Transcript Prototype drug - Nursing Pharmacology

15
Drugs for Seizures
Chapter 15
OVERVIEW:
Neuro System
Opioids
Salicylates
NSAIDs
Non-Opioid
Antidepressant /
Anxiolytic
Benzodiazepines
lorazepam (Ativan)
diazepam (Valium)
GABA
A
Antagonist
zolpidem (Ambien)
aspirin (ASA)
ibuprofen (Motrin)
acetaminophen (Tylenol)
tramadol (Ultram)
Anti-Migraine
ergotamine (Cafergot)
Sumatriptan (Imitrex)
escitalopram (Lexapro)
MAOIs
morphine (Infumorph)
Central Acting
Tri-Cyclic
Antidepressa
nt
Opioid
Antagonists
naloxone (Narcan)
Phenytoin-Like
Drugs
phenytoin (Dilantin)
valproic acid (Depakote)
Succinimides
ethosuximide (Zarontin)
Barbiturates
phenobarbital (Luminal)
Phenothiazines
chlorpromazine (Thorazine)
NonPhenothiazines
halperidol (Haldol)
Atypical
Antipsychotics
risperidone (Risperdal)
Antiseizure Pharmacotherapy
• Goal: suppress neuronal activity enough to
prevent abnormal or repetitive firing
• Drugs act through three mechanisms:
• Stimulating an influx of chloride ions
• Delaying an influx of sodium
• Delaying an influx of calcium
• Directed at controlling movement of
electrolytes across neuronal membranes or
affecting neurotransmitter balance
• Some drugs act by more than one mechanism
Pharmacotherapy Illustrated: Model of the GABA Receptor–Chloride Channel Molecules
in Relationship to Antiseizure Pharmacotherapy
Barbiturates and GABA Agents
• Monitor Patient’s condition
• Liver and kidney function
• Pregnancy Category D
• Common side effects
Patient Teaching
• Use reliable contraception
• Immediately report pregnancy
• Report excessive signs of bleeding
• Report drowsiness and bone pain
Drugs that Potentiate GABA Action
• Act by changing the action of gamma-aminobutyric acid
(GABA), the primary inhibitory neurotransmitter in the
brain
• Predominate effect of GABA potentiation is CNS
depression
Benzodiazepines—
Schedule IV Drug
• Monitor for drug-abuse potential
• Pregnancy risk—Pregnancy Category D
• Contraindicated in narrow-angle glaucoma
• Respiratory depression may result with other CNS
depressants.
• Common side effects include dizziness, drowsiness
• Overdose—give flumazenil (Romazicon)
Patient Teaching
• Avoid alcohol, OTC drugs, and herbal medications
• Avoid nicotine
• Avoid driving and hazardous activities
• Rebound seizures if discontinued abruptly
• Take with food
• Drug often used illegally
Hydantoin and Phenytoin-like Drugs
• Monitor serum-drug levels
• Monitor for signs of toxicity
• Monitor for blood dyscrasias and bleeding disorders
• Monitor liver and kidney function
• Fatal hepatotoxicity can occur
Hydantoin and Phenytoin-like Drugs
Contraindications
• Patients with hypersensitivity to hydantoin products
should be cautious.
• Rash, seizures due to hypoglycemia, sinus bradycardia,
and heart block
Patient Teaching
• Routine labs for serum level
• Routine labs for liver and kidney function
• Immediately report signs of toxicity
• Immediately report unusual bleeding
• Immediately report liver or brain disease
• Immediately report heart block, hypoglycemia, or
pregnancy
Succinimides
• Do not abruptly withdraw medication
• Use with caution with antiseizure medications,
phenothiazines, and antidepressants
• Pregnancy risk—pregnancy Category C
Common Adverse Reactions
• Drowsiness, headache, fatigue, dizziness
• Depression or euphoria
• Nausea, vomiting, weight loss
• Abdominal pain
Life-Threatening Reactions
• Severe mental depression with suicide intent
• Stevens-Johnson syndrome
• Blood dyscrasias
Patient Teaching
• Immediately report mood changes or suicidal thoughts
• Avoid driving and hazardous activities
• Do not suddenly stop taking
• Take with food
• Report symptoms of fever or sore throat
• Report weight loss and anorexia
Dosage Procedure
• Start with smallest initial dose
• Add additional drugs, if necessary
• Ensure compatibility with other medications
• Monitor serum-drug levels
Withdrawal of
Antiseizure Medications
• Should be seizure free at least three years
• Withdraw gradually over several months
• Resume medications if seizures return
• Be aware of rebound seizures
Drugs That Potentiate
GABA Action
• Barbiturates
• Benzodiazepines
• Miscellaneous GABA agents
Barbiturates
phenobarbital (Luminal)
• Mechanism of action: changing the action of
GABA
• Primary use: controlling seizures
• Adverse effects: dependence, drowsiness,
vitamin deficiencies, laryngospasm
• Prototype drug:
Prototype Drug: Phenobarbital (Luminal)
Benzodiazepines
• Prototype drug: diazepam (Valium)
• Mechanism of action: similar to that of
barbiturates but safer
• Primary use: for short-term seizure control
• Adverse effects: drowsiness and dizziness
Prototype Drug: Diazepam (Valium)
Diazepam Animation
Click here to view an animation on the topic of diazepam.
