Pharmacology Flashcards
define saturable binding
all the sites of a receptor can be filled with drugs, finite binding sites. when all sites are filled, there is no further response
how is total binding defined
by high affinity and low affinity binding sites and a non-specific linear component partition. High affinity shows sharp binding.
On rate K on versus off rate K off
Kon-2nd order rate at which drug binds to receptor, dependent on concentration
Off rate-First order rate at which drug unbinds, not dependent on concentration
How is half life affected if clearance increases or decreases or distribution volume
Half life is increased by an increase in the volume of distribution and increased by a decrease in the rate of clearance
parameters of pharmacokinetics/ what governs the concentration of drugs in the plasma
bioavailability(area under the curve)
distribution volume
halflife
clearance
concentratio of drug at plasma is used to show conc of drug at receptor
true. Plasma concentration can be easily measured
Define bioavailability
How much of the drug taken up by the body reaches the plasma, area under the curve
A drug applied directly into the bloodstream by IV has 100%bioavailability. True/false
true. all the amount of the drug enters the plasma
What is the area under the curve
integral of plasma concentration over time. Relates amount of drug Q to the clearance Cl
Peak of curve shows max concentration at tmax
Hepatic First pass efffect
reduces bioavailability of the drug eg a pill administered goes through absorption in the intestines, metabolism in the liver by biotransformation enzymes, elimination in the gall bladder before going into the plasma/systemic circulation
What does the rea under the curve compare
different routes of administraation eg iv versus pill
Different drugs. drug A and B
How do you reach steady state
when clearance equates the amount of drug you’re applying
4 waters in distribution volume
interstitial water plasma water transcellular water intracellular water deep fatty layer. clearnace occurs when drug is unbound
Elimination time constant is the slope in the semilogarithmic scale
Total clearance divided by distribution volume. The bigger the distribution volume eg into deeper compartments, the longer it takes for the elimination of the drug to be complete. The faster the clearance the faster the elimination of the drug.
amount/initial concentration gives
distribution volume.
