PHARMAcology

• 3 phases of drug action: pharmaceutic, pharmacokinetics, pharmacodynamics
• disintegration - breakdown of tablet into smaller particles
• dissolution - dissolving of smaller particles in the GI fluid before absorption
• rate limiting- time it takes for a drug to disintegrate and dissolve
• pharmacokinetic phase - drug movement to achieve drug action
• 4 basic components of pharmacokinetics : absorption, distribution, metabolism, excretion
• absorption- movement of drug particles from GI tract to body fluids
• 3 types of absorption: passive, active, pinocytosis
• passive absorption - from the site of administration into bloodstream; absorbed through plasma by diffusion (movement from higher concentration to lower)
• active absorption- requires carrier like enzyme / protein
• pinocytosis- cells carry drug across membrane by engulping drug particles
• factors affecting absorption: surface area, contact time w/ surface, circulation, solubility, ionization, drug form and concentration, bioavailability, route of administration
• additives- alter location of disintegration of drugs
• enteric coating- allows drug to dissolve in alkaline pH greater than 7.0
• distribution - transport of drugs from blood to the site of action
• volume of distribution- degree of distribution of a drug into various body compartments
• factors affecting distribution: perfusion rate, permeability of membranes, protein binding, tissue localization, blood brain barrier, placenta
• metabolism- breakdown of the drug
• biotransformation- body changes the chemical structure of the drug to form metabolite
• metabolite- more water soluble compound. major organ is liver
• first pass phenomenon- first absorbed through small intestines then liver via portal circulation
• variations of metabolism: pharmacogenetics, circadian rhythms, effects of gender and age
• pharmacogenetics- hereditary influences on drug responses
• circadian rhythms- rate of drug absorption
• excretion - drugs remove from the body
• kidney- major organ of excretion
• minor organs of excretion : lungs, biliary, intestines, sweat, saliva, and breast milk
• 2 types of clearance drugs: renal clearance and hepatic clearance
• clearance of drugs- elimination of drugs from circulation by all routes
• plasma half-life- elimination half-life of a drug is a pharmacokinetic parameter; time it takes for concentration of drug in the plasma / total amount in the body to be reduced by 50%
• pharmacodynamic phase- study of mechanism of drug action on living tissues
• chemotherapeutic drugs- alter abnormal parasite or growth on the body such as bacteria, viruses
• 7 effects of drugs : therapeutic effect/ desired effect, adverse drug reaction (ADR), adverse event, side-effect, drug toxicity, drug abuse, hypersensivity/ allergies
• 5 therapeutic effects of desired effects: curative, supportive, substitutive, chemotherapeutic, and restorative
• adverse drug effect- unwanted or harmful reaction experienced. require drug to be discontinued or dose reduced
• adverse EVENT- harm occurs while pt taking drug
• side-effect - effect caused by drug whether beneficial, neutral, or harmful.
• drug toxicity- adverse effect bec. the dose / plasma concentration has risen above therapeutic range
• drug abuse- misuse of recreational or therapeutic drugs may lead to addiction or dependence
• hypersensitivity or allergies- exaggerated adverse reaction to drug