Hydantoins
• Prototype drug: phenytoin (Dilantin)
• Mechanism of action: to densitize sodium
channels
• Primary use: treating all types of epilepsy
except absence seizures
• Adverse effects: CNS depression, gingival
hyperplasia, skin rash, cardiac dysrhythmias,
and hypotension
Prototype Drug: Phenytoin (Dilantin)
Prototype Drug: Phenytoin (Dilantin)
Phenytoin-Like Drugs
Valproic acid (Depakene)
• Mechanism of action: to desensitize sodium
channels
• Primary use: for absence seizures
• Adverse effects: limited CNS depression,
visual disturbances, ataxia, vertigo,
headache
• Prototype drug:
• Additional adverse reactions:
gastrointestinal effects, hepatotoxicity,
pancreatitis
Valproic Acid Animation
Click here to view an animation on the topic of valproic acid.
Prototype Drug: Valproic Acid (Depakene, Depakote)
Succinimides
ethosuximide (Zarontin)
• Mechanism of action: suppress calcium influx
• Primary use: for absence seizures
• Adverse effects: rare but include drowsiness,
dizziness, lethargy
• Very rare but serious side effects: systemic lupus
erythematosis, leukopenia, aplastic anemia,
Stevens-Johnson syndrome
• Prototype drug:
Prototype Drug: Ethosuximide (Zarontin)
Drugs That Potentiate
GABA Action
• Include barbiturates, benzodiazepines, and
miscellaneous GABA agents
• Suppress the firing ability of neurons
Treating Seizures with Barbituates
• Low margin for safety
• High potential for dependence, and they cause
• Profound CNS depression
• Overall effective against all major seizure types
except absence seizures
Examples of Barbiturates
• Phenobarbital (Luminal)
• Amobarbital (Amytal)
• Secobarbital (Seconal)
• Pentobarbital (Nembutal)
Treating Seizures
with Benzodiazepines
• Indications include absence seizures and
myoclonic seizures
• Tolerance may develop quickly
• one of most widely prescribed classes, used
also for anxiety, skeletal muscle spasms, and
alcohol withdrawal symptoms
Examples of Benzodiazepines
• Clonazepam (Klonopin)
• Clorazepate (Tranxene)
• Lorazepam (Ativan)
• Diazepam (Valium)
Newer GABA-related Drugs
• Gabapentin (Neurontin)
• Pregabalin (Lyrica)
• Tiagabine (Gabitril)
• Topiramate (Topamax)
Hydantoin and Newer Drugs
• Delay an influx of sodium ions across neuronal
membranes
• Sodium movement is factor that determines
whether neuron will undergo an action potential
• Sodium channels are not blocked; they are just
desensitized
Treating Seizures With Hydantoins and
Related Drugs
• Useful in treating all types of epilepsy except
absence seizures
• Provides effective seizure suppression, without
the abuse potential or CNS depression associated
with barbiturates
• Phenytoin-related drugs used less frequently
Examples of Hydantoins
• Phenytoin (Dilantin)—most common
• Fosphenytoin (Cerebyx)
Examples of Phenytoin-like
Drugs
• Carbamazepine (Tegretol)—tonic-clonic and
•
•
•
•
partial seizures
Felbamate (Felbatol)
Lamotrigine (Lamictal)
Valproic acid (Depakene, Depakote)—absence
seizures
Zonisamide (Zonegran)
Treating Seizures with Succinimides
• Suppress seizures by delaying calcium influx into
neurons
• Generally only effective against absence
seizures
• Ethosuximide (Zarontin) is the most commonly
prescribed drug in this class
Succinimides
• Examples of succinimides
• Ethosuximide (Zarontin)
• Methsuximide (Celontin)
• Phensuximide (Milontin)
NCLEX-RN Review
Question 1
The nurse evaluates patient teaching related to causes of
seizures. Further teaching is needed if the patient makes
which of the following statements?
