Transcript CNS Analgesic Agents

Central Nervous System
ANALGESIC DRUGS – LILLEY – CH 10 & 44
CNS DEPRESSANTS & MUSCLE RELAXANTS – LILLEY– CH 12
ANTIEPLEPTIC DRUGS – LILLEY – CH13
A N T I PA R K I N S O N I A N D R U G S – L I L L E Y - - C H 1 4
CNS STIMULANTS -LILLEY – CH 16
CNS Pharmacology
Objectives
 Discuss the the actions and uses of an opioid agonist, agonist-
antagonist, and antagonist
 Describe how the nursing process is applied to clients receiving
sedative-hypnotic agents
 Describe the role of the nurse in promoting client compliance with
drug therapy for seizure activity
 Identify the variety of conditions and disorders being treated with CNS
stimulants
 Describe the actions and intended effects of the classes of medications
used in the treatment of Parkinson’s disease
CNS- Analgesic Agents
Pain
 Defn:
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Medications that relieve pain without causing loss of
consciousness
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Painkillers
CNS – Analgesic Agents
Pain
 Pain
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Whatever the patient says it is – Perception
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It exists whenever the patient says it exists
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It’s an unpleasant sensory and emotional experience
associated with actual or potential tissue damage
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Pain is a personal and individual experience
CNS– Analgesic Agents
Pain
 Subjective:
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Pain Threshold:
The level of stimulus needed to produce the perception of pain
 A measure of the physiologic response of the nervous system
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Pain Tolerance:
The amount of pain a patient can endure without its with normal
function with normal function
 The point at which the pain becomes unbearable
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CNS – Analgesic Agents
Classification of Pain
 Classification of pain by onset and duration:
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Acute pain:
Sudden onset
 Usually subsides once treated
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Chronic pain:
Persistent or recurring
 Often difficult to treat

CNS – Analgesic Agents
Classification of Pain
 Classification of Pain
 Somatic
 Visceral
 Vascular
 Referred
 Neuropathic
 Phantom
 Cancer
 Psychogenic
 Central
CNS – Analgesic Agents
Pain Transmission
 Pain Transmission – Gate Theory
 Impulses travel from damaged tissues and are sensed
in the brain
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Substances released that stimulate nerve endings:
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Many current pain theories are aimed at altering this system
Bradykinin, histamine, potassium, prostaglandins, serotonin
Nerves stimulated:
“A” fibers: large fibers covered with myelin sheath, with rapid
conduction – results: sharp & well localized pain
 “C” fibers: small fibers with no myelin sheath, with slow
conduction – results: dull and non-localized pain

CNS – Analgesic Agents
Pain Transmission
 Pain fibers enter the spinal cord and travel
up to the brain
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Enter through the dorsal horn – “the gate”
The gate regulates the flow of sensory impulses to the brain
 If no impulses are transmitted to higher centers in the brain, there
is no pain perception
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Activation of “A” fibers - closes the gate
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Allows the brain to evaluate, identify and localize the pain &
control the gate before it is open
Activation of “C” fibers – opens the gate
CNS – Analgesic Agents
Pain Transmission
 Body has endogenous neurotransmitters
 Enkephalins
 Endorphins
 Produced by body to fight pain
 Bind opioid receptors & inhibit transmission by
“closing the gate”
 Examples:
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Runner’s high
Rubbing a painful area stimulates large sensory fibers – result:
gait closed, pain recognition reduced
 Opiates use the same pathway
CNS – Analgesic Agents
Agonist
 Binds to an opioid pain receptor in the brain and
causes an analgesic response
CNS – Analgesic Agents
Opioids - Agonists
Chemical Category
Opioid Drugs
meperidine-like drugs
Agonist: merperidine (Demerol, Pethidine), fentanyl
(Sublimaze, Durgesic)
Methadone-like drugs
Agonist: C-II Dolphine, propoxyphene
Morphine-like drugs
Agonist: C-II: Morphine, Duramorph, Roxanol, MSContin, hydromorphone (Dilaudid), oxymorphine,
levorphanol, codeine, hydrocodone, oxycodone
(OxyContin);
C-I: heroin
Opioid/Acetaminophen Agonist: C-II: oxycodone with Tylenol (Percocet);
or ASA Combinations
oxycodone with ASA (Percodan); hydrocodone with
Tylenol (Vicodin, Lorcet)
CNS – Analgesic Agents
Opioid Analgesics
 Opioid pain relievers: Narcotics that contain
“opium”, derived from the opium poppy
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Very powerful
Addictive
 Indications: PAIN Management
 alleviate severe to moderate pain
 Often given with adjuvant analgesic agents to assist pain relief:
NSAIDS, Antidepressants, Anticonvulsants, corticosteroids
 Cough center suppression
 Treatment of diarrhea
 Balanced anesthesia
CNS –Analgesic Agents
Antagonists
 Reverse the effects of these agents on pain receptors
 Bind to a pain receptor and exert no response
 Also known as competitive antagonists
 Medications:
 naloxone (Narcan) – treat overdose
 Naltrexone (Trexan) – maintenance of opioid-free state &
psychosocial tx of alcoholism
CNS – Analgesic Agents
Side Effects
 Euphoria
 CNS depression
 Nausea and vomiting
 Respiratory depression
 Urinary retention
 Diaphoresis and flushing
 Pupil constriction (miosis)
 Constipation
 Itching
CNS – Analgesic Agents
Opioid Overdose
Triad
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Respiratory depression
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Respiratory rate <12/min, dyspnea, diminished
breath sounds, or shallow breathing
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Decreased level of consciousness
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Pinpoint Pupils (miosis)
CNS – Analgesic Agents
Opioid Effects
 Tolerance
 Common physiologic effect of chronic opioid tx
 Larger doses are required to produce the same level of analgesia
 Physical Dependence
 Physiologic adaptation of the body to the presence of an opioid
Tolerance and physical dependence are expected with
long term opioid treatment, and should not be
confused with:
 Psychological Dependence
 Pattern of compulsive drug use characterized by continued craving for an
opioid and the need to use the opioid for effects other than pain relief
CNS – Analgesic Agents
Withdrawal / Abstinence
 Syndrome
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Occurs when abruptly discontinued or when an opioid
antagonist is administered
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anxiety, irritability, chills & hot flashes, joint pain, lacrimation,
rhinorrhea, diaphoresis, nausea, vomiting, abdominal cramps,
diarrhea
CNS – Analgesic Agents
Non-opioids
 acetaminophen (Tylenol): blocks peripheral pain
impulses by inhibition of prostaglandin synthesis &
lowers febrile body temp – hypothalamus
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Max dose for healthy adult 4,000 mg per day
Check combinations of drug products
 acetylsalicylic acid (Aspirin): anti-
inflammatory, anti-pyretic, analgesic, anti-rheumatic
properties
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Check when ordered with NSAIDs or Plavix
CNS -- Analgesic Agents
Non-steroidal anti-inflammatory drugs
 NSAIDs – reduce inflammation
 Block Leukotriene (lipoxygenase) pathway

