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Drugs Producing Analgesia, Anesthesia and Neuromuscular Blocking

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What are the transmitters of the CNS
Neurotransmitters including norepinephrine, serotonin, and dopamine.
What is the Blood Brain Barrier?
blocks transport of fluids between the circulatory system and the brain.
What are the Adaptive Changes of the CNS?
↑ therapeutic effects
↓ side effects
Tolerance
Physical dependence
Define analgesics
drugs that relieve pain without causing loss of consciousness
What is pain
It is subjective; whatever the patient says it is.
What are Endogenous Opioid Peptides?
Opioid-peptides that are produced in the body:
Endorphins
Dynorphins
Enkephalins
What are the Opioid Receptors and reactions?
Mu - analgesia, resp depression, euphoria, sedation
Kappa - analgesia, sedation, ↓GI motility
Delta – analgesia
What are the Classifications of Opiods Analgesics?
Pure Opioid Agonist
Agonist-Antagonist Opioid
Pure Opioid antagonist
What Pain Assessments should be done?
OLDCART
Pain Scales
Anxiety, fear, past experiences
Barriers to assessment
What is the Equianalgesic dose?
analgesic dose compared to 10 mg morphine
Mu and kappa receptors
What is the prototype for opiods?
Morphine
Pharmacotherapeutics of opiods?
Moderate to severe pain
Acute chronic pain
Pain not relieved by nonpharmacologic measures or NSAIDS
Pain of a myocardial infarction (MI)
Pharmacodynamics of opiods?
Agonist to mu and kappa
↓ release of substance P (modulates pain perception)
Contraindications of opiods?
Pre-existing respiratory depression
Hypersensitivity
Other CNS depressant use
Antidote of opiods?
Nalaxone
What are the Adverse Effects of morphine?
Respiratory
Cardiovascular
Gastrointestinal
Genitourinary
What precautions are there with morphine?
Age related and pregnancy precautions
Opiod - Fentanyl (Sublimaze)
Equianalgesic dose
Adverse effects
Delivery systems
Opiod - Hydromophone (Dilaudid)
Equianalgesic dose
Opiod - Meperidine (demerol)
Synthetic
Short half life, multiple drug interactions
Equianalgesic dose
Metabolite: Normeperidine
Biliary or pancreatic disease
Dosing for rigors
Opiod - Methadone (Dolphine)
Half life 15-30 hrs v. 1.5-3 hrs for morphine
Pain relief
Tx of opioid addicts
Patient Controlled Analgesia (PCA)
Patients self administer parenteral opioids
Pump device
Basal (hourly) dose
Demand (bolus) dose
Advantages – steady state levels
Patient and family education
Opiod - Codeine
Prototype agent for mild to moderate pain
Less abuse potential
Side effects
Dose limiting
Antitussive effect

Combination with Acetaminophen
Pain relief by different mechanisms
Opiod - Oxycodone
Semi-synthetic
Various time released
Opiod - Propoxyphene
Mild analgesia, similar to codiene
What is the Prototype of Narcotic Agonist-Antagonist?
Pentazocine (Talwin)
Pharmacodynamics of Narcotic Agonist-Antagonist?
stimulates kappa receptors, weak antagonist to mu receptors. (Minimal respiratory depression.)
Contraindications of Narcotic Agonist-Antagonist?
known hypersensitivity, allergies to sulfites
What is the Opioid Antagonist (ANTIDOTE FOR ALL NARCOTIC ANALGESICS)?
Nalaxone - Rapidly displaces all receptor bound opioid molecules (pure agonist)
Dosing: 0.4 mg to 2 mg for adults
Routes IV, IM, SC
ANTIDOTE FOR ALL NARCOTIC ANALGESICS
What is the Adverse Effects of Nalaxone?
Dysphoria, vomiting, diarrhea, agitation
What is Anesthesia?
loss of sensation and usually of consciousness without loss of vital functions artificially produced by the administration of one or more agents that block the passage of pain impulses along nerve pathways to the brain
What are different types of Anesthesia?
General Anesthesia (GA)
Inhaled agents
Parenteral agents
Local Anesthesia
Neuromuscular Blocking Agents (NMB)
Depolarizing
Non-depolarizing
What are the Uses of Anesthesia?
Endotracheal Intubation
Mechanical ventilation
Muscle relaxation during surgery
Electroconvulsive therapy
Procedural sedation (formerly known as conscious sedation)
CNS Neural Physiology
Presynaptic release of neurotransmitters
Diffusion across synaptic cleft to post synaptic membrane (end of another neuron)
Post synaptic membrane has receptors for neurotransmitters
Neurotransmitter + receptor at post synaptic membrane leads to propagation of action potential
Action potential: Brief reversal of electrical polarization of nerve or muscle cell membrane
Remaining neurotransmitter is metabolized by postsynaptic enzymes or removed thru reuptake into presynaptic storage vesicles
What are the Pharmacodynamics of Anesthetic Agents?
Anesthetic may:
Decrease release of neurotransmitters
Increase reuptake and inhibition of post-synaptic enzymes
End result: Diminished post-synaptic response
What are the Stages of Anesthesia?
Stage I
Stage II
Stage I&II: anesthetic induction
Stage III
Anesthetic maintenance
Stage IV
Balanced anesthesia
What are the Nursing Responsibilities in Preoperative Environment?
Pre-anesthetic Medication
Sedatives
Anxiolytics

