Flashcards in Pharm Qiz 2 Deck (23):
What is the only volatile agent that is not a racemic mixture?
Low dose for expected results. O.5mg versed makes the patient blue for example(BIG REACTION TO SMALL DOSE)
Allergic reaction to a drug
Large dose for expected results, 380 mg dilaudid
hypo-reactivity secondary to chronic exposure
Define cross tolerance
hypo-reactivity between drugs of different classes, for example ether or alcohol, propofol and alcohol both affect GABA so it might take more drug to achieve the effect.
hypo-reactivity with only a few drug doses, the first time one receives fentanyl its the best it will ever be
Three ways one develops tolerance
1. cellular tolerance, neuronal adaptation(crack smoker having neuro changes)
2. Enzyme induction(drinks alcohol everyday)
3. Neurotransmitter depletion(big coffee drinkers deplete their catecholamine stores, so it would take more catecholamine support for them
hypo-reactivity due to the formation of antibodies
unusual drug effects in small percentage of patients regardless of dose
Define additive effects
2 drugs together have total effects of each drug added together, 1/2 mac Des + 1/2 mac of N20 = 1 mac
Define synergistic effect?
2 drugs interact to have effect greater than each effect if drug was given alone, 1/2 mac drug "a" + 1.2 mac drug "b" = 2 mac
Define agonist in relation to a drug effect
binds to receptor and activates, there is a conformational change at the receptor site
Define antagonist as related to a drug receptor
drug binds but does not activate or generate a response
What are two types of antagonist?
2. non competitive
Explain competitive antagonist
agonist can replace the antagonist on the receptor site, it takes greater does of antagonist to prevent being swept off the receptor site by the agonist
Explain noncompetative antagonist
Irreversible binding, large doses of agonist can't overcome the antagonist on the receptor site
In the two compartment model of pharmokinetics what happens?
Drug is administered IV into the central compartment, distributes to the peripheral compartment, and then returns to the central compartment for clearance
Define the central compartment
1. intravascular fluid
2. highly perfused tissue(heart, lung, brain,kidneys and liver)
3. 75% of cardiac output but only 10% of the blood mass
Define peripheral compartment
Everything else, majority of body weight, minority of cardiac output
-theoretical calculated volume
-rate of drug transfer from central compartment to peripheral compartment can vary with age
-peripheral drug compartment can exaggerate repeated drug doses
What do log graphs show concerning decreases in drug plasma versus time after IV bolus?
alpha shows distribution with a rapid fall off of concentration, while beta elimination will show a more slow decline
What is elimination 1/2 time?
-most common method of describing a drugs pharmakinetic behavior
-its the time necessary for the plasma concentration to decrease by half
-Inversely proportional to clearance
-5 elimination1/2 times necessary for 97% clearance of a drug