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Pharmacology > Local and General Anesthetics > Flashcards

Local and General Anesthetics Flashcards

1
Q

Local anesthetics - MoA

A

Reversible inhibition of action potential conduction by binding to sodium channels and decreasing the nerve membrane permeability to sodium. Nonpolar lipophilic form of the anesthetic molecule passes through the neuronal membrane and switches to the polar, hydrophilic form, in the cytoplasm of the neuron. This cationic form of the anesthetic binds to the cytoplasmic side of the sodium channel protein and prolongs the inactivation state of the sodium channel. With sodium channels blocked, the action potential cannot propagate along the neuronal fibers and sensory input is lost.

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2
Q

Local anesthetics - Indication

A

Topical: skin (pruritus), mucous membrane (pain caused by oral, nasal, laryngeal, rectal disorders or surgery), cornea (before diagnostic or surgical procedures, removal of foreign bodies and cataract surgery). Before venipuncture or minor surgery.

Infiltration (injecting directly into subc tissue): minor surgical procedures (suturing), removal of foreign bodies. Dental procedures. Epinephrine can be added to decrease the dose and prolong the duration of action.

Ionophoresis (uses a small electric current to force molecules of the anesthetic into the tissue): dental procedures.
- Zingo: needle-free device. Delivers powdered Lidocaine by rapid gas pressure
Nerve Block & Field Block: forms of regional anesthesia. Anesthetize an area of the body by blocking the conductivity of sensory nerves from that area. Local anesthetic is injected into or adjacent to a peripheral nerve or nerve plexus

Spinal Intrathecal: block somatosensory and motor fibers during surgery on lower limb or pelvic structures. Injected into subarachnoid, intrathecal space below the level spinal cord terminates.

Epidural: inject local anesthetic into the lumbar or caudal epidural (extradural) space. Labor and delivery.

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3
Q

Why does ester-type local anesthetics cause more frequently hypersensitivity?

A

They are metabolized by PABA which can cause allergic reactions.

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4
Q

Local anesthetics- Adverse effects

A

Caused by their absorption into the systemic circulation and subsequent alteration of CNS, cardiovascular and other organ system function.

CNS stimulation: restlessness, tremor, euphoria
CNS inhibition: drowsiness and sedation.

Toxicity: Headache, paresthesias and nausea
Higher cons: seizures –> coma
Death due to resp failure

Cardiavascular effects: hypotension, cardiac depression

Vasodilators  block vasoconstriction induced by SNS

Antiarrhythmic activity: toxic doses –> cardiac conduction suppression, tachyarrhythmia (wide QRS)

Blockade of autonomic ganglia and neuromuscular transmission –> Loss of visceral and skeletal muscle tone –> potentiate effect of neuromuscular blocking drugs (atracurium) + caution in pt w myasthenia gravis.

Hypersensitivity reactions.

Spinal anesthesia: headache (ass w CSF leakage from the lumbar puncture) and respiratory depression (if anesthetic ascends too high up the spinal cord). Risk of infection or meningitis (entry into the CNS)

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5
Q

Ester-Type local anesthetics + Potency and duration of action

A 
Cocaine - Medium
Procaine - Short
Chloroprocaine - Short
Tetracaine - Long
Benzocaine - Medium
Proparacaine - Short
All have low potency
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6
Q

Cocaine- MoA

A

Both local anesthetic and CNS stimulant. Causes vasoconstriction as a result of its sympathomimetic effect.

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7
Q

Cocaine - Indication

A

Occasionally used to anesthetize internal structures of the nose –> helps prevent bleeding after nasal surgery.

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8
Q

Procaine and Chloroprocaine - MoA

A

Metabolized to PABA

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9
Q

Procaine and Chloroprocaine - Indication

A

Procaine: infiltration, nerve block, spinal anesthesia
Chloroprocaine: epidural, infiltration and nerve bock anesthesia

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10
Q

Procaine and Chloroprocaine - Adverse effects

A

Allergic reactions

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11
Q

Tetracaine - Indication

A

Infiltration anesthesia

Also available in topical spray and gel formulations in combo with butamben (butyl aminobenzoate) and benzocaine

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12
Q

Benzocaine - Indication

A

Topical anesthetic
Sunburn
Pruritus and other skin conditions.
Anesthetize mucus membrane (available in cough lozenges and spray to relive cough)

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13
Q

Benzocaine - Adverse effects

A

Hypersensitivity reactions which can exacerbate preexisting dermatitis.

