Pharmacology · chapter 12 · Anticonvulsant Drugs and Drugs to Treat Epilepsy, Migraine Headaches, and Intracranial Emergencies
Epilepsy and Anticonvulsant Drugs
The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.
Key points
Seizure versus epilepsy
Seizures are a sudden and temporary disturbance in the electrical activity of the brain that can cause changes in behavior, movement, or consciousness. Epilepsy, on the other hand, is a neurological disorder characterized by recurrent seizures.
Review every medication the client takes
Therefore, the nurse should thoroughly evaluate all the medications a client is currently taking, including over-the-counter products and herbal supplements.
Hydantoin adverse effects
Although hydantoins can be effective in controlling seizures, they can have significant adverse effects, including dizziness, drowsiness, and coordination problems. Long-term use can lead to complications such as osteoporosis and gingival hyperplasia (gum overgrowth).
Trough levels
Trough levels indicate the lowest concentration of the drug in the blood and are typically measured just before the client’s next scheduled dose.
Phenytoin therapeutic range
The goal is to achieve a therapeutic effect without clinical signs of toxicity, which is more likely to occur when serum total concentrations range between 10 and 20 mcg/mL.
Barbiturates: addiction, tolerance, overdose
Notably, barbiturates have a high risk of addiction, tolerance, and overdose, so their use has declined in favor of safer alternatives.
Phenobarbital lowers other drug levels
Phenobarbital is the most used barbiturate for the treatment of seizures. Therapeutic drug monitoring is required. Phenobarbital is also a strong CYP inducer and will decrease the concentration of many other drugs.
Benzodiazepine contraindications
Benzodiazepines are contraindicated in hypersensitivity to the drug and its properties, in angle closure glaucoma, and with concomitant use with opioids.
Benzodiazepines with opioids
Benzodiazepines—when used in combination with opioid drugs—may depress the central nervous system, causing serious adverse effects including respiratory depression and death.
Giving IV lorazepam and its reversal
Intravenous administration of lorazepam should be via slow intravenous push (2 mg/minute) for active seizures. If respiratory depression develops, flumazenil should be used as a competitive antagonist to reverse the effects of the lorazepam (Ghiasi et al., 2023).
Carbamazepine boxed warning
Carbamazepine may cause serious adverse effects including aplastic anemia and agranulocytosis. Carbamazepine may cause serious dermatologic reactions including toxic epidermal necrolysis and Stevens-Johnson syndrome.
Valproic acid therapeutic range
Generally, the total serum concentration of valproic acid is maintained between 50 and 100 µg/mL for epilepsy.
Valproate boxed warning
Valproates may cause serious adverse effects including pancreatitis, abnormal bleeding, and clotting times. Valproates are known to cause abnormalities in the development of the fetus.
Do not smoke or drink alcohol
Do not use alcohol or smoke—alcohol can depress the central nervous system, and smoking may cause vasoconstriction, resulting in reduced elimination of the drug.
Terms to know
- idiopathic seizure
- Sometimes the cause of a seizure cannot be identified—a condition called an idiopathic seizure (Centers for Disease Control and Prevention, 2020b, 2020c).
- Absence seizures
- Absence seizures, also known as petit mal seizures, cause rapid blinking or a few seconds of staring into space.
- Tonic-clonic seizures
- Tonic-clonic seizures involve both tonic (muscle stiffness) and clonic (muscle jerking) phases and are commonly known as grand mal seizures.
- Secondary generalized seizures
- Secondary generalized seizures begin in one part of the brain but then spread to the other side.
- Dependence
- Dependence occurs when someone uses high doses of a substance and they cannot function normally without the use of the substance.
Practice questions
Stuck on select-all-that-apply? How to take them one option at a time.
The graded version needs JavaScript. Every question is below anyway, with the answer and why.
Every question here, with the answer
A nurse must draw a trough phenytoin level for a client with epilepsy. When should the blood be drawn?
- Any time, because timing does not matter for phenytoin.
- Shortly after the dose is given.
- At the same time the dose is given.
- Just before the next scheduled dose.
Answer: Just before the next scheduled dose.
A trough level shows the lowest drug concentration and is drawn just before the next scheduled dose. Samples after the dose reflect peak levels, which show the threshold for dose-related adverse effects, and timing does matter.
A client with an active seizure receives IV lorazepam and then develops slow, shallow breathing. Which drug does the nurse anticipate giving?
- Flumazenil
- Phenobarbital
- Phenytoin
- Additional lorazepam
Answer: Flumazenil
If respiratory depression develops after lorazepam, flumazenil is used as a competitive antagonist to reverse it. More lorazepam or phenobarbital would deepen CNS and respiratory depression, and phenytoin does not reverse lorazepam.
A client is being discharged on an anticonvulsant drug. Which teaching points should the nurse include? Select all that apply.
- Do not skip doses or stop the drug on your own.
- Keep scheduled blood tests.
- Avoid alcohol and smoking.
- Stop the drug once you have been seizure-free for a month.
- Report a new skin rash to the provider.
Answer: Do not skip doses or stop the drug on your own., Keep scheduled blood tests., Avoid alcohol and smoking., Report a new skin rash to the provider.
Clients take anticonvulsants as prescribed without skipping or stopping, avoid alcohol and smoking, keep laboratory testing because many drugs need blood-level monitoring, and report rash as a possible adverse reaction. Stopping without the provider's direction is exactly what the teaching warns against.
A client who takes an opioid for chronic pain is admitted after a seizure. The provider considers a benzodiazepine for seizure control. Which concern should the nurse raise?
- The combination can cause respiratory depression and death.
- Benzodiazepines cause gingival hyperplasia.
- Benzodiazepines lower opioid blood levels.
- Opioids block the anticonvulsant effect completely.
Answer: The combination can cause respiratory depression and death.
Benzodiazepines are contraindicated with opioids, and the boxed warning states the combination may depress the CNS and cause respiratory depression and death. Gingival hyperplasia is a hydantoin effect, and the other interactions are not described in the section.
A client with a history of bone marrow depression is being considered for seizure therapy. Which drugs does the section list as contraindicated with bone marrow depression or suppression? Select all that apply.
- Carbamazepine
- Valproic acid
- Ethosuximide
- Lorazepam
- Levetiracetam
Answer: Carbamazepine, Valproic acid
Carbamazepine is contraindicated in individuals with previous bone marrow depression, and valproic acid lists bone marrow depression among its contraindications. The contraindications given for levetiracetam, lorazepam and ethosuximide do not include bone marrow depression.
A client taking valproic acid reports severe abdominal pain. Why is this finding a priority?
- It shows the drug level is below 50 µg/mL.
- It is an expected sign of the drug working.
- It means the client is developing gingival hyperplasia.
- Valproates can cause pancreatitis.
Answer: Valproates can cause pancreatitis.
Valproates carry a boxed warning for pancreatitis, and the drug should be stopped if acute pancreatitis develops. Abdominal pain does not indicate a low level or a therapeutic effect, and gingival hyperplasia is linked to hydantoins.
Where every quote comes from
Section 12.1 Epilepsy and Anticonvulsant Drugs of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.
The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.