Busy. Please wait.
or

show password
Forgot Password?

Don't have an account?  Sign up 
or

Username is available taken
show password

why


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.


Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.

Remove Ads
Don't know
Know
remaining cards
Save
0:01
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
Retries:
restart all cards




share
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

PK

Pharmacokinetics

TermDefinition
Biopharmaceutics study of the interrelationship of the physical and chemical properties of the drug, dosage form, and route of administration on the rate and extent of systemic drug absorption
What does biopharmaceutics provide? provides the scientific basis for design and development of dosage forms
pharmacokinetics study of the time course of drug absorption, distribution, metabolism, excretion--a scientific discipline that deals with mathematical description of biologic processes affecting drugs
Two types of PK experimental, theoretical
experimental pk developing biological sampling techniques and analytical methods for measurement of drug concentration
theoretical pk development of mathematical models that predict drug disposition after drug administration
therapeutic window (experimental pk) more clinically useful index of safety-- describes the dosage range between the minimum effective therapeutic dose, and the minimum toxic dose
therapeutic index (experimental pk) estimates the safety of the drug--calculated ration of the LD50 to the ED50
three other types of pk population, regional, clinical
types of theoretical pk models compartment, physiologic pk, empirical
population pk identification, quantification, and explanation of interpatient variability in developing drug dosing strategies- optimizing dosing strategies for a population or subgroup
what does population pk examine? examines the relationship of demographic, genetic, pathophysiological, environmental, and other drug related factors that contribute to variability observed in safety and efficacy of the drug
bayesian theory provides a quantitative tool for incorporating subjective judgment with objective data in making risk decisions, especially when complex decisions involving several variables are involved
what was bayesian theory originally developed to do? to improve forecast accuracy in medicine by combining subjective prediction with newly collected laboratory data
equation for bayesian theory prob (pk parameter/plasma drug concentration) = [prob(P) * (Prob(C/P)] / Prob(C)
regional pk the study of pk within a given defined anatomic area of the body between specific afferent and efferent blood vessels- provides a link between systemic pk and molecular pharmacology
clinical pk application of pharmacokinetic principles to the safe and effective therapeutic management of drugs in an individual patient
theoretical approach to developing a kinetic model (6 steps) 1. conceptualize the system, 2. codify current facts, 3. test competing hypotheses, 4. identify controlling factors, 5. estimate inaccessible system variables, 6. predict system response under new conditions
clinical application of pk models plasma, tissue, urine drug concentrations, optimum dosage regimen, interactions, concentrations correlate to therapeutic effect, bioavailability
basic assumption in pk changes in plasma drug concentrations directly reflect changes in drug concentration in tissues where the disease process is being modified by the drug (may not be true for all drugs)
principle of kinetic homogeneity predictable relationship between plasma drug concentration and concentration at receptor site, plasma concentration does not equal the receptor site C but indicated how it changes over time- how therapeutic C are established
compartment models body can be represented as a series or system of compartments that communicate reversibly with each other- compartment represent a group of similar tissues or fluids
one compartment model most frequently used in clinical practice
basic assumption of one compartment model all body tissues and fluids are considered as a part of this single compartment- distribution is instantaneous
basic assumption- two compartment model body is compromised of rapidly distributing tissues called central compartment, and slowly distributing tissues- peripheral compartment
central compartment highly perfused organs often have similar drug distribution patterns
peripheral compartment tissues or organs to which drugs distribute slowly
mammillary model most common compartmental model used in pk consists of one or more peripheral compartments- elimination occurs from the central compartment
caternary model consists of compartment joined to one another like a train
physiologic pk model describes drug movement and disposition in the body based on organ blood flow and organ spaces penetrated by the drug
two types of PPK model blood flow-limited (perfusion) or diffusion limited (membrane-limited)
basic assumption of blood flow-limited model transmembrane movement of a drug is rapid without any resistance from capillary membrane- tissue to venous drug blood concentration ratio is constant- drug doesn't bind either to plasma or tissues
basic assumption of diffusion-limited model cell membrane acts as a major barrier for drug, blood flow is very rapid but drug penetration is slow thus, drug concentration gradient is established between tissue and venous blood- time lag in equilibration between blood and tissue is complicated
diffusion-limited model for tissue distribution in which the tissue is subdivided into compartments representing capillary bed, interstitial fluid, and intercellular space (Q is blood flow)
advantages of ppk models drug concentrations are calculated based on tissue size and blood flow, predicts pk of a drug when only animal data is available
limitation of ppk models information required for adequately describing a ppk model are experimentally difficult to obtain
interspecies scaling- application of ppk model allometric method that allows approximate interspecies scaling based on size, aging rate, and life span of species- uses a physiologic variable that is graphed against body weight of the species on log-log axes= linear relationship,
basic assumptions of interspecies scaline physiological variables like HR, organ weight are related to the weight or body surface area of the species, all mammals use same energy source and energy transport systems across animal species
summary of compartment model simple and flexible for clinical pk application, extrapolation to specifc tissue compartments are not accurate, empirical model lacks physiologic relevanct
summary of ppk model realistic model that accounts for distribution, binding, metabolism, and blood flow of drug, reliable estimations based on tissue size and blood flow, complex model
statistical moment theory (SMT) empirical pk study time-related changes in macroscopic events
macroscopic event overall event brought about by constitutive elements involved
mean residence time (MRT) describes the average time for all the drug molecules to reside in the body- uses the area under the curve
MRT = AUMC/AUC AUMC- area under the first moment vs time curve from zero to infinity/ AUC- area under plasma time versus concentration curve from time zero to infinity
intestinal reserve length concept interrelates physiological, physicochemical and dosage form factors that affect drug absorption
predictive capability of compartment pk plasma conc vs time, population pk, variability within specific population based on fitted rate constants from in vivo experiments
predictive capability of reserved length effect of drug release/dissolution, transit, and permeability on fraction of drug absorption
predictive capability of macroscopic mass balance approach effect of drug release/dissolution, transit and permeability on fraction of drug absorption
predictive capability of compartmental absorption and transit model plasma conc vs time based on pk and biopharmaceutic data of the compound
predictive capability of physiological based pk plasma conc vs time profile based on tissue kp data that can be scaled between species
Created by: 1614571257