Chapter 24: Drugs for Seizure Disorders

Adverse effects of lamotrigine (Lamictal)

RISK FOR SUICIDE, dizziness, diplopia, blurred vision, nausea, vomiting, headache severe skin reactions, and aseptic meningitis

Why is drowsiness a side effect of antiepileptic drugs?

we are suppressing the firing of the neurons in the brain (side effect is worse when they first initiate the drug)

Phenytoin (Dilantin) therapeutic level

10-20 mcg/mL

Phenytoin half life

8-60 hours

Status epilepticus

A condition in which seizures recur every few minutes or last more than 30 minutes.

The nurse is conducting discharge teaching related to a new prescription for phenytoin [Dilantin]. Which statements are appropriate to include in the teaching for this patient and family? (Select all that apply.) A. "Be sure to call the clinic if you or your family notice increased anxiety or agitation." B. "You may have some mild sedation. Do not drive until you know how this drug will affect you." C. "This drug may cause easy bruising. If you notice this, call the clinic immediately." D. "It is very important to have good oral hygiene and to visit your dentist regularly." E. "You may continue to have wine with your evening meals, but only in moderation."

A, B and D Rationale: Patients taking an antiepileptic drug are at increased risk for suicidal thoughts and behavior beginning early in their treatment. The U.S. Food and Drug Administration (FDA) advises that patients, families, and caregivers be informed of the signs that may precede suicidal behavior and be encouraged to report these immediately. Mild sedation can occur in patients taking phenytoin, even at therapeutic levels. Carbamazepine, not phenytoin, increases the risk for hematologic effects, such as easy bruising. Phenytoin causes gingival hyperplasia in about 20% of patients who take it; dental hygiene is important. Patients receiving phenytoin should avoid alcohol and other central nervous system depressants, because they have an additive depressant effect.

The nurse is caring for a patient receiving phenytoin [Dilantin] for the treatment of tonic-clonic seizures. Which symptoms, if present, would indicate an adverse effect of this drug? (Select all that apply.) A. Swollen, tender gums B. Measles-like rash C. Productive cough D. Unusual hair growth E. Nausea and vomiting

A, B, and D Rationale: Adverse effects associated with phenytoin at therapeutic doses include mild sedation, gingival hyperplasia (swollen, tender gums), morbilliform (measles-like) rash, cardiovascular effects, and other effects, such as hirsutism (unusual hair growth) and interference with vitamin D metabolism.

The nurse is caring for a pt who is taking phenytoin (Dilantin). Which medication, if ordered by the physician, should the nurse question? A. cimetidine (Tagamet) B. captopril (Capoten) C. pantoprazole (Protonix) D. ondansetron (Zofran)

A. Rationale: Cimetidine will elevate phenytoin levels by reducing the rate at which it is metabolized. Phenytoin levels may increased to toxic levels. Make sure that the pt discusses all meds and OTC meds they take.

Which instruction would be inappropriate to include in the teaching plan for a patient started on carbamazepine [Tegretol]? A. "Take the medication with a glass of grapefruit juice each morning." B. "Notify the physician if you are gaining weight or your legs are swollen." C. "Nausea, vomiting, and indigestion are common side effects of carbamazepine." D. "Have liver function tests performed on a routine basis."

A. Rationale: Grapefruit juice can inhibit the metabolism of carbamazepine, possibly leading to increased plasma drug levels; therefore, it should be avoided. Carbamazepine can inhibit renal excretion of water by promoting increased secretion of antidiuretic hormone. Weight gain and swollen extremities can be a sign of water retention and should be reported to the physician. Nausea, vomiting, and indigestion are common adverse effects of valproic acid, and the patient should be made aware of them. Liver function studies are monitored for patients taking valproic acid because of the risk of liver toxicity.

The nurse receives a laboratory report indicating that the phenytoin [Dilantin] level for the patient seen in the clinic yesterday is 16 mcg/mL. Which intervention is most appropriate? A. Continue as planned, because the level is within normal limits. B. Tell the patient to hold today's dose and return to the clinic. C. Consult the prescriber to recommend an increased dose. D. Have the patient call 911 and meet him/her in the emergency department.

A. Rationale: The therapeutic range for phenytoin is 10 to 20 mcg/mL. Because this level is within normal limits, the nurse would continue with the routine plan of care.

The nurse suspects that a female patient is experiencing phenytoin toxicity if which manifestation is noted? (Select all that apply.) A. The patient complains of excessive facial hair growth. B. The patient is walking with a staggering gait. C. The patient's gums are swollen, tender, and bleed easily. D. The patient complains of double vision. E. The nurse observes rapid back-and-forth movement of the patient's eyes.

B, D, and E Rationale: Manifestations of phenytoin toxicity can occur when plasma levels are higher than 20 mcg/mL. Nystagmus (back-and-forth movement of the eyes) is a common indicator of toxicity, as are ataxia (staggering gait), diplopia (double vision), sedation, and cognitive impairment. Hirsutism (excess hair growth in unusual places) and gingival hyperplasia (swollen, tender, bleeding gums) are adverse effects of phenytoin.

