Chapter 10 Analgesics And Local Anesthetics

1. Chapter 10Analgesics And Local Anesthetics

2. 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

3. Pain-Control Options

4. 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

5. Adverse effect – physical dependence • Usually develop symptoms when patient stops taking drug • Withdrawal signs and symptoms • Irritability, sweating, insomnia, tachycardia

6. 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.

7. 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.

8. 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 ()

9. 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

10. Table 10-4: Oral Opioid Analgesics

11. 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.

12. 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

13. 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

14. Table 10-5: Screening Questions for Potential Opioid Abuse

15. 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

16. 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.

17. Nonopioid Preparations • NSAIDs • Propoxyphene (Darvon, Darvocet) • High rate of addiction • Significant toxic when combined with other meds • Ranks 2nd to barbiturates in causing fatalities

18. Capsaicin (Zostrix) • Derived from seeds of hot chili peppers • Arthritic or atypical pain, now more for athletes • Topically applied cream

19. 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

20. 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 physician’s clinical practice, injections • Origination of local anesthetics – during the 1500s

21. 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

22. Local Anesthetic Action • Diminishes the ability of the nerve fiber to conduct action potentials. • Pain perception is decreased followed by decrease in motor control.

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

24. 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.

25. 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.

26. 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.

27. 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

28. 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.

29. 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

30. 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

31. 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.

32. What to Tell the Athlete • Pg 143