Pharmacokinetics and Pharmodynamics

what is pharmacology? the study of substances that interact with living systems what is toxicology? the study of undesirable effects of chemicals on living things what is pharmacy? the practice of preparation and dispensing medications what is the brand name? name of medication owned by a manufacturer, trade name what is the generic name? drug that is comparable to brand drug in dosage form, strength, route of administration, quality and performance characteristics, intended use -cost less what is the formulary? list of preferred brand name and generic medications covered by an insurance company what is pharmacokinetics? study of movement of the drug through the body What steps does a drug take as it moves absorption, distribution, metabolism, and through the body? (from input to output excretion 4) what is pharmacodynamics? study of the interactions of drugs and living tissues, the effect of the drug on the body over time -What the drug does to the body how much drug reaches the site of action, (route administered) what are the factors that determine a drug's action? (3) -how much activity is at the site of action, (tissue concentration) -possible interactions with other drugs or foods 1/8 what is absorption? passage of drug across cell membranes and into blood what factors affect absorption? - dosage form - blood flow to absorption site -contact time -solubility/permeability, pH what is diffusion? crossing membrane from high to low concentration where are acidic drugs absorbed? in the stomach where are basic drugs absorbed? in the small intestine what are the factors that affect GI absorption? GI mobility gut pH, GI surface area, blood flow, presence/absence of foods and -other meds =drug compensation what are the routes of administration? enteral and parenteral what are enteral drugs? Drugs which enter the GI tract -PO -SL -PR what are parenteral drugs? drugs that bypass the digestive system entirely -IV -IM -SQ/SC -Topical -Transdermal what does the route of administration depend on? patient, drug and situation what are the advantages of oral medications? cheap, "easy", simple to take 2/8 possible destruction from stomach acid, what are the disadvantages of oral medfirst pass effect, may not be tolerated if ications? patients are nauseated or vomiting taken under the tongue, rapid absorption, bypasses the stomach, no first pass effect what are the advantages of sublingual drugs? what are the disadvantages of sublingual drug must be highly lipid soluble, limited drugs? availability rapid absorption, better tolerated in pawhat are the advantages of per rectum tients who are nauseated or vomiting, no drugs? pass effect what are the disadvantages of per rec- patients don't like them, must be highly tum drugs? lipid soluble very fast effect, no barriers to absorption, what are the advantages of intravenous close control of blood levels, little variadrugs? tion of effect overdose is difficult to counteract, pain at IV site, potential tissue damage, requires skilled care for administration what are the disadvantages of IV? what are the advantages of intramuscu- rapid absorption, sustained release poslar drugs? sible slow absorption if improperly injected what are the disadvantages of intramusinto adipose tissue, pain at site of injeccular drugs? tion what are the advantages of subcutaneous drugs? rapid absorption, sustained release possible what are the disadvantages of subcuta- pain at injection site, lipodystrophy (dentneous drugs? ing in tissue due to repetitive injections) what are the advantages of topical drugs? direct delivery to affected areas, minimizes systemic side effects what are the disadvantages of topical drugs? local irritation, can be messy, rub in completely for absorption what are the advantages of transdermal drugs? 3/8 achieve systemic efficacy by application to skin, can by used by patients who are NPO, sustained release possible drug must be highly lipid soluble, dose what are the disadvantages of transdervariability, adhesive can cause irritation, mal drugs? adhesive can peel off prematurely clearance, volume of distribution, what are the parameters of pharmokinethalf-life, protein binding and bioavailabilics? ity what is clearance? the rate at which a drug is removed from the body, volume per unit time what are the main elimination points for a drug? mainly kidneys, lungs, intestines what is the volume of distribution? hypothetical estimate of drug distribution in the body, amount of drug in plasma, interstitial fluid, intracellular fluid that the drug is evenly distributed and what does the volume of distribution as- that metabolism or elimination has not sume and why is this an issue? taken place, this does not correspond to any real volume what does volume of distribution depend route, rate of blood flow, tissue permeon? ability, protein binding ability what are the special considerations for loading dose, boluses, elderly and obese volume of distribution? single large dose that rapidly attains therapeutic levels, creates steady state what is the loading dose? when can the loading dose be toxic? if it is too high what is a bolus? subsequent loading dose what is half life? amount of time it takes for 50% of a drug to be eliminated from the body 4/8 what does the half life depend on? clearance and volume of distribution what can longer half lives lead to? increased systemic side effects how many half lives does it take to totally eliminate the drugs? approx. 