Chapter 10 Analgesic Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

 Medications that relieve pain without causing loss of consciousness  “Painkillers”  Opioid analgesics  Adjuvant analgesic drugs Analgesics Copyright © 2014 by Mosby, an imprint of Elsevier Inc.2

 An unpleasant sensory and emotional experience associated with actual or potential tissue damage  A personal and individual experience  Whatever the patient says it is  Exists when the patient says it exists Pain Copyright © 2014 by Mosby, an imprint of Elsevier Inc.3

 Pain results from stimulation of sensory nerve fibers called nociceptors  These receptors transmit pain signals from various body regions to the spinal cord and brain Nociception Copyright © 2014 by Mosby, an imprint of Elsevier Inc.4

Nociception (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.5

 Level of stimulus needed to produce the perception of pain  A measure of the physiologic response of the nervous system Pain Threshold Copyright © 2014 by Mosby, an imprint of Elsevier Inc.6

 The amount of pain a person can endure without it interfering with normal function  Varies from person to person  Subjective response to pain, not a physiologic function  Varies by attitude, environment, culture, ethnicity Pain Tolerance Copyright © 2014 by Mosby, an imprint of Elsevier Inc.7

 Acute pain  Sudden onset  Usually subsides once treated  Chronic pain  Persistent or recurring  Lasts 3 to 6 months  Often difficult to treat Classification of Pain by Onset and Duration Copyright © 2014 by Mosby, an imprint of Elsevier Inc.8

Classification of Pain  Somatic  Visceral  Superficial  Deep  Vascular  Referred  Neuropathic  Phantom  Cancer  Central Copyright © 2014 by Mosby, an imprint of Elsevier Inc.9

Classroom Response Question A patient with bone cancer tells the nurse that he is in pain. The nurse knows that bone pain is classified as which type of pain? A.Somatic pain B.Referred pain C.Visceral pain D.Neuropathic pain Copyright © 2014 by Mosby, an imprint of Elsevier Inc.10

 Most common and well-described theory  Uses the analogy of a gate to describe how impulses from damaged tissues are sensed in the brain  Many current pain management strategies are aimed at altering this system Gate Theory of Pain Transmission Copyright © 2014 by Mosby, an imprint of Elsevier Inc.11

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.12 Gate Theory of Pain Transmission (cont’d)

 Tissue injury causes the release of:  Bradykinin  Histamine  Potassium  Prostaglandins  Serotonin  These substances stimulate nerve endings, starting the pain process Pain Transmission Copyright © 2014 by Mosby, an imprint of Elsevier Inc.13

 The nerve impulses enter the spinal cord and travel up to the brain  The point of spinal cord entry or the “gate” is the dorsal horn  This gate regulates the flow of sensory impulses to the brain Pain Transmission (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.14

 Closing the gate stops the impulses  If no impulses are transmitted to higher centers in the brain, there is no pain perception Pain Transmission (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.15

 Body has endogenous neurotransmitters  Enkephalins  Endorphins  Produced by body to fight pain  Bind to opioid receptors  Inhibit transmission of pain by closing gate Pain Transmission (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.16

 Rubbing a painful area with massage or liniment stimulates large sensory fibers  Result  Closes gate  Reduces pain sensation Pain Transmission (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.17

 PCA and “PCA by proxy”  Patient comfort vs. fear of drug addiction  Opioid tolerance  Use of placebos  Recognizing patients who are opioid tolerant  Breakthrough pain  Synergistic effect Treatment of Pain in Special Situations Copyright © 2014 by Mosby, an imprint of Elsevier Inc.18

 Assist primary drugs in relieving pain  NSAIDs  Antidepressants  Anticonvulsants  Corticosteroids  Example: Adjuvant drugs for neuropathic pain  amitriptyline (antidepressant)  gabapentin or pregabalin (anticonvulsants) Adjuvant Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc.19

 Synthetic drugs that bind to the opiate receptors to relieve pain  Very strong pain relievers Opioid Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc.20

 Drug reaches a maximum analgesic effect  Analgesia does not improve, even with higher doses  pentazocine  nalbuphine Opioid Ceiling Effect Copyright © 2014 by Mosby, an imprint of Elsevier Inc.21

 codeine sulfate  meperidine HCl (Demerol)  methadone HCl (Dolophine)  morphine sulfate  hydromorphone  fentanyl (Duragesic)  oxycodone  Others Opioid Analgesics (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.22

 Three classifications based on their actions:  Agonist  Partial agonist  Antagonist Opioid Analgesics: Mechanism of Action Copyright © 2014 by Mosby, an imprint of Elsevier Inc.23

