The nurse is caring for a client who has been taking phenytoin (Dilantin) for several years to control tonic-clonic seizures. The client tells the nurse that he wants to stop taking the medication because it makes his gums swell and bleed. What is the most appropriate response by the nurse?

This is because phenobarbital, a medication used to treat seizures, can cause serious side effects on the respiratory system, such as weak or shallow breathing, apnea, respiratory arrest, and death². Respiratory depression is more likely to occur in patients who are elderly, debilitated, or have underlying lung disease². The nurse should monitor the patient's respiratory rate, oxygen saturation, and level of consciousness, and be prepared to administer oxygen or mechanical ventilation if needed³.

Choice B is wrong because hyperglycemia is not a common or serious adverse effect of phenobarbital. Phenobarbital does not affect blood glucose levels directly, but it may interfere with the metabolism of some oral antidiabetic drugs, such as sulfonylureas. Therefore, patients who take both phenobarbital and antidiabetic drugs may need to adjust their doses or monitor their blood glucose more frequently.

Choice C is wrong because hypertension is not a common or serious adverse effect of phenobarbital. Phenobarbital may cause hypotension or orthostatic hypotension in some patients, especially when given intravenously or in high doses². The nurse should monitor the patient's blood pressure and heart rate, and avoid sudden changes in position³.

Choice D is wrong because insomnia is not a common or serious adverse effect of phenobarbital. Phenobarbital is a barbiturate that has sedative and hypnotic properties. It may cause drowsiness, dizziness, lethargy, and impaired cognition in some patients². The nurse should advise the patient to avoid driving or operating machinery while taking phenobarbital, and to avoid alcohol and other CNS depressants³.

This statement accurately describes the action of amantadine, which is a medication that has both antiviral and antiparkinsonian effects. The mechanism of action of amantadine in the treatment of parkinsonism is not fully understood, but it may involve increasing dopamine release in the brain, stimulating norepinephrine response, or activating dopaminergic receptors¹². The other choices are incorrect for the following reasons:

- B. "Dopamine in the central nervous system is decreased". This statement is incorrect because amantadine does not decrease dopamine levels, but rather enhances them. Decreasing dopamine levels would worsen the symptoms of parkinsonism, which are caused by a deficiency of dopamine in the basal ganglia.

- C. "Acetylcholine in the central nervous system is increased". This statement is incorrect because amantadine does not affect acetylcholine levels or activity. Acetylcholine is another neurotransmitter that is involved in the regulation of movement and cognition. Increasing acetylcholine levels would have anticholinergic effects, such as dry mouth, blurred vision, constipation, and confusion.

- D. "Acetylcholine in the central nervous system is decreased". This statement is incorrect because amantadine does not affect acetylcholine levels or activity. Decreasing acetylcholine levels would have cholinergic effects, such as salivation, lacrimation, urination, and diarrhea.