Correct Answer: B

Rationale: Phenytoin is primarily used as an anticonvulsant to prevent and control seizures. It works by stabilizing electrical activity in the brain, making it effective in managing conditions like epilepsy. Antidiabetic medications are used to regulate blood sugar levels, mood stabilizers help manage mood disorders, and antianxiety agents are used to reduce anxiety symptoms, none of which are the primary therapeutic action of Phenytoin.

Correct Answer: B

Rationale: Naloxone is the drug of choice for managing opioid overdoses as it competitively antagonizes opioid receptors, reversing the respiratory depression and sedation caused by opioids. It is essential in the emergency treatment of opioid overdose to prevent fatal outcomes.

Correct Answer: B

Rationale: Clients with conditions like pernicious anemia or other causes of vitamin B12 deficiency may require lifelong cyanocobalamin supplementation to prevent deficiency. This is because their bodies are unable to absorb B12 from dietary sources adequately, necessitating ongoing injections to maintain optimal B12 levels.

Correct Answer: A

Rationale: Labetalol should be taken with food to increase absorption and reduce the risk of orthostatic hypotension. Taking it with food helps in better absorption and minimizes the potential drop in blood pressure when standing up, which can occur with this medication.

Correct Answer: B

Rationale: The correct instruction for the nurse to include when educating a client with a new prescription for Atorvastatin to treat Hyperlipidemia is to avoid drinking grapefruit juice. Grapefruit juice can increase the blood levels of atorvastatin, leading to an elevated risk of serious side effects such as liver damage and muscle problems. It is essential for the client to be aware of this potential interaction and to follow the nurse's advice to avoid grapefruit juice while taking Atorvastatin.