 Bind to an opioid pain receptor in the brain  Cause an analgesic response (reduction of pain sensation) Agonists Copyright © 2014 by Mosby, an imprint of Elsevier Inc.24

 Bind to a pain receptor  Cause a weaker neurologic response than a full agonist  Also called partial agonist or mixed agonist Agonists-Antagonists Copyright © 2014 by Mosby, an imprint of Elsevier Inc.25

 Reverse the effects of these drugs on pain receptors  Bind to a pain receptor and exert no response  Also known as competitive antagonists Antagonists Copyright © 2014 by Mosby, an imprint of Elsevier Inc.26

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.27

 Main use: to alleviate moderate to severe pain  Often given with adjuvant analgesic drugs to assist primary drugs with pain relief  Opioids are also used for:  Cough center suppression  Treatment of diarrhea  Balanced anesthesia Opioid Analgesics: Indications Copyright © 2014 by Mosby, an imprint of Elsevier Inc.28

 Known drug allergy  Severe asthma  Use with extreme caution in patients with:  Respiratory insufficiency  Elevated intracranial pressure  Morbid obesity and/or sleep apnea  Paralytic ileus  Pregnancy Opioid Analgesics: Contraindications Copyright © 2014 by Mosby, an imprint of Elsevier Inc.29

Classroom Response Question A patient is recovering from an appendectomy. She also has asthma and allergies to shellfish and iodine. To manage her postoperative pain, the physician has prescribed patient-controlled analgesia (PCA) with hydromorphone (Dilaudid). Which vital sign is of greatest concern? A.Pulse B.Blood pressure C.Temperature D.Respirations Copyright © 2014 by Mosby, an imprint of Elsevier Inc.30

 CNS depression  Leads to respiratory depression  Most serious adverse effect  Nausea and vomiting  Urinary retention  Diaphoresis and flushing  Pupil constriction (miosis)  Constipation  Itching Opioid Analgesics: Adverse Effects Copyright © 2014 by Mosby, an imprint of Elsevier Inc.31

 A common physiologic result of chronic opioid treatment  Result: larger dose is required to maintain the same level of analgesia Opioids: Opioid Tolerance Copyright © 2014 by Mosby, an imprint of Elsevier Inc.32

 Physiologic adaptation of the body to the presence of an opioid  Opioid tolerance and physical dependence are expected with long-term opioid treatment and should not be confused with psychologic dependence (addiction) Opioids: Physical Dependence Copyright © 2014 by Mosby, an imprint of Elsevier Inc.33

Opioids: Psychologic Dependence  A pattern of compulsive drug use characterized by a continued craving for an opioid and the need to use the opioid for effects other than pain relief Copyright © 2014 by Mosby, an imprint of Elsevier Inc.34

Classroom Response Question A patient who has metastasized bone cancer has been on transdermal fentanyl patches for pain management for 3 months. He has been hospitalized for tests and has told the nurse that his pain is becoming “unbearable.” The nurse is reluctant to give him the ordered pain medication because the nurse does not want the patient to get addicted to the medication. The nurse’s actions reflect A.appropriate concern for the patient’s best welfare. B.appropriate caution for a patient who is already on a long- term opioid. C.an uncaring attitude toward the patient. D.a failure to manage the patient’s pain properly. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.35

 naloxone (Narcan)  naltrexone (ReVia)  Regardless of withdrawal symptoms, when a patient experiences severe respiratory depression, an opioid antagonist should be given. Opioid Analgesics: Toxicity and Management of Overdose Copyright © 2014 by Mosby, an imprint of Elsevier Inc.36

Toxicity and Management of Overdose (cont’d)  Opioid withdrawal/opioid abstinence syndrome  Manifested as:  Anxiety, irritability, chills and hot flashes, joint pain, lacrimation, rhinorrhea, diaphoresis, nausea, vomiting, abdominal cramps, diarrhea, confusion Copyright © 2014 by Mosby, an imprint of Elsevier Inc.37

Opioid Analgesics: Interactions  Alcohol  Antihistamines  Barbiturates  Benzodiazepines  Monoamine oxidase inhibitors Copyright © 2014 by Mosby, an imprint of Elsevier Inc.38

 Analgesic and antipyretic effects  Little to no antiinflammatory effects  Available over the counter and in combination products with opioids Nonopioid Analgesics: Acetaminophen (Tylenol) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.39

