Cerenia (Maropitant)

Antiemetic Neurokinin-1 (NK1) receptor antagonist

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 2 mg/kg q24h Duration: Up to 5 days for acute vomiting; for motion sickness, administer 1 hour before travel
Notes: For motion sickness, use 8 mg/kg (range 8-10 mg/kg) once daily, but not for more than 2 consecutive days. Administer with food to increase bioavailability.
Dog SC 1 mg/kg q24h Duration: Up to 5 days
Notes: For acute vomiting, injectable formulation can be used. Do not exceed 5 days of therapy.
Cat PO 2 mg/kg q24h Duration: Up to 5 days
Notes: Administer with food to increase bioavailability. For motion sickness, give 1 hour before travel.
Cat SC 1 mg/kg q24h Duration: Up to 5 days
Notes: For acute vomiting, injectable formulation can be used. Do not exceed 5 days of therapy.

Clinical Indications & Species Uses

General Indications
  • Prevention and treatment of vomiting in dogs and cats
Dog (Canine)
  • Prevention and treatment of acute vomiting
  • Prevention of vomiting due to motion sickness
  • Prevention of chemotherapy-induced nausea and vomiting
  • Adjunct in the management of gastroenteritis
  • Prevention of vomiting associated with pancreatitis
Cat (Feline)
  • Prevention and treatment of acute vomiting
  • Prevention of vomiting due to motion sickness
  • Prevention of chemotherapy-induced nausea and vomiting

Pharmacology & Mechanism of Action

Drug Class: Antiemetic | Pharmacological Group: Neurokinin-1 (NK1) receptor antagonist

Mechanism of Action: Maropitant is a selective antagonist of the neurokinin-1 (NK1) receptor, which is the receptor for substance P. Substance P is a neuropeptide involved in the transmission of emetic signals, particularly in the central nervous system (chemoreceptor trigger zone and vomiting center) and in the gastrointestinal tract. By blocking NK1 receptors, maropitant inhibits both central and peripheral emetic pathways, providing broad-spectrum antiemetic activity against various stimuli including motion sickness, chemotherapy, and visceral stimuli.

Pharmacodynamics: Maropitant has a high affinity for NK1 receptors and a long duration of action. It effectively prevents vomiting induced by central and peripheral stimuli. In dogs, it has been shown to have a rapid onset of action (within 1-2 hours) and a duration of up to 24 hours. In cats, the duration is similar. It also has some anti-inflammatory effects due to substance P modulation, which may contribute to its efficacy in reducing visceral pain and inflammation.

⚡ Pharmacokinetics Summary

Absorption: Maropitant is well absorbed after oral administration in dogs and cats. The oral bioavailability is approximately 37% in dogs and 50% in cats, but it is significantly increased when administered with food. The injectable formulation is administered subcutaneously and is rapidly absorbed.
Distribution: Maropitant is widely distributed in tissues, with a large volume of distribution. It crosses the blood-brain barrier to exert its central antiemetic effects. It is also distributed into the gastrointestinal tract, where it acts locally.
Metabolism: Maropitant is extensively metabolized in the liver, primarily by cytochrome P450 enzymes (CYP3A). It undergoes oxidative metabolism and conjugation. The metabolites are less active than the parent compound.
Excretion: Maropitant is excreted primarily in the feces (approximately 70%) and to a lesser extent in the urine (approximately 20%). Biliary excretion is the major route of elimination for the metabolites.
Half-Life: The elimination half-life of maropitant is approximately 5-8 hours in dogs and 8-10 hours in cats after oral administration. After subcutaneous injection, the half-life is slightly longer.
Bioavailability: Oral bioavailability is approximately 37% in dogs and 50% in cats when fasted, but increases to near 100% when administered with food. The subcutaneous formulation has high bioavailability (approximately 90-100%).
Protein Binding: Maropitant is highly protein-bound (greater than 99%) in plasma, primarily to albumin and alpha-1-acid glycoprotein.

