Chapter 21: Therapeutic Drug Monitoring

Question 1

Therapeutic drug monitoring (TDM)

Answer 1

Goal is to establish optimal therapeutic drug regimens for individual patients

Question 2

Absorption

Answer 2

The rate at which a drug leaves the site of administration; the pH of a drug affects its absorption

Question 3

Factors that influence absorption

Answer 3

Blood flow, total surface area, amount of contact time at the absorptive surface

Question 4

Bioavailability

Answer 4

Indicates the fractional extent to which a dose of drug reaches its site of action; more useful than absorption

Question 5

First-pass effect

Answer 5

Dose should be adjusted accordingly so the drug can be carried to the target organ

Question 6

First-pass elimination

Answer 6

Partitioning into lipids located in liver tissue, filtration, elimination as a volatile substance

Question 7

Rate of delivery and drug distribution

Answer 7

Blood flow, capillary permeability, binding of drugs to proteins, tissue volume

Question 8

Drug binding

Answer 8

Drugs need to be free to be effective, but too much free drug is toxic; binding of a drug to plasma proteins limits its concentration

Question 9

Metabolism (biotransformation)

Answer 9

Essential to eliminate drug compounds and cease their biological activity (has to be excreted before it becomes toxic); phase 1 (functionalization) and phase 2 (conjugation)

Question 10

First order kinetics

Answer 10

More drug = faster reaction (dependent on drug concentration); occurs at low doses of the drug

Question 11

Zero order kinetics

Answer 11

Adding more drug does not increase the reaction (saturated and independent of drug concentration); occurs at high doses of the drug

Question 12

Cytochrome P450 (CYP) monooxygenase system

Answer 12

Major enzyme system that metabolizes drugs

Question 13

Excretion

Answer 13

The kidneys are the most important organs for drug excretion; polar compounds are more efficiently excreted

Question 14

Four parameters affect drug dosage changes

Answer 14

Clearance, distribution volume, elimination half-life, extent and rate of bioavailability

Question 15

Clearance

Answer 15

Measure of the body’s efficiency in drug elimination; does not indicate how much drug is being removed

Question 16

Total body clearance

Answer 16

Sum of all clearances from various body organs

Question 17

Volume of distribution

Answer 17

Measure of the amount of space the body has to contain the drug; equal to the amount of drug in the body divided by the concentration of the drug in plasma

Question 18

Elimination half life (t1/2)

Answer 18

Time required for an amount of drug in the blood to decline to one-half of its measured value

Question 19

Steady state

Answer 19

Point when the total amount of drug does not change over multiple loading dose intervals

Question 20

Peak drug concentration

Answer 20

Highest plasma drug concentration achieved after a given dose

Question 21

Trough level

Answer 21

Minimum drug concentration just before the next dose; lowest concentration of effectiveness

Question 22

Specimen of choice for therapeutic drugs

Answer 22

Serum, plasma, whole blood (reject gel-separated samples)

Question 23

Amikacin

Answer 23

Preferred agent for initial treatment of nosocomial gram-negative infections in hospitals

Question 24

Gentamicin

Answer 24

Used to treat many serious gram-negative bacilliary infections

Question 25

Tobramycin

Answer 25

Useful for treating P. aeruginosa

Question 26

Vancomycin

Answer 26

Used to treat severe infections caused by gram-positive bacteria in patients who did not respond to penicillin

Question 27

Phenobarbital (Luminal)

Answer 27

Used for routine sedation or to relieve anxiety

Question 28

Phenytoin (Diphenylhydantoin, Dilantin, Diphenylan)

Answer 28

Used to treat tonic-clonic (grand mal) seizures

Question 29

Valproic acid (Depakene)

Answer 29

Used to treat simple and complex absence (petit mal) seizures

Question 30

Carbamazepine (Tegretol and Carbatrol)

Answer 30

Used as an anticonvulsant and for relief of trigeminal neuralgia pain

Question 31

Ethosuximide (Zarontin)

Answer 31

Drug of choice in the management of absence seizures

Question 32

Primidone (Mysoline)

Answer 32

Used to manage partial seizures (psychomotor)

Question 33

Toprimate (Topamax)

Answer 33

Used to treat partial seizures in adults

Question 34

Lamotrigine (Lamictal)

Answer 34

Used as an add-on drug for other antiseizure medications; can also treat bipolar disorder

Question 35

Levetiracetam (Keppra)

Answer 35

Useful for partial seizures, tonic clonic seizures, and monoclonic seizures

Question 36

Methotrexate (Amethopterin, Rheumatrex, Trexall)

Answer 36

Often used in the management of lymphoblastic leukemia in children

Question 37

Lithium (Eskalith and Lithobid)

Answer 37

Useful in the treatment of manic depression

Question 38

Theophylline (Aminophylline and Uniphyl)

Answer 38

Useful in the treatment of asthma

Question 39

Digoxin (Lanoxin)

Answer 39

Used to treat heart failure

Question 40

Lidocaine (Xyloxaine)

Answer 40

Used for acute treatment of ventricular arrhythrmias that occur after myocardial infarction

Question 41

Procainamide (Procan or Procanbid)

Answer 41

Local anesthetic

Question 42

Quinidine (Quinaglute and Quinidex)

Answer 42

Antimalarial agent

Question 43

Cyclosporine A

Answer 43

Inhibits proliferation and activation of T cells

Question 44

Tacrolimus

Answer 44

Prevents the rejection of liver and renal allografts

Question 45

Sirolimus

Answer 45

Has been effective in preventing rejection of solid organ allograft