PHARMACOKINETICS AND DRUG ADM HIGH YIELD PART B Flashcards
what is pharmacokinetics?
study of time course of drug ADME
what are the variables of pharmacokinetics?
age
organ function
health
what are some of the considerations of pharmacokinetics?
absorption
distribution
metabolism
elimination
bioavailability can be measured via what routes?
any route
how do drugs move across membrane barriers?
passive diffusion
pH
what law defines how most drugs move across the membrane via passive diffusion?
ficks law of diffusion
rate of diffusion is increased when?
area is large
membrane is thin
concentration gradient is high
in relation to the Henderson hasselback equation, when in the plasma, when the pH is greater than the pka, what dominates?
the unprotonated form dominates
in relation to the Henderson hasselback equation, when in the gastric environment, where the pH is less than the pka, what form dominates?
the protonated form dominates
how are drugs transported across the membrane barrier?
active transport
paracellular transport
factors that affect absorption?
concentration
physical state of formulation and dissolution rate
area of absorbing surface
what is the main affect on oral absorption?
gastric emptying
what delays gastric emptying?
increase fats and carbs
high calories, large volume
high intensity exercise
cold beverage
what accelerates gastric emptying?
moderate exercise
recumbent position
warm/hot beverage
examples of drugs that affect oral absorption? how?
penicillin (increases drug degradation since PCN is sensitive to stomach acid)
aspirin (more time in the stomach may cause gastric irritation)
what are the factors that affect absorption?
vascularity and blood flow inflammation edematous vasoconstrictors lipid solubility BBB, placenta, fat, skin
determinants of distribution?
organ perfusion/blood flow
size of the organ
solubility
binding
what is the equation for volume of distribution?
Vd is?
Vd=amount of drug/C
apparent volume of distribution
the two compartment model considers the movement of drugs between what two compartments?
central and peripheral compartment
the two compartment model consists of what two phases?
distribution phase
elimination phase
what are the factors that affect distribution?
plasma proteins
plasma proteins as carriers
protein binding and drug action
the fraction of bound drug is determined by?
drug concentration
affinity of binding sites
number of binding sites
what are the conditions and diseases that affect protein binding?
hypoalbuminemia
acute phase reactions response increases alpha-1-acid glycoprotein like cancer, MI, crohns disease
what are the sites of distribution?
tissue binding
bone
fat
