C H A P T E R 2 6
Opioids, opioid antagonists and antimigraine agents
403
an analgesic that is long acting but not too sedating is
desired for an outpatient, hydromorphone might fit those
objectives. Fentanyl, which is available for injection, is
also available as a lozenge for treating breakthrough
pain, as a transdermal patch and in an ionic delivery
system, which activates the release of the drug as needed
for treating breakthrough pain in cancer people. See the
Critical thinking scenario for information about using
morphine to relieve pain.
Ergot derivatives
constrict cranial
blood vessels
Triptans
bind serotonin
receptors to cause
cranial vasoconstriction
Narcotics
occupy opioid
receptors to block
pain response
Opioid receptors
Spinal cord
Gate
open
Gate
closed
Large-
diameter
fibres
Cutaneous
stimulation
massage
heat, cold
vibration
pain sensation
Small-
diameter
fibres
Substantia
gelatinosa
Pain
sensation
FIGURE 26.2
Sites of action. Opioid agonists occupy opioid receptors
to block pain response. Ergot derivatives constrict cranial blood
vessels and triptans bind serotonin receptors to cause cranial
vasoconstriction.
Because of physical and cultural differences among
various ethnic groups, people from certain groups
respond differently to particular medications. Nurses
should keep in mind that people in some ethnic groups
are genetically predisposed to metabolise medications
differently. For example, people of Arab descent
may not achieve the same pain relief from opioids as
people in other ethnic groups; their inborn differences
in metabolism may require larger doses to achieve
therapeutic effects.
Some African American people seem to have a
decreased sensitivity to the pain-relieving qualities of
some opioids, although the reason for this is unknown.
Moreover, increasing the dosage of these medications
may not increase the level of pain relief and actually
may be toxic. In such cases, another class of medication
might be used to “boost” the pain-relieving qualities of
the opioid.
Among some immigrant and first-generation Asian
Americans, it may not be socially acceptable to show
strong emotion, such as that associated with pain. The
sensitive nurse will frequently ask such people if they are
comfortable or require additional medication.
Although many of these studies were done on
American people, ethnic minority groups (e.g. Asians,
people from the Middle East) are increasing in New
Zealand and Australia. Therefore, healthcare providers
will need to carefully monitor opioid responses of people
from ethnic minority groups.
■■
BOX 26.2
Differences in responses to opioid
therapy
CRITICAL THINKING SCENARIO
Using morphine to relieve pain
THE SITUATION
L.M., a 25-year-old businessman, was in a car crash and
suffered a fractured pelvis, a fractured left tibia, a fractured
right humerus, and multiple contusions and abrasions.
For the first 2 days after surgery to reduce the fractures,
L.M. was heavily sedated. As healing progressed, he was
taught to use a patient-controlled analgesia (PCA) system
using morphine. PCA provides a baseline, constant infusion
of morphine and gives the person control of the system
to add bolus doses of morphine if they feel that pain is
not being controlled. The system prevents overdose by
locking out extra doses until a specific period of time has
elapsed. L.M. became agitated when he was not able to
give himself a bolus because the appropriate time between
boluses had not elapsed. The nurse working with L.M.
noted an increase in blood pressure, pulse and respiration.
L.M. had no fever. He did seem very anxious and rated his
pain at 10. The nurse tried several non-pharmacological
measures to alleviate the pain and spent time talking with
L.M. and reassuring him. By day 5, L.M. was switched to an
oral morphine and plans were made to wean him from the
opioids.
CRITICAL THINKING
What basic principles must be included in the care plan
for L.M.?
Think about the difficult position the floor nurse
