C H A P T E R 2 6
Opioids, opioid antagonists and antimigraine agents
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Migraine headaches are severe, throbbing headaches
on one side of the head that may be associated with
an aura or warning syndrome. These headaches
are thought to be caused by arterial dilation and
hyperperfusion of the brain vessels.
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Treatment of migraines may involve either ergot
derivatives or triptans. Ergot derivatives cause
vasoconstriction and are associated with sometimes
severe systemic vasoconstrictive effects, whereas
triptans, a newer class of selective serotonin receptor
blockers, cause CNS vasoconstriction but are not
associated with as many adverse systemic effects.
CHAPTER SUMMARY
■■
Pain occurs any time that tissue is injured and various
chemicals are released. The pain impulses are carried
to the spinal cord by small-diameter A-delta and
C fibres, which form synapses with interneurons in
the dorsal horn of the spinal cord.
■■
Opioid receptors found throughout various tissues
in the body react with endogenous endorphins and
encephalins to modulate the transmission of pain
impulses.
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Opioids, derived from the opium plant, react with
opioid receptors to relieve pain. In addition, they lead
to constipation, respiratory depression, sedation and
suppression of the cough reflex; they also stimulate
feelings of well-being or euphoria.
KEY POINTS
Care considerations for
people receiving antimigraine agents
Assessment: History and examination
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■
Assess for contraindications or cautions: any
known allergies to any components of the drugs
to avoid hypersensitivity reactions
; history of MI,
CAD or hypertension,
which may be exacerbated
by the drug
; hepatic or renal dysfunction,
which
could alter the metabolism and excretion of the
drug
; pruritus or malnutrition,
which could be
exacerbated by ergot derivatives
; and current
status of pregnancy and breastfeeding,
which
would be cautions to the use of these drugs
.
■
■
Perform a physical assessment
to establish
baseline
status before beginning therapy, determine drug
effectiveness and evaluate for any potential
adverse effects.
■
■
Assess neurological status, including level of
orientation, affect and reflexes,
to evaluate CNS
effects of the drugs
.
■
■
Monitor for complaints of extremity numbness and
tingling
to identify effects on vascular constriction.
■
■
Inspect the skin for localised oedema, itching
or breakdown with ergot derivatives
to evaluate
potential dermatological effects.
■
■
Assess vital signs, including pulse rate and blood
pressure; obtain an ECG as appropriate
to evaluate
cardiac status for changes.
■
■
Monitor the results of laboratory tests, including
liver and renal function tests,
to determine the
need for dose adjustment and identify possible
toxic effects.
Implementation with rationale
■
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Administer the drug to relieve acute migraines;
these drugs are not used for prevention.
■
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Administer at the first sign of a headache and do
not wait until it is severe,
to improve therapeutic
effectiveness.
■
■
Arrange for safety precautions if CNS or visual
changes occur
to prevent injury.
■
■
Provide comfort and safety measures, such as
environmental controls and stress reduction,
for
the relief of headache.
Provide additional pain
relief as needed.
■
■
Monitor the blood pressure of any person with a
history of CAD, and discontinue the drug if any
sign of angina or prolonged hypertension occurs,
to prevent severe vascular effects.
■
■
Offer support and encouragement
to help the
individual cope with the disorder and associated
drug regimen.
■
■
Provide thorough teaching, including drug name,
prescribed dose and schedule for administration;
measures to avoid adverse effects; warning
signs that may indicate possible problems; signs
of ergotism if taking ergot derivatives; safety
measures such as avoiding driving and avoiding
overdose; and importance of follow-up monitoring
and evaluation
to enhance the person’s knowledge
about drug therapy and to promote compliance.
Evaluation
■
■
Monitor the person’s response to the drug (relief of
acute migraine headaches).
■
■
Monitor for adverse effects (CV changes,
arrhythmias, hypertension, CNS changes).
■
■
Evaluate the effectiveness of the teaching plan
(person can give the drug name and dosage and
describe possible adverse effects to watch for,
specific measures to prevent them and warning
signs to report).
■
■
Monitor the effectiveness of comfort measures and
compliance with the regimen.
