Anesthetics pharm

syds quizlet

What are the types of esters?

Cocaine, procaine, chloroprocaine, benzocaine, and tetracaine one 'i'

What are the types of amides?

Lignocaine, Mepivacaine, Prilocaine, Bupivacaine, Ropivacaine, Articaine two 'i's

What is the primary mechanism of action of local anesthetics?

They block voltage-gated Na+ channels in their charged cationic form, thereby inhibiting the initiation and propagation of action potentials

What forms of local anesthetics are able to cross membranes?

Only the non-ionized/uncharged (lipid soluble) forms

What types of tissue has poor quality of block achieved with local anesthetics?

Because local anesthetics are weak bases, infected tissue with low pH has poor block quality as the charged form predominates and is incapable of crossing the membrane

How are ester-type local anesthetics metabolized?

They are rapidly hydrolyzed in the blood by pseudocholinesterase. Tend to have short half lives

what adverse effects are more common with esters?

Anaphylaxis and allergies

How are ester-type local anesthetics most often used?

generally surface anesthetics

How are amide-type local anesthetics metabolized?

hydrolyzed by the liver and tend to have longer half lives

What is the adverse effect of prilocaine?

Methemoglobinaemia due to -O-toluidine production

what type of local anesthetic has immediate action?

lignocaine which is a multi-action/versatile surface & injectable amide LA

what is the cardiac action of lidocaine (lignocaine)?

Antiarrhythmic and classified as a class IB agent

what type of local anesthetic does not cause vasodilation?

Cocaine

What are the adverse effects of cocaine?

tachycardia, hypertension, and addiction

What is the effect of adding a vasoconstrictor like epinephrine to a local anesthetic?

It reduces local blood flow, slows systemic absorption reducing toxicity, prolongs the duration of action, and decreases bleeding in the surgical field.

What are the disadvantages of using vasoconstrictors with local anesthetics?

Intense vasospasm and ischemia in tissues with end arteries (fingers, toes, ear, nose, penis), epinephrine systemic toxicity, delayed wound healing

What happens to the duration of lidocaine when combined with a vasoconstrictor?

duration of action is doubled from 1-2 to 2-4 hours by enhanced neuronal uptake

When is Bupivacaine used?

Longer duration procedures (not used topically or intravenously)

What are the cardiotoxic effects of Bupivacaine?

Cardiac arrest with seizure at 0.75% concentration during epidural anesthesia

What structural characteristic of a local anesthetic determines its onset and potency?

Higher lipophilicity allows for faster penetration of tissue membranes, leading to quicker onset and higher potency.

How does the state of a nerve channel affect its sensitivity to local anesthetics?

Local anesthetics bind more effectively when the Na+ channel is in an open or inactivated state, which occurs during frequent stimulation.

What types of nerve fibers have higher intrinsic susceptibility?

Smaller fibers more sensitive and myelinated fibers blocked earlier than non-myelinated of same diameter

How does anatomic arrangement affect local anesthetic action?

Anesthetic placed outside the nerve bundle will be effective in sequence from proximal to distal affecting motor fibers earlier

What types of general anesthetics are gas?

Nitrous Oxide (N2O) and Xenon

What types of general anesthetics are volatile liquids?

Halothane, Isoflurane, Desflurane, Enflurane, Sevoflurane, and Ether

What types of general anesthetics are fast inducers?

Barbiturates and Non-barbiturates

What are the types of barbiturates?

Thiopental and Methohexital

What are the types of non-barbiturates?

Propofol and Etomidate

What types of general anesthetics are slow inducers?

Benzodiazepines and Opiates

What are the types of Benzodiazepines?

Lorazepam, Midazolam, and Diazepam

What are the types of Opiates?

Fentanyl, Alfentanil, Remifentanil, Sufentanil

What types of general anesthetics inhibit glycine and GABA(a) Cl- ion channels?

inhalation anesthetics, barbiturates, benzodiazepines and propofol

What is the mechanism of action of fluorinated anesthetics?

inhibit excitatory ion channels and glutamate receptors (AMPA, kainate, and NMDA)

What is the relationship between MAC and anesthetic potency?

They are inversely related; a smaller MAC value indicates a more potent anesthetic agent.

How does the Blood:Gas partition coefficient affect anesthetic induction?

A higher coefficient leads to a slower speed of induction and recovery

What does a high Oil:Gas partition coefficient indicate?

Higher lipid solubility, higher potency, a smaller MAC, and generally faster induction and recovery.

What is the primary CNS effect of inhaled anesthetics?

They cause vasodilation, which increases cerebral blood flow and intracranial pressure.

Which inhaled anesthetics are known to potentially provoke seizures?

Enflurane and sevoflurane

What is the primary CVS effect of inhaled anesthetics?

Hypotension because of depressed contractility (halthan, enflurane) and vasodilation (Sevoflurane, isoflurane, desflurane)

Which inhaled anesthetics sensitizes the heart to arrhythmogenic action of epinephrine/NE?

Halothane and enflurane.

Which inhaled anesthetics are preferred for patients with asthma or COPD?

Halothane and sevoflurane

Which inhaled anesthetic has the lowest rate of hepatic metabolism?

Nitrous oxide (N2O) but can be metabolized by gut bacteria

What are the advantages of using nitrous oxide (laughing gas)?

rapid Induction and recovery

What are the risks of prolonged exposure to Nitrous Oxide?

Megaloblastic anemia, bone marrow depression, neurotoxicity, and increased risk of abortion/birth defects in OR staff.

What are the pharmacokinetics of Halothane?

Reduces cardiac output and sensitize myocardium to arrhythmias from catecholamines.

Which inhaled anesthetic has the highest rate of hepatic metabolism?

Halothane, which is associated with a risk of hepatitis.

What is the advantage of thiopental sodium?

Undergoes rapid redistribution because of very high lipid solubility and redistribution

What is an adverse effect of thiopental sodium?

Induces ALA synthetase; precipitation of acute intermittent porphyria

What are the clinical uses of propofol?

↓ incidence of post op nausea and vomiting (antiemetic) and used in refractory status epilepticus (anticonvulsant)

What is the mechanism of action of ketamine?

produces "dissociative anesthesia" due to noncompetitive blocker of neuronal postsynaptic NMDA receptor with analgesic action

What are the clinical uses of ketamine?

useful in resistant depression with suicidality (effective in hours), status epilepticus, and hypovolemic shock (inhibits neuronal NE reuptake)

What are the contraindications of ketamine?

Hypertension, Ischemic heart disease, schizophrenia, and glaucoma

How is neurolept analgesia and anesthesia acheived?

Simultaneous administration of fentanyl (an opioid) + droperidol (a neuroleptic agent) produces a state called neurolept analgesia