Cisapride

Overview

Cisapride is an oral gastrointestinal prokinetic agent used in veterinary medicine to improve gastrointestinal motility. It is most commonly used in dogs and cats for disorders associated with reduced gastric or intestinal motility, including gastrointestinal stasis, gastroesophageal reflux, and constipation or megacolon in cats.

The drug is no longer commercially available and must typically be obtained through veterinary compounding pharmacies. Despite its withdrawal from the human market because of cardiac safety concerns, clinically significant cisapride-associated arrhythmias have not been reported in veterinary patients.

Mechanism of Action (MOA): Cisapride is primarily a 5-HT₄-receptor agonist that enhances acetylcholine release at the myenteric plexus of the gastrointestinal tract. This stimulates smooth muscle contraction, increases esophageal peristalsis and lower esophageal sphincter tone, enhances gastric contractions, accelerates gastric emptying, and promotes motility in the small and large intestine.

Cisapride is widely distributed after oral administration and undergoes hepatic metabolism, with elimination occurring through both urine and feces. The elimination half-life in dogs is approximately 4–10 hours and about 5–6 hours in cats. Because the canine esophagus is primarily composed of striated muscle, cisapride is generally ineffective for treatment of megaesophagus in dogs.

Indications

Cisapride is used in veterinary medicine as a gastrointestinal prokinetic agent to improve motility of the upper and lower gastrointestinal tract. It is most useful in conditions associated with reduced gastric emptying or intestinal motility when mechanical obstruction has been ruled out.

• Gastrointestinal hypomotility and stasis: Used in cases where gastric or intestinal motility is reduced, helping to stimulate coordinated smooth muscle contractions throughout the gastrointestinal tract.
• Gastroesophageal reflux: May help reduce reflux episodes by increasing lower esophageal sphincter pressure and improving esophageal peristalsis.
• Constipation and megacolon (cats): Frequently used as part of the medical management of mild to moderate feline constipation or megacolon to enhance colonic motility.
• Delayed gastric emptying: May be beneficial in conditions involving impaired gastric motility once obstructive disease has been excluded.

Dosage (Reference)

Dog

In dogs, cisapride is used to stimulate gastrointestinal motility and improve gastric emptying. The medication is given orally and is often administered shortly before feeding to enhance its prokinetic effect.

Cat

In cats, cisapride is commonly used to manage constipation or megacolon by stimulating colonic motility. The dose may be adjusted depending on the severity of the condition and the patient’s response to treatment.

Warnings & Precautions

Cisapride stimulates gastrointestinal motility and therefore should only be used in patients where increased intestinal movement is safe and appropriate. Careful patient selection is important to avoid complications associated with excessive GI motility or drug accumulation.

• Hypersensitivity: Cisapride is contraindicated in animals with known hypersensitivity to the drug.
• Gastrointestinal obstruction or perforation: Do not use in patients with suspected or confirmed GI obstruction, perforation, or active gastrointestinal hemorrhage, as increased motility may worsen the condition.
• Electrolyte abnormalities: Correct hypokalemia or hypomagnesemia before initiating therapy, as electrolyte disturbances may increase the risk of cardiac rhythm abnormalities.
• Hepatic disease: Use cautiously in animals with significant liver impairment because cisapride is metabolized in the liver and drug accumulation may occur.
• Risk of cardiac arrhythmias: In human medicine, cisapride has been associated with QT interval prolongation and serious arrhythmias. Although this has not been reported in veterinary patients, caution is advised in animals with underlying cardiac disease.
• Drugs affecting potassium balance: Use cautiously in patients receiving medications that may cause sudden decreases in plasma potassium levels (e.g., potassium-wasting diuretics or insulin).

Drug Interactions

Cisapride undergoes hepatic metabolism and may interact with several medications that influence gastrointestinal motility, electrolyte balance, or hepatic enzyme activity. Many interactions are theoretical or based on human data, but they may still be clinically relevant in veterinary patients.

