Pharmacology 3 Flashcards
What is Pharmacodynamics?
Study of how drugs affect the body
What are the 4 major Drug targets?
Ion Channels
Receptors
Transporter proteins
Enzymes
What are 4 Major drug properties?
Selectivity
Specificity
Potency
Efficacy
What is Selectivity?
Describe ability of a drug to bind to a particular receptor - some bind to more than 1 so low selectivity e.g a B-Blocker propranolol
What is Drug Specificity?
Refers to how drugs interact with a receptor when bound - specific ligands called ligand specificity but can bind with different configurations
What is Drug Potency?
Dosage of drug needed to induce an effect dependent on receptor affinity
What will a drug with Low affinity do?
Weakly bind to a receptor and readily disassociate from it, large doses to induce effect
What will a drug with High affinity do?
Bind strongly to a receptor and stay bound giving rise to large physiological response
What is Drug Efficacy?
Ability of drug to induce an effect - full agonists and partial agonists effect (therapeutic effect)
How is Potency and Efficacy studied?
Dose response curves with organ bath experiments
How does Dose Response Curve work?
Measure tissue response (force of contractions) to treatment with increasing drug concentration until Emax reached, converted and then plotted - sigmoidal curve
How to Determine Potency and Efficacy from a Dose response curve?
2 values important, maximal response of the drug and EC50 (drug conc 50%)
What is a Quantal response?
All or Nothing response - taking sample of population and determine dose at which drug is effective - histogram for median
How can Toxic effects be in terms?
Median Lethal dose LD50 or Medial toxic dose TD50
What is Therapeutic dose?
Produces a therapeutic effect in half or treated median effected dose ED50 , can calculate therapeutic index
What are 5 Main Mechanisms for Drug Antagonism?
Chemical Receptor Non-competitive Pharmacokinetic Physiological
What is Receptor Antagonism?
Describes blockade of receptor by a drug molecule, no efficacy but have an affinity compete for receptor site
What does High/Low affinity lead to?
Low - reversible competitive
High - irreversible competitive
What does Non-competitive Antagonist do?
Drug binds to an Allosteric site on receptor and prevent activation - converts to partial and activate signalling pathways
What is Pharmacokinetic Antagonism?
Acts to increase clearance, reduce plasma concentrations that effect half life of drug
What is Physiological Antagonism?
Interaction between 2 drugs that initiate opposing effects via different receptors
What is tolerance?
Maintenance of drug response requiring increasing doses
What is tolerance caused by?
Pharmacokinetic - metabolism of drug
Pharmacodynamic - Down regulation of receptors
What is cross tolerance?
Repeated use of a drug effects the therapeutic function of another drug
