Chapter 10 Analgesics And Local Anesthetics

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Chapter 10Analgesics And Local Anesthetics
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Introduction

• 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

• 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
• 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
• Irritability, sweating, insomnia, tachycardia

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Endogenous opioids

• 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.)

• 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

• Identified in the peripheral nerves.
• Endogenous opioids bind and decrease the
  excitability of the peripheral sensory neurons
  analgesia.
• Receptors are classified into three categories (
  Table 10-3, pg 136)
• Mu (µ)
• Kappa (?)
• Delta (?)

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Exogenous Opioids

• 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

• 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

• Sedation
• Nausea/vomiting
• Constipation
• Paragoric was used as an anti-diahrreal
• 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

• 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

• 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

• 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

• The use of a drug or preparation to produce
  partial or complete loss of sensation to a
  specific area
• Commonly used in a physicians clinical practice,
  injections
• Origination of local anesthetics during the
  1500s

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Local Anesthetics (cont.)

• 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

• 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

• Minor surgical procedures
• Dental procedures
• Others
• Diagnosis of bursitis, etc.
• Musculotendinous or joint pain (controversial use)

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Local Anesthetics

• 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.)

• 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.)

• Drug metabolism by the body will diminish the
  effects of the anesthetic.
• Dental procedure, return of motor then sensation.
• 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

• Injectable
• Topical (transdermal delivery)
• Not as effective as injected
• 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
• Central nerve block
• More serious conditions

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Commonly Used Local Anesthetics

• 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.
• 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

• 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

• Local anesthetics can have serious and toxic
  effects if used in excessive dosages
• There is a rare possibility of an overdose

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Adverse Effects of Local Anesthetics (cont.)

• 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.
• Other possible side effects include allergic
  reactions and cardiac arrest, sometimes leading
  to death.

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What to Tell the Athlete

• Pg 143