Pharmacology Flashcards
pharmacodynamics
what a drug does to the body (biological effects and mechanism of action)
pharmacokinetics
what the body does to the drug (absorption, distribution, metabolism and excretion of drugs and their metabolism)
Absorption
drug is absorbed from the site of administration, entry into plasma
Distribution
drug reversibly leaves the bloodstream and is distributed into interstitial and intracellular fluids
metabolism
drug transformation by metabolism by the liver and other tissue
excretion
drug and/or drug metabolites excreted in urine, faeces or bile
What is a drug?
any single synthetic, or natural substance known structure used in treatment, prevention, or diagnosis of disease
How do drugs move around the body?
bulk flow (via circulatory system) or diffusion
agonist
a drug that binds to a receptor to produce a cellular response
antagonist
a drug that reduces or blocks the action of an agonist by binding to the same receptor
what does the the proportion of ionisation of a drug defend on ?
the pKa of the drug and local pH
endocytosis
transport of large drugs across the cell membrane
what do the pKa and pH look like when 50% of the drug is ionised and 50% is unionised
pH=pKa
Reaction for acids
AH—> A- + H+
Reaction for bases
BH—> B + H+
what determines the proportion of ionised and unionised drugs in a given pH environment
The Henderson- Hasselbach equation
what ways can the small molecules cross cell membrane?
Passive diffusion, facilitated diffusion, active transport, endocytosis
medicine
a chemical preparation containing one or more drugs used with the intention of causing therapeutic effect
how do drugs act?
by binding to regulatory proteins (enzymes, carrier molecules, carrier molecules, ion channels and receptors)
receptors
macromolecules on, or within the cytoplasm or in some cases in the nucleus, cells that mediate biological action of hormones, neurotransmitters and other endogenous substances.
example of agonist
adrenaline is a drug (and hormone) that binds to receptors (beta adrenoceptors) in the heart to increase cardiac rate and force
example of antagonist
beta blockers are a class of drug that bind to beta receptors in the heart to block the binding of adrenaline, they increase In the cardiac rate and force caused by adrenaline
what shape is relationship between response and agonist concentration on semi logarithmic graph
S shaped
what’s an agonist with low efficacy
a partial agonist
Drug targets in the body
enzymes, carrier molecules, ion channels, receptors, DNA and RNA
endogenous
substance within the body
exogenous
substance from outside the body
affinity
the ‘strength association’ between ligand and receptor
efficacy
the ability of the agonist to evoke a response (higher the efficacy, the larger the response)
potency
amount of drug needed to produce a given effect
relationship between agonist concentration and receptor occupancy
the higher dose given the greater concentration of agonists , meaning more receptors occupied giving a greater response
What’s EC50
the concentration of agonist that elicits half a maximal response (at which 50% of the receptors are occupied)
ED50
dose at which 50% of receptors are occupied
why is a semi logarithmic plot used
it allows a very large range of agonist concentration to be plotted conveniently. (response is plotted on y axis and is regular scale whereas the agonist concentration is plotted on a log scale on the x axis)
What can be determined from the semi logarithmic plot
EC50 and ED50
what is the response between the concentration (or dose) and agonist concentration said to be?
sigmoidal
What is potency determined by?
EC50
What is efficacy determined by?
maximum response
What’s the antagonists efficacy like
they have none
