This chapter discusses opioid (narcotic) analgesics and antagonists. It describes how opioid analgesics work by binding to opioid receptors in the central nervous system and spinal cord. The chapter categorizes opioids and explains their mechanisms of action, pharmacokinetics, pharmacologic effects, adverse reactions, addiction potential, overdose, withdrawal, drug interactions, and allergic reactions. It also provides examples of red flags that could indicate a potential for addiction.

1. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Chapter 7Chapter 7
Opioid (Narcotic) AnalgesicsOpioid (Narcotic) Analgesics
and Antagonistsand Antagonists
By Gaurang Chauhan
7th
sem.,B.ph
L.J.I.P

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Opioid AnalgesicsOpioid Analgesics
 Opioid (nonnarcotic) analgesics are usedOpioid (nonnarcotic) analgesics are used
to manage dental pain in patients whoto manage dental pain in patients who
cannot tolerate NSAIDS or when NSAIDscannot tolerate NSAIDS or when NSAIDs
are contraindicated.are contraindicated.
 Opioid analgesics are divided into threeOpioid analgesics are divided into three
groupsgroups——opioid agonists, mixed opioids,opioid agonists, mixed opioids,
and antagonists.and antagonists.
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3. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
 Mechanism of ActionMechanism of Action
 Opioid analgesics bind to several differentOpioid analgesics bind to several different
opioid receptors in the CNS and spinal cord toopioid receptors in the CNS and spinal cord to
produce therapeutic and adverse effects.produce therapeutic and adverse effects.
 These drugs alter the patient’s perception orThese drugs alter the patient’s perception or
reaction to pain.reaction to pain.
 Opioids can be complete agonists, partialOpioids can be complete agonists, partial
agonists, agonist-antagonists, or antagonists atagonists, agonist-antagonists, or antagonists at
the receptor site.the receptor site.
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4. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
 Mechanism of ActionMechanism of Action
 Stimulation ofStimulation of μμ receptors produces analgesia,receptors produces analgesia,
sedation, miosis, pruritus, respiratory depression,sedation, miosis, pruritus, respiratory depression,
euphoria, physical dependence, constipation.euphoria, physical dependence, constipation.
 Stimulation ofStimulation of κκ receptors produces analgesia,receptors produces analgesia,
sedation, and myosis.sedation, and myosis.
 Stimulation ofStimulation of δδ is thought to produce analgesia.is thought to produce analgesia.
 Stimulation ofStimulation of σσ receptors produces autonomicreceptors produces autonomic
stimulation, dysphoria, hallucinations,stimulation, dysphoria, hallucinations,
nightmares, and anxiety.nightmares, and anxiety.
 Stimulation ofStimulation of εε receptors produces analgesia.receptors produces analgesia.
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5. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
 PharmacokineticsPharmacokinetics
 Most opioid analgesics are well absorbed fromMost opioid analgesics are well absorbed from
the gastrointestinal tract.the gastrointestinal tract.
 Absorption also occurs from the lungs, nasal andAbsorption also occurs from the lungs, nasal and
oral mucosa, and the skin.oral mucosa, and the skin.
 Opioids are bound to plasma protein to varyingOpioids are bound to plasma protein to varying
degrees and are also distributed to the placenta.degrees and are also distributed to the placenta.
 These drugs are metabolized in the liver andThese drugs are metabolized in the liver and
undergo variable first-pass metabolism.undergo variable first-pass metabolism.
 These drugs are excreted by the kidneys.These drugs are excreted by the kidneys.
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6. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
 Pharmacologic EffectsPharmacologic Effects
 These drugs produce varying degrees of analgesiaThese drugs produce varying degrees of analgesia
depending on the strength of the individual drug.depending on the strength of the individual drug.
 Morphine is the opioid agonist by which all othersMorphine is the opioid agonist by which all others
are measured.are measured.
 Opioid analgesics produce euphoria and sedationOpioid analgesics produce euphoria and sedation
at usual therapeutic doses.at usual therapeutic doses.
 Opioid analgesics depress the cough center in theOpioid analgesics depress the cough center in the
medulla and produce an antitussive effect.medulla and produce an antitussive effect.
