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Analgesics are drugs that
relieve pain without causing loss of consciousness.
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Opioid
a general term defined as any drug, natural or synthetic, that has actions similar to those of morphine.
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Narcotic
has been used to mean an analgesic, a central nervous system (CNS) depressant, and any drug capable of causing physical dependence.
Opiod is the better Term
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What are the main classes of opioid receptors
Mu
Kappa
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At each type of receptor, a drug can act in one of three ways:
as an agonist, partial agonist, or antagonist.
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Drugs that bind opioid receptors fall into three major groups:
- (1) pure opioid agonists,
- (2) agonist-antagonist opioids,
- (3) pure opioid antagonists.
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Opioids are the most effective
analgesics available
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Morphine and other pure opioid agonists relieve
pain by mimicking the actions of endogenous opioid peptides.
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Morphine has multiple pharmacologic effects:
- oAnalgesia
- oSedation
- oRespiratory depression
- oCough suppression
- oSuppression of bowel movements
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Opioid-induced sedation and euphoria can complement
pain relief
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Because opioids produce euphoria and other desirable subjective effects, they have a
high liability for abuse.
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Opiods' principal indication is
relief of moderate to severe pain.
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What is the most serious adverse effect of an opioid
Respiratory Depression
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Other important adverse effects of Opioids are
- constipation,
- urinary retention,
- orthostatic hypotension,
- emesis,
- elevation of intracranial pressure (ICP).
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Morphine is administered by several routes
- oral, intramuscular (IM),
- intravenous (IV),
- subcutaneous (subQ),
- epidural,
- intrathecal.
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Morphine must be able to cross the
blood-brain barrier to relieve pain.
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oral doses of morphine must be______than parenteral doses to produce ______
Larger
equivalent analgesic effects.
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Because the blood-brain barrier is poorly developed in infants, these patients need
smaller doses of opioids (adjusted for body weight) than do older children and adults.
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With prolonged opioid use
tolerance develops to analgesia, euphoria, sedation, and respiratory depression
but NOT to constipation and miosis.
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With prolonged opioid use what kind of tolerance develops
Physical tolerance
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withdrawal syndrome associated with opioids, although unpleasant is ....
is not dangerous.
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To minimize symptoms of abstinence, opioids should be
withdrawn gradually
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Precautions to opioid use include
pregnancy, labor and delivery, head injury, and decreased respiratory reserve.
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Patients taking opioids should avoid
alcohol and other CNS depressants
because these drugs can intensify opioid-induced sedation and respiratory depression.
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Patients taking opioids should avoid what kind of drug
anticholinergic drugs (eg, antihistamines, tricyclic antidepressants, atropine-like drugs)
because these drugs can exacerbate opioid-induced constipation and urinary retention.
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Opioid overdose produces a classic triad of signs which are
coma, respiratory depression, and pinpoint pupils.
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All strong opioid agonists are essentially equal to
morphine with regard to analgesia, abuse liability, and respiratory depression.
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Fentanyl is available in______formulations for administration by_____Routes
Five
- Three routes
- parenteral, transdermal, and transmucosal.
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The advantage of fentanyl is
in its many routes
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Use of meperidine (Demerol) should not exceed_____hours
48 hours
to avoid accumulation of normeperidine, a toxic metabolite.
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Like morphine, codeine and other moderate to strong opioid agonists produce
analgesia, sedation, euphoria, respiratory depression, constipation, urinary retention, cough suppression, and miosis
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Codeine and other moderate to strong opioid agonists differ from morphine in that they produce
less analgesia and respiratory depression and have a lower potential for abuse.
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The combination of codeine with a nonopioid analgesic (eg, aspirin, acetaminophen) produces
greater pain relief than can be achieved with either agent alone.
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Most agonist-antagonist opioids act as
agonists at kappa receptors
and antagonists at mu receptors.
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Pentazocine and other agonist-antagonist opioids produce
less analgesia than morphine and have a lower potential for abuse.
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As a rule, opioids should be administered on a
fixed schedule (with supplemental doses for breakthrough pain) rather than as needed (PRN).
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