What is the rationale for combining levodopa with carbidopa?

Correct Answer: B

Rationale: Levodopa treats Parkinson's by crossing the blood-brain barrier and converting to dopamine, but peripheral metabolism by dopa decarboxylase reduces its availability and causes side effects like nausea. Carbidopa, a peripheral dopa decarboxylase inhibitor, doesn't cross into the CNS, so it prevents levodopa breakdown outside the brain, increasing its CNS entry and efficacy. It doesn't stimulate dopamine receptors—levodopa's metabolite does that. Absorption isn't directly enhanced; bioavailability improves due to less peripheral loss. Peripheral dopamine production decreases with carbidopa, not increases, reducing side effects. COMT inhibition (e.g., entacapone) is a separate strategy. By blocking peripheral conversion, carbidopa ensures more levodopa reaches the brain, optimizing therapy and minimizing adverse effects.

Correct Answer: C

Rationale: Nystatin, an antifungal for candidiasis, is Category C, indicating potential fetal risks aren't fully ruled out. Assessing whether the client could be pregnant is critical to evaluate safety, as pregnancy might necessitate alternative treatments or physician consultation to avoid harm. Diet type or fat content minimally affects nystatin's topical or oral efficacy, unrelated to its safety profile. Height and weight influence dosing for some drugs, but nystatin's standard dosing isn't weight-based for most indications. Pregnancy status directly impacts risk-benefit decisions, especially for a reproductive-age female, aligning with pharmacological precautions. The nurse's review of this data ensures no teratogenic effects are risked unknowingly, making C the most critical assessment prior to administration.

Correct Answer: B

Rationale: Digoxin slows heart rate via vagal stimulation, treating heart failure but risking bradycardia if the rate drops too low. A heart rate of 58 bpm is below the typical threshold (60 bpm) for holding digoxin, indicating potential toxicity or excessive effect, especially in heart failure where compensatory tachycardia may mask issues. Holding the dose and notifying the physician allows reassessment of digoxin levels or need for adjustment, prioritizing safety. Administering as ordered risks worsening bradycardia, potentially leading to hemodynamic instability. Half-dosing lacks protocol support and delays medical input. Blood pressure informs but doesn't address the primary concern. Holding and notifying aligns with nursing judgment and digoxin's narrow therapeutic index, making B the best action to prevent adverse outcomes.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.