Nokea
Which of the following statements about the major distribution barriers (blood-brain or fetal-placental) is true?
- A. Water soluble and ionized drugs cross these barriers rapidly.
- B. The blood-brain barrier slows the entry of many drugs into and from brain cells.
- C. The fetal-placental barrier protects the fetus from drugs taken by the mother.
- D. Lipid-soluble drugs do not pass these barriers and are safe for pregnant women.
Correct Answer: B
Rationale: Choice B is correct because the blood-brain barrier, with its tight junctions, slows entry of many drugs, especially water-soluble ones, protecting the brain. Choice A is incorrect as water-soluble, ionized drugs cross poorly due to barrier selectivity. Choice C is wrong because the fetal-placental barrier doesn't fully block drugs—many cross and affect the fetus. Choice D is incorrect since lipid-soluble drugs readily pass these barriers, posing risks in pregnancy.
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A patient is taking drug A and drug B. The primary care NP notes increased effects of drug B. The NP should suspect that in this case drug A is a cytochrome P450 (CYP450) enzyme:
- A. inhibitor.
- B. substrate.
- C. inducer.
- D. metabolizer.
Correct Answer: A
Rationale: The correct answer is A because a CYP450 inhibitor (drug A) reduces metabolism of drug B, increasing its effects. Choice B is incorrect as a substrate is acted upon, not inhibiting. Choice C is wrong since an inducer increases metabolism, reducing effects. Choice D is inaccurate as 'metabolizer' isn’t a CYP450 role.
The primary care NP sees a 5-year-old child for a prekindergarten physical examination. The child's parents do not have immunization records, and a local record search does not provide proof of vaccinations, although the parent thinks the child may have had some vaccines several years ago. The NP's initial action will be to:
- A. assume the child is unvaccinated and start the full series.
- B. check titers for all vaccine-preventable diseases.
- C. administer a single dose of each vaccine today.
- D. consult state immunization registry again.
Correct Answer: A
Rationale: The correct answer is A because without records, assuming unvaccinated and starting the series ensures protection. Choice B is incorrect (titers not practical initially). Choice C is wrong (single doses insufficient). Choice D is inaccurate (registry already checked).
Herbal products that may increase INR include:
- A. Ginkgo biloba
- B. St John's wort
- C. Valerian root
- D. All of the above
Correct Answer: A
Rationale: Choice A is correct because ginkgo biloba can increase INR by enhancing warfarin's effect through antiplatelet activity, risking bleeding. Choice B is incorrect as St John's wort induces CYP2C9, decreasing INR and warfarin efficacy. Choice C is wrong because valerian root doesn't significantly alter INR. Choice D is incorrect since only ginkgo biloba increases INR.
Clinical judgment in prescribing includes:
- A. Factoring in the cost to the patient of the medication prescribed
- B. Always prescribing the newest medication available for the disease process
- C. Handing out drug samples to poor patients
- D. Prescribing all generic medications to cut costs
Correct Answer: S
Rationale: Choice A is correct because clinical judgment involves balancing efficacy, safety, and cost to ensure patients can afford and adhere to treatment, which is critical for successful outcomes. Choice B is incorrect as always choosing the newest medication ignores evidence-based practice; newer drugs may lack long-term data or be unnecessarily expensive. Choice C is wrong because distributing samples isn't a sustainable prescribing strategy and may not meet ongoing needs. Choice D is also incorrect since mandating generics could compromise efficacy if a brand-name drug is clinically necessary.
Pharmacokinetic changes in the elderly that affect drug dosing include:
- A. Decreased renal function
- B. Increased liver metabolism
- C. Decreased body fat
- D. All of the above
Correct Answer: A
Rationale: Choice A is correct because decreased renal function in the elderly slows drug excretion, requiring dose adjustments to prevent accumulation, per geriatric pharmacology. Choice B is incorrect as liver metabolism decreases, not increases. Choice C is wrong because body fat increases, not decreases. Choice D is incorrect since only A is accurate.