Intravenous GA

*Benzodiazepine (diazepam, lorazepam, midazolam)

-facilitate GABA-mediated inhibition at GABAa receptors

• slower onset of central action but longer duration then barbiturates

• sedative (only large dose anesthetic) • prolong recovery

* anterograde amnesia (used as premed.)

• reduce anxiety

• minimal respir. or cardiovasc depressant (the benzodiazepine receptor antagonist, Flumazenil, accelerates recovery from midazole and other benzodiazepines)

* NOT analgesic

Intravenous GA

*Narcotics (Opioids)- high potency opioid

* analgesic, only large dose anesthetic

• little effect on circulation

* respiratory depression (can be severe)

• effects reversed by opioid antagonist naloxone!

Intravenous GA

*Narcotics (Opioids)- high potency opiod

* analgesic, only large dose anesthetic

• little effect on circulation

* respiratory depression (can be severe)

• effects reversed by opioid antagonist naloxone!

Intravenous Agents GA

*Narcotics (Opioids)

* analgesic, only large dose anesthetic

• little effect on circulation

* respiratory depression (can be severe)

• effects reversed by opioid antagonist naloxone!

Intravenous GA

*dissociative anesthesia (the patient remains conscious but has marked catatonia, analgesia, and amnesia)

• NMDA antagonist (blocks glutamate (NMDA) receptor)- blocks excitation by glatamate at NMDA receptors

• catatonia, amnesia, marked analgesia

* cardiovascular stimulation (hr, bp, co)

• little respiratory depression

* may post-op disorientation, illusions, vivid dreams etc. thus not commonly used in the US (can be reduced by preoperative use of benzodiazepines)

Intravenous GA

-facilitate GABA-mediated inhibition at GABAa receptors

-extensively used as a component in balanced anesthesia and "day surgery"

• rapid onset and recovery

• pat. can move sooner, “feels better” • some hypotension

* respiratory depressant

• antiemetic!

• pain at injection site, ~expensive

• extensively used as component

• now most popular IV anesthetic

IV, GA -facilitate GABA-mediated inhibition at GABAa receptors

• rapid-onset hypnotic, LOC within seconds

• rapid recovery

• minimal cardiovascular and respiratory depression

• no analgesia, requires premedication --the drug is not analgesic, and it's primary advantage is in anesthesia for patients with limited cardiac or respiratory reserve

* high incidence of nausea and vomiting

Inhaled Anesthetics GA

*Halogenated Hydrocarbons

-slow induction (INC blood:gas)

-most ptent (DEC MAC)

**Hepatotoxicity

**Sensitizes myocardium to E/NE

-INC cerebral blood flow

Inhaled Anesthetics GA

*Halogenated Hydrocarbons

-intermediate induction/potency

**Furanes (fluoride) can be nephrotoxic 

-dec minute volume

-muscle relaxation

(Fluoranes Fluoride Floppy Muscles)

Inhaled Anesthetics GA

*Halogenated Hydrocarbons

**Furanes (fluoride) can be nephrotoxic 

*Changes in renal concentraion ability

-dec minute volume

-muscle relaxation

(Fluoranes Fluoride Floppy Muscles)

Inhaled Anesthetics GA

*Halogenated Hydrocarbons

Inhaled Anesthetics GA

-fast induction (dec blood:gas)

-least potent (INC MAC)

Inhaled Anesthetics GA

*Halogenated Hydrocarbons

**Furanes (fluoride) can be nephrotoxic 

-dec minute volume

-muscle relaxation

(Fluoranes Fluoride Floppy Muscles)

Ester, LA

*intermediate

• first known LA

• still useful (vasoconstriction)

• but: easily absorbed -> systemic toxicity

• CNS stimulation, euphoria -> abuse potential

*When cocaine is used as a drug of abuse, its CV toxicity includes severe hypertension with cerebral hemorrhage, cardiac arrhythmias, and myocardial infarction

Ester, LA

*short duration

• introduced 1905; still used

• readily hydrolyzed in plasma -> short duration

• often combined with epinephrine for infiltration, nerve block, spinal anesthesia

Ester, LA

**ALL LA are capable of producing a spectrum of central effects, including light-headedness or sedation, restlessness, nystagmus, and tonic-clonic convusions. Severe convulsion may be followed by coma with respiratory and CV depression. **With the exception of cocaine, all local anesthetics are vasodilators--> patients with preexisting CV disease may develop heart block and other disurbances of cardiac electrical function at high plasma level of LA

Ester, LA

*long

• effective topical LA

• the most commonly used drug for spinal an.

* more lipophilic - thus more potent, long lasting, and toxic - than procaine and cocaine

Ester, LA

*surface use only

• ester of para-aminobenzoic acid (PABA) that lacks the terminal amino group

• poorly water soluble -> can be applied as dusting powder or ointment to wounds and ulcerated surfaces w/o major concern for systemic toxicity

Amide, LA

*intermediate

* well tolerated, one of most commonly used

• more prompt, intense, longer a. than procaine

* drug of choice for patients with ester sensitivity

Amide, LA

*Prilocaine is metabolized to products that include 0-toluidine, an agent capable of converting hemoglobin to methemoglobin---> can cause decompensation in patients with cardiac or pulmonary disease

Amide, LA

* long

• particularly long action, some nerve blocks last for >24 -> advantage for postoperative analgesia

• used for epidural an. in obstetrics: low dose relieves pain of labor, but permits motor activity to aid expelling fetus

• no behavioral effects in neonate

• more lipophilic -> more potent, toxic (heart)

**a recemic mixture, may produce severe cardiovascular toxicity, including arrhythmias and hypotension

Amide, LA

*intermediate

• ~ more rapid, longer action than lidocaine

• has been widely used in obstetrics

• now less, because of some transient neuro- behavioral effects in neonate