Questions: Allow 2 to 4 weeks for full therapeutic effects.

The answer is the third one: Allow 2 to 4 weeks for full therapeutic effects.

Explanation for each option:

• Take the medication with grapefruit juice to increase absorption: This is incorrect. Grapefruit juice can interact with many medications, including buspirone, and can lead to increased levels of the drug in the bloodstream, potentially causing adverse effects.

• Use the medication only as needed for anxiety: This is incorrect. Buspirone is typically prescribed to be taken on a regular schedule, not on an as-needed basis, because it needs to build up in the system to be effective.

• Allow 2 to 4 weeks for full therapeutic effects: This is correct. Buspirone often takes several weeks to achieve its full therapeutic effect, so patients should be advised to continue taking it as prescribed and not expect immediate relief.

• Take the medication on an empty stomach: This is incorrect. Buspirone can be taken with or without food, but it is important to be consistent in how it is taken to maintain stable blood levels of the medication.

Summary: The nurse should instruct the client to allow 2 to 4 weeks for full therapeutic effects of buspirone.