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14
Q

Proparacaine - Indication

A

Instillation during eye surgery and other opth procedures.

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15
Q

Amide-Type Local anesthetics + Potency and duration of action

A 
Lidocaine - Short 
Etidocaine - Long
Bupivacaine - Medium
Mepivacaine - Short
Ropivacaine - Long
Levobupivacaine 
Prilocaine - Short
Dibucaine

All have intermediate potency except Bupivacaine (high) and Ropivacaine (high)

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16
Q

Lidocaine - Indication

A

Infiltration
Nerve block
Epidural
Spinal anesthesia

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17
Q

Etidocaine - Indication

A

Infiltration and nerve block anesthesia

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18
Q

Bupivacaine - Indication

A

Obstetric anesthesia
Postsurgical pain (Liposome-encapsulated for long acting analgesia)
Epidural, infiltration, nerve block and spinal anesthesia

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19
Q

Bupivacaine - Adverse effects

A

Cardiac depression

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20
Q

Mepivacaine - Indication

A

Epidural, infiltration, nerve block and spinal anesthesia

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21
Q

Ropivacaine - Indication

A

Epidural, infiltration, nerve block anesthesia

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22
Q

Levobupivacaine - MoA

A

Isolated S(-)stereoisomer of racemic bupivacaine

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23
Q

Levobupivacaine - Indication

A

Epidural anesthesia for labor and delivery.

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24
Q

Prilocaine - MoA

A

Is a congener of lidocaine, it is converted to O-toluidine, a toxic metabolite that can cause methemoglobinemia if it accumulates.

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25
Q

Prilocaine - Indication

A

Limited to topical and infiltration anesthesia

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26
Q

Prilocaine - Adverse effects

A

Methemoglobinemia

27
Q

Dibucaine - Indication

A

Ointment to relieve pain and itching of hemorrhoids(piles) and other problems in the rectal area.

28
Q

General Anesthetics

A

Diethyl ether

Cyclopropane

29
Q

General Anesthetics - MoA

A

Increase GABA and glycine inhibitory effects and decrease excitatory effects by blocking serotonergic, nicotinic and glutaminergic neurotransmission (Glutamate- NMDA/AMPA)

30
Q

Diethyl ether - Adverse effects

A

Postop nausea and vomiting

31
Q

Cyclopropane - Adverse effects

A

Cardiac arrhythmia, dizziness, nausea, vomiting

32
Q

Inhalation anesthetics - MoA

A

They bind to specific amino acid residues in the transmembrane portions of the gamma-aminobutyric acid (GABAa) receptor-chloride ion channel. They increase the chloride influx and potassium efflux from neurons. Both of these actions cause hyperpolarization of neuronal membranes and reduce membrane excitability. They also reduce sodium and calcium influx, this prevents nerve firing and release of neurotransmitters.

33
Q

Induction stages

A

1: neurons in the spinal cord are prevented from firing and analgesia and conscious sedation occur.
2: Depression of inhibitory neurons in CNS –> increased excitement, involuntary muscle movements, HR, BP and respiration
3: suppression of the reticular-activating system, loss of consciousness, loss of muscle tone and inhibition of spinal reflexes
4: Medullary paralysis. Respiratory and cardiovascular failure

34
Q

Nonhalogenated anesthetics

A

Nitrous oxide

35
Q

Nitrous oxide - Indication

A

Minor surgery and dental procedures
Component of balanced anesthesia in comb w another anesthetic.
Produces more analgesia

36
Q

Nitrous oxide - Adverse effects

A

Chronic exposure: Megaloblastic anemia

´´laughing gas´ ´causes mild euphoria when adm.

37
Q

Halogenated anesthetics

A 
Halothane
Enflurane
Isoflurane
Desflurane
Sevoflurane
38
Q

Halogenated anesthetics - Adverse effects

A

Hepatotoxicity (halothane hepatitis), Malignant hyperthermia (muscle fiber breakdown, rhabdomyolysis and renal failure )–> discontinue + treatment w dantrolene; prevents Ca release from SR (necessary to prevent fatality)

Respiratory and cardiovascular depression
Uterine relaxation
Decreased BP and CO

39
Q

Halothene - Adverse effects and Contraindication

A

Toxicity of liver: halothane hepatitis (results from a reactive intermediate metabolite that acetylates liver proteins and produces an immune reactions that is fatal in half of all cases.
Cardiac dysrhythmias (sensitized heart to catecholamine)
Hypersensitivity reaction and hepatitis
Airway irritation
Bronchodilation
Reduced CO

Contra:
Converted to reactive intermediate metabolites that can produce hypersensitivity and hepatitis –> person who is anesthetized with halothane should not be reexposed to it for 6-12 months

40
Q

Enflurane
Isoflurane
Desflurane
Sevoflurane - MoA

A

Exhibit more rapid induction and recovery than halothane. They undergo less metabolic degradation.

