Lecture 15 Flashcards
What questions does pharmacology try to awnser?
the mechanism of action of the drug, is the drug toxic?, how is it metabolized? Etc.
What is toxicology? What questions do they awnser?
Toxicology is the study of the adverse effects of drugs/chemicals on biological systems (including non humans). It tries to awnser the mechanism of action of the chemical, how it can be treated and how it can be avoided.
What are drugs? How do they act and give examples of receptors
A drug is a chemical substance used in the, treatment, cure, prevent, diagnosis of disease or used to otherwise enhance physical or mental well-being.
They act by reacting with specific receptors (typically proteins) within the body to form a drug-receptor complex, this will generate the biological response (via conformational change to the receptor activating it), this is known as receptor theory and examples are ligand gated ion channels, G protein-coupled receptors, nuclear receptors, enzymes, DNA and more
What is the difference between an agonist and antagonist?
An agonist is a durg on endogenous (naturally found inside us) ligand that binds to the receptor and induces an effect. An antagonist is a drug that binds to the receptor but doesn’t induce an effect (no shape change), this prevents an agonist from inducing an effect.
How do ligand-gated ion channels (ionotropic receptors) work?
Ligand gated ion channels provide a means for the ions to pass through the cell membrane. They are receptors which consist of 5 subunit proteins which get together to form a channel on the cellular membrane, when there is nothing bound to this channel no ion can pass, when an agonist binds it changes the shape enough that the ions can now flow through following the concentration and electricaal gradient and changing the physiology of the cell (e.g starting action potentials).
They have a timescale of milliseconds and examples are nicotinic and acetylcholine receptors.
Cl- is hyperpolarisation, Na+ is depolarisation.
What is an example of an agonist for an ion channel agonist?
Nicorette (active drug being nicotine), is taken to relieve symptoms of craving and withdrawel caused by smoking, it acts on nicotinic receptors that normally respond to acetylcholine(nicotine is ten times more potent than acetylcholine, leading to pleasure and reward feelings, leading to the addiction).
How does nicorette help stop smoking addiction?
There is a pleasure/reward pathway in the brain, these are typically relatively low without outside input, following a natural high this pathway acts far more, nicotine highjacks this and activates it really heavily, to counteract this the brain reduces the effectiveness of this pathway and hence withdrawel results if the nicotine is stopped. nicorette activates a little bit of the pathway (lower concentration of nicotine than smoking), just enough to stop the withdrawl but not enough to lead to addiction.
Absorption of nicotine via the lungs is faster than via the liver.
