Correct Answer: A

Rationale: The nurse should check the client's vital signs first because nausea and weakness can be signs of digoxin toxicity. Vital signs can provide immediate information on the client's condition and help guide further interventions.

Correct Answer: A

Rationale: Caffeine can increase the risk of theophylline toxicity as it competes for the same metabolic pathways, so clients should avoid consuming caffeine while on theophylline to prevent adverse effects.

Correct Answer: B

Rationale: Maintaining a consistent sodium intake is crucial when taking Lithium to help regulate lithium levels in the body and prevent toxicity. Sodium levels can impact the effectiveness and safety of Lithium therapy, making it important to advise clients to maintain a stable sodium intake.

Correct Answer: B

Rationale: Nitroglycerin patches should be removed for 12 hours each day to prevent the development of tolerance. This nitrate-free interval ensures the medication remains effective in managing angina.

Correct Answer: B

Rationale: The correct statement the nurse should include is that the client may experience a headache while taking Ondansetron. Headache is a common side effect of this medication, and clients need to be informed about this potential adverse reaction to enhance their understanding and management of side effects.