Pharmacokinetics/Pharmacodynamics Flashcards
toxicology
the study of adverse effects of drugs and other chemicals
3 properties of an ideal drug
effectiveness, safety and selectivity
Therapeutic uses of a drug
prevention, diagnosis, cure and symptom relief
Pharmacokinetics
the study of the action of the drugs in the body so its “what the body does to the drug”
Pharmacodynamics
the study of the biochemical and physiologic effects of drugs on the function of living organisms and of their component parts
-“what the drug does to the body”
4 properties of Pharmacokinetics
Absorption, Distribution, Biotransformation (metabolism) and Excretion
Pharmacokinetics: Absorption
1st property, it is the movement of the drug, how fast the med is dissolved and distributed
Pharmacokinetics: Distribution
2nd property, plasma to the tissue
Pharmacokinetics: Biotransformation (metabolism)
3rd property, enzymatic mediated alteration of a drug, med is broken down and metabolized, chemical inactivation can occur
Pharmacokinetics: Excretion
4th property, movement of drug out of body
bioavilability
how much of the drug that is administered reaches its site of action
chemical equivalence
contain the same amount of the identical chemical compound (drug)
bioequivalence
comparing 2 different drugs to see if they contain same ingredients, are identical in strength, have same rate and extent of bioavailability
duration of action beginning and ending
begins at the onset of action and ends at the termination of effect
Therapeutic range is inbetween what?
the minimum effective concentration and the toxic concentration
which factors affect absorption?
drug characteristics, route of administration, blood flow, cell membranes
lipid soluble absorbed fast or slow?
fast
distribution is determined by 3 factors
1) blood flow to the tissues
2) exiting the vascular system
3) entering the cells
which types of ways can the drug exit the vascular system?
capillary beds
blood-brain barrier
placental drug transfer
protein binding
which factors determine the ability of a drug to cross the cell membrane?
lipid solubility, presence of a transport system
where does Biotransformation (metabolism) occur mostly?
in the liver
P450 system is produced by and what is it?
liver, composed of 12 enzyme families
CYP1, CYP2, CYP3 do what and what are they?
they metabolize drugs, they are apart of the P450 system that is produced by the liver
which enzyme metabolizes approx 50% of all drugs?
CYP3A4
Therapeutic consequences of drug metabolism?
accelerated renal excretion of drugs, drug inactivation, increased therapeutic action, activation of prodrugs, increased/decreased toxicity
inducers
increase rate of metabolism
inhibitors
decrease the rate of metabolism
Biotransformation: first pass effect
meds taken orally pass from the intestine directly to the liver by way of hepatic portal blood flow
how does the liver excrete?
bile
which organ excretes the most?
kidneys
how can some drug escape elimination and become reabsorbed?
they escape by distal tubular reabsorption
do plasma drug levels determine drug concentration at the site of action?
rarely
plasma levels defined
the minimum effective concentration and toxic concentration, therapeutic effect is in between these
what determines a drugs dosing interval?
drug half life
half life
the time required for the amount of drugs in the body to decrease by 50%
what effects half life?
volume distribution, clearance
how many half lives does it take to reach a steady state concentration in the body?
4-5 half lives
once a steady state is reached, any change upward or downward will require how many half lives until a new steady state is achieved and how long will it take until the drug is eliminated once it is stopped?
4-5 half lives
dose-response relationships determine
minimal/maximal amount of drug needed to elicit a response
potency of a drug
the drug activity measured in terms of the dose required to produce a particular effect.
if you increase activity at a decreased dose what will happen to the potency of the drug?
increase
do efficacy and relative potency relay on eachother?
no
efficacy of a drug
maximal effect produced by a drug (effectiveness)
intrinsic activity
the ability of a drug to activate a receptor upon binding
which drugs do not produce intrinsic activity?
antagonist
agonist
activate receptors
hormones, neurotransmitters and other endogenous regulators activate the receptors to which they bind. These are considered which kind of drugs?
agonist
what kind of affinity (relationship) do agonists have and what kind of intrinsic activity?
high affinity (fits receptors wells) and high intrinsic activity
what kind of affinity (relationship) do antagonists have and what kind of intrinsic activity?
high affinity (fits receptors well) and no intrinsic factor (does not activate the receptor)
antagonist
prevents receptor activation by other drugs (blocks them)
partial agonist
act as agonists and antagonist
what kind of affinity (relationship) do partial agonists have and what kind of intrinsic activity?
fit receptor site , has some affinity and has low intrinsic activity
