Pharmacology Flashcards
The study of drugs that interact with the human body is defined as:
Pharmacology
Define pharmacodynamics
What a drug does to the body
Define Pharmacokinetics
What the body does to a drug
What are examples of pharmacodynamics?
Biological effects and mechanism of action
What are examples of pharmacokinetics?
Absorption, distribution, metabolism and excretion of drug and their metabolites
What must a drug act with in order to be useful as a therapeutic agent?
A degree of selectivity
In which group of individuals is polypharmacy most common?
Elderly patients
What do drugs bind to?
Target molecules
What two factors is selectivity a result of?
- Binding site specificity
- Ligand specificity
Define an agonist
A drug that activates a receptor and causes a response
Give an example of an agonist
Acetylcholine
Define an antagonist
A drug that combines with a receptor but does not activate it. It blocks the action of the agonist by binding to the same receptor.
What two qualities to agonists posses
Affinity and efficacy
Define affinity
Strength of association between ligand and receptor
If an agonist possesses low affinity for the receptor, how will the dissociation rate present?
Fast dissociation rate
If an agonist possesses a medium affinity for the receptor, how will the dissociation rate present?
Moderate dissociation rate
If an agonist possesses a high affinity for the receptor, how will the dissociation rate present?
Slow dissociation rate
Define dissociation rate
The rate at which a ligand dissociates from a receptor/protein
Define efficacy
The ability of an agonist to evoke a cellular response
What do antagonists lack?
Efficacy
What do antagonists posses?
Affinity
At what level of agonist concentration would there most likely be 100% receptor occupancy?
High concentration
How would you describe the relationship between agonist concentration and response in a linear plot?
Hyperbolic
What is the meaning of EC50 when plotted on a graph?
It is the concentration of agonist that elicits a half maximal response
How would you describe the relationship between agonist concentration and response on a semi-logarithmic plot?
Sigmoidal
The binding of an agonist and antagonist at the same site where they have to compete is termed…
Competitive antagonism
The binding of an agonist to an orthosteric site and an antagonist to a seperate allosteric site is termed…
Non-competitive antagonism
The process by which a drug enters the body from it sight of administration and enters the general circulation
Absorption
The transport of a drug by the general circulation
Distribution
The process by which tissue enzymes (principally those in the liver) catalyse the chemical conversion of a frequently lipid soluble drug to an often less active and more polar form that’s more readily excreted from the body
Metabolism
The process that removes the drugs from the body (principally occurs in the kidneys)
Excretion
Metabolism and excretion as a pair can be referred to as?
Elimination
What are the phsyicochemical factors that control drug absorption?
- solubility
- chemical stability
- lipid to water partition coefficient
- degree of ionisation
A drug must dissolve in order to be absorbed. True or false?
True
What happens to the rate of diffusion when lipid solubility increases?
It increases
Only charged forms of drug can readily diffuse across the lipid layer. True or false?
False. Only UNCHARGED forms of drug can readily diffuse across the lipid layer.
What does degree of ionisation depend upon?
The pKa of the drug and local pH
Define pKa
PH at which 50% of drug us ionised and 50% unionised
What type of acid and base is week absorbed?
Weak acids and bases
What are some factors that affect GI absorption?
- GI motility
- pH at absorption site
- blood flow to stomach and intestines
- drug manufacture
- Physicochemical interactions
- presence of transporters in membranes of epithelial cells that facilitate drug absorption
Fraction of drug that reaches systemic circulation after oral ingestion, is known as?
Oral availability
The fraction of a drug that reaches the systemic circulation after absorption is known as?
Systemic availability
Define enteral
Via the GI tract
Define parenteral
A route that is not via GI tract
