Cisapride is a serotonin 5-HT4 receptor agonist and prokinetic agent that stimulates gastrointestinal motility. It is one of the most important medications in rabbit medicine, where gastrointestinal stasis (GI stasis) is a life-threatening emergency and one of the most common reasons rabbits present to veterinarians. In cats, cisapride is the treatment of choice for megacolon and chronic constipation. Although withdrawn from the human market in 2000 due to the risk of fatal cardiac arrhythmias, cisapride remains widely available through veterinary compounding pharmacies and is considered safe in animal patients at appropriate doses. This is a prescription medication requiring veterinary supervision.
What Is Cisapride Used For?
- GI stasis in rabbits — the most critical indication; GI stasis is a condition where normal gut motility slows or stops, and it is often fatal without treatment
- Post-surgical ileus — restoring gut motility after anesthesia and surgery
- Megacolon in cats — chronic colonic dilation with loss of motility
- Gastroparesis — delayed gastric emptying
- Chronic constipation — in cats and rabbits
- Cecal impaction — in rabbits, to help restore cecal motility
How Does Cisapride Work?
Cisapride stimulates gastrointestinal motility through two primary mechanisms:
- 5-HT4 receptor agonism — activates serotonin type 4 receptors on enteric neurons, enhancing the release of acetylcholine at the myenteric plexus and stimulating coordinated, propulsive contractions throughout the GI tract
- 5-HT3 receptor antagonism — may contribute to antiemetic effects
Unlike metoclopramide (which primarily acts on the upper GI tract), cisapride stimulates motility throughout the entire gastrointestinal tract, including the stomach, small intestine, cecum, and colon. This full-length GI activity makes it particularly valuable in rabbits, where the cecum and colon are critical sites of normal digestive function.
GI Stasis in Rabbits: A Life-Threatening Emergency
GI stasis is the most common serious medical condition in pet rabbits and understanding it is essential to appreciating why cisapride is so important:
- The rabbit GI tract must be in constant motion — rabbits cannot vomit and rely on continuous gut motility to process the high-fiber diet their system requires
- When motility slows, ingesta becomes dehydrated and compacted
- Cecal bacteria begin to shift, with harmful gas-producing bacteria overgrowing
- Gas accumulation causes painful distension, which further reduces motility (a vicious cycle)
- Hepatic lipidosis (fatty liver) can develop within 24 to 48 hours as the rabbit stops eating
- Without treatment, GI stasis can be fatal within 48 to 72 hours
Common triggers of GI stasis include: pain from any cause, stress, dietary changes, inadequate fiber, dehydration, dental disease, surgery/anesthesia, and environmental changes.
Dosage
Dosing must be determined by your veterinarian.
| Species | Typical Dose | Route | Frequency |
|---|---|---|---|
| Rabbits | 0.5—1 mg/kg | Oral | Every 8—12 hours |
| Cats | 0.5—1 mg/kg | Oral | Every 8—12 hours |
Cisapride is most commonly available as a compounded oral suspension from veterinary compounding pharmacies. It should be administered 15 to 30 minutes before feeding when possible, as food enhances absorption.
For rabbit GI stasis, cisapride is part of a multimodal treatment approach:
- Fluid therapy (subcutaneous or intravenous) to rehydrate gut contents
- Cisapride to stimulate motility
- Pain management (meloxicam or other rabbit-safe analgesics) — pain inhibits motility
- Simethicone for gas distension
- Syringe feeding (Critical Care or similar) if the rabbit is not eating
- Warmth and a quiet, low-stress environment
- Gentle abdominal massage
- Encouraging movement/exercise
Side Effects
Common side effects:
- Mild abdominal cramping
- Soft stool or increased fecal output (often desirable)
- Mild diarrhea
Serious side effects:
- Cardiac arrhythmias — QT prolongation and torsades de pointes (the reason for human market withdrawal); this risk appears to be very low in veterinary patients at recommended doses, but caution is warranted in animals with pre-existing cardiac disease
- GI cramping — excessive motility stimulation causing discomfort
- Diarrhea — persistent diarrhea warrants dose reduction
In rabbits, monitor for normal fecal pellet production (a sign of restored motility), appetite, and overall demeanor. Improvement is typically seen within 12 to 24 hours of starting multimodal therapy.
Contraindications
- Gastrointestinal obstruction — cisapride must NOT be used if a mechanical GI obstruction is suspected; stimulating motility against an obstruction can cause intestinal rupture; radiographs should be taken before starting prokinetics
- GI perforation — active perforation or peritonitis
- Concurrent QT-prolonging drugs — see drug interactions below
- Known cardiac disease — use with caution
Drug Interactions
- Azole antifungals (ketoconazole, itraconazole, fluconazole) — increase cisapride levels by inhibiting metabolism; concurrent use is contraindicated due to cardiac arrhythmia risk
- Macrolide antibiotics (erythromycin, clarithromycin) — similar CYP3A4 inhibition increasing cisapride levels (note: macrolides are also contraindicated orally in rabbits)
- Other QT-prolonging drugs — additive cardiac risk
- Anticholinergic drugs (atropine) — oppose the prokinetic effects of cisapride
Species-Specific Considerations
Rabbits:
- Cisapride is an essential component of the GI stasis treatment protocol
- The rabbit cecum is a large fermentation chamber (up to 10 times the size of the stomach) — restoring cecal motility is critical
- Rabbits produce two types of droppings: hard fecal pellets and cecotropes (soft, nutrient-rich droppings that are re-ingested); resumption of cecotrope production is a sign of GI recovery
- GI stasis can develop secondary to virtually any illness or stressor in rabbits
- Prevention through proper diet (unlimited timothy hay, limited pellets, fresh greens) is paramount
Cats:
- Primary use is for idiopathic megacolon and chronic constipation
- May be used long-term with periodic reassessment
- Cats with megacolon that do not respond to medical management (cisapride + lactulose + dietary modification) may require subtotal colectomy
Storage
Store compounded cisapride suspensions according to the compounding pharmacy’s instructions, typically refrigerated. Shake well before each use. Use within the specified beyond-use date. Protect from light.
Always consult your veterinarian before starting, stopping, or changing any medication. GI stasis in rabbits is a medical emergency requiring immediate veterinary attention. This information is for educational purposes and does not replace professional veterinary advice.