Correct Answer: B

Rationale: When administering transdermal Methylphenidate, the patch should be left on for 9 hours per day to ensure optimal absorption and effectiveness of the medication. This duration helps maintain a consistent level of the drug in the child's system. Incorrect options: A) Applying one patch once per day is not the correct dosing regimen for transdermal Methylphenidate. C) The patch should not be applied to the child's waistline as it is recommended to apply it to a clean, dry area. D) Using the opened tray within 6 months is not directly related to the administration of transdermal Methylphenidate.

Correct Answer: D

Rationale: In severe Aspirin toxicity, respiratory depression can occur due to increasing respiratory acidosis. Aspirin toxicity leads to metabolic acidosis, stimulating the respiratory center in the brain to increase the respiratory rate initially. However, as the toxicity worsens, respiratory muscle fatigue and depression can occur, resulting in respiratory depression. This can lead to hypoxia, respiratory failure, and ultimately, respiratory arrest.

Correct Answer: C

Rationale: The correct instruction for taking Lovastatin is to take it at bedtime. Cholesterol production in the liver is highest at night, so taking Lovastatin at bedtime aligns with the body's natural rhythm and maximizes its effectiveness.

Correct Answer: C

Rationale: The interaction between oxycodone and ibuprofen results in an increase in the expected therapeutic effect of both medications. Oxycodone is a narcotic analgesic, while ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID). They work through different mechanisms but complement each other in pain management. When taken together, they can enhance the pain-relieving effects of each other, providing better pain relief for the client.

Correct Answer: A

Rationale: Performing immediate gastric lavage is the appropriate action for a client with severe lithium toxicity, indicated by a plasma lithium level of 2.1 mEq/L. Gastric lavage can help reduce the client's lithium level by removing the unabsorbed drug from the stomach.