if prone to motion sickness) would
help to reduce incidence
of CINV.
In addition to adverse effects
of chemotherapy, patients might
experience side effects from the
antiemetic medication itself and
so it is important that they are
made aware of some of the more
common problems so as not to be
alarmed if they do occur, as well
as some of the potentially more
serious adverse effects that would
require medical attention.
Informing patients of potential
side effects can help to dictate
when best to administer their
medication. Any antiemetic that
may cause sedation or blurred
vision would be best taken
before bedtime and the patient
should avoid driving or operating
machinery if drowsiness occurs.
Conversely, dexamethasone can
cause sleep disturbances and
therefore is better administered
in the morning, or earlier in
the afternoon (for example,
second dose of a twice-daily
dosing regimen). Patients with
comorbidities would also find this
information useful. A patient who
normally suffers from constipation,
for example, may need to increase
their laxative medication if they were
given ondansetron or aprepitant.
More severe or persistent
side effects warrant contact
with the chemotherapy team.
Extrapyramidal side effects as an
adverse effect of haloperidol, for
86 | 2019 | hospitalpharmacyeurope.com
example, require medical review.
Similarly, any symptoms persisting
for more than a few days may
require a change in antiemetic.
Examples of symptoms requiring
a medical review include: vomiting
persisting for more than two days
(especially in elderly patients who
are at higher risk of dehydration);
blood in the vomit; faecal smell in
the vomit (possible GI obstruction);
and dizziness or vertigo. 14
Another important factor
to consider for the pharmacist
counselling a patient regarding
CINV is the possibility of
anticipatory nausea and vomiting
(ANV). Up to 20% of patients may
experience nausea before a cycle
of chemotherapy, and up to 30%
report this by the fourth cycle of
treatment, the risk increasing with
each repeated exposure. 15
AN is also a key predictor
of CINV in a complex inter-
relationship of uncontrolled CINV
leading to more AN in subsequent
cycles and AN increasing the risk
of CINV in the next cycle. AN
contributes to a higher level of
CINV risk in subsequent cycles, so
this is a variable that needs to be
considered in risk assessment for
CINV, and antiemetics adjusted
accordingly. Nevertheless,
uncontrolled CINV in the previous
cycle is the key factor for CINV in
the subsequent cycle, increasing
the likelihood of CINV by 6.5-times
in cycle 2 and 14-times in cycle 3. 16
While ANV may be treated