Patient safety
Quiet Environment
How is the Anesthetic potency of volatile anesthetics is measured?
Minimum alveolar concentration – MAC
What is the Prototype Agent for Inhalant Anesthetics Agents?
Isoflurane (Forane)
What are the actions of Isoflurane (Forane)?
Halogenated ether
Part of balanced anesthesia
Used to induce and maintain anesthesia
Used for sedation and analgesia
What is the Contraindication with Isoflurane (Forane)?
History of malignant hyperthermia
Inhalant Anesthetics Agents have what negative effects?
Respiratory depression
Prolonged hypotension
Postoperative respiratory depression and cardiovascular insults; increased risk with:
Chronic respiratory problems
Cardiac problems
Significant obesity
What is Nitrous oxide used for?
Adjunct in balanced anesthesia to decrease the MAC of halogenated agents
Powerful analgesic, weak anesthetic
What is the prototype of Parenteral Anesthetic Agents?
propofol (Diprivan)
What are the actions of Parenteral Anesthetic Agents?
Non-barbituate hypnotic agent
Rapid loss of consciousness after IV administration
Effects are short lived – administer as a continuous infusion induction agent
What are the Contraindication of Parenteral Anesthetic Agents?
allergy to soybeanoil, egg phosphatide or glycerol
Adverse Effect of Parenteral Anesthetic Agents?
Nausea and vomiting
What are the actions of Local Anesthetic Agents?
Reversibly block all nerve impulses by disrupting permeability to sodium during action potential

Affects nerve fibers sequentially: temperature, pain, touch, proprioception, skeletal muscle tone (autonmic, sensory, motor)
Prototype Agent of Local Anesthetic Agents?
lidocaine (Xylocaine)
What are the actions of lidocaine (Xylocaine)?
Amide local anesthetic
Indications: Infiltration anesthesia, nerve blocks, spinal and epidural blocks
Duration of action depends on strength
Addition of epinephrine; areas to avoid
What Contraindication does lidocaine (Xylocaine) have?
hypersensitivity to amide local anesthetics, sulfites or methylparaben
What is a side effect of lidocaine (Xylocaine)?
Risk of systemic toxicity
What are the actions of Neuromuscular Blocking Agents (NMB)?
Directly interfere with neurotransmission at the end plate (site of communication between a nerve and a muscle)

Clinical Use: Facilitate endotracheal intubation and mechanical ventilation
What are the actions of NMB - Non-depolarizing agents?
Prevent neural communication by depolarizing the muscle; muscle remains in a relaxed state
What are the actions of NMB - depolarizing agents?
Cause muscle depolarization and prevent repolarization; muscle has rapid contractions (fasiculations) followed by flacid paralysis.
The muscle is unalbe to receive further communication
What is the prototype and actions for Nondepolarizing NMB?
prototype agent: tubocurarine (Tubocuraine)
Used to conserve energy or reduce agitation in ICU settings
ECT therapy; diagnosis of MG
What is the prototype and actions for depolarizing NMB?
prototype agent: succinylcholine
Short acting
Assist with endotracheal intubation, endoscopy
Contraindicated in familial pseudjocholinesterase, narrow angle glaucoma. Use with caution in hyperkalemia
Neuromuscular Blocking Agents (NMB)
NMB DO NOT PROVIDE ANALGESIA OR SEDATION
(Opioid analgesics and benzodiazepines are administered to manage pain, anxiety and fear)
What are some occupation issues with some anethesia?
Chronic accidental exposure to isoflurane may increase incidence of SAB, birth defects and stillbirths

Gluteraldehyde, a disinfectant agent for heat sensitive medical devices
Asthma-like symptoms
Rash
HA
Burning eyes
OSHA standards require proper training to be given to all employees exposed to hazardous chemicals

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