Correct Answer: A

Rationale: The correct answer is A: Ondansetron. Ondansetron is a commonly used antiemetic for managing nausea and vomiting in clients undergoing chemotherapy. It works by blocking serotonin to reduce these symptoms effectively. Metoclopramide (choice B) is another antiemetic but is more commonly used for gastric motility disorders. Promethazine (choice C) is an antihistamine with antiemetic properties, but ondansetron is often preferred for chemotherapy-induced nausea and vomiting due to its efficacy and fewer side effects. Lorazepam (choice D) is a benzodiazepine used for anxiety and insomnia, not typically for managing nausea and vomiting in this context.

Correct Answer: C

Rationale: Phenytoin, an antiarrhythmic and anticonvulsant medication, is also used off-label for treating neuropathic pain. While its primary indications are for managing heart rhythm disorders and seizures, it has shown efficacy in managing neuropathic pain, expanding its clinical utility. Choices A, B, and D are incorrect as phenytoin is not commonly used for headaches, cold remedies, or antianxiety purposes.

Correct Answer: C

Rationale: The correct instruction for taking levothyroxine is to take the medication first thing in the morning on an empty stomach. This timing is important for optimal absorption of the medication. Taking levothyroxine with food or at bedtime can interfere with its absorption. Milk and other foods, as well as certain medications, can reduce the effectiveness of levothyroxine by interfering with its absorption, so it should be taken separately from these items. Therefore, the correct choice is to take the medication first thing in the morning on an empty stomach.

Correct Answer: D

Rationale: When administering Phenytoin, monitoring the patient's behavior is important to assess for any changes that may indicate adverse effects. Monitoring therapeutic blood levels helps ensure the medication is within the effective range and not causing toxicity. Additionally, being vigilant for signs of Stevens-Johnson syndrome, a severe skin reaction associated with Phenytoin use, is crucial for early detection and intervention. Therefore, monitoring behavior, therapeutic blood levels, and for signs of Stevens-Johnson syndrome are all essential when administering Phenytoin.

Correct Answer: C

Rationale: Thrombocytopenia, a decrease in platelet count, is a known adverse effect associated with heparin therapy. It can lead to an increased risk of bleeding and should be closely monitored during treatment. Choices A, B, and D are incorrect. Hypertension is not typically associated with heparin use; hyperglycemia is not a common adverse effect of heparin; leukopenia is not a primary side effect of heparin therapy.