3. Administering a drug of greater potency is better because drugs of greater potency do not
require as high a dose.
a. Both parts of the statement are
... [Show More] true.
b. Both parts of the statement are false.
c. The first part of the statement is true; the second part is false.
d. The first part of the statement is false; the second part is true.
ANS: D
The first part of the statement is false, the second part is true. The absolute potency of a drug
is immaterial as long as the appropriate dose is administered. If equally efficacious, both
drugs will produce the same effect. Both meperidine and morphine, for example, have the
ability to treat severe pain, but approximately 100 mg of meperidine would be required to
produce the same action as 10 mg of morphine. The dose of meperidine needed to produce
pain relief is larger than that for morphine. Less potent drugs require higher doses to produce
therapeutic effects whereas more potent drugs can reach toxic levels at lower doses.
DIF: Application REF: Characterization of Drug Action (Potency) | p. 11
OBJ: 1 TOP: NBDHE, 6.0. Pharmacology
4. Which of the following statements is true regarding the therapeutic index (TI) of a drug?
a. A drug with a large TI is more dangerous than a drug with a small TI.
b. The formula for TI is ED50/LD50.
c. ED50 is 50% of the effective clinical dose.
d. TI is the ratio of the median lethal dose to the median effective dose.
ANS: D
LD50 is the dose causing death in 50% of test animals and ED50 is the dose required to
produce the desired clinical effect in 50% of test animals. The greater the TI, the safer the
drug. The formula is TI = LD50/ED50. The ED50 is the dose required to produce the desired
clinical effect in 50% of test animals, not 50% of the effective clinical dose.
DIF: Comprehension
REF: Characterization of Drug Action (Therapeutic Index) | p. 12
OBJ: 1 TOP: NBDHE, 6.0. Pharmacology
5. Which of the following statements is true concerning the mechanism of action of drugs?
a. Drugs are capable of imparting a new function to the organism.
b. Drugs either produce the same action as an exogenous agent or block the action of
an exogenous agent.
c. Drugs either produce the same action as an exogenous agent or block the action of
an endogenous agent.
d. Drugs either produce the same action as an endogenous agent or block the action
of an endogenous agent.
ANS: D
Drugs either produce the same action as an endogenous agent or block the action of an
endogenous agent. Drugs do not impart a new function to the organism; they merely either
produce the same action as an endogenous agent or block the action of an endogenous agent.
DIF: Comprehension REF: Mechanism of Action of Drugs | pp. 12-13
OBJ: 2 TOP: NBDHE, 6.0. Pharmacology [Show Less]