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