Lecture 2(b): Pharmacodynamics, How Drugs Act Flashcards
What is pharmacodynamics?
The study of the biochemical and physiological effects of drugs and the mechanisms of drug action and the relationship between drug concentration and effect
What is the coupling process between drug and receptor? what are drugs called in the scenario? important consideration?
Ligand - drug or neuroT, anything that will bind to a receptor
L + R = L.R
Combination is not perfect key and hole - will bind to wherever is most attractive
What are the characteristics of receptors? How many coils/how many coils in a protein?
Membrane-spanning protein, binding sites for endogenous NTs and drug molecules
Composed of 7 or 12 alpha helical coils, (NTs and drug binds within TM coils held by ionic forces) 4 coils (m1,2,3,4) come together to form a protein
Describe how receptors undergo the binding process? what is the resulting response?
Reversible binding activates receptor causing conformational change, intensity of signal determined by number of percentage of drug-receptor interaction, NT’s and drugs interact with binding site on receptor or to a nearby site
Initiate cellular response similar to that of NT (agonist) - doing exact same thing as a normal neurot (copies effect)
1. binding to nearby site which facilitates NT (also agonist)
Blocks normal NT binding site (antagonist)
What are the different receptor proteins? explain their functions
Ion channel receptors - central channel forms a pore, NT/drug will open a pore (ex: GABAa receptor - not just one key/drug is accepted)
carrier proteins - transports small organic molecules (NTs), requires energy/active process, terminates NT action
g protein-coupled receptor- found on postsynaptic side, induces release of intracellular (g protein), controls enzymatic activity on postsynap side
enzymes - ase, the off, regulate breakdown of NTs, drug interaction can increase/decrease activity
What are acetylcholine esterase and monoamine oxidase?
Acetylcholine esterase - ACh (synaptic cleft): AChE inhibitors prevent breakdown of NT, found in insecticides, nerve gas
Monoamine oxidase - NE/DA presynaptic, MAOIs (inhibits) = antidepressants
What does chronic exposure to a drug lead to?
Down regulation or desensitization - body attempting to prevent how many cells can activate (like tolerance)
Up-regulation or increased sensitivity - heightened feelings/drugs affects
What is the dose-response relationship? the dose-response curve (3 measures vs)
- Quantified drug-receptor interactions, data used to create drug-response curves
- Potency - absolute # of drug molecules required to elicit a response, Efficacy - max effect obtainable, Variability - individual differences in drug response
In speaking of drug responsiveness, what is the effective dose and lethal dose?
MATH ALERT
If E = 54 and L = 85 what is the therapeutic index?
ED50 - effective dose, provides therapeutic response in 50% pop
LD50 - lethal dose, dose required to kill 50% pop tested
What is a placebo effect? how does it work? why increase?
ny medical procedure/agent that produces an effect in a patient because of its therapeutic intent and not its specific nature, whether chemical or physical
Patient reports therapeutic effect
Administered via single-blind and double-blind protocols
Not simply a psychological phenomenon - indirect physiological responses influences biomarkers (endogenous opioids), may reduce anxiety, lowers stress response
Possible release of endogenous opioids (fMRI data)
Faith in healthcare system, access to way more info regarding health = ability to diagnose has improved, because of awareness, patients are more psychosomatic
