pharmacokinetics/pharmacodynamics

Question 1

Michaelis-Menten Kinetics

Answer 1

hyperbolic curve

Km= inversely related to the affinity of the enzyme for its substrate

Vmax= directly proportional to the enzyme concentration

Question 2

Km (Michaelis-Menten Kinetics)

Answer 2

Km= [s] at 1/2Vmax

Question 3

sigmoid curve

Answer 3

indicates cooperative kinetics in an enzymatic rxn (i.e. hemoglobin)

Question 4

Lineweaver-Burk plot

Answer 4

inc y-intercept, dec Vmax

further to the right the X-intercept, the greater the Km and the lower the affinity

Question 5

Reversible Competitive inhibitor graph changes

Answer 5

unchanged Vmax
increased Km

decreased potentcy

Question 6

Irreversible competitive inhibitors/noncompetitive inhibitors graph changes

Answer 6

dec Vmax, unchanged Km, decreased efficacy

Question 7

**Volume of Distribution equation*

Answer 7

D/C = (amount of drug given/plasma drug concentration)

must account for weight. Should only be in L

Question 8

Volume of Distribution characteristics

Answer 8

Blood= low 
ECF = medium
Tissues/Fat= High

Question 9

What type of drug must be used for blood Vd

Answer 9

large/charged molecules; protein/plasma bound

Question 10

What type of drug must be used for ECF Vd

Answer 10

small hydrophilic molecule

Question 11

What type of drug must be used for blood Vd

Answer 11

small lipophilic molecules, especially if bound to tissue protein

Question 12

Clearance equation

Answer 12

(rate of elimination/plasma concentration) = [(0.7Vd)/half-life] = KeVd

Question 13

Half-life (t1/2)

Answer 13

0.693Vd/CL in first order elimination

takes 4 halflives to reach Css in 1*

Question 14

amount cleared by half-life

Answer 14

1st=50%; 2nd=75%; 3rd=87.5%; 4th=94%

Question 15

**Loading Dose Equation*

Answer 15

Css*Vd

Question 16

Maitenance Dose Equation

Answer 16

Css*CL

Question 17

additive

Answer 17

effect of A&B is equal to sum of individual effects

Question 18

permissive

Answer 18

presence of A is required for full effect on B

Question 19

synergistic

Answer 19

effect of A&B is greater than sum of individual effects

Question 20

tachyphylactic

Answer 20

acute decrease to response to drug after repeated admin

Question 21

zero order elimination

Answer 21

Cl is linear, constant amount excreted

phenytoin, ethanol, asa(toxic)

Question 22

1* order elimination

Answer 22

Cl is exponentially decreased, proportional amount excreted

Question 23

Weak acids

Answer 23

phenobarbital, methotrexate, ASA

tx: na bicarb

Question 24

Weak bases

Answer 24

amphetamines, TCAs

tx: ammonium chloride

Question 25

Phase I metabolism

Answer 25

Hydolysis, Oxidation, Reduction

Question 26

Phase II metabolism

Answer 26

Methylation, Acetylation, Glucuroniation, Sulfation

Question 27

efficacy

Answer 27

maximal effect a drug can produce (Vmax, y-value);

partial agonists less than full

Question 28

potency

Answer 28

amount of drug needed for given effect (EC50, x-value)

Question 29

competitive antagonist receptor binding change

Answer 29

decreased potency, no change in efficacy

ex: Diazepam + flumazenil at GABA

Question 30

noncompetitive antagonist receptor binding change

Answer 30

decreased efficacy

ex: norepi + phenoxybenzamine at a-receptors

Question 31

partial agonist receptor binding

Answer 31

decreased efficacy

ex: morphine vs. buprenorphine

Question 32

Therapeutic index

Answer 32

(Lethal Dose/Effective Dose)

larger the index, the better