Wayne Hodgson; Week 3 MED1011; Pharmacology
A drug is a substance biologically active in small quantities, is also administered to give a desired physiological or psychological effect. Drugs have chemical names, non-proprietary/generic names and proprietary/trade names.
Drugs act on receptors that can be specific or selective for tissue/receptor. Targets are usually proteins, such as receptors (nicotinic, muscarinic, a-adrenoreceptor), ion channels (calcium channels), enzymes (acetylcholinesterase, COX), carriers/transporters (noradrenaline/serotonin transporters).
Pharmacokinetic properties (what drug does to the body) are size of molecule, charge, lipid solubility. Pharmacodynamic properties (what body does to drug) are how the drug binds to the target site, and how binding translates to a biological effect. Pharmaceutical phase > pharmacokinetic phase > pharmacodynamic phase.
Drug receptor interactions have a binding affinity, dependant on Kd of drug d.(dissociation constant can be negative for drug/receptor compound or positive). Is the force of attraction between the two.
Dose-response relationship concepts are affinity, efficacy, agonist and partial agonist, antagonism (competitive/non-competitive, chemical, pharmacokinetic). Affinity is ability of drug to bind to its receptor, efficacy is the relationship between receptor occupancy and response. Potency is proportional to efficacy and affinity. Agonists have both efficacy and affinity at target site.
Concentration response curves have the effect/response on the y-axis and the concentration on the x-axis.They are logarithmic concentration response curves.
Antagonists have no efficacy. Can be competitive, non-competitive, irreversible, reversible.
Some drugs do not provide effects through receptors, instead have osmotic effects, pH changes, physical and chemical properties, disruption of cells.