Pharmacokinetics Absorption/Distribution Flashcards
Pharmacokinetics relationship between what 2 things?
dose-concentration
Biophase (PK-PD link) reflects what relationship?
plasma-effect site
Pharmacodynamics reflects what relationship?
concentration-effect
What does ADME stand for?
Absorption, Distribution, Metabolism, Excretion
Simply define pharmacokinetics.
what the body does to a drug.
Name 4 drug properties that affect absorption.
size, shape, degree of ionization(acidic/alkaline), lipid solubility
What conditions at the site affect absorption?
blood flow, surface area, membrane thickness, presence of other substances, metabolism (1st pass hepatic metabolism), GI motility, pH
The rate of diffusion is directly proportional to what?
concentration gradient, surface area
The rate of diffusion is inversely proportional to what?
membrane thickness
What’s Fick’s Law of Diffusion equation?
Rate of diffusion= conc. grad. * SA * Diffusion Coef / membrane thicknss
Define Bioavailability.
Fraction of unchanged drug that reaches the systemic circulation following administration by any route
Where is the principle route of absorption for oral route?
largest surface area of the small intestine
Name 4 medications highly susceptible to first pass hepatic metabolism.
Aspirin, levadopa, metoprolol, morphine
What common medication is hydrolyzed in the stomach?
penicillin
True/False: Transmucosal meds (SL/buccal/intranasal) are subject to 1st pass hepatic effect.
False
What percentage of body weight does water make up in men? women? infants?
60% men; 50% women; 70% infants
How many L is total body water?
42L
How many L of fluid is intracellular? Extracellular?
28L, 14L
What % of CO is central compartment?
75%, peripheral comp. 25%
What % of weight is central compartment
10%, peripheral comp. 90%
Define Vd and it’s equation.
Vd relates the amount of drug given to plasma concentration. Vd=amount of drug/desired plasma conc.
True/False: Small plasma concentration=large Vd.
True.
What kind of drugs have large Vd?
Lipid soluble drugs, lipophilic. Needs larger dose for effect. Propofol
What kind of drugs have low Vd?
hydrophilic drugs, highly water soluble, higher plasma concentrations. Neuromuscular blocking drugs