4-5 proportion of administered drug that reaches circulation what is bioavailability? what route of administration drugs are considered to be 100% bioavailable? intravenous drugs because they're administered directly into the bloodstream why aren't other routes of administration considered to be 100% bioavailable? they lose some drug molecules in absorption, reducing bioavailability what is drug metabolism? chemical alteration of a drug where does drug metabolism mainly occur? in the liver and small intestine what is the first pass effect? process by which a drug passes from the GI tract to the liver for breakdown before systemic distribution what does drug metabolism involve? enzymes bio-transforms active part of drug to inwhat do the enzymes do to the drugs? active by making the drug more water soluble and easier to excrete via kidneys what are examples of enzymes involved in drug metabolism? cytochrome P450 what route of administration drugs are subject to first pass effect? oral what happens when a drug has a large very little drug reaches systemic circulafirst pass? tion what is cytochrome P450? important liver enzyme, 6 isoenzymes in this system 5/8 alters metabolism/clearance of other what happens if a drug/food induces or medications, toxicity and reduced efficainhibits this cytochrome P450 system? cy what are the major inhibitors of cytochrome P450? PPIs, cimetidine, antidepressants, antifungals, antivirals, cholesterol medications and grapefruit juice what is the affect of grapefruit juice on cytochrome P450? inhibits the system which increases serum concentrations of meds that use CP450, can make other drug levels toxic what is drug excretion? removal of drug from the body how are drugs excreted from the body? lungs, urine, feces, saliva, breast milk but importantly kidneys why is it important to know that kidneys providers need to consider kidney funcare the main way that drugs are excreted tion when prescribing medications from the body? what is creatine clearance? indicator of glomerular filtration rate (GFR) and kidney function, mL/min what is the formula for creatine clearance? rate of excretion into urine/serum concentration what happens to creatine clearance as someone ages? it decreases, drugs may accumulate how can drugs produce effects? chemical alteration of body fluids, chemical alterations of cell membranes, drug-receptor interactions and drug-enzyme interactions what are receptors? cellular sites with which a drug can interact to produce a biological response what are the receptor responses? agonists and antagonists what is an agonist? drug that binds to receipt and produces effects by stimulating receptor what is an antagonist? blocks or reverses the effect of agonists, have no effect of their own, competes with agonist for receptor sites 6/8 what is the dose response curve? used to determine both the therapeutic dose and the dose that will result in undesirable effects what is efficacy? maximum response a drug can produce what is potency? dose that is required to produce a response, often expressed as dose of a drug required to achieve 50% of the desired therapeutic effect what does potency depend on? efficacy a measure of the drug safety what is the therapeutic index? what is the calculation for therapeutic index? toxic dose (TD…€)/effective dose (ED…€ a drug with a ______ TI is safer than a drug with a ______ TI higher, lower what is a peak? maximum concentration of drug in the blood what is a trough? minimum concentration in blood what do you use the peaks and troughs for? to determine if dosing is correct what is the therapeutic window? range of plasma concentrations that will elicit a desired response what is synergism? increased effect of a drug caused by a 2nd drug or food what is antagonism? blockade of drug effect by a 2nd drug or food what are predictable side effects? dose related, may or may not improve as patients continue with meds 7/8 what are toxic side effects? too much of desired actions, accumulation of drug what are unpredictable side effects? allergic reactions (anaphylaxis; urticaria, angioedema, cytotoxic, immune complex and delayed) what are secondary side effects? unwanted effects on other body systems what is pharmacoeconomics? evaluation of cost of one medication to another what was the controlled substance act of regulations set to control drug traffic, re1970? quires DEA license to prescribe where are PAs allowed to prescribe? all 50 states, including Guam and DC how many states allow PAs to prescribe controlled substances? 48 (not Kentucky or Florida) what does NYS allow PAs to prescribe? Schedule II-V drugs, have to have DEA license and electronically prescribe what is DEA schedule I? high abuse potential, no medical use, unsafe, illegal (heroin, LSD) what is DEA schedule II? high abuse potential, medical use, track use, no refills (Oxy, hydrocodone, morphine) what is DEA schedule III? less abuse potential than I or II but may still cause dependence if abused (Tylenol with codeine) what is DEA schedule IV? sleep meds, tranquilizers, can still lead to dependence (diazepam, ambien) what is DEA schedule V? limited opiate ingredients (cough suppressants with Codeine) 8/8