ANALGESIC DRUGS – LILLEY – CH 11

CNS DEPRESSANTS & MUSCLE RELAXANTS – LILLEY– CH 13

CNS STIMULANTS -LILLEY – CH 14

ANTIEPLEPTIC DRUGS – LILLEY – CH 15

ANTIPARKINSONIAN DRUGS – LILLEY -- CH 16

Central Nervous System

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 AgentsPain

Defn:

Medications that relieve pain without causing loss of consciousness

Painkillers

CNS – Analgesic AgentsPain

Pain

Whatever the patient says it is – Perception

It exists whenever the patient says it exists

It’s an unpleasant sensory and emotional experience associated with actual or potential tissue damage

Pain is a personal and individual experience

CNS– Analgesic AgentsPain

Subjective:

Pain Threshold: The level of stimulus needed to produce the perception of

pain A measure of the physiologic response of the nervous

system

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

CNS – Analgesic AgentsClassification of Pain

Classification of pain by onset and duration:

Acute pain: Sudden onset Usually subsides once treated

Chronic pain: Persistent or recurring Often difficult to treat

CNS – Analgesic AgentsClassification of Pain

Classification of Pain Somatic Visceral Vascular Referred Neuropathic Phantom Cancer Psychogenic Central

CNS – Analgesic AgentsPain Transmission

Pain Transmission – Gate Theory Impulses travel from damaged tissues and are

sensed in the brain Many current pain theories are aimed at altering this system

Substances released that stimulate nerve endings: 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 AgentsPain Transmission

Pain fibers enter the spinal cord and travel up to the brain 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

Activation of “A” fibers - closes the gate 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 AgentsPain Transmission

Body has endogenous neurotransmitters Enkephalins Endorphins

Produced by body to fight painBind opioid receptors & inhibit transmission

by “closing the gate”Examples:

Runner’s high Rubbing a painful area stimulates large sensory fibers

– result: gait closed, pain recognition reducedOpiates use the same pathway

CNS – Analgesic AgentsAgonist

Binds to an opioid pain receptor in the brain and causes an analgesic response

CNS – Analgesic AgentsOpioids - 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, MS-Contin, hydromorphone (Dilaudid), oxymorphine, levorphanol, codeine, hydrocodone, oxycodone (OxyContin);C-I: heroin

Opioid/Acetaminophen or ASA Combinations

Agonist: C-II: oxycodone with Tylenol (Percocet); oxycodone with ASA (Percodan); hydrocodone with Tylenol (Vicodin, Lorcet)

CNS – Analgesic AgentsOpioid Analgesics

Opioid pain relievers: Narcotics that contain “opium”, derived from the opium poppy 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 AgentsAntagonists

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 AgentsSide Effects

EuphoriaCNS depressionNausea and vomitingRespiratory depressionUrinary retentionDiaphoresis and flushingPupil constriction (miosis)ConstipationItching

CNS – Analgesic AgentsOpioid Overdose

Triad

Respiratory depression Respiratory rate <12/min, dyspnea,

diminished breath sounds, or shallow breathing

Decreased level of consciousness

Pinpoint Pupils (miosis)

CNS – Analgesic AgentsOpioid 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 AgentsWithdrawal / Abstinence

Syndrome

Occurs when abruptly discontinued or when an opioid antagonist is administered

anxiety, irritability, chills & hot flashes, joint pain, lacrimation, rhinorrhea, diaphoresis, nausea, vomiting, abdominal cramps, diarrhea

CNS – Analgesic AgentsNon-opioids

acetaminophen (Tylenol): blocks peripheral pain impulses by inhibition of prostaglandin synthesis & lowers febrile body temp – hypothalamus 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 Check when ordered with NSAIDs or Plavix

CNS -- Analgesic AgentsNon-steroidal anti-inflammatory drugs

NSAIDs – reduce inflammation Block Leukotriene (lipoxygenase) pathway

Salicylates

Cox1 isoform of the enzyme promotes synthesis of homeostatic prostaglandins Indomethacin (Indocin); ibupofen (Motrin); naproxen

(Naprosyn); nabumetone (Relafen)

Cox2 inhibitors block the cyclooxygenase cox2 pathway - prevent GI side effects Celecoxib (Celebrex)

CNS – Analgesic AgentsMedication Orders

Joint Commission Requirements

Pain medication for severe, moderate, and/or mild pain

Example:

Morphine 5 mg IM q4h prn severe painPercocet 1-11 tablets q6h prn moderate painTylenol 650 mg po q4h prn mild pain

CNS – Analgesic AgentsInteractions

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 AgentsNursing 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 Baseline vital signs and pulse oximetry Monitor for side effects, change in pt status, & status

of pain relief

CNS – Analgesic AgentsNursing Implications

Patient Education

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 AgentsNursing Implications

Nursing Actions:

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 AgentsNursing Implications

Monitor for therapeutic effects

Decreased complaint of pain Decreased severity of pain Increased periods of comfort Improved activities of daily living, appetite, and sense

of well-being 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 nurseb. administer oxygenc. administer an opiate antagonist per standing ordersd. perform a thorough assessment, including mental

status examination