Which statements describe the pharmacodynamic concept of half-life?
a. Half-life varies from drug to drug.
b. Liver or kidney impairment shortens a medication's half-life.
c. Half-life reflects the speed with which a drug is metabolized and excreted from the body.
d. Medications with a short half-life must be administered more frequently than those with a long half-life.
e. Spacing of doses to maintain consistent therapeutic effects is based on the medication's half-life.
f. After two to three half-lives, the dose of medication administered equals the amount of medication metabolized and excreted.