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| Pronunciation | /məˈrɒpɪtænt/mə-ROP-i-tant |
| Trade names | Cerenia, others |
| Other names | (2S,3S)-2-Benzhydryl-N-(5-tert-butyl-2-methoxybenzyl) quinuclidin-3-amine, maropitant citrate (USANUS) |
| AHFS/Drugs.com | International Drug Names |
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| Routes of administration | Oral,subcutaneous,Intravenous transdermal |
| Drug class | Antiemetic |
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| Pharmacokinetic data | |
| Bioavailability | Oral: 20–30% dogs, 50% cats SQ: 90% (both) |
| Protein binding | 99.5% |
| Metabolism | Liver (CYP3A12 and CYP2D15) |
| Metabolites | CJ-18,518 |
| Eliminationhalf-life | 6–8 hours (SQ) |
| Duration of action | 24 hours (SQ) |
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| Chemical and physical data | |
| Formula | C32H40N2O |
| Molar mass | 468.685 g·mol−1 |
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Maropitant (INN;[3] brand name:Cerenia, used as maropitantcitrate (USAN), is aneurokinin-1 (NK1) receptor antagonist developed byZoetis specifically for the treatment ofmotion sickness and vomiting in dogs. It was approved by the FDA in 2007, for use in dogs[4][5] and in 2012, for cats.[6]
Maropitant mildly reduces intra-procedural inhaled anesthesia dose requirements but does not confer analgesia itself.[7][8]
Injectable maropitant is used indogs to treat and prevent acutevomiting; tablets are used for preventing vomiting from a variety of causes, though it requires a higher dose to prevent vomiting frommotion sickness. The injectable version is also licensed for preventing and treating acute vomiting incats.[9][5][10][11]
Maropitant is effective in treating vomiting from a variety of causes, includinggastroenteritis,chemotherapy, andkidney failure;[12][13] when given beforehand, it can prevent vomiting caused by using anopioid as apremedication.[10][14] Some have claimed that maropitant is better at treating vomiting than nausea, pointing to cats withchronic kidney disease who, when receiving maropitant, had a reduction in vomiting but no corresponding increase inappetite.[6]
Maropitant has been used in acute cases ofrapid orlabored breathing to prevent vomiting that could lead toaspiration pneumonia.[15] It has been given in combination with abenzodiazepine to cats prior to stressful events (such as a veterinary visit) to possibly relieve hypersensitivity.[16]
When compared to otherantiemetics, maropitant has similar or greater effectiveness tochlorpromazine andmetoclopramide for centrally mediated vomiting induced byapomorphine orxylazine.[11] It works better than chlorpromazine and metoclopramide for vomitingperipherally induced induced withsyrup of ipecac.[17] Unlikedimenhydrinate andacepromazine, which are used for motion sickness, maropitant does not cause sedation.[18]
Maropitant has been used as an adjunct treatment in severebronchitis due to its weak anti-inflammatory effects.[15] It alleviatesvisceral pain and has been found to reduce the amount of general anesthesia (bothsevoflurane andisoflurane) needed in some operations.[12][19]
Some believe that maropitant can be used inrabbits andguinea pigs to relieve pain caused byileus (impaired bowel movements), though it lacks antiemetic effects in rabbits, who cannot vomit.[20]
Maropitant is givenorally,subcutaneously, andintravenously.[5]
Maropitant is only indicated for dogs at least 16 weeks old, as some very young puppies suffered bone marrowhypoplasia (incomplete development ).[5] It should also be used with caution in animals with suspected GI obstruction or toxin ingestion, as it can mask symptoms, thereby delaying the diagnosis.[13][18]
It is not recommended to give maropitant for more than five consecutive days, as it tends to accumulate in the body due to one of the liver enzymes responsible for its metabolism,CYP2D15, becoming saturated. However, there have been studies wherebeagles who were given maropitant for two weeks in a row showed no signs of toxicity.[18]
Because maropitant is metabolized by the liver, caution should be taken when giving it to dogs withliver dysfunction.[5][12] Caution should also be taken when giving it with other drugs that are also highlyprotein-bound, such asNSAIDs,anticonvulsants, and some behavior-modifying drugs;[5] such drugs compete with maropitant forbinding to plasma proteins, increasing the concentration of unbound maropitant in the blood.[21] Maropitant should also not be used withcalcium channel antagonists (used to treat high blood pressure) or in animals withheart disease, as it has a slight affinity forcalcium andpotassium channels.[22]
