C H A P T E R 5 9
Antiemetic agents
931
BOX 59.1
Drug therapy across the lifespan
Antiemetic agents
CHILDREN
Parents should be taught to call their healthcare provider
or a local poison control centre if their children ingest
potentially toxic substances.The professionals will advise
them of the best treatment in each individual case.
Antiemetics should be used with caution in children
who are at higher risk for adverse effects, including
central nervous system (CNS) effects, as well as fluid and
electrolyte disturbances.
Prochlorphenazine is often a drug of choice with
children, and it has established oral, rectal and parenteral
doses. Promethazine often has fewer adverse effects,
but it should not be used with children who have liver
impairment, Reye’s syndrome or sleep apnoea.The
serotonin 5-HT
3
agents have been used very successfully
in children younger than 2 years of age. Care should be
used when determining dose and timing of dose.
ADULTS
Antiemetics are often used after surgery or chemotherapy,
and precautions should be used to ensure that CNS effects
do not interfere with mobility or other activities.
PREGNANCY AND BREASTFEEDING
The safety of these drugs during pregnancy and
breastfeeding has not been established. Use should be
reserved for those situations in which the benefit to the
mother outweighs the potential risk to the fetus.The drugs
may enter breast milk and also may cause fluid imbalance
that could interfere with milk production. It is advised that
caution be used if one of these drugs is prescribed during
breastfeeding.
OLDER ADULTS
Older adults are more likely to develop adverse effects
associated with the use of these drugs, including sedation,
confusion, dizziness, fluid imbalance and cardiovascular
effects. Safety measures may be needed if these effects
occur and interfere with the person’s mobility and balance.
Older adults are also more likely to have renal and/
or hepatic impairment related to underlying medical
conditions, which could interfere with the metabolism
and excretion of these drugs.The dose for older adults
should be started at a lower level than that recommended
for young adults.The person should be monitored very
closely, and dose adjustment should be made based on
the individual’s response.
TABLE 59.1
DRUGS IN FOCUS Antiemetic agents
Drug name
Dosage/route
Usual indications
Phenothiazines
chlorpromazine (Largactil)
Adult: 10–25 mg PO q 4–6 hours
Paediatric: 0.5 mg/kg PO q 4–6 hours;
1.1 mg/kg PR q 6–8 hours or 0.5 mg/kg IM
q 6–8 hours
Treatment of nausea and vomiting,
including that specifically associated with
anaesthesia; severe vomiting; intractable
hiccoughs
prochlorperazine
(Nausetil, Stemetil)
Adult: 5–10 mg PO b.d. or 12.5 mg IM
Paediatric (>10 kg): 0.25 mg/kg b.d or t.d.s.
Treatment of severe nausea and vomiting,
including that specifically associated with
anaesthesia
promethazine (Avomine,
Phenergan)
Adult: 25 mg PO q.i.d.
Paediatric (6–12 years): 10 mg q.i.d.
Paediatric (2–5 years): 5 mg q.i.d.
Prevention and control of nausea and
vomiting associated with anaesthesia and
surgery
Non-phenothiazine
domperidone (Motilium)
Adult: 10 mg PO t.d.s. or q.i.d. 15–30 minutes
Treatment of nausea and vomiting before
meals
metoclopramide
(Maxolon)
Adult: 10 mg PO t.d.s.
Paediatric (15–20 years): 5–10 mg PO t.d.s.
Treatment of nausea and vomiting,
especially related to chemical stimulation
of the chemoreceptor trigger zone in
adults
5-HT
3
receptor blockers
dolasetron (Anzemet)
Adult: 100 mg PO within 1 hour of procedure;
12.5 mg IV for postoperative vomiting;
1.8 mg/kg IV or 100 mg IV injection before
chemotherapy
Paediatric (2–16 years): 1.8 mg/kg before
chemotherapy, diluted in apple or apple-
grape juice; 1.8 mg/kg IV 30 minutes
before chemotherapy; 1.2 mg/kg IV for
postoperative vomiting
Treatment of nausea and vomiting
associated with emetogenic
chemotherapy; prevention of
postoperative nausea and vomiting
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