Pharmacokinetics

Question 1

pharmacokinetics

Answer 1

what body does to drug
ADME

Question 2

pharmacodynamics

Answer 2

what drug does to human body

Question 3

drug absorption oral

Answer 3

oral
stomach
small intestine
through hepatic portal vein
liver
part recycles from liver to small intestine
part goes liver to systemic circulation

Question 4

passive diffusion

Answer 4

high to low concentration (i.e. gut lumen to blood)

Question 5

active transport

Answer 5

drugs moved across gut wall by transporter proteins
normally used for nutrients from food

Question 6

disintegration

Answer 6

solid dosage form breaks into smaller pieces in GI tract

Question 7

disolution

Answer 7

small pieces dissolve and release active ingredient
required for drug absorption

Question 8

fastest to slowest rate of absorption

Answer 8

IV
SL
ODT
IR tablet
ER tablet

Question 9

primary way IR formulations get destroyed in gut

Answer 9

hydrolysis

Question 10

prevents drug degradation in stomach

Answer 10

enteric coating

Question 11

micronized

Answer 11

drugs with very small particle diameters to increase dissolution rate by reducing particle diameter to increase surface area

Question 12

solubility

Answer 12

how well drugs dissolve in GI fluids
typically lower for lipophilic

Question 13

bioavailability

Answer 13

extent of drug absorption into systemic circulation
percentage of drug absorbed from extravascular compared to intravascular administration (oral vs IV)
high = >70% (levofloxacin, linezolid)
low = <10%
F x Dose = Cl x AUC

Question 14

AUC

Answer 14

shows bioavailability
100 x (AUC extravasc/AUC intravasc) x (dose IV/dose extravasc)

Question 15

dose of new dosage form

Answer 15

= amount absorbed from current dosage form / F of new dosage form

Question 16

distribution

Answer 16

drug molecules move from systemic circulation to various tissues and organs
higher with high lipophilicity, low molecular weight, unionized status and low protein binding

Question 17

albumin

Answer 17

main protein responsible for drug binding

Question 18

unbound/free drug

Answer 18

exerts therapeutic/toxic effects

Question 19

affect of low serum albumin and high protein-bound drug

Answer 19

more drug will be in unbound form than intended = higher therapeutic/toxic effects

Question 20

highly protein bound compounds examples

Answer 20

phenytoin
calcium
need correction formulas for hypoalbuminemia
do not need corrections if “free phenytoin” or “ionized calcium” reported

Question 21

calcium correction formula

Answer 21

serum Ca + [(4-albumin) x 0.8]
reports mg/dL

Question 22

phenytoin correction formula

Answer 22

serum phenytoin / [(0.2 x albumin) + 0.1]
reports mcg/mL

Question 23

volume of distribution

Answer 23

amount of drug in body / concentration of drug in plasma = dose / serum concentration

Question 24

metabolism

Answer 24

drug is converted to facilitate elimination

Question 25

primary sites for drug metabolism

Answer 25

gut liver

Question 26

first-pass metabolism

Answer 26

metabolism of drug before it gets.to systemic circulation reduces bioavailability of oral formulations Phase 1 reactions (oxidation, reduction, hydrolysis - such as adding hydroxyl group to make drug more hydrophilic) then Phase 2 reactions (conjugation)

Question 27

drugs with high first-pass metabolism

Answer 27

lidocaine - cannot be given orally on IV

Question 28

excretion

Answer 28

removal of drugs from body

Question 29

pH affect on excretion

Answer 29

weak base - acidic urine increases excretion weak acid - alkaline urine increases excretion

Question 30

clearance

Answer 30

rate of elimination / drug concentration = (drug eliminated / how many hours to eliminate) / plasma concentration efficiency of drug removal from body

Question 31

most reliable measurement of drug's bioavailability

Answer 31

AUC

Question 32

first-order kinetics

Answer 32

constant percentage of drug is removed per unit of time most drugs follow this

Question 33

zero-order kinetics

Answer 33

a set of amount (mg) of drug removed per unit time

Question 34

Michael-Mentin Kinetic /non-linear/saturable

Answer 34

enzymes for metabolism get saturated follows first-order at very low concentration at high concentrations, approach zero-order = inc dose causes disproportionate increase i n drug concentration

Question 35

drugs that follow Michael-Mentin Kinetics

Answer 35

phenytoin, theophylline, voriconazole doses should be inc in small increments

Question 36

eliminatio rate constant (ke)

Answer 36

fraction of drug liminated per unit of time ke = Cl/Vd = how much of drug remaining is cleared per hour (ke = 0.1 hr means 10% of drug is cleared every hour

Question 37

predicting drug concentration

Answer 37

C2 = C1 x e^(-ke x t)

Question 38

half-life

Answer 38

time for drug concentration to dec by 50% t 1/2 = 0.693/ke

Question 39

steady state

Answer 39

where drug intake equals drug eliminatino 5 half-lives required to eliminate >95% or drug

Question 40

loading dose

Answer 40

rapidly achieves therapeutic concentration of drug = [(desired concentration) x Vd] / F