• Anticholinergic agents (e.g., atropine): May reduce the prokinetic effect of cisapride by decreasing gastrointestinal smooth muscle activity.
• Opioids (e.g., morphine, fentanyl): These drugs can slow gastrointestinal motility and may counteract the promotility effects of cisapride.
• Benzodiazepines: Cisapride may enhance the sedative effects of benzodiazepines or alcohol.
• Cyclosporine: Concurrent administration may increase the risk of cyclosporine toxicity due to altered drug metabolism or absorption.
• Potassium-wasting diuretics (e.g., furosemide): May cause hypokalemia, which can increase the risk of cardiac rhythm abnormalities when cisapride is used.
• Insulin: Insulin-induced decreases in serum potassium may increase the risk of cardiac arrhythmias during treatment.
• Highly protein-bound drugs (e.g., NSAIDs, anticoagulants, sulfonamides): Because cisapride is highly protein bound, it may theoretically displace other highly bound drugs and temporarily increase their free plasma concentrations.
• Drugs with a narrow therapeutic index (e.g., digoxin, warfarin): Faster gastrointestinal transit may alter absorption; closer monitoring of drug levels or therapeutic effects may be necessary.
• CYP3A enzyme inhibitors: Drugs that inhibit hepatic CYP3A metabolism may increase cisapride concentrations and raise the risk of cardiotoxicity. Examples include azole antifungals (e.g., ketoconazole, itraconazole), macrolide antibiotics, chloramphenicol, cimetidine, fluvoxamine, ondansetron, and grapefruit products.
• Drugs that prolong the QT interval: Concurrent use with medications that increase the QT interval (e.g., amiodarone, certain fluoroquinolones, macrolide antibiotics, or domperidone) may increase the risk of cardiac arrhythmias.

Side Effects & Overdose

Side Effects

Cisapride is generally well tolerated in dogs and cats at recommended doses. Most adverse effects are mild and related to increased gastrointestinal motility. Serious adverse reactions are uncommon in veterinary patients.

• Gastrointestinal signs: Vomiting, diarrhea, abdominal discomfort, or increased intestinal sounds may occur due to enhanced GI motility.
• Lethargy or behavioral changes: Some animals may show mild lethargy, agitation, or abnormal behavior.
• Neurologic signs: Ataxia, hypersalivation, muscle fasciculations, or incoordination have been reported rarely.
• Cardiac effects: Although uncommon in veterinary patients, QT interval prolongation and arrhythmias are theoretically possible.

Overdose

Large overdoses of cisapride may result in exaggerated gastrointestinal and neurologic effects. Toxicity is uncommon but may occur with accidental ingestion of high doses.

• Gastrointestinal signs: Severe diarrhea, vomiting, abdominal discomfort, or hypersalivation.
• Neurologic effects: Lethargy, agitation, ataxia, tremors, abnormal behavior, or seizures in severe cases.
• Hyperthermia: Elevated body temperature may occur in some animals.
• Management: Treatment is primarily supportive and may include gastrointestinal decontamination (when appropriate), monitoring of vital signs, and symptomatic therapy.
• Activated charcoal: May be administered to bind unabsorbed drug following recent ingestion.

Key Notes

Practical clinical considerations that may help optimize the safe and effective use of cisapride in veterinary patients:

• Compounded medication: Cisapride is no longer commercially manufactured in many countries and is typically obtained from veterinary compounding pharmacies.
• Colonic motility effects: Cisapride has strong activity on the colon and is often preferred over other prokinetic agents when stimulation of colonic motility is required.
• Limited effect in canine megaesophagus: The canine esophagus is primarily composed of striated muscle, which responds poorly to cisapride; therefore the drug is generally ineffective for this condition.
• Combination therapy: Cisapride is frequently used alongside dietary modification, stool softeners, or laxatives when managing chronic constipation or megacolon in cats.
• Response monitoring: Clinical response should be evaluated regularly, as the degree of improvement in gastrointestinal motility may vary between patients.