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Ch. 28 Opioid Narcotic Analgesics, Opioid Antagonists and Non-Opioid Centrally Acting Analgesics

Terms in this set (56)

Analgesics
drugs that relieve pain WITHOUT causing loss of LOC
Opioid
general term defined as any drug, natural or synthetic that has actions similiar to those of morphine
Narcotic
has been used to mean an

- analgesic
- a CNS depressant
- any drug capable of causing physical dependence
The body has 3 families of peptides
1. enkephalins
2. endorphins
3. dynorphins

have opioid like properties
Endogenous opioid peptides are found in the
CNS and peripheral tissue
There are 3 main classes of opioid receptrs
1. mu
2. kappa
3. delta
from a pharm perspective, mu receptors are the most important bc
opioid analgesics act primarily by activating mu receptors
drugs that act at opioid receptors are classified on the basis of
how they affect receptor fx
At each type of receptor, a drug can act in 1 of 3 ways:
1. agonist
2. partial agonist
3. antagonist
Opioids are the most effective
analgesics
Morphine and other pure opioid agonists relieve pain by
mimicking the actions of endogenous opioid peptides
Morphine has multiple pharm effects:
1. analgesia
2. sedation
3. respiratory depression
4. cough suppression
5. suppression of bowel movements
Opioid induced sedation and euphoria
can complement pain relief
Bc opioids produce euphoria and other desirable subjective effects,
they have a high liability for abuse
Opioids' main INDICATION is
relief of moderate to severe pain
the most serious ADVERSE EFFECT of opioids is
respiratory depression
Other important adverse effects of opioids are
- constipation
- urinary retention
- orthostatic hypotension
- emesis
- iCP elevation
Morphine is admin by several routes
oral
IM
IV
Subcut
epidural
intrathecal
Morphine must be able to
cross BBB to relieve pain
Bc of the 1st pass metabolism, oral doses of morphine must be
LARGER THAN parenteral doses to produce analgesic effects.
Bc the BBB is poorly developed in infants, these pts need
SMALLER doses of opioids (adjusted for body weight) than do older children and adults
With prolonged use, tolerance develops to
analgesia
euphoria
sedation
respiratory depression

BUT NOT TO
- constipation
- miosis
cross tolerance exists among the various opioid agonists but not between
opioid agonists and general CNS depressants
With prolonged opioid use, what develops?
physical dependence
An abstinence syndrome will occur if the opioid is
abruptly withdrawn
In contrast to withdrawal syndrome associated with general CNS depressants, the withdrawal syndrome associated with OPIOIDS,
is unplesant but not dangerous
To minimize Sx oc abstinence, opioids should always
be withdrawn gradually
Precautions to opioid use include
pregnancy
labor and delivery
head injury
decreased respiratory reserve
Patients taking opioids should avoid what?
alcohol and other CNS depressants bc these drugs can intensify opioid induced sedation and respiratory depression.
Patients taking opioids should avoid anti-cholinergic drugs such as
anti-histamines
tricyclic anti-depressants
atropine like drugs

bc these drugs can exacerbate opioid induced constipation and urinary retention
opioid OD produces a class triad of signs (3)
1. coma
2. respiratory depression
3. pin point pupils
All strong opioid agonists are essentially equal to morphine with regard to
- analgesia
- abuse liability
- respiratory depression
New opioids with low potential for
respiratory depression and abuse
Fentanyl is available in 5 forms for admin by 3 routes:
1. parenteral
2. transdermal
4. transmucosal
the advantage of fentanyl is in
its many routes
Use of Meperidine (Demerol) should NOT EXCEED
48 hours to avoid accumulation of normedperidine - a toxic metabolite
like morphine, codeine and other moderate to strong opioid agonists produce
- analgesia
- seation
- euphoria
- respiratory depression
- constipation
- urianry retention
- cough suppresion
- miosis
CODEINE and other moderate to strong opioid agonists produce differ from morphine in that they produce MORE OR LESS
- respiratory depression
- abuse
LESS
The combo of codeine with a non-opioid analgesic (aspirin, acetaminophen) produces
GREATER pain relief than can be achieved with either agent alone
Most agonist-antagonist opioids acta s agonists at
KAPPA receptors and

antagonists are MU-receptors
Naloxone and other pure opioid antagonists can REVERSE
- respiratory depression
- coma
- analgesia
- and most other effects of pure opioid agonists
Pure opioid ANTAGONISTS are used primarily to Tx what?
Opioid OD
If administered in excessive dosages to an individual who is physically DEPENDENT on opioid AGONISTS,

naloxone will do what?
precipitate an immediate withdrawal reaction
Opioid dosage must be INDIVIDUALIZED. patients with a LOW tolerance to pain or with extremely painful conditions need what?
HIGHER doses
Patients with sharp, stabbing pain need _________ doses than patients with dull pain.
HIGHER DOSES
Elderly adults generally require higher or lower doses than younger adults?
LOWER DOSES
Neonates require higher or lower doses
relatively low doses
As a rule, opioids should be administered in what type of schedule?
a fixed schedule.

(with supplemental doses for breakthrough pain)

rather as needed (PRN)
Most PCA devides are eletronically controlled pumps
that can be activated by the patient to deliver a preset dose of opioid thorugh an indwelling catheter.

some PCA devices also deliver a basal opioid infusion
PCA devices provide
steady plasma drug levels

thereby, maintaining continuous pain control while avoiding unnecessary sedation and respiratory depression
Use of parenteral opioids during delivery can cause what?
suppression of uterine contractions

and cause respiratory depression in the neonate
addiction
a behavior pattern characterized by continued use of a psychoactive substance despite
- physical
- psychologic
- social harm
physical dependence
IS NOT ADDICTION
physical dependence
a physiological need for a drug, marked by unpleasant withdrawal symptoms when the drug is discontinued
Abuse
drug use that's inconsistent with medical or social norms
bc of excessive and inappropriate fears about addiction and abuse, doctors freq perscribe less pain meds than pts need
and nurses freq administer less med than was prescribed.
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