Transcript PowerPoint

Chapter 9: Opioid Analgesics
Presented by:
Steffani and Katie
Location of opioid
receptors in the brain and
in the brain stem:
Thalamus
Brain Stem
Limbic System
How are pain impulses modulated as they
enter the spinal cord?

The pain impulses can be modulated by one of 2
pathways by activating pain-inhibitory systems.
Both systems activate norepinephrine and
serotonin – releasing neurons in the spinal cord
which inhibits the release of transmitters for pain
neurons.
Substance P:
 A neuropeptide
(amino-acid chain) that is a
pain-signaling neurotransmitter.
 It
is influenced by narcotic analgesics by
inhibiting the release of Substance P
presynaptically.
Effects of Endorphins:
To inhibit the release of transmitters from
primary afferent (nociceptive) pain
neurons.
What is?

Opioid Agonist: Drug that has an affinity for cell
receptors to induce changes in the cell
characteristics of the natural ligand for that
receptor. Example: Morphine
Opioid Antagonist: Drug that has an affinity for
the receptor but, once attached, has no effect other
than to BLOCK the receptor from the drugs that
DO cause an effect. Example: Naloxone
What is?

Mixed Agonist-antagonist: Drug that produces an
agonist effect at one receptor and an antagonist
effect at another receptor. These are useful in
treating opioid dependency because they limit
withdrawal symptoms to some degree.
 Example: Nubain
Partial Agonist: Drug that binds to opioid
receptors but has a low intrinsic activity (low
efficacy). Example: Ultram
Why Misuse or Abuse Opioids?
 Addiction is
reinforced by the positive
physical feelings (euphoric state, strong
feeling of well-being and contentment, and
lack of concern).
 Provides user with an experience that the
brain equates with profoundly important
events like eating, drinking and sex.
 Becomes an acquired drive state that
permeates all aspects of human life. (See
page 271)
Naloxone and Naltrexone

Both are pure opioid antagonists.
 However, naloxone is the prototype antagonist. It
must be given intravenously and has a brief
duration of effectiveness (needs to be re-injected
at short intervals).
 Naltrexone is different in that it is orally
administered and has a longer duration of
effectiveness.
 Naltrexone is indicated for use in the treatment of
alcohol abuse.
Handling and Treating Opioid
Dependency:
1.
RAAD: Rapid, Anesthesia-aided Detoxification:
Administering an opioid antagonist while patient is under
general anesthesia. This procedure cycles at which time
the withdrawal symptoms are blunted (the idea is to
detoxify a patient while unconscious).
2. Use naltrexone, methadone or LAAM (levo-alpha
acetylmethadol) to reduce opioid cravings paired with
supportive psychotherapy to address underling causes of
addiction and prevent relapse. Also, psychotherapy is
needed to treat comorbid psychological disorders.

Thoughts for and against the existence of
endogenous opioid peptides (endorphins)
that serve as natural opioids.

We believe they exist as natural analgesics
that dampen pain and influence emotions.

Katie personally experienced this effect
during distance running and childbirth.
Buprenorphine:

A semisynthetic, partial agonist opioid with long
lasting analgesic properties.

It has a potential use as a substitute for methadone
or a step down drug from methadone for the
detoxification and maintenance of opioid users.
Options in the pharmacological management
of opioid withdrawal and the prevention of
relapse:
Data support lifelong opioid maintenance as a
treatment option since the rate-of return to
illicit opioid use is significant despite
treatment interventions.