Transcript Chapter_11
CHAPTER 11 Analgesic Drugs Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Analgesics Medications that relieve pain without causing loss of consciousness “Painkillers” Opioids NSAIDs Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 2 Pain Whatever the patient says it is Exists when the patient says it exists An unpleasant sensory and emotional experience associated with actual or potential tissue damage A personal and individual experience Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 3 Nociception 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 4 Nociception (cont’d) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 5 Pain Threshold Level of stimulus needed to produce the perception of pain A measure of the physiologic response of the nervous system Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 6 Pain Tolerance 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 7 Classification of Pain by Onset and Duration Acute pain Sudden onset Usually subsides once treated Chronic pain Persistent or recurring Lasts 3 to 6 months Often difficult to treat Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 8 Classification of Pain Somatic Referred Visceral Neuropathic Superficial Phantom Deep Cancer Vascular Central Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 9 Pain Transmission Gate Theory Most common and well described 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 10 Pain Transmission Gate Theory (cont’d) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 11 Pain Transmission Tissue injury causes the release of: Bradykinin Histamine Potassium Prostaglandins Serotonin These substances stimulate nerve endings, starting the pain process Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 12 Pain Transmission (cont’d) Two types of nerves stimulated “A” fibers “C” fibers Types of pain related to proportion of “A” to “C” fibers in damaged areas Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 13 Pain Transmission (cont’d) These pain fibers 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 14 Pain Transmission (cont’d) Closing the gate stops the impulses If no impulses are transmitted to higher centers in the brain, there is no pain perception Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 15 Pain Transmission (cont’d) Activation of large-diameter “A” fibers closes gate Inhibits transmission to brain Limits perception of pain Activation of small-diameter “C” fibers opens gate Allows impulse transmission to brain Pain perception Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 16 Pain Transmission (cont’d) Gate innervated by nerve fibers from brain, allowing the brain some control over gate Allows brain to: Evaluate, identify, and localize pain Control the gate before it is open Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 17 Pain Transmission (cont’d) Body has endogenous neurotransmitters Enkephalins Endorphins Produced by body to fight pain Bind to opioid receptors Inhibit transmission of pain by closing gate Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 18 Pain Transmission (cont’d) Rubbing a painful area with massage or liniment stimulates large sensory fibers Result Closes gate Reduces pain sensation Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 19 Treatment of Pain in Special Situations 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 20 Adjuvant Drugs Assist primary drugs in relieving pain NSAIDs Antidepressants Anticonvulsants Corticosteroids Example: Adjuvant drugs for neuropathic pain Amitriptyline (antidepressant) Gabapentin or pregabalin (anticonvulsants) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 21 Opioid Ceiling Effect Drug reaches a maximum analgesic effect Analgesia does not improve, even with higher doses pentazocine nalbuphine Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 22 Opioid Analgesics Pain relievers that contain opium, derived from the opium poppy or chemically related to opium Very strong pain relievers Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 23 Opioid Analgesics (cont’d) codeine sulfate meperidine HCl (Demerol) methadone HCl (Dolophine) morphine sulfate propoxyphene HCl hydromorphone oxycodone fentanyl Others Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 24 Opioid Analgesics: Mechanism of Action Three classifications based on their actions: Agonist Partial agonist Antagonist Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 25 Agonists Bind to an opioid pain receptor in the brain Cause an analgesic response (reduction of pain sensation) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 26 Agonists-Antagonists Bind to a pain receptor Cause a weaker neurologic response than a full agonist Also called partial agonist or mixed agonist Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 27 Antagonists Reverse the effects of these drugs on pain receptors Bind to a pain receptor and exert no response Also known as competitive antagonists Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 28 Opioid Receptors Five types of opioid receptors Mu* Kappa* Delta* Sigma Epsilon *Primary receptors Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 29 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 30 Opioid Analgesics: Indications Main use: to alleviate moderate to severe pain Often given with adjuvant analgesic drugs to assist primary drugs with pain relief Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 31 Opioid Analgesics: Indications (cont’d) Opioids are also used for: Cough center suppression Treatment of diarrhea Balanced anesthesia Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 32 Opioid Analgesics: Contraindications Known drug allergy Severe asthma Use with extreme caution if: Respiratory insufficiency Elevated intracranial pressure Morbid obesity Sleep apnea Paralytic ileus Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 33 Opioid Analgesics: Adverse Effects Euphoria CNS depression Leads to respiratory depression Most serious adverse effect Nausea and vomiting Urinary retention Diaphoresis and flushing Pupil constriction (miosis) Constipation Itching Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 34 Opioids: Opioid Tolerance A common physiologic result of chronic opioid treatment Result: larger dose is required to maintain the same level of analgesia Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 35 Opioids: Physical Dependence 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) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 36 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 37 Opioids Misunderstanding of these terms leads to ineffective pain management and contributes to the problem of undertreatment Physical dependence is seen when the opioid is abruptly discontinued or when an opioid antagonist is administered Opioid withdrawal/opioid abstinence syndrome Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 38 Toxicity and Management of Overdose naloxone (Narcan) naltrexone (Revia) These drugs bind to opiate receptors and prevent a response Used for complete or partial reversal of opioidinduced respiratory depression Regardless of withdrawal symptoms, when a patient experiences severe respiratory depression, an opioid antagonist should be given. Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 39 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 40 Nonopioid Analgesics: Acetaminophen Analgesic and antipyretic effects Little to no antiinflammatory effects Available over the counter and in combination products with opioids Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 41 Mechanism of Action Similar to salicylates Blocks pain impulses peripherally by inhibiting prostaglandin synthesis Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 42 Indications Mild to moderate pain Fever Alternative for those who cannot take aspirin products Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 43 Toxicity and Managing Overdose 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 44 Dosage Maximum daily dose for healthy adults is 4000 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 (overthe-counter and prescription) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 45 Interactions Dangerous interactions may occur if taken with alcohol or other drugs that are hepatotoxic Should not be taken in the presence of Drug allergy Liver dysfunction Possible liver failure G-6-PD deficiency Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 46 Herbal Products: Feverfew 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 47 Analgesics: Nursing Implications 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 48 Analgesics: Nursing Implications (cont’d) Perform a thorough pain assessment, including pain intensity and character, onset, location, description, precipitating and relieving factors, type, remedies, and other pain treatments Assessment of pain is now being considered a “fifth vital sign” Rate pain on a 0 to 10 or similar scale Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 49 Analgesics: Nursing Implications (cont’d) 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 50 Analgesics: Nursing Implications (cont’d) Patients should not take other medications or over-the-counter preparations without checking with their physician Instruct patients to notify physician for signs of allergic reaction or adverse effects Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 51 Opioid Analgesics: Nursing Implications 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 52 Opioid Analgesics: Nursing Implications (cont’d) 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 53 Opioid Analgesics: Nursing Implications (cont’d) 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 54 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 55 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) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 56