PSA Pharmacology Principles 1 — Questions and Answers
Question 1: What is bioavailability?
- The fraction of an administered drug dose that reaches systemic circulation in active form (Correct answer)
- The drug's shelf life
- How quickly a drug is manufactured
- The number of doses in a package
Correct answer: The fraction of an administered drug dose that reaches systemic circulation in active form
Bioavailability measures what proportion of the administered drug reaches the bloodstream in active form. IV drugs have 100% bioavailability; oral drugs vary.
Question 2: What is a drug's half-life?
- The time required for the drug's plasma concentration to decrease by 50% (Correct answer)
- Half of the recommended dose
- The time until the drug expires
- The time from first dose to full effect
Correct answer: The time required for the drug's plasma concentration to decrease by 50%
Half-life determines dosing frequency: drugs with short half-lives need more frequent dosing, while long half-life drugs can be given less often.
Question 3: What is the therapeutic index?
- The ratio between the toxic dose and the therapeutic dose — drugs with a narrow index require careful monitoring (Correct answer)
- The number of conditions a drug treats
- The maximum number of doses per day
- The drug's effectiveness rating
Correct answer: The ratio between the toxic dose and the therapeutic dose — drugs with a narrow index require careful monitoring
A narrow therapeutic index means the difference between an effective dose and a toxic dose is small, requiring careful dosing and monitoring (e.g., warfarin, lithium, digoxin).
Question 4: What is the difference between pharmacokinetics and pharmacodynamics?
- Pharmacokinetics is what the body does to the drug; pharmacodynamics is what the drug does to the body (Correct answer)
- They are the same thing
- Pharmacodynamics studies drug manufacturing
- Pharmacokinetics studies drug marketing
Correct answer: Pharmacokinetics is what the body does to the drug; pharmacodynamics is what the drug does to the body
Pharmacokinetics covers absorption, distribution, metabolism, and excretion (ADME). Pharmacodynamics covers the drug's mechanism of action and effects on the body.
Question 5: What does 'loading dose' mean?
- A higher initial dose given to rapidly achieve therapeutic drug levels (Correct answer)
- The maximum safe dose
- A dose taken before exercise
- The dose that causes side effects
Correct answer: A higher initial dose given to rapidly achieve therapeutic drug levels
A loading dose is an initially higher dose designed to quickly bring drug levels into the therapeutic range, followed by lower maintenance doses.
Question 6: What is renal dosing adjustment?
- Reducing drug doses for patients with kidney impairment to prevent accumulation and toxicity (Correct answer)
- Increasing doses for kidney patients
- Stopping all drugs if kidneys are impaired
- Only applies to kidney medications
Correct answer: Reducing drug doses for patients with kidney impairment to prevent accumulation and toxicity
Many drugs are eliminated by the kidneys. When kidney function is reduced, doses must be decreased or intervals extended to prevent dangerous drug accumulation.
PSA Pharmacology Principles 1
What is bioavailability?