 Opioid analgesics increase smooth muscle toneOpioid analgesics increase smooth muscle tone
and decrease propulsive contractions and motility.and decrease propulsive contractions and motility.
This effect makes them useful for treating diarrhea.This effect makes them useful for treating diarrhea.
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7. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
 Adverse ReactionsAdverse Reactions
 Adverse reactions are an extension of theAdverse reactions are an extension of the
opioids’ pharmacologic effects.opioids’ pharmacologic effects.
 Adverse reactions are proportional to opioidAdverse reactions are proportional to opioid
analgesic strength.analgesic strength.
 Adverse reactions are many and includeAdverse reactions are many and include
respiratory depression, nausea and emesis,respiratory depression, nausea and emesis,
constipation, myosis, urinary retention, CNSconstipation, myosis, urinary retention, CNS
depressant effects, and histamine release.depressant effects, and histamine release.
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8. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
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Opioid AnalgesicsOpioid Analgesics
 AddictionAddiction
 The degree of addiction is related to opioidThe degree of addiction is related to opioid
analgesic strength.analgesic strength.
 Addiction is usually not a problem in dentistryAddiction is usually not a problem in dentistry
because the duration of action is short andbecause the duration of action is short and
weaker opioids are used.weaker opioids are used.
 The rate of development of tolerance is relatedThe rate of development of tolerance is related
to the strength of the opioid and the frequencyto the strength of the opioid and the frequency
of use.of use.
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10. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
 Overdose and WithdrawalOverdose and Withdrawal
 The major symptoms of opioid analgesic overdoseThe major symptoms of opioid analgesic overdose
include respiratory depression, pinpoint pupils, andinclude respiratory depression, pinpoint pupils, and
coma.coma.
 Withdrawal occurs with the abrupt discontinuationWithdrawal occurs with the abrupt discontinuation
of opioid analgesics.of opioid analgesics.
 Symptoms include yawning, lacrimation,Symptoms include yawning, lacrimation,
perspiration, rhinorrhea, gooseflesh, irritability,perspiration, rhinorrhea, gooseflesh, irritability,
nausea, vomiting, tachycardia, tremors, chills.nausea, vomiting, tachycardia, tremors, chills.
 Addiction, overdose, and withdrawal can be treatedAddiction, overdose, and withdrawal can be treated
with opioid antagonists.with opioid antagonists.
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11. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
 Red Flags of AddictionRed Flags of Addiction
 Asks for the opioid analgesic by name and saysAsks for the opioid analgesic by name and says
that this is the only drug that works for themthat this is the only drug that works for them
 Patient claims allergies to NSAIDs or lowerPatient claims allergies to NSAIDs or lower
potency opioid analgesicspotency opioid analgesics
 Calls with a request for an opioid analgesic justCalls with a request for an opioid analgesic just
as the office is closing or after hoursas the office is closing or after hours
 Cancels dental appointment but still requests theCancels dental appointment but still requests the
opioid analgesic even though they will be “out ofopioid analgesic even though they will be “out of
town on business”town on business”
 Continually changing practitionersContinually changing practitioners
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12. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Opioid AnalgesicsOpioid Analgesics
 Red Flags of AddictionRed Flags of Addiction
 Claims a “low pain threshold”Claims a “low pain threshold”
 Experiences pain for days after scaling andExperiences pain for days after scaling and
root planingroot planing
 Needs refills several days after anNeeds refills several days after an
uncomplicated dental procedureuncomplicated dental procedure
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Opioid AnalgesicsOpioid Analgesics
 Allergic ReactionsAllergic Reactions
 The most common allergic reactions are skin rashThe most common allergic reactions are skin rash
and urticaria.and urticaria.
 They are due to the histamine-releasing propertiesThey are due to the histamine-releasing properties
of opioid analgesics.of opioid analgesics.
 Drug InteractionsDrug Interactions
 Opioid analgesics produce additive CNSOpioid analgesics produce additive CNS
depressant effects when given with other drugsdepressant effects when given with other drugs
that depress the CNS.that depress the CNS.
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