdominal pain (colic) associated with spasmodic colic, flatulent colic, and simple impactions | 0.3 mg/kg (30 mg or 1.5 mL per 100 kg of body weight) | slow IV | one time | — | 🌎 NA |
| To treat esophageal obstruction | 0.3 mg/kg | IV | once | — | 🌎 NA |
- To treat esophageal obstruction: Administer with oxytocin (0.11-0.22 Units/kg IV once). Oxytocin use should be avoided in mares, or dose significantly reduced. Do not use in pregnant mares.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
N-butylscopolammonium bromide (also known as hyoscine butylbromide) is a potent, injectable anticholinergic and antispasmodic agent primarily used in equine medicine.
- Key Clinical Use: Rapid relief of abdominal pain associated with spasmodic colic, flatulent colic, and simple impactions in horses. It is also used to facilitate rectal examinations and colonoscopy.
- Clinical Pearl: Because it is a quaternary ammonium compound, it is highly polar and does not readily cross the blood-brain barrier. This means it provides excellent peripheral antispasmodic effects on the gastrointestinal and urinary tracts without the profound central nervous system (CNS) side effects (such as excitement or severe sedation) often seen with tertiary amines like atropine or scopolamine.
- It has a much shorter duration of action than atropine, making it ideal for brief interventions where prolonged ileus is undesirable.
Mechanism of action
N-butylscopolammonium bromide acts as a competitive antagonist at muscarinic acetylcholine receptors located on smooth muscle cells.
- Mechanism: Blocks acetylcholine binding → prevents intracellular calcium release → induces profound relaxation of gastrointestinal and urinary smooth muscle.
- Pathway: Parasympathetic inhibition → decreased GI peristalsis and reduced rectal pressure.
- Duration: Visceral antinociceptive and spasmolytic effects are brief, typically lasting 15-20 minutes in horses.
Safety & warnings
Contraindications
- Impaction colics associated with ileus
- Glaucoma
- Horses intended for food purposes
- Nursing foals
- Pregnant or lactating mares
Adverse effects
- Transient tachycardia
- Decreased borborygmal sounds
- Transient pupil dilation
- Decreased secretions
- Dry mucous membranes
Precautions
Not for use in patients with ileus or when decreased GI motility may be harmful. Because this drug can cause increases in heart rate, heart rate cannot be used as a valid pain indicator for 30 minutes after injection. When used for labeled indications, a lack of response may indicate a more serious problem that may require surgery or more aggressive care. The manufacturer has not studied the safety of IM administration.
Drug interactions
May cause additive effects if used with N-butylscopolammonium
These drugs and N-butylscopolammonium may counteract one another's actions on GI smooth muscle
Monitoring
- Heart rate (Note: heart rate cannot be used as indicator for pain for the first 30 minutes after administration)
- GI motility via gut sounds and feces output
Pharmacokinetics
Half-life
Elimination
Eliminated within 48 hours in urine and feces equally.
Overdose
Dosages up to 10X (3 mg/kg) were administered to horses as part of preapproval studies. Clinical effects noted included dilated pupils (returned to normal in 4-24 hours), tachycardia (returned to normal within 4 hours) and dry mucous membranes (returned to normal in 1-2 hours). Gut motility was inhibited, but returned to baseline within 4 hours and normal feces were seen within 6 hours. Two of the four horses treated at 10X dosage developed mild signs of colic which resolved without further treatment.
Available products
Formulations
- Injection
Veterinary
- N-butylscopolammonium bromide Injection: 20 mg/mL in 50 mL multi-dose vials, Buscopan (BIVI)
- Buscopan Compositum (UK only): contains metamizole 500 mg/mL and hyoscine butylbromide 4 mg/mL
Human-labeled
- Buscopan or Buscapina (Available internationally, none in the USA)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
The commercially available injection should be stored at room temperature (15-30°C).
Client information
Important Note: This medication requires accurate patient assessment, intravenous administration, and subsequent monitoring. It should only be administered by a licensed veterinarian.
- Why it's used: It rapidly relaxes the intestines to relieve pain from gas or spasms (colic) and makes procedures like rectal examinations safer and more comfortable for your horse.
- What to expect: You may notice your horse's heart rate increase temporarily, their mouth may seem dry, and their pupils might dilate slightly. These effects are normal and wear off quickly (usually within 30 minutes to a few hours).
- Monitoring: Because the drug temporarily raises the heart rate, your veterinarian will not be able to use heart rate to gauge your horse's pain level for about 30 minutes after the injection.
- Follow-up: If your horse's colic signs return after the medication wears off, it may indicate a more serious issue requiring further medical or surgical intervention.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.