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Cox1 isoform of the enzyme promotes synthesis of
homeostatic prostaglandins
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Salicylates
Indomethacin (Indocin); ibupofen (Motrin); naproxen
(Naprosyn); nabumetone (Relafen)
Cox2 inhibitors block the cyclooxygenase cox2
pathway - prevent GI side effects
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Celecoxib (Celebrex)
CNS – Analgesic Agents
Medication Orders
 JCAHO Requirements
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Pain medication for severe, moderate, and/or mild pain
Example:
Morphine 5 mg IM q4h prn severe pain
Percocet 1-11 tablets q6h prn moderate pain
Tylenol 650 mg po q4h prn mild pain
CNS – Analgesic Agents
Interactions
 Dangerous interactions may occur if taken with
alcohol
 Should not be taken in the presence of:
 Liver dysfunction
 Possible liver failure
 When taking other hepatotoxic drugs
CNS – Analgesic Agents
Nursing Implications
 Assessment
 Allergy History / Idiosyncratic Reactions
 History of alcohol use
 Medical history – possible contraindications
 Medication reconciliation – possible drug interactions
 Thorough pain assessment – Fifth Vital Sign
Intensity, character, onset, location, description, precipitating and
relieving factors, type, remedies, and other pain treatments
 Pain Scale / Nonverbal
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Baseline vital signs and pulse oximetry
Monitor for side effects, change in pt status, & status of pain
relief
CNS – Analgesic Agents
Nursing Implications
 Patient Education
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Do not take other medications or OTC medications unless prescribed
by physician
Pain scale
Signs & Symptoms of drug allergies or adverse effects
Safety measures
Pain management – includes both pharmacologic and
non-pharmacologic approaches:

Position of comfort, distraction, therapeutic touch, comfort foods &
beverages, visitors, spirituality, presence!
CNS – Analgesic Agents
Nursing Implications
 Nursing Actions:
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Administer oral forms with food to minimize gastric upset
Ensure safety measures – prevent orthostatic hypotension
Withhold dose and contact physician with any change in pt
status
Check dosages carefully
Follow proper administration guidelines – po, sq, IM, IV –
including dilution, rate of administration
Side Effects: constipation – increase fluids, stool softeners
CNS – Analgesic Agents
Nursing Implications
 Monitor for therapeutic effects
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Decreased complaint of pain
Decreased severity of pain
Increased periods of comfort
Improved activities of daily living, appetite, and sense of wellbeing
Decreased fever (acetaminophen & NSAIDs)
CNS – Analgesic Agents
 For the best results in treating severe pain associated
with pathologic spinal fractures related to metastatic
bone cancer, which type of dosage schedule should
be used? Plan medication administered:
 a. As needed.
 b. Around the clock.
 c. On schedule during waking hours only.
 d. Around the clock, with added doses as needed for
breakthrough pain.
CNS Analgesic Agents
 A patient is receiving an opioid via a PCA pump as part of
the postoperative pain management program. During
rounds, the nurse notices that his respirations are 8 breaths
per minute and he is extremely lethargic. After stopping
the opioid infusion, what should the nurse do next?
 a. notify the charge nurse
 b. administer oxygen
 c. administer an opiate antagonist per standing orders
 d. perform a thorough assessment, including mental status
examination