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PTP 546
Module 15
Pharmacology of Anesthetics
Jayne Hansche Lobert, MS, RN, ACNS-BC, NP
Lobert
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Pharmacology of Anesthetics
• Anesthetic Agents
– Characteristics
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Produce loss of consciousness and sensation
Provide amnesia
Relax skeletal muscles
Inhibit sensory and autonomic reflexes
Possess minimal side effects
Rapid onset of anesthesia
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Pharmacology of Anesthetics
• Stages of Anesthesia
– Stage I: Analgesia
• Somewhat aware but begins to lose somatic sensation
– Stage II: Excitement/Delirium
• Appearance of agitation and restlessness
– Stage III: Surgical Anesthesia
• Overall goal is to reach this stage quickly and maintain this
stage for the duration of the surgery
– Stage IV: Medullary Paralysis
• Reduction of Vitals: cessation of spontaneous respirations;
BP issues cardiopulmonary collapse
• Would require intensive support
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Pharmacology of Anesthetics
• General Anesthetics
– Inhaled Anesthetics
• Volatile Liquids: Desflurane; Isoflurane
• Gas: Nitrous Oxide
– Intravenous Anesthetics
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Barbiturates
Benzodiazepines
Opioids
Ketamine
Propofol
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Pharmacology of Anesthetics
• Pharmacokinetics of General Anesthesia
– Route:
• IV or Inhaled
– Distribution:
• Widely distributed throughout body
• Highly lipid soluble deposits in adipose tissues
– Metabolism & Excretion:
• Via Liver and Lungs
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Pharmacology of Anesthetics
• General Anesthetics
– Action: inhibit neuronal activity throughout the
CNS unconsciousness and amnesia; produces
immobility and inhibits motor responses to painful
stimuli
– Therapeutic Effect: anesthesia  allows for
surgical intervention
– Side Effects: residual effects may be associated
with length of anesthesia, dose, age, adipose
tissues
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Pharmacology of Anesthetics
• Local Anesthetics
– Ex: Bupivacaine (Marcaine); Lidocaine (Xylocaine)
• Action: drug produces a loss of sensation in the specific body
part or region
• Therapeutic Effect and Clinical Use:
– Topical Administration & Transdermal administration
– Infiltration anesthesia: injection into local tissues to be numbed
– Peripheral nerve block: brachial plexus catheters with ropivacaine
during and following shoulder arthroplasty
– Central neural blockade: injectio into epidural/intrathecal/ spinal
sac
– Sympathetic block
– Intravenous regional anesthesia/block: ex: veins drained and
filled with anesthetic: numbing distal to extermity, example hand
surgery.
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Pharmacology of Anesthetics
• Adjuvants in General Anesthesia
– Preop Medications
• Barbiturates: decreases level of consciousness very
quickly
• Benzodiazepines: decrease anxiety
• Opioids
• Antihistamines
• Antacids: position in surgery, no acid refulx.
• Anticholinergics- decrease secretions to keep from
aspirating on own spit.
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Pharmacology of Anesthetics
• Adjuvants in General Anesthesia
– Neuromuscular Blockers (paralyzing agents)
• Nondepolarizing Blockers
– Pancuronium (Pavulon); Vecuronium (Norcuron)
• Depolarizing Blockers
– Succinylcholine (Anectine)
– Action: complete muscle paralysis; no analgesia;
no anesthesia.
– Side Effects: residual paralysis
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Pharmacology of Anesthetics
• Local Anesthetics
– Side Effects:
• Extension of loss of motor function
• Potential for systemic effect
– CNS symptoms somnolence, confusion, agitation and
excitation
– CV symptoms
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