A patient has been given a prescription for levodopa-carbidopa (Sinemet) for her newly diagnosed Parkinson’s disease. She asks the nurse, “Why are there two drugs in this pill?” The nurse’s best response reflects which fact?

Carbidopa allows for larger doses of levodopa to be given.

Carbidopa prevents the breakdown of levodopa in the periphery.

There are concerns about drug-food interactions with levodopa therapy that do not exist with the combination therapy.

Carbidopa is the biologic precursor of dopamine and can penetrate into the central nervous system.

Answer and Explanation

The Correct Answer is B

Choice A reason: Carbidopa does not allow larger levodopa doses but reduces the dose needed by preventing peripheral breakdown. This increases levodopa’s availability to cross the blood-brain barrier, improving efficacy without increasing side effects like nausea from peripheral dopamine.
Choice B reason: Carbidopa inhibits peripheral dopa decarboxylase, preventing levodopa’s conversion to dopamine outside the brain. This increases levodopa’s central nervous system availability, enhancing dopamine production in the basal ganglia to alleviate Parkinson’s symptoms, making it the primary reason for the combination.
Choice C reason: Drug-food interactions (e.g., protein competing with levodopa absorption) persist with levodopa-carbidopa, as carbidopa does not affect intestinal absorption. This is not the primary reason for the combination, which focuses on peripheral metabolism inhibition.
Choice D reason: Carbidopa is not a dopamine precursor and cannot cross the blood-brain barrier. Levodopa is the precursor, converted to dopamine in the brain. Carbidopa’s role is to block peripheral conversion, not to act as a precursor itself.

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Correct Answer is D

Explanation

Choice A reason: Bisphosphonates are generally safe for clients with diabetes and normal renal function (serum creatinine 0.8 mg/dL is within normal range, indicating adequate kidney function). These drugs inhibit osteoclast activity, reducing bone resorption, and are not contraindicated in diabetes unless renal impairment is present, which is not the case here.
Choice B reason: Vertebral compression fractures are a common complication of osteoporosis. Bisphosphonates are often prescribed to strengthen bones and prevent further fractures by inhibiting bone resorption. Recent fractures do not contraindicate their use; in fact, they are indicated to improve bone density and reduce future fracture risk.
Choice C reason: Calcium channel blockers, used for hypertension, do not interact significantly with bisphosphonates. These drugs work on different systems—bisphosphonates on bone metabolism and calcium channel blockers on vascular smooth muscle. There is no evidence suggesting this combination poses a risk, making bisphosphonates appropriate for this client.
Choice D reason: Bisphosphonates, especially oral ones, require patients to sit upright for 30–60 minutes post-dose to prevent esophageal irritation and ensure proper absorption. A client with a spinal cord injury unable to tolerate sitting up cannot comply with this requirement, increasing the risk of esophageal damage, making bisphosphonates a poor choice.

Correct Answer is ["3.3"]

Explanation

Step 1 is: Convert pounds to kilograms 12 ÷ 2.2 = 5.4545 Result = 5.4545 kg

Step 2 is: Multiply by dosage per kg 5.4545 × 15 = 81.818 Result = 81.818 mg

Step 3 is: (125 ÷ 5) = 25 Result = 25 mg/mL

Step 4 is: (81.818 ÷ 25) = 3.27272 Result = 3.3 mL after rounding to the nearest tenth

Final answer =

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A patient has been given a prescription for levodopa-carbidopa (Sinemet) for her newly diagnosed Parkinson’s disease. She asks the nurse, “Why are there two drugs in this pill?” The nurse’s best response reflects which fact?

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Naxlex Comprehensive Predictor Exams

The nurse is caring for several clients with osteoporosis. For which client would bisphosphonates not be a good option?

Correct Answer is D

Explanation

Correct Answer is ["3.3"]

Explanation

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