1.
2.
3.
4.
“Seizures can be caused by inflammation of the
brain.”
“Seizures can be caused by low blood sugar.”
“My relative had seizures because of a large
tumor growing in his muscles.”
“Seizures may occur after a head injury.”
NCLEX-RN Review
Question 1 – Answer
1.
2.
3.
4.
“Seizures can be caused by inflammation of the
brain.”
“Seizures can be caused by low blood sugar.”
“My relative had seizures because of a large tumor
growing in his muscles.”
“Seizures may occur after a head injury.”
NCLEX-RN Review
Question 1 – Rationale
Rationale: Seizures may be caused by
inflammation, head injuries, or low blood sugar
levels. Rapid-growing, space-occupying lesions in
the brain, which increase intracranial pressure, may
cause seizures, but not tumors, within the muscles.
NCLEX-RN Review
Question 2
The nursing student asks the nurse to explain the action of
the antiseizure medication, phenytoin. The nurse explains
the mechanism of action as:
1.
2.
3.
4.
Suppression of the influx of chloride into the
neuron
Stimulation of the influx of calcium into the neuron
Suppression of the influx of sodium into the neuron
Stimulation of calcium and sodium needed to
suppress seizure activity
NCLEX-RN Review
Question 2 – Answer
1.
2.
3.
4.
Suppression of the influx of chloride into the neuron
Stimulation of the influx of calcium into the neuron
Suppression of the influx of sodium into the
neuron
Stimulation of calcium and sodium needed to suppress
seizure activity
NCLEX-RN Review
Question 2 – Rationale
Rationale: The influx of sodium into a neuron
enhances neuronal activity. The delay of an
influx suppresses neurotransmitter frequency.
NCLEX-RN Review
Question 3
The nurse recognizes that several chemicals inhibit
neurotransmitter function in the brain. The primary
inhibitory transmitter in the brain is:
1.
2.
3.
4.
Sodium
GABA
Chloride
Calcium
NCLEX-RN Review
Question 3 – Answer
1.
2.
3.
4.
Sodium
GABA
Chloride
Calcium
NCLEX-RN Review
Question 3 – Rationale
Rationale: GABA drugs mimic GABA
by stimulating the influx of chloride
ions into the neuron, leading to the
suppression of neuron firing.
NCLEX-RN Review
Question 4
The patient, age 8, is prescribed valproic acid (Depakene)
for treatment of a seizure disorder. The nurse should
monitor the patient closely for:
1.
2.
3.
4.
Hyperthermia
Vitamin B deficiency
Restlessness and agitation
Respiratory distress
NCLEX-RN Review
Question 4 – Answer
1.
2.
3.
4.
Hyperthermia
Vitamin B deficiency
Restlessness and agitation
Respiratory distress
NCLEX-RN Review
Question 4 – Rationale
Rationale: Valproic acid may produce an
idiosyncratic response in children, including
restlessness and psychomotor agitation.
NCLEX-RN Review
Question 5
Discharge teaching for a patient receiving carbamazepine
(Tegretol) should include:
1.
2.
3.
4.
Monitoring blood glucose and reporting
decreased levels
Expecting a discoloration of contact lenses
Immediately reporting unusual bleeding or
bruises to the health care provider
Expecting a green discoloration of urine
NCLEX-RN Review
Question 5 – Answer
1.
2.
3.
4.
Monitoring blood glucose and reporting decreased
levels
Expecting a discoloration of contact lenses
Immediately reporting unusual bleeding or bruises
to the health care provider
Expecting a green discoloration of urine
NCLEX-RN Review
Question 5 – Rationale
Rationale: Carbamazepine affects vitamin
K metabolism and may lead to blood
dyscrasias and bleeding.