 Similar to salicylates  Blocks pain impulses peripherally by inhibiting prostaglandin synthesis Acetaminophen: Mechanism of Action Copyright © 2014 by Mosby, an imprint of Elsevier Inc.40

 Mild to moderate pain  Fever  Alternative for those who cannot take aspirin products Acetaminophen: Indications Copyright © 2014 by Mosby, an imprint of Elsevier Inc.41

 Maximum daily dose for healthy adults is being lowered to 3000 mg/day  2000 mg for elderly or those with liver disease  Inadvertent excessive doses may occur when different combination drug products are taken together  Be aware of the acetaminophen content of all medications taken by the patient (OTC and prescription) Acetaminophen: Dosage Copyright © 2014 by Mosby, an imprint of Elsevier Inc.42

 Should not be taken in the presence of  Drug allergy  Liver dysfunction  Possible liver failure  G6PD deficiency  Dangerous interactions may occur if taken with alcohol or other drugs that are hepatotoxic Acetaminophen: Contraindications/Interactions Copyright © 2014 by Mosby, an imprint of Elsevier Inc.43

 Even though available over the counter, lethal when overdosed  Overdose, whether intentional or resulting from chronic unintentional misuse, causes hepatic necrosis: hepatotoxicity  Long-term ingestion of large doses also causes nephropathy  Recommended antidote: acetylcysteine regimen Acetaminophen: Toxicity and Managing Overdose Copyright © 2014 by Mosby, an imprint of Elsevier Inc.44

Classroom Response Question Copyright © 2014 by Mosby, an imprint of Elsevier Inc.45 A patient with a history of heavy alcohol use needs a medication for pain. The recommended maximum daily dose of acetaminophen for this patient would be A.1000 mg. B.2000 mg. C.3000 mg. D.4000 mg.

 Related to the marigold family  Antiinflammatory properties  Used to treat migraine headaches, menstrual cramps, inflammation, and fever  May cause GI distress, altered taste, muscle stiffness  May interact with aspirin and other NSAIDs, and anticoagulants Herbal Products: Feverfew Copyright © 2014 by Mosby, an imprint of Elsevier Inc.46

 Before beginning therapy, perform a thorough history regarding allergies and use of other medications, including alcohol, health history, and medical history  Obtain baseline vital signs and I&O  Assess for potential contraindications and drug interactions Analgesics: Nursing Implications Copyright © 2014 by Mosby, an imprint of Elsevier Inc.47

 Perform a thorough pain assessment, including pain intensity and character, onset, location, description, precipitating and relieving factors, type, remedies, and other pain treatments  Pain is now considered a “fifth vital sign”  Rate pain on a 0 to 10 or similar scale Analgesics: Nursing Implications (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.48

 Be sure to medicate patients before the pain becomes severe so as to provide adequate analgesia and pain control  Pain management includes pharmacologic and nonpharmacologic approaches; be sure to include other interventions as indicated Analgesics: Nursing Implications (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.49

 Patients should not take other medications or OTC preparations without checking with their physician  Instruct patients to notify physician for signs of allergic reaction or adverse effects Analgesics: Nursing Implications (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.50

 Oral forms should be taken with food to minimize gastric upset  Ensure safety measures, such as keeping side rails up, to prevent injury  Withhold dose and contact physician if there is a decline in the patient’s condition or if vital signs are abnormal, especially if respiratory rate is less than 10 to 12 breaths/min Opioid Analgesics: Nursing Implications Copyright © 2014 by Mosby, an imprint of Elsevier Inc.51

 Check dosages carefully  Follow proper administration guidelines for IM injections, including site rotation  Follow proper guidelines for IV administration, including dilution, rate of administration, and so on Opioid Analgesics: Nursing Implications (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.52

 Constipation is a common adverse effect and may be prevented with adequate fluid and fiber intake  Instruct patients to follow directions for administration carefully and to keep a record of their pain experience and response to treatments  Patients should be instructed to change positions slowly to prevent possible orthostatic hypotension Opioid Analgesics: Nursing Implications (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.53

 Monitor for adverse effects  Contact physician immediately if vital signs change, patient’s condition declines, or pain continues  Respiratory depression may be manifested by respiratory rate of less than 10 breaths/min, dyspnea, diminished breath sounds, or shallow breathing Opioid Analgesics: Nursing Implications (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.54

 Monitor for therapeutic effects  Decreased complaints of pain  Decreased severity of pain  Increased periods of comfort  Improved activities of daily living, appetite, and sense of well-being  Decreased fever (acetaminophen) Opioid Analgesics: Nursing Implications (cont’d) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.55