Maropitant is safer than other antiemetics used in veterinary medicine, in part because of its high specificity for its target and thus not binding to other receptors in thecentral nervous system.[6] Side effects in dogs and cats includehypersalivation,diarrhea,loss of appetite, andvomiting.[12][16] Eight percent of dogs taking maropitant at doses meant to prevent motion sickness vomited right after, likely due to the local effects maropitant had on the gastrointestinal tract. Small amounts of food beforehand can prevent such post-administration vomiting.[11]
One of the most common side effects of subcutaneous administration is moderate to severe pain at the injection site.[10] Although the manufacturer recommends keeping maropitant at room temperature, many people have noted that keeping it in the fridge reduces the sting upon injection. Only unbound maropitant causes pain – it is normally formulated withbeta-cyclodextrin to increase solubility; at cooler temperatures, more of the maropitant remains bound to the cyclodextrin, leaving less maropitant unbound.[14][20]
While there is no pain related to the intravenous administration of maropitant, pushing a dose in too quickly can temporarilyreduce blood pressure.[10][18]
Fewer than 1 in 10,000 dogs and cats experienceanaphylactic reactions.[22]
Signs of maropitant overdose includelethargy, irregular or labored breathing,lack of muscle coordination, and tremors. Overdose of the oral formulation can causesalivation and nasal discharge, while overdose of intravenous maropitant can sometimes lead to reddish urine.[12] The LD50 is high, being over 2,000 mg/kg for oral maropitant in rats.[23]
Vomiting is caused when impulses from thechemoreceptor trigger zone (CRTZ) in the brain are sent to thevomiting center in themedulla. Motion sickness specifically occurs when signals to the CRTZ originate from theinner ear: motion is sensed by the fluid of thesemicircular canals, which causes overstimulation. The signal travels to the brain'svestibular nuclei, then to the CRTZ, and finally to the vomiting center.[24]
Maropitant has a similar structure tosubstance P, the key neurotransmitter in causing vomiting, which allows it to act as anantagonist and bind to the substance P receptorneurokinin 1 (NK1).[5][25] It is highly selective for NK1 over NK2 and NK3.[10][20] Maropitant binds to the neurokinin receptors in thevagus nerves leaving the GI tract, as well as to receptors in the CRTZ and the vomiting center.[17][24] By virtue of working at the last step in triggering vomiting, it can prevent a broader range of stimuli than most antiemetics can.[25] It is effective against emetogens that act at thecentral nervous system (such asapomorphine in dogs andxylazine in cats), those that act in the periphery (e.g.syrup of ipecac),[14][18] and those that act in both (e.g.cisplatin).[11]
Maropitant'sbioavailability is unaffected by the presence of food.[12] Bioavailability is 91% at the standard subcutaneous dose but 24% at the standard oral dose; the standard oral dose is higher to partially compensate for incomplete bioavailability.[5][18] It binds to plasma proteins at a rate of 99.5%; it has a low volume of distribution (9 L/kg) and is thus not extensively absorbed.[5][10] Subcutaneously administered maropitant had peak plasma concentration around half an hour after administration; the mean half-life is 6–8 hours, and a single dose lasts 24 hours in dogs.[10] Orally administered maropitant reached its peak plasma concentration within two hours.[12]
Maropitant undergoes1st-pass metabolism by liver enzymes, mainlyCYP2D15 (which has high affinity for maropitant and clears over 90% of it) but also by the lower-affinityCYP3A12.[11][12] Repeat dosing of maropitant eventually saturates CYP2D15, causing the drug to accumulate due to reduced clearance.[5] Thus, it is recommended to not use maropitant for more than five days straight, and to have a two-day rest period to allow maropitant to clear the body to prevent accumulation.[18][26] Maropitant has over 21 metabolites, though its major one (produced byhydroxylation) is CJ-18,518.[12]
Maropitant clearance is slower in cats.[18]
In February 2025, theCommittee for Veterinary Medicinal Products (CVMP) of theEuropean Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the veterinary medicinal product Elmaro for cats and dogs.[27] The applicant for this veterinary medicinal product is Elanco GmbH.[27] Elmaro is a generic of Cerenia, which has been authorized in the EU since June 2006.[27]
In April 2025, the CVMP adopted a positive opinion, recommending the granting of a marketing authorization for the veterinary medicinal product Emevet, chewable tablet, intended for dogs.[28] The applicant for this veterinary medicinal product is CP-Pharma Handelsgesellschaft mbH.[28]
