Download Use of Local Anesthetics

Chapter 10
Analgesics And Local
Anesthetics
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Introduction
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At times athletes, coaches, and others
will self-prescribe or encourage the use
of analgesics and/or local anesthetics to
allow players to participate in a contest
Pain tells us something!! Pain can be
masked by meds, can lead to further
damage
OTC meds used for short term relief,
physician referral for continued pain
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Pain-Control Options
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Analgesics
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An analgesic is a drug or preparation
that will reduce or eliminate pain.
Two categories: Non-opioids & opioids
Opioid – from the opium poppy
– Well known to relieve moderate and/or
severe pain symptoms
– Semi-synthetic and synthetic derivatives
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Two of the most noted of these compounds
are morphine and codeine
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Adverse effect – physical dependence
– Usually develop symptoms when patient
stops taking drug
– Withdrawal signs and symptoms
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Irritability, sweating, insomnia, tachycardia
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Endogenous opioids
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Endorphins and enkephalins are
circulating throughout the body on an
“as-needed” basis.
The endorphins are naturally occurring
morphine-like substances and are
thought to bind to receptor sites on
the pain mediating pathways.
The enkephalins have a similar
function to the endorphins; they bind
to different receptor sites but provide
the same type of pain mediation.
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Endogenous Opioids
(cont.)
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These endogenous opioids are
considered to be more potent than
morphine.
Endogenous opioids are available to
the CNS for analgesia.
– Not in the concentration of exogenous
opioids.
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Opioids’ Mechanism of
Action
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Identified in the peripheral nerves.
– Endogenous opioids bind and decrease
the excitability of the peripheral sensory
neurons = analgesia.
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Receptors are classified into three
categories: ( Table 10-3, pg 136)
– Mu (µ)
– Kappa ()
– Delta ()
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Exogenous Opioids
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Tightly controlled prescription
medication, potential for addiction
Mainly used for cancer patients
Can be used for postsurgical pain
control
Acute pain situations should not need
opioids after 1 week
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Table 10-4: Oral Opioid
Analgesics
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Specific Agents
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2004 – 2.04 billion prescriptions for
hydrocodone were written
Hydrocodone combined with
acetaminophen has antitussive action;
most commonly prescribed for pain
Oxycodone (OxyContin, Percocet,
Percodan, Oxycodone, etc.)
– Prepared in combination with
acetaminophen or other similar
analgesics.
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Codeine is another mild to moderate
analgesic that can be prescribed by
the physician or dentist to alleviate
pain in the athlete.
Codeine is also used as an antitussive.
Adverse effect of codeine is
constipation
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Adverse Effects Of
Exogenous Opioids
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Sedation
Nausea/vomiting
Constipation
– Paragoric was used as an anti-diahrreal
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Opioids with alcohol or other CNS
depressants has an additive effect =
lethal
Physicians be aware of any person
who has addictive behaviors before
they prescribe one of the opioids for
analgesia
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Table 10-5: Screening
Questions for Potential
Opioid Abuse
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Opioids can induce a tolerance effect
– Means that an increasing amount of the
drug is required to maintain the same
level of analgesia
– Affected by dose, frequency, regularity
– Does not indicate addiction
– Normal if taken for long periods of time
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Rehabilitation
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As mentioned, opioids can create
sedation, drowsiness, and an overall
mental “slow down.”
It is wise to schedule rehabilitation or
other activities that require mental
acuity at times when the drug is at a
period of reduced activity.
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Nonopioid Preparations
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NSAIDs
Propoxyphene (Darvon, Darvocet)
– High rate of addiction
– Significant toxic when combined with
other meds
– Ranks 2nd to barbiturates in causing
fatalities
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Capsaicin (Zostrix)
– Derived from seeds of hot chili peppers
– Arthritic or atypical pain, now more for
athletes
– Topically applied cream
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Athletes’ Understanding
of Analgesic Drugs
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Monitor OTC product use – reduction
in pain may allow for further damage
Athlete should report use of herbal
products because of adverse
interactions
ATC must watch for signs of addiction
What to Tell the Athlete, pg 140
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Local Anesthetics
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The use of a drug or preparation to
produce partial or complete loss of
sensation to a specific area
Commonly used in a physician’s clinical
practice, injections
Origination of local anesthetics – during
the 1500s
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Local Anesthetics (cont.)
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“Caine” suffix (cocaine)
– Incas used the cocoa leaf as a local
anesthetic
– 1800s – cocaine was derived from the
cocoa leaf
– Liquid solution was used for local
anesthetic purposes
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Local Anesthetic Action
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Diminishes the ability of the nerve
fiber to conduct action potentials.
Pain perception is decreased followed
by decrease in motor control.
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Use of Local Anesthetics
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Minor surgical procedures
Dental procedures
Others
– Diagnosis of bursitis, etc.
– Musculotendinous or joint pain
(controversial use)
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Local Anesthetics
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When compared to general anesthetics,
use of local anesthetic allows for a more
rapid recovery and there are few, if any,
residual effects, such as lethargy or
confusion.
Local anesthetic activity will be effective
due to infiltration of the target tissues.
Epinephrine is often added to local
anesthetics to provide a longer duration of
action.
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Local Anesthetics (cont.)
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Epinephrine is a local vasoconstrictor,
which diminishes blood flow and reduces
absorption of the anesthetic.
If the concentration is appropriate it will
begin to affect the outer fibers of the
nearest peripheral nerves followed by the
inner part of the nerve.
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Local Anesthetics (cont.)
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Drug metabolism by the body will
diminish the effects of the anesthetic.
– Dental procedure, return of motor then
sensation.
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Depending on the type of anesthetic
used, this entire process can take from
minutes to hours to fully complete.
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Delivery and Use of Local
Anesthetics
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Injectable
Topical (transdermal delivery)
– Not as effective as injected
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Peripheral nerve block
– Injected close to a nerve trunk to block afferent
transmission in minor surgical procedures, tooth
extraction, or in relieving chronic pain conditions
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Central nerve block
– More serious conditions
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Commonly Used Local
Anesthetics
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Table 10-6, pg 142
Procaine (Novocain)
– First widely used injectable
– In the mid 20th century, other local anesthetics were
produced that have better anesthetic properties.
However, the term “Novocain” is still sometimes used
by the lay public as the description for a local
anesthetic.
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Cocaine
– Used in some nasal surgeries in a controlled surgical
setting as a local anesthetic with vasoconstricting
properties.
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Physician Use
Considerations
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There are three main considerations
when a physician uses a local
anesthetic:
– Time to effect
– Length of time the anesthetic is effective
– Adverse effects
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Adverse Effects of Local
Anesthetics
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Local anesthetics can have serious and
toxic effects if used in excessive dosages
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There is a rare possibility of an overdose
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Adverse Effects of Local
Anesthetics (cont.)
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Altered CNS activity, including both
excitation and depression.
– The signs of CNS excitation can include
confusion, agitation, generalized excitation,
and seizures.
– CNS depression can be exhibited by
decreased respiration.
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Other possible side effects include
allergic reactions and cardiac arrest,
sometimes leading to death.
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What to Tell the Athlete
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Pg 143
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