Pharmacokinetics 4

Question 1

Co-administration of which drug reduces the observed potency of codeine?
a. diltiazem
b. fluoxetine
c. phenytoin
d. rifampin

Answer 1

B. fluoxetine

Question 2

The ________ is the most important mechanism of drug biotransformation in the body.

Answer 2

P450 system

Question 3

_________ can influence the enzymatic activity of the P450 system.

Answer 3

Exogenous chemicals

Question 4

_________ stimulate the synthesis of additional enzymes

Answer 4

Enzyme inducers

Question 5

Enzyme inducers _______ drug clearance

Answer 5

increase

Question 6

Common enzyme inducers include

Answer 6

ethanol
tobacco
phenytoin
barbiturates
rifampin
carbamazepine

Question 7

_____ compete for binding sites on the enzymes

Answer 7

Enzyme inhibitors

Question 8

Enzyme inhibitors ______ drug clearance.

Answer 8

reduce

Question 9

Common enzyme inhibitors include

Answer 9

SSRIs, omeprazole, and grapefruit juice
isoniazid, ketoconazole, erythromycin, cimetidine

Question 10

The most important cytochrome P450 enzyme is

Answer 10

CYP 3A4 (metabolizes nearly 50% of the drugs we administer)

Question 11

The P450 system carries out most of the body’s ______ biotransformations.

Answer 11

phase 1

Question 12

The P450 enzymes are located in the

Answer 12

smooth endoplasmic reticulum of the hepatocyte
also located in extrahepatic tissue such as the lung, kidneys, skin, adrenal gland, and GI tract

Question 13

________ contribute to variations in enzyme efficiency, and this can affect the observed drug potency from patient to patient.

Answer 13

Genetic polymorphisms

Question 14

Which statement regarding renal clearance is true?
a. acidic urine promotes thiopental excretion
b. basic urine enhances morphine reabsorption
c. protein-bond drugs are filtered at the glomerulus
d. organic anion transporters secrete drug into the distal convoluted tubule

Answer 14

b. basic urine enhances morphine reabsorption
morphine is a weak base; as a weak base, the non-ionized fraction increases in an alkalotic environment; therefore, basic urine enhances morphine reabsorption

Question 15

What two processes deliver a drug to the renal tubule?

Answer 15

glomerular filtration
organic ion transporters

Question 16

__________ are resistant to glomerular filtration.

Answer 16

Highly protein-bound drugs

Question 17

_________ in the ultrafiltrate tend to be eliminated in the urine.

Answer 17

Hydrophilic drugs

Question 18

___________ in the ultrafiltrate tend to get reabsorbed into the peritubular fluid.

Answer 18

Liphophilic

Question 19

Renal clearance is determined by the drug’s

Answer 19

polarity and the pH of the ultrafiltrate

Question 20

Clearance of drugs such as furosemide, morphine, and dopamine rely on

Answer 20

organic ion transporters located in the proximal renal tubules

Question 21

__________ influences whether drugs are excreted in the urine or reabsorbed into the peritubular capillaries.

Answer 21

Urine pH

Question 22

In terms of urine pH and elimination, remember that

Answer 22

like dissolves like!

Question 23

Acidic urine favors ________ of acid drugs and _______ of basic drugs

Answer 23

reabsorption; excretion

Question 24

Basic urine favors _______ of basic drugs and ______ of acidic drugs

Answer 24

reabsorption; excretion

Question 25

Liphophilic drugs must _________ before they can be excreted by the kidneys.

Answer 25

undergo biotransformation reactions to increase their water solubility

Question 26

Drugs that are not bound to plasma proteins will be __________ by the glomerulus.

Answer 26

freely filtered

Question 27

Organic anion transporters (OAT) includes

Answer 27

furosemide, thiazide diuretics, and penicillin

Question 28

Organic cation transporters (OCT) include

Answer 28

morphine, meperidine, and dopamine

Question 29

What two things will acidify the urine?

Answer 29

ammonium chloride or cranberry juice

Question 30

Acidifying the urine will help to

Answer 30

eliminate basic drugs

Question 31

What two things will alkalize the urine?

Answer 31

sodium bicarbonate or acetazolamide

Question 32

Identify the drugs that are metabolized by nonspecific plasma esterases. (select 3)
a. esmolol
b. atracurium
c. cocaine
d. remifentanil
e. succinylcholine
f. fospropofol

Answer 32

a. esmolol
b. atracurium
d. remifentanil

Question 33

Enzymatic drug metabolism in the plasma tends to occur via one of three pathways which include

Answer 33

pseudocholinesterase
nonspecific esterases
alkaline phsophatase

Question 34

Unlike hepatic enzymes, plasma enzymes do not

Answer 34

undergo enzyme induction

Question 35

Examples of drugs that undergo pseudocholinesterase metabolism include

Answer 35

ester-type local anesthetics, mivacurium, and succinylcholine

Question 36

Examples of drugs that undergo alkaline phosphatase metabolism include

Answer 36

fospropofol

Question 37

Examples of drugs that undergo nonspecific esterases metabolism include

Answer 37

remifentanil, esmolol, clevidipine, and atracurium
remimazolam, & etomidate (+ hepatic)

Question 38

Drugs that undergo Hoffman elimination include

Answer 38

cisatracurium and atracurium (to some degree)

Question 39

___________ extends the duration of action of succinylcholine, mivacurium, cocaine, and ester local anesthetics.

Answer 39

Pseudocholinesterase deficiency