CPD ARTICLE
primarily effective against central stimulation.
Maropitant has demonstrated efficacy in dietary
indiscretion, pancreatitis, canine parvoviral enteritis
and gastritis of unknown aetiology 2 . The lack of
prokinetic properties with maropitant allows for
safer use in patients with suspected gastrointestinal
obstruction relative to for example metoclopramide.
A single daily dose of maropitant was also shown
to be more effective at managing vomiting due to
miscellaneous causes compared to metoclopramide
administered two to three times daily 3 . Maropitant
has become the standard of care in chemotherapy
patients due to its efficacy in preventing vomiting
following cisplatin and doxorubicin administration.
Maropitant has a 24-hour duration of effect in dogs,
but is cleared more slowly in cats with a half-life of
13-17 hours compared to only 4-hours in dogs 4 . The
dosages vary depending on the formulation and
required effect.
• The injectable dose of 1mg/kg, q24h, sub-
cutaneously should be administered at least 1
hour prior to anaesthesia or chemotherapy for
optimal effect.
• The oral dose is higher (2mg/kg, q24h) due to
decreased oral bioavailability but food does not
affect oral drug absorption.
The intravenous use of maropitant is reportedly
well tolerated off-label. A 2-day rest period is
recommended following the label dosing maximum
of 5 consecutive days of administration. This is due to
saturation of the hepatic cytochrome p-450 enzymes
responsible for its biotransformation. However, a dose
of 2 mg/kg, orally, once daily in healthy beagles was
safely administered to healthy beagles for 14 days 5 .
Maropitant undergoes primarily hepatic clearance
and little renal clearance, which suggests that doses
are unlikely to need reduction in renal dysfunction
be the drug must be avoided in cases with hepatic
dysfunction. In cats, maropitant is approved for
injectable use but oral tablets are also commonly
prescribed off-label. The drug is highly protein bound
which may cause interactions with other highly
protein bound drugs such as some non-steroidal anti-
inflammatories and benzodiazepines. Adverse effects
at label doses are uncommon. Pain on injection can
be avoided by refrigerating the vial 6 .
Maropitant is not approved for use in puppies younger
than 8 weeks of age and kittens under 16 weeks of
age. The higher dose for use against motion sickness
in puppies is also only approved for puppies 16 weeks
or older, this is due to bone marrow hypoplasia being
reported in 8-week-old puppies given 6-10mg/kg
once daily.
Pathophysiology of Emesis
Cancer Chemotherapy
Opioids
Chemoreceptor Trigger
Zone (CTZ)
(Outside BBB)
Dopamine D 2
5HT 3 ,
Opioids Receptors,
substance P
Celebral Cortex
Smell
Sight
Thought
Anticipatory
emesis
Vomiting Centre
(medulla)
Muscarinic, 5HT 3 &
Histaminic H 1 ,
substance P
Vestibular
Nuclei
Motion
sickness
Chemo and radio therapy
Gastroenteritis
Pharynx & GIT
5HT 3 receptors, substance P
Figure 1: Graphical representation of Pathophysiology of Emesis
Issue 03 | JULY 2018 | 29
Muscarinic
Histaminic H 1