Copyright © 2017, Elsevier Inc. All rights reserved. Chapter 14 Antiepileptic Drugs Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Epilepsy Seizure Brief episode of abnormal electrical activity in nerve cells of the brain Convulsion Involuntary spasmodic contractions of any or all voluntary muscles throughout the body, including skeletal, facial, and ocular muscles Epilepsy Chronic, recurrent pattern of seizures Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Epilepsy (Cont.) Primary (idiopathic) Cause cannot be determined Roughly 50% of epilepsy cases Secondary (symptomatic) Distinct cause is identified Trauma, infection, cerebrovascular disorder Copyright © 2017, Elsevier Inc. All rights reserved.

Classification of Epilepsy Generalized onset seizures Formerly known as grand mal seizures Tonic-clonic seizures Absence seizures Partial onset seizures Simple (formerly known as petit mal seizures) Complex Secondary generalized tonic-clonic Unclassified seizures Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Status Epilepticus Multiple seizures occur with no recovery between them Result: hypotension, hypoxia, brain damage, and death True medical emergency Copyright © 2017, Elsevier Inc. All rights reserved.

Antiepileptic Drugs (AEDs) Also known as anticonvulsants Goals of therapy To control or prevent seizures while maintaining a reasonable quality of life To minimize adverse effects and drug-induced toxicity AED therapy is usually lifelong Combination of drugs may be used Copyright © 2017, Elsevier Inc. All rights reserved.

Antiepileptic Drugs (Cont.) Single-drug therapy is started before multiple-drug therapy is tried. Serum drug concentrations must be measured. Therapeutic drug monitoring Serum concentrations of phenytoin, phenobarbital, carbamazepine, and primidone correlate better with seizure control and toxicity than do those of valproic acid, ethosuximide, and clonazepam. Copyright © 2017, Elsevier Inc. All rights reserved.

Antiepileptic Drugs (Cont.) Antiepileptic drugs traditionally used to manage seizure disorders include: Barbiturates Hydantoins Iminostilbenes plus valproic acid Second- and third-generation antiepileptics Copyright © 2017, Elsevier Inc. All rights reserved.

Mechanism of Action and Drug Effects Exact mechanism of action is not known. Pharmacologic effects: Reduce nerve’s ability to be stimulated Suppress transmission of impulses from one nerve to the next Decrease speed of nerve impulse conduction within a neuron Copyright © 2017, Elsevier Inc. All rights reserved.

Antiepileptic Drugs: Indications Prevention or control of seizure activity Long-term maintenance therapy for chronic, recurring seizures Acute treatment of convulsions and status epilepticus Other uses Copyright © 2017, Elsevier Inc. All rights reserved.

Antiepileptic Drugs: Adverse Effects Numerous adverse effects; vary per drug Adverse effects often necessitate a change in medication Black box warning as of 2008 Suicidal thoughts and behavior Long-term therapy with phenytoin (Dilantin) may cause gingival hyperplasia, acne, hirsutism, and Dilantin facies. Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved. Antiepileptic Drugs valproic acid gabapentin (Neurontin) lamotrigine (Lamictal) felbamate (Felbatol) levetiracetam (Keppra) topiramate (Topamax) zonisamide (Zonegran) tiagabine (Gabitril) Copyright © 2017, Elsevier Inc. All rights reserved.

Antiepileptic Drugs (Cont.) pregabalin (Lyrica) permapanel (Fycompa) ezogabine (Potiga) vigabatrin (Sabril) Copyright © 2017, Elsevier Inc. All rights reserved.

Barbiturates: Phenobarbital and Primidone (Mysoline) Primidone is metabolized in the liver to phenobarbital. Most common adverse effect: sedation Therapeutic effects: serum drug levels of 10 to 40 mcg/mL Contraindications: known drug allergy, porphyria, liver or kidney impairment, and respiratory illness Adverse effects: cardiovascular, CNS, gastrointestinal (GI), and dermatologic reactions Copyright © 2017, Elsevier Inc. All rights reserved.

Hydantoins: Phenytoin Phenytoin (Dilantin) has been used as a first-line drug for many years and is the prototypical drug. Adverse effects: gingival hyperplasia, acne, hirsutism, Dilantin facies, and osteoporosis Therapeutic drug levels are usually 10 to 20 mcg/mL. Copyright © 2017, Elsevier Inc. All rights reserved.

Hydantoins: Phenytoin (Cont.) Intravenous (IV) administration Very irritating to veins Slow IV directly into a large vein through a large-gauge (20-gauge or larger) venous catheter Diluted in normal saline (NS) for IV infusion Filter must be used Saline flush Copyright © 2017, Elsevier Inc. All rights reserved.

Hydantoins: Fosphenytoin (Cerebyx) Injectable prodrug of phenytoin Water-soluble phenytoin derivative that can be given intramuscularly or intravenously—by IV push or continuous infusion—without causing burning on injection associated with phenytoin Adverse effects Copyright © 2017, Elsevier Inc. All rights reserved.

