Buscopan is the brand name for N-butylscopolammonium bromide (also known as hyoscine butylbromide), an antispasmodic drug FDA-approved for use in horses to control abdominal pain (colic) associated with gastrointestinal spasm. It is a quaternary ammonium anticholinergic agent that acts on smooth muscle in the GI tract without significant central nervous system effects. Buscopan is commonly used in equine practice as a first-line treatment for spasmodic colic and as a diagnostic aid.
Overview
Buscopan works by blocking the action of acetylcholine at muscarinic receptors on gastrointestinal smooth muscle, relieving spasm and the pain associated with it. Because it is a quaternary ammonium compound, it does not readily cross the blood-brain barrier and has minimal central anticholinergic effects. Its onset of action is rapid (within minutes when given IV), and its duration of effect is approximately 30 minutes to a few hours. This short duration is clinically useful because it allows veterinarians to reassess the horse quickly; if pain returns after Buscopan wears off, the colic may have a more serious underlying cause.
Uses
- Spasmodic colic — primary FDA-approved indication for relief of smooth muscle spasm-related abdominal pain
- Gas colic — often used in combination with other treatments
- Diagnostic aid — the short duration helps differentiate simple spasmodic colic from conditions requiring surgery
- Rectal examination aid — relaxes the rectum for safer palpation during colic workup
- Uterine/urinary smooth muscle spasm — occasional off-label use
Dosage
Buscopan should only be administered by or under the direct supervision of a veterinarian.
| Indication | Dose | Route | Frequency |
|---|---|---|---|
| Colic / abdominal spasm | 0.3 mg/kg IV (approximately 150 mg for a 500 kg horse) | Intravenous (slow) | May repeat once after 30 minutes if needed |
Buscopan is supplied as a 20 mg/mL injectable solution. It is given as a slow intravenous injection. The maximum recommended number of doses is two within a 24-hour period. If pain persists or recurs after two doses, further diagnostic workup is warranted to rule out a surgical lesion.
Side Effects
| Common (Expected) | Serious (Contact Your Vet) |
|---|---|
| Transient tachycardia (elevated heart rate) | Prolonged tachycardia |
| Decreased gut sounds (temporary) | Ileus (prolonged gut stasis) |
| Dry mucous membranes | Worsening colic signs |
| Mild transient mydriasis (pupil dilation) | Signs of surgical colic masked by drug |
The transient tachycardia and decreased borborygmi (gut sounds) are expected pharmacologic effects and typically resolve within 20-30 minutes. These effects are important to note because elevated heart rate and absent gut sounds are also indicators of serious colic; veterinarians must account for Buscopan’s effects when interpreting these parameters during a colic examination.
Drug Interactions
- Other anticholinergic drugs: Additive effects on heart rate and GI motility reduction.
- NSAIDs (flunixin, phenylbutazone): Often used concurrently in colic cases; no direct pharmacologic interaction, but combined use may further mask colic severity.
- Detomidine / xylazine (alpha-2 agonists): May be used together during colic workup; monitor cardiovascular parameters.
Contraindications
- Horses with known obstruction or surgical colic (antispasmodics may delay surgical referral)
- Horses with tachycardia from other causes (e.g., endotoxemia, dehydration)
- Horses with glaucoma (anticholinergic effect on intraocular pressure)
- Known hypersensitivity to N-butylscopolammonium bromide
Storage
- Store at controlled room temperature, 59-86 degrees F (15-30 degrees C).
- Protect from light.
- Do not freeze.
- Keep out of reach of children and animals.
Frequently Asked Questions
How quickly does Buscopan work? When given IV, Buscopan typically provides relief within 5-15 minutes. Its effects last approximately 30 minutes to 2 hours.
Is Buscopan a pain killer? Buscopan relieves pain caused by smooth muscle spasm, but it is not a traditional analgesic. It works by relaxing the spasming gut muscle rather than blocking pain signals. For other types of colic pain, NSAIDs like flunixin are more appropriate.
Can I keep Buscopan in my barn to give my horse during colic? Buscopan is an injectable medication that should be administered by a veterinarian. It requires IV injection and cardiovascular monitoring. Horse owners should have oral Banamine (flunixin) paste available for emergency colic management and call their veterinarian immediately.
Why does my horse’s heart rate go up after Buscopan? Tachycardia is a normal, expected side effect of the anticholinergic mechanism. It typically resolves within 20-30 minutes. Your veterinarian will account for this when monitoring your horse.
This information is for educational purposes only and does not replace professional veterinary advice. Always consult your veterinarian before administering any medication to your horse.