Available Formulations & Strengths

Oral Tablet 16 mg, 24 mg, 60 mg, 160 mg (PO)
Injectable Solution 10 mg/mL (20 mL vial) (SC)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to maropitant or any component of the formulation
  • Use in animals with known gastrointestinal obstruction or perforation
  • Use in animals with severe hepatic impairment (caution)
  • Use in pregnant or lactating animals (safety not established)
Warnings & Clinical Precautions:
  • Use with caution in animals with hepatic disease, as maropitant is metabolized in the liver.
  • Use with caution in animals with cardiovascular disease, as NK1 receptors may be involved in cardiovascular regulation.
  • Do not use in animals with a known hypersensitivity to the drug.
  • Safety in puppies and kittens less than 8 weeks of age has not been established.
  • For motion sickness, use only for short-term prevention (not more than 2 consecutive days) due to potential for decreased efficacy with prolonged use.
  • Administer oral tablets with food to enhance absorption.
  • Subcutaneous injection may cause transient pain or swelling at the injection site.

Adverse Effects & Reactions

Common:

  • Vomiting (paradoxical)
  • Diarrhea
  • Anorexia
  • Lethargy
  • Injection site reactions (pain, swelling)

Serious / Severe:

  • Hepatotoxicity (rare)
  • Cardiac arrhythmias (rare)
  • Seizures (rare)

Rare:

  • Allergic reactions (urticaria, anaphylaxis)
  • Ataxia
  • Hypersalivation

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
CYP3A inhibitors (e.g., ketoconazole, itraconazole) May increase maropitant plasma concentrations, potentially leading to increased adverse effects. Moderate
CYP3A inducers (e.g., phenobarbital, rifampin) May decrease maropitant plasma concentrations, reducing efficacy. Moderate
Other antiemetics (e.g., metoclopramide, ondansetron) Additive antiemetic effects; may be beneficial but should be used with caution to avoid excessive sedation. Mild
NSAIDs (e.g., carprofen, meloxicam) No significant interaction reported, but concurrent use may increase risk of gastrointestinal irritation. Mild

Overdose & Toxicity Management

Signs of Toxicity:

  • Vomiting
  • Diarrhea
  • Lethargy
  • Ataxia
  • Tremors
  • Seizures (in severe cases)

Emergency Treatment Protocol: There is no specific antidote for maropitant overdose. Treatment is symptomatic and supportive. Induce emesis if recent ingestion and the animal is conscious, then administer activated charcoal to reduce absorption. Provide intravenous fluids to maintain hydration and electrolyte balance. Monitor for neurological signs and treat seizures with diazepam or barbiturates if necessary. In severe cases, hospitalization and intensive care may be required.

Food Animal Withdrawal Times

Maropitant is not approved for use in food-producing animals. Withdrawal times have not been established. Do not use in animals intended for food production.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F), excursions permitted between 15-30°C (59-86°F).

Handling & Special Conditions: Protect from moisture. Keep the container tightly closed. Do not freeze the injectable solution.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs and cats (Cerenia, Zoetis).

Extra-Label (Off-Label) Use: In the United States, maropitant is FDA-approved for use in dogs and cats. Extra-label use in other species is permitted under the Animal Medicinal Drug Use Clarification Act (AMDUCA) only by or on the order of a licensed veterinarian within a valid veterinarian-client-patient relationship. However, due to lack of safety and efficacy data, extra-label use in food animals is prohibited.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Maropitant is a highly effective antiemetic for dogs and cats, with a broad spectrum of activity. It is particularly useful for preventing motion sickness and chemotherapy-induced vomiting. The injectable formulation is convenient for hospitalized patients, while oral tablets are suitable for home use. When using for motion sickness, it is important to administer the higher dose (8 mg/kg in dogs) and give it at least 1 hour before travel. For acute vomiting, the lower dose (2 mg/kg) is effective. Maropitant should be used with caution in animals with hepatic disease, and liver function should be monitored during prolonged therapy. It is generally well-tolerated, with mild gastrointestinal effects being the most common adverse reactions. Always follow label instructions and consult a veterinarian for appropriate dosing and duration of therapy.

References & Literature

  • 📚 Plumb's Veterinary Drug Handbook
  • 📚 Papich Veterinary Pharmacology and Therapeutics
  • 📚 Compendium of Veterinary Products (CVP)