8 - ANESTHETIC AGENTS

a. Minimum Alveolar Concentration

a. Minimum Alveolar Concentration

1. A measure of potency for general anesthetics

   a. Minimum Alveolar Concentration

   b. Blood/Gas Partition Coefficient

   c. Structure-Activity Relationship

   d. NOTA

Nitrous Oxide

2. Laughing Gas

a. Halothane

3. Most Potent Inhalational Anesthetic

   a. Halothane

   b. Nitrous Oxide

   c. Procaine

   d. Desflurane

b. Enflurane

4. Anesthetic agent for asthmatic patients

   a. Halothane

   b. Enflurane

   c. Isoflurane

   d. Desflurane

a. Lidocaine

5. The most widely used local anesthetic

   a. Lidocaine

   b. Procaine

   c. Bupivacaine

   d. Halothane

Anesthesia

loss of all sensation to pain

Analgesia

selective loss of pain sensation

Local anesthetics

• block conduction nerve impulses

• NO loss of consciousness

General anesthetics

• produces loss of consciousness

• Used during surgical

Local anesthetics

MOA: reversible inhibition of action potential conduction by binding to the sodium channel

tremor, euphoria

S/E of local anesthetics after CNS stimulation

Drowsiness, Sedation

S/E of local anesthetics after Inhibition

seizure, coma

Ingestion of a high dose of local anesthetics can cause

• Procaine

• Chloroprocaine

Short acting Ester-Type Local Anesthetics:

• Cocaine

• Benzocaine

Intermediate-Acting Ester-Type Local Anesthetics:

Tetracaine

Long-Acting Local Anesthetics:

Procaine

1st Synthetic LA (not available)

Cocaine

1st Natural LA

Benzocaine

A LA that is found in cough lozenges, sprays

parenteral

short acting agents are used in what form?

• Lidocaine

• Prilocaine

intermediate acting Amide Type Local Anesthetics

Lidocaine

• most widely used LA

• safe for pregnant

Prilocaine

congener of lidocaine

O-Toluidine

Toxic form of Prilocaine

methemoglobinemia

The toxic form of Prilocaine can cause:

Lidocaine + Prilocaine

an EMLA that is used for circumcision

• Bupivacaine

• Levobupivacaine

• Ropvacaine

• Dibucaine

• Etidocaine

Long acting Amide Type Local Anesthetics

Bupivacaine

an Amide Local Anesthetics that is used for labor or delivery but it can cause cardiotoxicity

Levobupivacaine

• less cardiotoxic than bupivacaine

• PREFERRED drug for epidural anesthesia for labor and delivery

Ropivacaine

an Amide Local Anesthetics that cause fewer cases of cardiac toxicity but is less potent

Dibucaine

an Amide Local Anesthetics that is used for haemorrhoids (pain)

General anesthetics

• potentiate GABA activity at the GABAA-chloride ionophore

• inhibit sodium and calcium influx through membrane channels

Minimum Alveolar Concentration

determines the potency

Blood-Gas Partition Coefficient

Solubility of inhalational anesthetics in blood

Low potency

High MAC = __ potency

• Slow onset

• Slow recovery

High B/G Ratio =

Methoxyflurane or Halothane

Most potent MAC

Nitrous Oxide

Least potent MAC

Methoxyflurane or Halothane

Highest B/G Ratio

Desflurane

Lowest B/G Ratio

Nitrous Oxide

The only Nonhalogenated Drug that is used today

Nitrous Oxide

• Produces greater analgesia

• NO CV or Respiratory Depression

Dental Surgery

Nitrous Oxide is used for ___ surgery

• Megaloblastic Anemia

• Mild Euphoria

S/E of Nitrous Oxide

Halogenated Anesthetics

• more rapid rate of induction and recovery

• lower incidence of postoperative N/V

• not flammable

• dose-dependent respiratory and CV depression

• uterine relaxation

• little analgesia or skeletal muscle relaxation

disadvantage for Halogenated Anesthetics

Halothane

• most potent inhalation

• Slow onset and recovery

• sensitizes the heart to catecholamines

• hepatotoxicity

• malignant hyperthermia

Enflurane & Esflurane

more rapid induction and recovery than halothane

Enflurane

a nonhalogenated drug that is used for asthma

Isoflurane

a nonhalogenated drug that is used for neurosurgery

Halothane

• most potent inhalational

• Disad: Slow onset and recovery

• sensitizes the heart to catecholamines

• hepatotoxicity

• malignant hyperthermia (NOT FOR CHILD)

malignant hyperthermia

Halothane can cause ___ so it is not used to child

Desflurane & Sevoflurane

more rapid than any halogenated agents

Desflurane

a general anesthetic that is irritating to respiratory tract

Sevoflurane

a general anesthetic that is close to an ideal anesthetic (for kids)

• Barbiturates

• Benzodiazepines

• Opioids

• Propofol

• Etomidate

• Ketamine

PARENTERAL ANESTHETICS

Fentanyl + Droperidol

a parenteral anesthetic that is used neuroleptanesthesia (twilight sleep)

Propofol

Michael Jackson’ Drug

Milk of Amnesia

Propofol is also known as

Etomidate

a parenteral anesthetic that is safe for people w/ CVD (twilight sleep)

Ketamine

• produces dissociative anesthesia

• often used in pediatrics

• blocks N-methyl-d-aspartate (NMDA) receptors