pharmacology Flashcards
what is pharmocology
the study of drugs
Structure, targets, and mechanisms of action
Distribution in and handling by the body
Effects on the body, including desirable responses
what is pharmacokinetics
what the body does to the drug
what are the main stages of pharmacokinetics
administraction
absorption
first pass metabolism
distribution
metabolism
inhibition and induction
excretion
what are the methods administration of drugs
- oral
- injection
- inhilation
- sublingual or buccal
- rectal
- epithelial surfaces
what is the absorption of a drug
- process of transfer of the drug from the site of administration into the general circulation
- influences the access to the systemic circulation
what is the distribution of a drug
a compound is transferred from the general circulation to other parts of the body and into the tissues
what is first pass metabolism
a drug gets metabolized at a specific location in the body that results in a reduced concentration of the active drug upon reaching its site of action or the systemic circulation
what is excretion of a drug
the process by which drugs or their metabolites are removed from the body
what are the methods of excretion of drugs
- renal
- biliary
- respiratory
- dermal
- faecal
what is pharmacodynamics
what the drug does to the body
what is a theraputic effect of a drug
intended biological effect
what is a side effect
Undesirable secondary effect - occurs in addition to the desired therapeutic effect
what is the administration of a drug that produces a side effect
Administration of a drug or combination of drugs under normal conditions / dose
what do side effect occur
interacts with same type of receptor at different sites around the body
Interacts with more than one type of receptor
Most can be predictable by knowing the pharmacology of the drug
What is an adverse effect
harmful reaction
what is the administration of a drug that causes an adverse effect
Administration of a drug or combination of drugs under normal conditions of use
what is a toxic effect
Deleterious, undesired effect; following administration of a higher dose of the drug
what are the molecular mechanisms of action on a receptor
(Direct physicochemical effect)
Transport systems
Enzymes
Interaction with the 4 major types of receptors
what is the direct physiochemical effect
dont need to bind to a receptor
- bulk forming laxatives
- antacids
- osmotic diurects
how can drugs inhibit an enzyme
- Binding to the active site – enzyme not able to bind to substrate
- Binding to another site in the enzyme, changing its conformation – enzyme not able to bind to substrate
what are the 4 major types of receptors
ligand-gated ion channels
g protein-coupled receptors
kinase-linked receptors
nuclear receptors
what is the speeds of the 4 receptors
ligand-gated ion channels- milliseconds
g protein-coupled receptors- seconds
kinase-linked receptors-hours
nuclear receptors-hours
what is a receptor
A protein molecule on the surface / inside the cell
A protein recognition molecule for a chemical mediator
A molecule on the surface of a cell (or inside it) that receives an external signal and produces some type of cellular response
what is the drug-receptor interaction
A drug can change the amplitude and speed of body functions
A drug modulate intrinsic physiological functions
what is an agonist
Bind and simulate physiological regulatory effects of endogenous compounds
what is a partal agonist
an agonist which is unable to induce maximal activation of a receptor population, regardless of the amount of drug applied
what is an antagonist
Bind but do not have regulatory effects and prevent the binding of the endogenous compounds
what is a competitive antagonist
binds to the same site as the agonist but does not activate it, thus blocks the agonist’s action
what is a non-competitive antagonist
binds to an allosteric (non-agonist) site on the receptor to prevent activation of the receptor
what is an irreversible antagonist
Binds irreversibly to the receptor (but interacts with same part of the receptor)
what are the types of non-competitive antagonist
irreversible and allosteric effect
what is the allosteric effect of anantagonist
Interacts with a different part of the receptor
what kind of antagnomism is this
resersible competitive antagonism
what kind of antagonism is this
irreversible competitive antanonism
what is functional/ physiological antagonism
Drugs that have opposing physiological actions at different receptors
what is chemcal antagonism
Binds to and inactivates the agonist (not the receptor)
what is the two-state model of ligand binding theory
Receptors can be in active (constitutive activity) or inactive states
what is an inverse agonist
inverse agonists bind with active receptors, and move them towards the inactive state
what is the mechanism for inverse agonists
Inverse agonists bind to a receptor and stabilize it in its inactive conformation. So unlike full or partial agonists, they decrease receptor activity.
what is drug selectvity
drug’s ability to bind to particular receptor, types or subtypes
what is Desensitisation or Tachyphylaxis
effect of a drug gradually diminishes when it is given continuously or repeatedly
what is tolerance
a more gradual decrease in responsiveness to a drug
what are Drug-Receptor mechanisms
Change in receptors
Translocation of receptors
what is the drug response relationship
A measure of drug activity expressed in terms of the amount required to produce an effect of given intensity
what is the measure of potency of the drug
A measure of potency: half maximal effective concentration (EC50)
In vivo, what is an ED50 (half maximal effective dose)
The concentration of a drug, antibody or toxicant which induces a response halfway between the baseline and maximum after a specified exposure time
what is cmax
is the maximum (or peak) serum concentration that a drug achieves in a specified compartment or test area of the body after the drug has been administered and before the administration of a second dose
what is tmax
The time it takes for a drug to reach the maximum concentration (Cmax) after administration of a drug that needs to be absorbed
what is the half life of a drug
Time for plasma drug concentration to reduce by half
Useful to know time taken to reach steady state and time required for drug elimination
what is EC50 and ED50
EC50 (half maximal effect in an individual) / ED50 (50% subjects respond to a drug)
what is TD50
toxic dose
what is LD50
lethal dose
what is the theraputic window
The range of drug concentrations within which the drug exhibits maximum efficacy (desired effect) and minimum toxicity in the majority of patients
what is the theraputic index
how the theraputic window is quantified
what is the equation for theraputic index
TI= TD50/ED50
what is the toxic region
adverse effects of drug apparent at the concentrations
what is the subtheraputic wregion
drug concentrations too low for optimal effects
what does a large theraputic index mean
wide theraputic window
what does a small theraputic index mean
narrow theraputic window
