Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
pharm
intro to pharmacokinetics and pharmacodynamics
| Question | Answer |
|---|---|
| four characteristics for therapeutic drug monitoring (TDM) | narrow therapeutic window, a significant degree of PK variability, a relationship between the plasma concentration and clinical effect, an established therapeutic target concentration range |
| defining ADME | absorption, distribution, metabolism, elimination |
| absorption | the process by which unchanged drug proceeds from the site of administration to the site of measurement |
| oral absorption at | intestines |
| IM absorption at | muscular |
| IV absorption at | systemic |
| distribution | the reversible transfer of a drug to and from the site of measurement and the peripheral tissues (heart, kidney, bone, brain, adipose tissue) |
| elimination | irreversible loss of drug from the site of measurement, occurs by two processes |
| two processes of elimination | excretion and metabolism |
| metabolism | the conversion of one chemical species to another |
| example of metabolism | unchanged drug to metabolite |
| excretion | the irreversible loss of chemically unchanged drug |
| example of excretion | urinary excretion, biliary excretion, fecal excretion |
| two primary processes of absorption | passive diffusion and active transport |
| when is absorption not required | when a drug is given via IV |
| factors that affect drug absorption | surface area, nature of epithelial membranes, presence of bile and mucus, blood perfusion, differences in luminal pH along the GI tract |
| surface area | larger surface area means higher drug absorption |
| nature of epithelial membranes | problem with GI tract means a disruption of absorption |
| presence of bile and mucus | thicker mucus, lower drug absorption |
| blood perfusion | higher blood perfusion, higher drug absorption |
| differences in luminal pH along the GI tract | pH will affect location of drug absorption |
| order of fastest to slowest dosage form and absorption rate | IV, sublingual/orally dissolving tablet, immediate release tablet, extended-release tablet |
| IV | fastest and fully absorbed |
| extended-release tablet | slowest and takes time to be fully absorbed |
| bioavailability | extent to which a drug is absorbed into the systemic circulation |
| bioavailability is the percentage of | drug absorbed from extravascular relative to intravascular administration |
| drugs with good absorption = | high bioavailability (>70%) |
| drugs with poor absorption = | low bioavailability (<10%) |
| area under the curve (AUC) = | most reliable measurement of drugs bioavailability, represents the amount of the drug that has reached the systemic circulation |
| Cmax | maximum concentration of drug in the body |
| Tmax | time at which the drug concentration is at its maximum |
| high volume of distribution | extensively leave the bloodstream to enter body tissues, concentration in vasculature is low |
| low volume of distribution | primarily stay in the bloodstream because they are highly bound to plasma proteins or don't easily leave the circulation, concentration in vasculature is high |
| drug tissue distribution | how a drug moves from the bloodstream into organs and tissues, |
| determinants of drug distribution | dictated by the physiochemical properties of a drug as well as the physiologic factors of the patient. |
| physiochemical properties of drug distribution | molecular weight of drugs binding affinities to plasma proteins lipophilicity ionization state |
| physiologic factors | adipose tissue to skeletal muscle ratio biological sex |
| metabolism is a process by which | a drug is converted from its original chemical structure into other forms (metabolites) |
| primary sites for metabolism | gut and liver as they contain many drug-metabolizing enzymes (to get drug out of body or keep them from coming in) |
| first pass metabolism | blood from the stomach travels to the liver before it reaches the rest of the body before it's absorbed systemically |
| certain drugs with | extensive first-pass metabolism can bypass by given non-oral routes |
| phase I metabolizing enzymes are the conversion of | parent drug to a more polar metabolite (body can take polar more easily) |
| reactions of phase I | oxidations, reduction, hydrolysis (become more polar) |
| CYP3A4/5 family | is involved in the majority of Phase I metabolism which is where pharmacogenetics can be affected |
| CYP 450 enzymes | superfamily with increasing gene sequence similarities, work together with drug transporters to influence systemic bioavailability |
| phase II metabolizing enzymes | conjugation reactions is catalyzed by Sulfotransferases, UDP-glucuronosyltransferases, glutathione-S-transferases, N-Acetyltransferases, methyltransferases (get drugs out of body) |
| UGT and CYP34/5 are | involved in the metabolism of more than 75% of drugs |
| elimination | process of irreversible removal of drugs from the body, describe the efficiency of drug removal from the body |
| elimination occurs through | Kidneys > urine Gut > feces Skin > sweat |
| clearance | rate of drug removal in a certain volume of plasma over a certain amount of time |
| zero-order rate processes | the rate of drug elimination is independent of drug concentration |
| first-order rate processes | vast majority, the rate of drug elimination is dependent of drug concentration |
| less drug = | less clearance |
| more drug = | more clearance |
| glomerular filtration | affects all solutes of appropriate size MW ≤ 500 D influenced by protein binding passive and unidirectional |
| tubular secretion | occurs mostly in the proximal tubules of the nephron requires a carrier protein to bring drugs out saturable process not influenced by protein binding |
| reabsorption | occurs all along the nephron passive by nature & active favors lipid soluble, unionized drugs weak acids & weak bases depend on the urine pH and the pKa of the drug |
| renal clearance | a net result of filtration, secretion, and reabsorption |
| dosing in pediatrics | weight based dosing, different because of development process |
| dosing in geriatrics | modifications based on a reduction in clearance secondary to reductions in liver and kidney function, less body fat/muscle, older=decrease kidney function, affects drug concentration |
| oxidation, reduction, and hydrolysis reactions introduce | functional groups to increase a drug's water solubility and can dramatically alter its pharmacological activity |
| CYP3A4/5 enzymes are | part of a larger enzyme superfamily and are primarily involved in phase I metabolism, influencing systemic bioavailability, phase II = UGT |
| pathways of renal clearance | glomerular filtration, tubular secretion, and reabsorption |
| sigmoidal curve | relation between concentration and effect |
| 50% effective concentration (EC50) | concentration where you obtain 50% maximum therapeutic affects |
| tolerance | 50% is the same but concentration to reach is higher |
| types of drug-receptor interactions (drugs do 1/3 of them) | agonists, antagonists, allosteric interactions |
| agonists | don't have to bind |
| full agonists | downstream affects |
| partial agonists | partial downstream affects |
| inverse agonists | undo affects |
| antagonists | bind to specific sites |
| competitive antagonists | 1 site drugs have to compete with |
| non-competitive antagonists | can bind on different sites |
| allosteric activators | activates chain reaction |
| allosteric inhibitors | inhibit |
| the therapeutic index | range of doses at which a medication is effective without unwanted adverse events/toxicities |
Created by:
leh195