41
Q

Enflurane

Isoflurane - Adverse effects

A

Little cardiac arrhythmias
Produce more muscle relaxation –> reduces the needed for muscle relaxant.
Bronchodilation
They cause more respiratory depression
At high concentration: CNS excitation –> seizures.
Enflurane: reduce CO
Isoflurane: reduce systemic vascular resitance

42
Q

Desflurane

Sevoflurane - Adverse effects

A

Desflurane: : Irritating to the resp tract; limits the concentrations of this agent that can be adm during induction.
Sevoflurane: renal toxicity
Both: Reduced systemic vascular resistance

43
Q

Parenteral anesthetics

A 
Barbiturates: Thiopental,  Methohexital
Benzodiazepine: Midazolam
Opioids: Fentanyl, Sufentanil, Alfentanil, Remifentanil
Propofol, Fospropofol
Etomidate
Ketamine
44
Q

Parenteral anesthetics - Indication

A

Preanesthetic sedation
Induction of anesthesia
Perioperative analgesia
Anesthesia for minor surgical and dignositic procedures

45
Q

Thiopental, Propofol, Fospropofol and Etomidate - MoA

A

Potentiate GABA activity at the GABAA receptor chloride ion channel

46
Q

Thiopental, Propofol - Indication

A

Primarly used for induction of anesthesia, their use is followed by the adm of an inhalation anesthetic to mainatain anesthesia.

47
Q

Thiopental - Adverse effects

A

Hangover (accumulated in fat and muscle –> more slowly eliminated from body)
Depression of cardiovascular and respiratory function

48
Q

Propofol - Adverse effects

A

Depression of cardiovascular and respiratory function

49
Q

Fospropofol - MoA and Indication

A

Phosphorylated prodrug of propofol.

Used in emergency department for rapid induction of anesthesia or for conscious sedation.

50
Q

Methohexital - Indication and Adverse effects

A

Rapid induction of anesthesia

Apnea, bronchospasm, respiratory depression

51
Q

Etomidate - Indication

A

Emergency department: rapid induction of anesthesia or for conscious sedation

52
Q

Etomidate - Adverse effects

A

Adrenal suppression

Transient skeletal muscle movements

53
Q

Fentanyl - MoA

A

Opioid agonist

54
Q

Fentanyl - Indication

A

Moderate to severe pain
Strong analgesic given iv or epidurally in combo with other drugs for surgical or obstetric analgesia and anesthesia.
Provide anesthesia during cardiac surgery
Produce neuroleptanesthesia (twilight sleep) in comb w droperidol
Used with or without a local anesthetic for epidural adm or by the spinal intrathecal route during labor or to provide postoperative analgesia.

55
Q

Fentanyl - Adverse effects

A

Neuroleptanesthesia: chest wall rigidity (due to effect on basal ganglia)
Respiratory depression

56
Q

Sufentanil - Indication

A

Used with or without a local anesthetic for epidural adm or by the spinal intrathecal route during labor or to provide postoperative analgesia.

57
Q

Alfentanil

Remifentanil - Indication

A

Iv, for induction or for ambulatory surgery

58
Q

Remifentanil - Adverse effect

A

respiratory depression

59
Q

Ketamine - MoA

A

Block the action of excitatory amino acids, primarily glutamate at NMDA receptors.

60
Q

Ketamine - Indication

A

Dissociative anesthesia (IV) (dissociated from environment without complete loss of consciousness)
Most often used in pediatric patients (less likely to experience the unpleasant effects during recovery) and is given in combo with a benzodiazepine for anesthesia during minor surgical or diagnostic procedures.
Status epilepticus

61
Q

Ketamine - Adverse effects

A 
Dissociative anesthesia:
Analgesia
Reduced sensory perceptions
Immobility
Amnesia

During recovery; delirium, hallucinations, irritational behavior

Hypersalivation, Tachycardia, Hypertension
Increased BP

62
Q

Midazolam - Indication

A

Preoperative sedation, endoscopy + other diagnostic procedures

63
Q

Antidode for Midazolam + Adverse effects

A

Flumazenil

Amnesia

Pharmacology (55 decks)

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