Chapter 7
Opioid (Narcotic) Analgesics
and Antagonists
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Opioid Analgesics
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Opioid (nonnarcotic) analgesics are used
to manage dental pain in patients who
cannot tolerate NSAIDS or when NSAIDs
are contraindicated.
Opioid analgesics are divided into three
groups—opioid agonists, mixed opioids,
and antagonists.
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Opioid Analgesics
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Mechanism of Action
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Opioid analgesics bind to several different
opioid receptors in the CNS and spinal cord to
produce therapeutic and adverse effects.
These drugs alter the patient’s perception or
reaction to pain.
Opioids can be complete agonists, partial
agonists, agonist-antagonists, or antagonists at
the receptor site.
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Opioid Analgesics
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Mechanism of Action
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Stimulation of μ receptors produces analgesia,
sedation, miosis, pruritus, respiratory depression,
euphoria, physical dependence, constipation.
Stimulation of κ receptors produces analgesia,
sedation, and myosis.
Stimulation of δ is thought to produce analgesia.
Stimulation of σ receptors produces autonomic
stimulation, dysphoria, hallucinations,
nightmares, and anxiety.
Stimulation of ε receptors produces analgesia.
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Opioid Analgesics
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Pharmacokinetics
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Most opioid analgesics are well absorbed from
the gastrointestinal tract.
Absorption also occurs from the lungs, nasal and
oral mucosa, and the skin.
Opioids are bound to plasma protein to varying
degrees and are also distributed to the placenta.
These drugs are metabolized in the liver and
undergo variable first-pass metabolism.
These drugs are excreted by the kidneys.
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Opioid Analgesics
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Pharmacologic Effects
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These drugs produce varying degrees of analgesia
depending on the strength of the individual drug.
Morphine is the opioid agonist by which all others
are measured.
Opioid analgesics produce euphoria and sedation
at usual therapeutic doses.
Opioid analgesics depress the cough center in the
medulla and produce an antitussive effect.
Opioid analgesics increase smooth muscle tone
and decrease propulsive contractions and motility.
This effect makes them useful for treating diarrhea.
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Opioid Analgesics
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Adverse Reactions
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Adverse reactions are an extension of the
opioids’ pharmacologic effects.
Adverse reactions are proportional to opioid
analgesic strength.
Adverse reactions are many and include
respiratory depression, nausea and emesis,
constipation, myosis, urinary retention, CNS
depressant effects, and histamine release.
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Opioid Analgesics
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Opioid Analgesics
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Addiction
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The degree of addiction is related to opioid
analgesic strength.
Addiction is usually not a problem in dentistry
because the duration of action is short and
weaker opioids are used.
The rate of development of tolerance is related
to the strength of the opioid and the frequency
of use.
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Opioid Analgesics
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Overdose and Withdrawal
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The major symptoms of opioid analgesic overdose
include respiratory depression, pinpoint pupils, and
coma.
 Withdrawal occurs with the abrupt discontinuation
of opioid analgesics.
 Symptoms include yawning, lacrimation,
perspiration, rhinorrhea, gooseflesh, irritability,
nausea, vomiting, tachycardia, tremors, chills.
 Addiction, overdose, and withdrawal can be treated
with opioid antagonists.
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Opioid Analgesics
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Red Flags of Addiction
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Asks for the opioid analgesic by name and says
that this is the only drug that works for them
Patient claims allergies to NSAIDs or lower
potency opioid analgesics
Calls with a request for an opioid analgesic just
as the office is closing or after hours
Cancels dental appointment but still requests the
opioid analgesic even though they will be “out of
town on business”
Continually changing practitioners
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Opioid Analgesics
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Red Flags of Addiction
Claims a “low pain threshold”
 Experiences pain for days after scaling and
root planing
 Needs refills several days after an
uncomplicated dental procedure
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Opioid Analgesics
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Allergic Reactions
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The most common allergic reactions are skin rash
and urticaria.
They are due to the histamine-releasing properties
of opioid analgesics.
Drug Interactions
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Opioid analgesics produce additive CNS
depressant effects when given with other drugs
that depress the CNS.
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