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pharmacokinetics, pharmacodynamics ppt
A science that draws on information from multiple disciplines, including: Anatomy Physiology Psychology Chemistry Microbiology - pharmacology what is the therapeutic objective of drug therapy? - provide max benefit with min harm factors that determine the intensity of drug responses - -administration -pharmacokinetics -pharmacodynamics -sources of individual variation define pharmacokinetics - the study of drug movement throughout the body what 4 things does pharmacokinetics pertain to? - -absorption -distribution -metabolism -excretion
define pharmacodynamics - study of what drugs do to the body and how they do it what 3 things does pharmacodynamics pertain to? - -receptor binding -post-receptor effects -chemical rxn example of physiologic variables - age, gender, height, weight examples of pathologic variables - diminished function of kidneys and liver how can genetic variables affect pharmacokinetics? - can alter the metabolism of drugs and predispose the patient to unique interactions the rate at and the extent to which a nutrient is absorbed and used - bioavailability drug movement from GI tract into bloodstream - drug absorption Breakdown of oral drug form into small particles - disintegration process of combining small drug particles w/ liquid to form a solution - dissolution
first pass effect name 3 absorption methods - -passive transport -active transport -pinocytosis diffusion across a membrane with no energy investment - passive transport diffusion that requires energy and carrier substance (enzyme) - active transport cell carries drug across membrane by engulfing drug particles - pinocytosis 5 factors affecting absorption - Blood circulation Pains and stress Food texture, fat, and temp pH Route of administration. how does drug move from the GI tract to the liver? - Via portal vein First pass effect Bioavailability ___% of drugs are absorbed via portal vein -
what happens to the remaining 30% of drugs that may not be absorbed via portal vein? - may be absorbed in the small intestine 5 factors affecting bioavailability - -Drug Form -Route of administration -Gastric mucosa and motility -Given with food or other drugs -Changes in liver metabolism 3 ways to distribute drugs? - -protein binding -free drugs -blood brain barrier the ability of certain drugs to bind to protein. - protein binding drugs not bound to protein - free drugs higher the protein bound drugs, the _______ the effects on the brain, hence a _________ dosage is needed - stronger; lower higher potency, _______ the effect lower potency, ________ the effect -
use of a higher dose than what is usually used for treatment to allow the drug to reach the critical concentration sooner - loading dose what determines when the steady state occurs? - half-life which organ is primarily responsible for excretion? - kidneys what are 3 functions of the kidneys? - -creatine clearance -BUN -glomerular filtration rate what are other ways drug is excreted? - -kidneys -liver (bile) -feces -lungs -saliva, sweat, breast milk how many half-lives does it take to eliminate? - 4 1/ highest concentration in plasma concentration - peak when does the peak usually take place? -
2-3 hours IV peak time - 30-60 min IM peak time - 2-4 hours indicates the lowest concentration - trough when is the trough drawn? - immediately before the next dose what happens if the peak or trough are imbalanced? - drug toxicity define: what the drug was made for (desirable response) - primary effect define: desirable or undesirable response (side effect) - secondary effect what is the drug response relationship? - the body's physiologic response to changes in drug potency define: how much drug needed for effect - potency
30-60 min after administration IM medications peak drug level time - 2-4 hours after injection the lowest plasma concentration of a drug, and it measures the rate at which the drug is eliminated - trough drug level define: most drugs produce their actions by activating or inhibiting specific cellular receptors - receptor theory name 3 reasons drugs bind to receptors: - -to activate receptor -to produce a response -to inactivate a receptor 4 receptor families -
- Cell membrane-imbedded enzymes
- Ligand-gated ion channels
- G protein-coupled receptor systems
- Transcription factors exact fit of a receptor - agonist agonistic behavior - -activate receptors -produce desired response
incomplete receptor fit - antagonists antagonistic behavior -
- prevent receptor activation
- block response specificity effects __________ selectivity effects ___________ - -organs -drugs the degree at which a drug is reactive to a particular receptor or receptors. - selectivity true or false: if the receptor takes more than one drug it is non-selective - TRUE true or false: some drugs can be both agonist and antagonists - TRUE Define drug specificity - Drug Produces only One Effect Bethanechol effect on: -heart
define: when the drug level exceeds therapeutic range - drug toxicity define: different drug effects due to genetic variations - biologic variations decrease drug responsiveness over time - tolerance Acute, rapid decrease in drug responsiveness regardless of time - tachyphylaxis Drug response not attributed to chemical drug properties - placebo effect allergic reaction, causing a widespread inflammatory response, swelling and release of fluids from the vascular system into the interstitium. - anaphylaxis altered drug effect due to interaction with another drug - drug interactions changes occurring in absorption, distribution, metabolism, and excretion - pharmacokinetic interactions sum of effects of two drugs - additive when the effect of a drug is much greater than effects of either drug alone -
synergistic when one drug reduces or blocks effect of other drug - antagonistic antagonists tend to be __________ - antidotes define: food may increase, decrease, or delay drug response - drug-nutrient interactions define: drugs may cause misinterpretation of test results - drug-laboratory interactions define: skin reaction caused by sunlight exposure - drug-induced photosensitivity
