Pharm 2 Flashcards
Local anesthetics are made of what 3 components
Why is each important
Aromatic - lipophilic
Ester or amide linkage - amides are favored. Esters broken down faster
Amine - basic crosses membrane, acidic binds to Na channel
Esters vs amides:
Half life
Where hydrolyzed/metabolized
How to tell which is which by name
Esters have shorter 1/2 life
Esters hydrolyzed by PsChEsterase
Amides metabolized by P450 in liver
Amides have i in name before caine (lidocaine), Esters don’t
Which type of bond in local anest. Is more allergic
Esters
Local anesthetics effect in axon
Interact with open and inactivated channel, blocking Na conductance
Why are the acidic and basic forms of a local anesthetic important
Basic form crosses membrane
Acidic form blocks sodium channel
Local anesthetics produce more rapid nerve block on axons with a _ firing rate because _
Rapid
They bind to open form of Na channel
Which functions are more disrupted by LA
Functions served by B/C fibers more than A
CNS neurons are _ sensitive than PNS neurons to local an
More
Which local an is especially cardiotoxic
Bupivacaine
Most amides last longer than esters, except 2:
Prilocaine
Articaine
2 ways an operator can cause excessive local an conc in blood
3 possible effects of overdose
Intravascular injection
Excessive quantities
Convulsions
Respiratory arrest
Cardiovascular collapse
Ideal anesthetic (7)
BRAUMS’S
Smooth and Rapid
Unconsciousness
Amnesia
Maintain physiologic functions while blocking reflexes
Skeletal muscle relaxation, NOT resp. Muscles
Block sensory stimuli
Recovery with no lasting effects
5 types of drugs in a cocktail, what do they do
Antimuscarinics - minimize salivation Analgesics - Preop pain relief, sedation NOx / Opioids - reduce anest. Requirement Anti-nicotinics - paralyze sk. Muscle Antiemetics
Meyer Overton correlation:
Implication in body
Correlation b/t solubility in olive oil and anesthetic potency
Anesthesia begins when anesthetic reaches critical conc. In membrane lipids
What are 2 protein targets of general anesth.
Definitive target
Ligand activated ion channels
GABA receptors
No definitive target
Synaptic transmission is _ sensitive to anesthetics than action potentials
More
Which structures in the brain do anesthetics effect directly
Thalamus
Hippocampus
Limbic system
4 stages of general anesthesia
Analgesia
Excitement
Surgical anesthesia
Medullary paralysis
Blood : gas partition coefficient
Low vs high
Ratio of conc of anest. In blood phase to the conc. In gas phase when anesthetic is in equilibrium b/t two phases
Low - faster induction and recovery (NOx)
Higher - slower induction and recovery
MAC
What determines it
Minimum alveolar conc.
Olive oil solubility determines it
MAC and blood solubility of a good inhalation anesthetic agent
Low MAC
Low blood solubility
NOx has a low blood/gas and high MAC. What does this mean
Fast induction, recovery
Not potent, doesn’t produce full surgical anesthesia
3 common volatile anesthetics
General properties of the three?
Isoflurane
Desflurane
Sevoflurane
Low b/g (~0.5)
Single digit MAC
Barbiturates act as CNS depressants by doing what?
Binds to GABA
Activates chloride channels
Hyperpolarizes post synaptic membrane
Provides inhibitory influence on synaptic transmission