ppt chapter 18

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 18

Drugs Treating Seizure Disorders


Question

• The following are symptoms of which disorder/disease: loss of consciousness with muscle twitching and mild alterations in consciousness with repetitive blinking?

– A. Epilepsy

– B. Seizures

– C. Parkinson disease

– D. Delirium


Answer

• B. Seizures

• Rationale: These symptoms are the classic presentation of seizure activity.


Epilepsy • Epilepsy is a brain disorder.

• Seizures are loss of consciousness with generalized muscle twitching or mild alterations in consciousness with repetitive blinking.

• Patients with patterns of seizures who are diagnosed with epilepsy are treated with antiepileptic drugs.

• The three main ways that antiepileptic drugs work are

– Decreasing the rate at which sodium flows into the cell

– Inhibiting calcium flow rate into the cell through specific channels

– Increasing the effect of the neuroinhibitor gamma-aminobutyric acid (GABA)


Physiology

• Action potentials within neurons are initiated by an influx of sodium into the cell.

• Influx of calcium through specialized voltage-dependent channels also plays a role in creating an action potential.

• When the cell fires, there is a release of neurotransmitters into the synaptic cleft.

• The neurotransmitter glutamate produces excitation.

• GABA normally acts as a counterbalance to glutamate, preventing hyperexcitation.


Physiology of Neurotransmitters


Pathophysiology • When a group of neurons exhibits coordinated, high-

frequency discharge, it is termed a focus.

• The causes of a focus include head trauma, tumor growth, hypoxia, and inherited birth defects.

• When the activity from a focus spreads to other areas of the brain, causing other neurons to join in the hyperactivity, seizures result.

• Seizures may result from either high levels of glutamate or low levels of GABA.

• Partial seizures occur when focus activity is limited to an area of the brain.

• When the focus activity is within both hemispheres, generalized seizure symptoms occur.


Antiepileptic Drugs that Decrease Sodium Influx

• Control seizures by decreasing sodium influx into the cells.

• Prototype drug: phenytoin (Dilantin)


Phenytoin: Core Drug Knowledge

• Pharmacotherapeutics

– Used to control partial and generalized seizures

• Pharmacokinetics

– Peak 1.5 to 3 hours. At low doses, the half-life is less than at the therapeutic dose.

• Pharmacodynamics

– The primary site of action is the motor cortex.

– Reversibly binds to sodium channels while they are in the inactive state


Phenytoin: Core Drug Knowledge (cont.)

• Contraindications and precautions

– Bradycardia and heart block

• Adverse effects

– Nystagmus, ataxia, dysarthria, slurred speech, mental confusion, tremor, and gingival hyperplasia

• Drug interactions

– Numerous drugs interact with phenytoin


Phenytoin: Core Patient Variables

• Health status

– Assess allergies and any cardiac conditions.

• Life span and gender

– Pregnancy Category D drug

• Lifestyle, diet, and habits

– Alcohol intake and nutritional status

• Environment

– Assess environment where the drug will be given.

– Oral given in any environment


Phenytoin: Nursing Diagnoses and Outcomes • Disturbed Sensory Perception related to adverse effects

of drowsiness and sedation

– Desired outcome: The patient will not experience adverse effects to the degree that sensory perception is altered enough to impair quality of life.

• Risk for Injury related to the adverse effects of drowsiness and sedation

– Desired outcome: The patient will not sustain any injury while taking phenytoin.


Phenytoin: Nursing Diagnoses and Outcomes (cont.)

• Altered Oral Mucous Membrane related to the adverse effect of gingival hyperplasia

– Desired outcome: The patient will demonstrate knowledge of optimal oral hygiene and experience no deterioration in dental health.

• Risk for Injury related to adverse effects of blood dyscrasias

– Desired outcome: The patient will return for follow-up blood work while taking phenytoin and will have no life-threatening blood disorders.


Phenytoin: Planning and Interventions

• Maximizing therapeutic effects

– Monitor blood levels of the drug.

– Titrate the dose upward gradually.

• Minimizing adverse effects

– Monitor blood levels—narrow therapeutic range.

– Administer IV push phenytoin no faster than 50 mg/minute in adults or 1 to 3 mg/kg/minute in neonates.


Phenytoin: Teaching, Assessment, and Evaluations

• Patient and family education

– Ensure proper administration of medication.

– Take medication with food to decrease GI upset.

– Notify the physician of adverse effects.

• Ongoing assessment and evaluation

– Ongoing assessments include monitoring patients closely for therapeutic responses, seizure control, and adverse effects to drug therapy.


Question

• What condition places the patient at greater risk for toxicity to phenytoin?

– A. Alcoholism

– B. Sinus bradycardia

– C. Obesity

– D. Malnutrition


Answer

• D. Malnutrition

• Rationale: Malnutrition causes a greater amount of free, active drug in the blood because less protein albumin is available for binding.


Antiepileptic Drugs that Decrease Calcium Influx

• Prototype drug: ethosuximide (Zarontin)


Ethosuximide: Core Drug Knowledge

• Pharmacotherapeutics

– Used to treat absence (petit mal) seizures

• Pharmacokinetics

– Administered: oral. Metabolism: liver. Excreted: kidneys. Peak: 3 to 7 hours. T½: 30 to 60 hours.

• Pharmacodynamics

– Inhibiting the influx of calcium ions


Ethosuximide: Core Drug Knowledge (cont.)

• Contraindications and precautions

– Hypersensitivity

• Adverse effects

– Drowsiness, dizziness, lethargy, nausea, and blood dyscrasias

• Drug interactions

– Known to interact with some of the other antiepileptic drugs


Ethosuximide: Core Patient Variables

• Health status

– Assess allergies, history of renal or hepatic dysfunction.

• Life span and gender

– Pregnancy Category C drug

• Environment

– Assess environment where the drug will be given.


Ethosuximide: Nursing Diagnoses and Outcomes

• Imbalanced nutrition: Less than Body Requirements related to adverse GI drug effects of anorexia, abdominal complaints, nausea, and vomiting

– Desired outcome: The patient will not experience major nutritional imbalances while receiving ethosuximide.

• Risk for Injury from falls related to CNS adverse effects of ethosuximide

– Desired outcome: The patient will not sustain an injury while receiving ethosuximide.


Ethosuximide: Nursing Diagnoses and Outcomes (cont.)

• Risk for Injury from blood dyscrasias related to adverse effects of ethosuximide

– Desired outcome: The patient will not experience major changes in his or her complete blood cell counts.


Ethosuximide: Planning and Interventions

• Maximizing therapeutic effects

– Monitor drug levels at the start of therapy and when changing dosage.

• Minimizing adverse effects

– Assess CBC, UA, and LFT.

– Taper dose gradually if need to discontinue the drug.


Ethosuximide: Teaching, Assessment, and Evaluations

• Patient and family education

– Teach patients to take the drug with milk or food if GI upset occurs.

– Notify the provider of adverse effects.

• Ongoing assessment and evaluation

– Ongoing assessments include monitoring patients closely for therapeutic responses, seizure control, and adverse effects of drug therapy.


Question

• Ethosuximide is used to treat __________ seizures.

– A. Absence

– B. Grand mal

– C. Generalized

– D. Febrile


Answer

• A. Absence

• Rationale: Ethosuximide is used to treat absence (petit mal) seizures.

ppt chapter 18

Documents