Maropitant is a competitive antagonist of substance P at the neurokinin-1 (NK1) receptor and has therefore become established in veterinary medicine primarily as a highly effective antiemetic. It is effective against both centrally mediated emetogenic stimuli (e.g. drug-induced or motion sickness-related nausea) and peripherally mediated stimuli (e.g. gastroenteritis or pancreatitis).

In dogs and cats, maropitant can be administered orally, subcutaneously, or intravenously at a dosage of 1–2 mg/kg, optimally 1–2 hours before triggering factor. The duration of action is up to 24 hours, and treatment may be continued for a maximum of up to five consecutive days.

Overall, undesirable effects of maropitant are of limited clinical relevance. The most common side effect is a short, mild to moderate pain reaction following subcutaneous injection, particularly with formulations containing metacresol. In addition, maropitant may cause a prolongation of the QT interval; therefore, it should not be used simultaneously with Ca²⁺ channel blockers. Caution is also advised in patients with impaired hepatic function as well as in very young animals (cats <16 weeks, dogs <8 weeks).

Classic indications for maropitant include antiemetic supportive therapy during chemotherapy and canine parvovirosis, as well as the prophylaxis of travel sickness in dogs and cats. Furthermore, maropitant is routinely used in the context of anaesthesia for the prevention of perioperative complications such as nausea and vomiting. In the surgical setting, particularly in association with opioid administration, several studies have demonstrated the superiority of maropitant compared with ondansetron and control groups.

Several studies indicate that, in addition to its antiemetic properties, maropitant exhibits additional beneficial effects. During visceral stimulation of the ovary, a reduction in inhalational anaesthetics of up to 30% was observed following bolus administration (5 mg/kg) and continuous rate infusion (150 μg/kg/h) (MAC-sparing effect). However, the clinical applicability of these findings is limited, as maropitant is neither approved for continuous rate infusion nor routinely administered at the high dosages used in these studies.

Moreover, adjunct positive effects of maropitant have been described in both dogs and cats, particularly in the context of visceral pain. Perioperatively, these effects manifested as a reduced requirement for additional analgesics and an improvement in postoperative well-being.

Another potential indication (off label) is the treatment of pruritus in cats with feline allergic dermatitis not caused by fleas or food, when conventional treatment methods prove ineffective. However, scientific studies on this indication are currently lacking.

In summary, maropitant is a versatile therapeutic agent that not only effectively prevents nausea and vomiting but may also contribute to a reduction in anaesthetic requirements and potentially to analgesia. Through its multiple mechanisms of action, maropitant plays an important role in improving patient comfort, stabilizing perioperative courses, and optimizing multimodal therapeutic approaches in veterinary medicine.

(The relevant references can be found in the recorded lecture video)