The nurse should monitor the client for gingival hyperplasia, which is an overgrowth of the gums that can occur as an adverse effect of phenytoin¹². Gingival hyperplasia can cause bleeding, inflammation, and infection of the gums, and may interfere with chewing and oral hygiene¹². The nurse should advise the client to brush and floss their teeth regularly, and to see a dentist for regular check-ups and cleaning¹².

Choice B is wrong because hypertension, or high blood pressure, is not a common or serious adverse effect of phenytoin¹³. Phenytoin may actually lower blood pressure in some cases, especially when given intravenously¹⁴. The nurse should monitor the client's blood pressure before and during phenytoin therapy, and report any significant changes to the prescriber¹⁴.

Choice C is wrong because diarrhea is not a common or serious adverse effect of phenytoin¹³. Phenytoin may cause constipation in some people, which can be relieved by increasing fluid and fiber intake, and using laxatives if needed¹⁵. The nurse should ask the client about their bowel habits and provide appropriate interventions as needed¹⁵.

Choice D is wrong because tachycardia, or fast heart rate, is not a common or serious adverse effect of phenytoin¹³. Phenytoin may cause bradycardia, or slow heart rate, in some cases, especially when given intravenously or in high doses¹⁴. The nurse should monitor the client's heart rate and rhythm before and during phenytoin therapy, and report any significant changes to the prescriber¹⁴.

- **"I should stop taking these medications if I have a rash or fever."** This statement is incorrect and indicates a need for further teaching because the client should not stop taking anticonvulsant medications abruptly, as this can cause withdrawal symptoms and increase the risk of seizures¹². The client should contact their healthcare provider if they have a rash or fever, as these could be signs of an allergic reaction or infection, but they should not stop the medication without medical advice¹².

- **"I should have my blood levels checked regularly to make sure I am taking the right dose."** This statement is correct for some anticonvulsant medications, such as phenytoin, carbamazepine, and valproate, but not for others, such as levetiracetam, lamotrigine, and gabapentin¹³. The client should ask their healthcare provider which medications require blood level monitoring and how often they need to have it done¹³.

The other statements by the client are correct and do not indicate a need for further teaching:

- **"I should avoid drinking alcohol while taking these medications."** This statement is correct because alcohol can interact with anticonvulsant medications and increase their side effects, such as drowsiness, dizziness, and impaired coordination¹². Alcohol can also lower the seizure threshold and trigger seizures in some people¹².

- **"I should take these medications at the same time every day."** This statement is correct because taking anticonvulsant medications at the same time every day helps maintain a steady level of the drug in the blood and prevent seizures¹². The client should follow the prescribed schedule and dosage of their medication and not miss or skip any doses¹².

- **"I should not drive or operate heavy machinery until I know how these medications affect me."** This statement is correct because anticonvulsant medications can cause side effects that impair the client's ability to drive or operate heavy machinery, such as blurred vision, confusion, fatigue, and poor

The correct answer is choice

A. "It blocks sodium channels in your brain cells, which reduces their excitability and prevents seizures."

The nurse should say: "Carbamazepine works by blocking sodium channels in your brain cells, which reduces their excitability and prevents seizures." This is the most accurate and simple explanation of the mechanism of action of carbamazepine⁴.

The other choices are incorrect and should not be said by the nurse:

- **"It enhances the activity of GABA in your brain, which inhibits the transmission of nerve impulses and prevents seizures."** This is not how carbamazepine works. This is a description of the mechanism of action of some other anticonvulsants, such as benzodiazepines and barbiturates¹².

- **"It modulates the activity of NMDA receptors in your brain, which reduces the influx of calcium and prevents seizures."** This is not how carbamazepine works. This is a description of the mechanism of action of some other anticonvulsants, such as felbamate and topiramate¹².

- **"It facilitates the opening of potassium channels in your brain cells, which stabilizes their membrane potential and prevents seizures."** This is not how carbamazepine works. This is a description of the mechanism of action of some other anticonvulsants, such as ezogabine and retigabine¹².

Valproic acid can interact with warfarin and increase the risk of bleeding by inhibiting the metabolism of warfarin and displacing it from plasma protein binding sites¹. The nurse should monitor the client's international normalized ratio (INR) and prothrombin time (PT) and adjust the warfarin dose accordingly.

Choice B. Metformin is wrong because valproic acid does not have a significant interaction with metformin. Metformin is an oral antidiabetic drug that lowers blood glucose levels by decreasing hepatic glucose production and increasing insulin sensitivity².

Choice C. Ibuprofen is wrong because valproic acid does not have a significant interaction with ibuprofen. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that reduces inflammation, pain, and fever by inhibiting cyclooxygenase enzymes².

Choice D. Levothyroxine is wrong because valproic acid does not have a significant interaction with levothyroxine. Levothyroxine is a synthetic thyroid hormone that replaces the deficient endogenous hormone in hypothyroidism².

Choice A is correct because diazepam is a benzodiazepine that can cause respiratory depression, especially when given intravenously. The nurse should monitor the client's respiratory rate and oxygen saturation and be prepared to provide respiratory support if needed²⁴.

- Choice B is correct because diazepam should be diluted with normal saline or dextrose 5% in water before administration to prevent venous irritation and thrombophlebitis. The concentration of diazepam should not exceed 5 mg/mL²⁴.

- Choice C is correct because diazepam should be injected slowly over at least 3 minutes to avoid adverse effects such as hypotension, bradycardia, cardiac arrest, or apnea. The maximum rate of injection is 5 mg/min²⁴.

- Choice D is correct because diazepam is incompatible with many other drugs and solutions, and can precipitate or adsorb to plastic tubing. The nurse should flush the IV line with normal saline before and after administration to prevent drug interactions and ensure complete delivery of the medication²⁴.

- Choice E is wrong because repeating the dose of diazepam every 15 minutes until seizure activity stops is not recommended. Diazepam has a short duration of action and can accumulate in the body with repeated doses, increasing the risk of toxicity and respiratory depression. If seizures persist after the initial dose of diazepam, the nurse should start emergency IV antiepileptic drug therapy with levetiracetam, sodium valproate, or phenytoin³⁶.