Share This Link

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.

- **"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.

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.

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 A is wrong because phenobarbital does not inhibit carbonic anhydrase in the brain. Carbonic anhydrase is an enzyme that catalyzes the reversible reaction of carbon dioxide and water to form bicarbonate and protons. Inhibiting carbonic anhydrase can reduce the production of cerebrospinal fluid, but it does not prevent seizures. In fact, some carbonic anhydrase inhibitors, such as acetazolamide, are used as anticonvulsants for certain types of seizures⁵.

Choice B is wrong because phenobarbital does not inhibit GABA transaminase in the brain. GABA transaminase is an enzyme that degrades GABA into succinic semialdehyde and glutamate. Inhibiting GABA transaminase can increase the availability of GABA and prevent seizures. Some anticonvulsants, such as vigabatrin, work by this mechanism⁵.

Choice D is wrong because phenobarbital does not enhance the binding of glutamate to its receptors in the brain. Glutamate is the major excitatory neurotransmitter in the brain and binds to various types of receptors, such as NMDA, AMPA, and kainate receptors. Enhancing the binding of glutamate to its receptors would increase the depolarization and excitability of neurons and trigger seizures. Some anticonvulsants, such as felbamate and topiramate, work by blocking glutamate receptors⁵.