Flashcards in Pharmacology Deck (52):
What is Pharmacodynamics
What a drug does to the BODY
What is Pharmacokinetics
What your BODY does to a DRUG
What is an agonist?
Drug that binds to a receptor to produce a cellular response.
E.g - Adrenaline to B1 receptors in the heart
What is affinity?
The strength of association between ligand and receptor
What is efficacy?
The ability of an agonist to produce a response
What is an antagonist?
Drug that blocks the binding of an agonist
An antagonist possess affinity and efficacy
Possess affinity but NOT efficacy
A competitive antagonist binds to the same/different site as an agonist
A non-competitive antagonist binds to the ______ site
Ligand Gated Ion Channels are made of ________ subunits
Ligand Gated Ion Channels allow for rapid/slow movement of ions
How many times does a G Protein Coupled Receptor span a membrane?
How many polypeptide subunits is a G protein made up of?
Describe the mechanism of action of G-protein
Receptor binds to GPCR, G-protein couples with receptor and GDP dissociates to form GTP, G protein dissociated into alpha and By subunits and alpha subunit combines with effector producing a cellular response
Gs alpha subunit activates/deactivates adenylyl cyclase to activate the cAMP pathway
cAMP activates _____
Protein Kinase A
What are the 4 fates of drugs in the body
Absorption is ....
Process by which a drug enters the body
Distribution is ....
Transfer of drug from systemic circulation to tissues
Metabolism is ....
Polarisation of drugs (mainly by liver) to be prepared for excretion
Removal of drugs from the body
Name the 4 factors affecting drug absorption
Lipid to water partition coefficient
Degree of ionisation
Solubility is .....
How well a drug dissolves
Chemical Stability is ....
Structural integrity of the drug (may be destroyed by stomach acid)
Lipid to water partition coefficient is ....
Rate of diffusion of the drug increases with the rate of solubility
i.e more soluble = more diffusion
Degree of ionisation refers to ....
The fact that only unionised drugs can pass the lipid bilayer
pKa is ....
pH at which 50% of the drug is ionised and 50% is unionised
Oral availability is ....
the fraction of drug that reaches the systemic circulation after oral ingestion
Enteral routes of administration
Sublingual (under tongue)
Rectal (up the pooper shooter)
Parenteral routes of administration (6)
Drugs are evenly distributed over the body?
What is the volume of distribution (Vd)
Volume at which a drug is dissolved (Vd)
What is MEC
Minimum Effective Concentration -
Minimum concentration for a drug to be effective
What is MTC
Maximum Toxic Concentration -
Maximum concentrado before unwanted side effects
How would you calculate the therapeutic ratio
What drug has a narrow therapeutic ratio
Cardiac glycosides e.g Digoxin
Describe first order kinetics
Rate of elimination is directly proportional to the drug concentration
If clearance is high then not much of the drug is lost in the urine
If rate of elimination is high then a lot of the drug is lost in the urine
Rate of elimination = Clearance X ______ _____
Steady state means
Drug absorbed = rate of elimination
Steady state of concentration is usually achieved after _ half lives
At what rate are drugs eliminated at in ZERO order kinetics
Constant rate (drug elimination not proportional to concentration)
What does drug metabolism do?
Makes drugs polar (less active)
Where does most drug metabolism occur?
What happens in phase 2 of drug metabolism by the liver?
Conjugation (increasing polarity) and addition of an endogenous compound
Drugs that pass first pass metabolism are excreted quicker/slower than the parent compound
How are most drugs filtered
Drugs bound to proteins cannot easily be filtered by glomerular filtration
What are the two systems of active tubular secretion?
Organic anion transporter (acids)
Organic cation transporter (bases)
What can active tubular secretion do that glomerular filtration cannot?
Secrete drugs that are protein bound
What percentage of water filtered by glomerular filtration is reabsorbed?