Which statement made by a female patient newly diagnosed with complex partial seizures and starting treatment with valproic acid indicates a need for further teaching by the nurse? A. "The medication should not make me feel sleepy." B. "I should take the medication on an empty stomach." C. "I'll need to discuss a reliable form of birth control with my gynecologist." D. "I'll call my physician immediately if I develop a yellow tint to my skin or my urine appears tea-colored."

B. Rationale: Gastrointestinal side effects, such as nausea, vomiting, and indigestion, can occur when valproic acid is taken on an empty stomach; this statement indicates that further teaching is needed. Valproic acid has minimal sedative effects, is teratogenic, and can lead to hepatotoxicity. Female patients of child-bearing age must use effective methods of birth control to prevent pregnancy and must be taught the signs of liver failure (abdominal pain, malaise, jaundice), which must be reported immediately.

A pt is newly prescribed carbamazepine (Tegretol) for seizure control. It is most important for the nurse to teach the pt to avoid which food? A. tomatoes B. grapefruit juice C. spinach D. kiwi fruit

B. Rationale: Grapefruit juice can inhibit the metabolism of carbamazepine causing plasma levels to rise.

The nurse is teaching a patient newly diagnosed with a seizure disorder about her disorder. Which statement made by the nurse best describes the goals of therapy with antiepilepsy medication? A. "With proper treatment, we can completely eliminate your seizures." B. "Our goal is to reduce your seizures to an extent that helps you live a normal life." C. "Seizure medication does not reduce seizures in most patients." D. "These drugs will help control your seizures until you have surgery."

B. Rationale: Seizure disorders are often treated successfully with medication in most patients. However, the dosages needed to completely eliminate seizures may cause intolerable side effects. Neurosurgery is indicated only for patients in whom medication therapy is unsuccessful.

Which medication should the nurse anticipate administering to a patient in convulsive status epilepticus to halt seizure activity? A. Phenytoin [Dilantin] 200 mg IV over 4 minutes B. Phenobarbital 30 mg IM C. Lorazepam [Ativan] 0.1 mg/kg IV at a rate of 2 mg/min D. Valproic acid [Depacon] 250 mg in 100 mL of normal saline infused IV over 60 minutes

C. Rationale: Intravenous benzodiazepines, such as lorazepam or diazepam, are used for abrupt termination of convulsive seizure activity. Lorazepam is preferred over diazepam because of its longer effects. Once seizures have been stopped with a benzodiazepine, phenytoin may be administered for long-term suppression. Phenytoin and valproic acid are not benzodiazepines.

The nurse is assessing a patient receiving valproic acid [Depakene] for potential adverse effects associated with this drug. What is the most common problem with this drug? A. Increased risk of infection B. Reddened, swollen gums C. Nausea, vomiting, and indigestion D. Central nervous system depression

C. Rationale: Valproic acid is generally well tolerated. Gastrointestinal effects, which include nausea, vomiting, and indigestion, are the most common problems but tend to subside with use and can be lessened by taking the medication with food. Valproic acid does not cause hematologic effects resulting in an increased risk of infection, nor does it cause gingival hyperplasia. It causes minimal sedation.

A pt is prescribed phenytoin (Dilantin) for epileptic seizures. Which of the following is the priority for pt teaching? A. teach the pt to adjust the dose according to the presence of symptoms B. tell the pt to take the medication with meals C. inform the pt about the prevention of gingival hyperplasia D. teach the pt to avoid abrupt cessation of treatment

D. Rationale: Stopping the med abruptly can cause a life threatening seizure or status epilepticus. The pt shouldn't adjust the dose without consulting the prescriber. Although teaching the pt to take the med with meals and avoid gingival hyperplasia are indicated, they aren't the priority.

Which medication can cause this acid-base disturbance: pH 7.32, paCO2 33, HCO3 20? A. Primidone [Mysoline] B. Lamotrigine [Lamictal] C. Lacosamide [Vimpat] D. Topiramate [Topamax]

D. Rationale: The arterial blood gas results reflect metabolic acidosis with partial respiratory compensation. Topiramate can cause metabolic acidosis, because it inhibits carbonic anhydrase; this increases renal excretion of bicarbonate, causing the plasma pH to fall. Hyperventilation is the most characteristic symptom. Primidone, lamotrigine, and lacosamide do not cause metabolic acidosis.