Carbamazepine (Tegretol) Second most commonly prescribed antiepileptic drug in the United States after phenytoin Autoinduction of hepatic enzymes Adverse reactions Drug interactions Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question A patient in a long-term care facility has a new order for carbamazepine (Tegretol) for seizure management. The nurse monitors for autoinduction, which will result in toxic levels of carbamazepine (Tegretol). lower than expected drug levels. gingival hyperplasia. cessation of seizure activity. Correct answer: B Rationale: Carbamazepine (Tegretol) is associated with autoinduction of hepatic enzymes. Autoinduction is a process in which, over time, a drug stimulates the production of enzymes that enhance its own metabolism, which leads to lower than expected drug concentrations. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Oxcarbazepine (Trileptal) Chemical analogue of carbamazepine Precise mechanism of action has not been identified Adverse reactions Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Ethosuximide (Zarontin) Used in the treatment of uncomplicated absence seizures Not effective for secondary generalized tonic-clonic seizures Contraindication: known allergy Adverse effects: GI and CNS effects Drug interactions: hepatic enzyme–inducing drugs Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Copyright © 2017, Elsevier Inc. All rights reserved. Miscellaneous Drugs ezogabine (Potiga) perampanel (Fycompa) vigabatrin (Sabril) eslicarbazepine (Aptiom) Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Gabapentin (Neurontin) Chemical analogue of GABA, a neurotransmitter that inhibits brain activity Believed to work by increasing the synthesis and synaptic accumulation of GABA between neurons Contraindication: known drug allergy Adverse effects: CNS and GI symptoms Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Lamotrigine (Lamictal) Also used for the treatment of bipolar disorder Contraindications: drug allergy Common adverse effects: relatively minor CNS and GI symptoms and possible Stevens-Johnson syndrome Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Levetiracetam (Keppra) Adjunct therapy for partial seizures with and without secondary generalization Contraindication: known drug allergy Mechanism of action: unknown Adverse effects: generally well tolerated, CNS No drug interactions Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Copyright © 2017, Elsevier Inc. All rights reserved. Pregabalin (Lyrica) Schedule V controlled substance Indication: adjunct therapy for partial seizures Most common uses: neuropathic pain, postherpetic neuralgia, and fibromyalgia Contraindication: known drug allergy Adverse drug reactions: primarily CNS related Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Audience Response System Question The nurse is assessing the current medication list of a newly admitted patient. The drug gabapentin (Neurontin) is listed, but the patient states that he does not have any problems with seizures. The nurse suspects that the patient is unaware of his own disease history. has been taking his wife’s medication by mistake. may be taking this drug for neuropathic pain. is reluctant to admit to having a seizure disorder. Correct answer: C Rationale: Gabapentin is commonly used to treat neuropathic pain. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Copyright © 2017, Elsevier Inc. All rights reserved. Nursing Implications Assessment Health history, including current medications Drug allergies Liver function studies, complete blood count Baseline vital signs Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question Before a patient is to receive phenytoin (Dilantin), the nurse practitioner orders lab work. Which lab result is of greatest concern? High white blood cell count Low serum albumin levels Low platelet levels High hemoglobin levels Correct answer: B Rationale: Phenytoin is highly bound to plasma proteins. If serum albumin levels are low, more free drug will be available to exert an effect, and toxicity may occur. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Nursing Implications (Cont.) Oral drugs Take regularly, same time each day. Take with meals to reduce GI upset. Do not crush, chew, or open extended-release forms. If patient is NPO for a procedure, contact prescriber regarding AED dosage. Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question A patient with unstable epilepsy is receiving IV doses of phenytoin (Dilantin). The latest drug level is 12 mcg/mL. Which administration technique will the nurse use? Administer the drug by rapid IV push. Infuse slowly, not exceeding 50 mg/min. Mix the medication with dextrose solution. Administer via continuous infusion. Correct answer: B Rationale: Phenytoin should be mixed only with normal saline, and it should be given by slow IV infusion (but not as a continuous infusion). Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Nursing Implications (Cont.) Intravenous forms Follow manufacturer’s recommendations for IV delivery—usually given slowly. Monitor vital signs during administration. Avoid extravasation of fluids. Use only normal saline with IV phenytoin (Dilantin). Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Teach patients to keep a journal to monitor: Response to AED Seizure occurrence and descriptions Adverse effects Instruct patients to wear a medical alert tag or ID. AEDs should not be discontinued abruptly. Follow driving recommendations. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.) Teach patients that therapy is long term and possibly lifelong (not a cure). Monitor for therapeutic effects: Decreased or absent seizure activity Monitor for adverse effects: Mental status changes, mood changes, changes in level of consciousness or sensorium Eye problems, visual disorders Sore throat, fever (blood dyscrasias may occur with hydantoins) Many others Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question Which information will the nurse provide to the patient who is receiving antiepileptic drug therapy? If you feel sleepy when taking the drug, decrease the dose by half. Take the drug on an empty stomach. Call your health care provider if you experience a sore throat or fever. Patients with epilepsy are not able to hold a job and work, so you should apply for benefits. Correct answer: C Rationale: To prevent complications, patients should be taught to call the health care provider if they experience fever, sore throat, excessive bleeding or bruising, and new onset of nosebleeds. Drowsiness is a common side effect of these drugs; the dose should never be altered without consulting the prescriber. These medications should be taken with food to decrease GI upset. Most patients with seizure disorders are able to work and are protected by the Americans with Disabilities Act. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.