Pharmacology Flashcards
Pharmacodynamics
What a drug does to an organism; the sum of all the actions of a drug.
Pharmacodynamics
What the organism does to the drug. Absorption, distribution, metabolism, and excretion.
Concentration Response Curve
Curve which shows the relationship between drug concentration and percentage response to that drug.
Emax (CR Curve)
The maximum effect that a drug can produce (top of the curve). e.g. 70bmp
EC50 (CR Curve)
Concentration of the drug that causes a 50% of the maximum response.
Relationship between drug-receptor affinity and Kd
Kd is the molar concentration of a drug required to occupy 50% of the receptors at equilibrium. The lower the kd, the more affinity a drug will have for its receptor.
How agonists work.
Unlike antagonists, they can have efficacy; they don’t just occupy space. They change the conformation of the receptor structure to alter function.
Partial Agonists vs Full Agonists
Partial: low efficacy (even if they bind to all the receptors they will not have a maximum response)
Full: high efficacy (produce a maximum response without binding to all of the receptors available.
Effect of antagonist on agonist concentration-response curve.
Causes curve to shift to the right -> because there is an antagonist present, it takes more of the agonist to achieve the same effect.
What is pA2
Measure of the affinity of the antagonist. The negative logarithm of the molar concentration of antagonist that necessitates that you double the agonist concentration to produce the same response. The bigger, the more affinity.
Half Life of a drug
Time taken for plasma concentration to fall by half
Elimination rate constant k
Rate at which drug is being excreted.
Equation relating half life and elimination constant k
T1/2= .693/k
What the body does to a drug
Absorption (solubility and pH dependent) Distribution (how much of it actually gets into the solution) Metabolism (oxidation and conjugation to make more water soluble) Excretion (renal, liver and metabolic clearance)
Bioavailability
Fraction of unchanged drug reaching the systemic cicrulation
Phases of drug trial (0 to III)
Phase 0: sub-therapeutic doses in healthy human subjects Phase 1: finding the therapeutic dose using health volunteers Phase 2: testing effectiveness in small amounts of patients Phase 3: testing side effect, effectiveness and comparing to other available drugs in a large amount of patients.
Effect of irreversible competitive antagonist on the response agonist curve
Reaction is not surmountable