Adverse effects of valproic acid

GI effects, hepatotoxicity, pancreatitis, teratogenic effects, hyperammonemia

carbamazepine (Tegretol) drug interactions

GRAPEFRUIT JUICE, warfarin, oral contraceptives, phenytoin, and phenobarbital

Adverse effects of oxcarbazepine (Trileptal)

Stevens-Johnson syndrome, toxic epidermal necrolysis, dizziness, drowsiness, double vision (diplopia), nystagmus, headache, nausea, vomiting, and ataxia

gabapentin (Neurontin) therapeutic uses

adjunctive therapy of partial seizures

Therapeutic uses of lamotrigine (Lamictal)

broad spectrum anti seizure activity and bipolar disorder

Focus may result from

congenital defects, hypoxia at birth, head trauma, brain infection, stroke, cancer, and genetic disorders

Generalized convulsive status epilepticus

continuous series of tonic-clonic seizures that last 20-30 minus

Oxcarbazepine (Trileptal)

indicated for mono therapy and adjunctive therapy of partial seizures in adults and children (one of the more common newer drugs)

Phenytoin (Dilantin) drug interactions

decreases effects of oral brith controls, warfarin, and glucocorticoids; increases levels of diazepam, isoniazid, alcohol, and cimetidine

Why are there different kinds of seizures?

depending on the area the neurons are firing in and what types of neurons are discharging, you can have different types of seizures

Adverse effects of pregabalin (Lyrica)

dizziness, somnolence, blurred vision, significant weight gain, angioedema, rhabdomyolysis, difficulty thinking, headache, peripheral edema, and dry mouth

General seizure precautions

don't do anything dangerous, fall risk, keep side rails up, don't get on ladders or anything that could endanger their life

Electroencephelogram (EEG)

electrodes are placed on the head and the electric pathways of the brain are mapped so they can determine where the seizures originate from in the brain

carbamazepine (Tegretol) uses

epilepsy, biolar disorder, and trigeminal and glossopharyngeal neuralgias (nerve pani)

Phenobarbital uses

epilepsy, sedation, and induction of sleep

Seizure disorders

group of disorders characterized by excessive excitability of neurons in the CNS

Why does a seizure occur?

if something happens that effects the homeostasis of the brain and the way it functions, the brain will get very irritable which causes the neurons to fire resulting in a seizure

What is a contraindication to neurosurgery in a pt with epilepsy?

if the seizure is from the speech area of the brain or an area that would be too complicated to get too

Phenytoin's effect on birth control and the fetus

it decreases the activity of birth control pills and can cause birth defects

What is another important thing to remember about topiramate (Topamax)

it has a major suicide risk

Which antiepileptic drug is unique and chemically different from all of the others?

levetiracetam (Keppra)

Goals of treatment for status epilepticus

maintain ventilation, correct hypoglycemia, terminate seizures

What should we tell pts who are started on antiepileptic medications?

make sure they know the medication doesn't mean they won't have any seizures; also they may need dose changes or different medications

Off label uses of gabapentin (Neurotonin)

neuropathic pain, prophylaxis of migraine, treatment of fibromyalgia, and relief of postmenopausal hot flashes

Adverse effects of phenobarbital

neurophsychologic effects, dependency, rickets and osteomalacia, nystagmus, and ataxia

Treatment options for epilepsy

neurosurgery, vagal nerve stimulation, ketogenic diet, and medication

Adverse effects of carbamazepine (Tegretol)

nystagmus, ataxia, leukopenia (low white blood cell count), anemia, thrombocytopenia (low platelet count), birth defects, rash, and photosensitivity reactions

Adverse effects of phenytoin (Dilantin)

nystagmus, sedation, ataxia, diplopia, skin rash, cognitive impairment, gingival hyperplasia, pregnancy effects, and cardiovascular effects

Phenobarbital drug interactions

oral contraceptives, warfarin, CNS depressants, and valproic acid

Valproic acid drug interactions

phenobarbital, phenytoin, topiramate, meropenem, and imepenem

pregabalin (Lyrica)

used for neuropathic pain, nerve pain, and adjunctive therapy of partial seizures

Valproic Acid (Depakote) common usage

used for pts who are aggressive, easily agitated, and angry to help calm them down

Goals of anti-epileptic treatment

reduce seizures to a level that allows pt to live as normal of a life as possible and balance the desire for complete seizure control with acceptable side effects

Therapeutic uses of valproic acid

seizure disorders, bipolar disorder, migraine, and behaviors in elderly pts with dementia

topiramate (Topamax) therapeutic use

seizures, bipolar disorder, cluster headaches, metabolic acidosis, neuropathic pain, binge eating disorder, bulimia nervosa, and alcohol and cocaine dependance

Lennox-Gastaut syndrome

severe form of epilepsy that usually develops during the preschool years; involves developmental delay and a mixture of partial and generalized seizures

Most common side effects of gabapentin

somnolence, dizziness, ataxia, fatigue, nystagmus, and peripheral edema

Effects of anti epileptic drugs

suppress discharge of neurons within a seizure focus and suppress propagation of seizure activity from the focus to other areas of the brain

Seizures are initiated by...

synchronous, high-frequency discharge from a group of hyper excitable neurons called a focus

Tonic-clonic seizure

tensing and relaxing of the muscles over and over again (oxygen demand and glucose demand are increased)

Why is it important that those taking anti-seizure medications don't skip any doses or stop taking it abruptly?

the risk for seizures increases when they stop taking their medication

Do antiepileptic drugs usually work for a broad spectrum of seizures?

there are some drugs that are used for specific types of seizures and there are drugs that aren't effective for other types

2 anti-seizure meds that put pts at risk of suicide

topiramate and lamotrigine

Can phenytoin be taken with food?

yes