test 1: lecture 9

Question 1

how do genetics effect pharmacokinetics

Answer 1

ADME
absorption: different types of GI tracts= different pH

distribution: variations in genes and receptors means drugs move through at different rates

metabolism: fast or slow metabolizers from mutations in CYP

excretion: mammals vs birds different urinary tracts

Question 2

with age absorption will change because of — in acid secretion and — splanchnic blood flow

Answer 2

decreased
decreased

with age things slow down

Question 3

what happens to distribution with age

Answer 3

increase fat

decreased water= decreased plasma protein levels with age

Question 4

how does age change metabolism

Answer 4

decreased metabolism in babies and old people = drugs stay in system at higher levels for longer

decreased hepatic enzyme activity, liver weight, hepatic blood flow

Question 5

how does age effect excretion

Answer 5

decreased renal function with age= drugs stay in system longer

Question 6

how does age effect 1/2 life of drugs?

Answer 6

overall increased 1/2 life

if lipophilic: drug stays in system longer

exception: if bound to albumin (plasma protein): drug will have shorter half life (less overall water with age)

metabolism slows down and GFR decreases= longer 1/2 life

Question 7

— is rapid drug induced loss of response

Answer 7

tachyphylaxis

becomes resistant very quickly

Question 8

what are some things that lead to decrease in response/tolerance

Answer 8

receptors changed, broken, degraded

2nd messangers used up

increased degradation

body tries to maintain set point (physiological adaptation)

Question 9

what are some diseases or diseased states what alter absorption

Answer 9

gastic stasis
malabsorption
mucosal edema

Question 10

what are some disease or disease states that effect distribution

Answer 10

• pH changes
• Alterations in plasma protein levels
• Impaired blood-brain
  barrier

Question 11

what are some disease or disease states that effect metabolism

Answer 11

• liver disease
• hypothermia

Question 12

what are some disease or disease states that effect excretion

Answer 12

• renal failure
• proteins in tubular fluid will bind drugs

Question 13

explain

Answer 13

drug interaction between 2 drugs leads to toxic effects

can also have beneficial effect (work together)

Question 14

what is site of action drug interactions

Answer 14

two drugs interact when given

can be external: mix to form new drug

can be internal: change in pH of GI changes how drugs work, receptors can change, drugs can alter the genome

Question 15

physiologic mechanism of drug interactions

Answer 15

Two drugs act at different sites to alter function may augment or offset each other

(example: effects on both the heart, arterioles, and kidneys will alter blood pressure)

Question 16

One drug changes the concentration of the other

Answer 16

PK
Pharmacokinetic

Question 17

One drug changes the effect of another

Answer 17

pharmacodynamics

Question 18

Any drug that affects — has the potential to alter absorption profiles of any additional drugs taken by the patient

Answer 18

gastrointestinal function

if you slow or speed up GI will effect the absorption of other drugs

Question 19

4 ways drug interaction can change PK mechanisms of distribution

Answer 19

alter blood flow: clearance or 1st pass effect
alter tissue uptake
alter active transport at site of action
alter plasma protein binding

Question 20

explain

Answer 20

give a 2nd drug that binds to receptor better, causes 1st drug to be kicked off and floating in plasma, this increases the level of free drug A→can lead to toxic levels

eventually body will find a way to balance new drugs by redistribution or excretion, levels return to normal

Question 21

— is well known to induce cytochrome P450 enzymes, an important mechanism for metabolism of many drugs.

Answer 21

Phenobarbital

Question 22

how does phenobarbital effect warfarin

Answer 22

pheno = increases activity of CYP450

this means will decrease effectivness of warfarin, will need to increase warfarin dose

if you stop phenobarbital suddenly, can result in too high warfarin and dose will need to be lowered again