Pathophysiology
Of Seizures
/
Discussion
Seizures
• Abnormal or uncontrolled neuronal discharges in the brain
• Affect
• Consciousness
• Motor activity
• Sensation
• Symptom of an underlying disorder
Convulsion
• Involuntary violent spasm of large muscles of face, neck,
arms, and legs
• Not synonymous with seizure
Different etiologies of seizure activity
• Most common serious neurologic problem
affecting children
• May present as an acute situation, or they may
occur on a chronic basis
Known Causes of Seizures
• Infectious diseases
• Trauma
• Metabolic disorders
• Vascular diseases
• Pediatric disorders
• Neoplastic disease
Additional Known Causes
of Seizures
• Medications
• High doses of local anesthetics
• Eclampsia
• Drug abuse
• Withdrawal syndromes from alcohol or sedative-hypnotic
drugs
Pregnancy and Epilepsy
• Several antiseizure drugs decrease effectiveness of
oral contraceptives
• Most antiseizure drugs are pregnancy category D
• Eclampsia - severe hypertensive disorder of
pregnancy, characterized by seizures, coma, and
perinatal mortality
Epilepsy
• Seizures occurring chronically
• International Classification of Epileptic Seizures
• Partial (focal)
• Generalized
• Special epileptic syndromes
Seizures in Neonates, Infants, and
Children
• Congenital abnormalities of CNS
• Perinatal brain injury
• Metabolic imbalances
Later-Childhood Etiology
• CNS infections
• Neurological degenerative disorders
• Inherited epilepsies
Adult Etiology
• Cerebral trauma
• Cerebrovascular disorders
• Neoplastic disease
Signs and Symptoms of Seizures
• Related to area of brain with abnormal activity
• International Classification of Epileptic
Seizures: classifies seizures
Simple Partial Seizures
• Olfactory, auditory, and visual hallucinations
• Intense emotions
• Twitching of arms, legs, and face
Complex Partial (psychomotor) Seizures
• Aura (preceding)
• Brief period of confusion or sleepiness afterward
with no memory of seizure (postictal confusion)
• Fumbling with or attempting to remove clothing
• No response to verbal commands
Generalized Seizures
• Absence (petit mal)
• Atonic (drop attacks)
• Tonic-clonic (grand mal)
Absence Seizures
• Lasting a few seconds
• Seen most often in children (child stares into space,
does not respond to verbal stimulation, may have
fluttering eyelids or jerking)
• Misdiagnosed often (especially in child) as ADD or
daydreaming
Atonic Seizures
• Falling or stumbling for no reason
• Lasting a few seconds
Tonic-Clonic Seizures
• Preceeded by aura
• Intense muscle contraction (tonic phase) followed
by alternating contraction and relaxation of muscles
(clonic phase)
• Crying at beginning as air leaves lungs; loss of
bowel/bladder control; shallow breathing with
periods of apnea; usually lasting 1–2 minutes
• Disorientation and deep sleep after seizure
(postictal state)
Special Syndromes
• Febrile seizures
• Myoclonic seizures
• Status epilepticus
Febrile Seizures
• Tonic–clonic activity lasting 1–2 minutes
• Rapid return to consciousness
• Occurs in children usually between 3 months
and 5 years of age
Myoclonic Seizures
• Large jerking movements of a major muscle
group, such as an arm
• Falling from a sitting position or dropping what
is held
Status Epilepticus
• Considered a medical emergency
• Continuous seizure activity, which can lead to
coma and death
Choice of Drug Depends Upon
• Type of seizure
• Patient’s history and diagnostic studies
• Associated pathologies
Once Medication is Selected
• Patient placed on low initial dose
• Amount gradually increased
• If seizure activity remains, different medication
added in small increments
• Newer antiseizure drugs have less adverse side
effects than older drugs
• Most cases require only a single drug
New FDA Warnings
• Study included patients with epilepsy, bipolar
disorder, psychoses, migraines, and neuropathic
pain
• Popular antiseizure examples found to almost
double risk of suicidal behavior and ideation
Drug Therapy for Epilepsy
• Assessment
• History of seizure activity
• Allergies and drug history
• Knowledge of disease process
• Knowledge of drug therapy
• Patient lifestyle
Drug Therapy for Epilepsy (cont'd)
• Nursing Diagnoses
• Low Self-Esteem (situational or chronic; related to disease effects)
• Impaired Social Interaction (related to disease, lack of seizure
control)
• Deficient Knowledge (drug therapy)
Risk for Injury (related to seizures or adverse drug effects)
•
Drug Therapy for Epilepsy (cont'd)
• Planning
• Experience therapeutic effects dependent on the reason the drug is
given
• Be free from, or experience minimal, adverse effects.
• Understanding of disease and drug regimen and purpose
• Understanding of drug regimen
• Demonstrate proper self-administration
Drug Therapy for Epilepsy (cont'd)
• Implementation
• Monitoring neurological status
• Ensuring lab values in normal range
• Patient/family teaching about disease
• Patient/family teaching about drugs
• Patient/family teaching about care during seizure activity
Drug Therapy for Epilepsy (cont'd)
• Evaluation
• Effectiveness of drug therapy
• Patient goals
Nursing Process Focus: Patients Receiving Antiseizure Drug
Therapy
Nursing Process Focus: Patients Receiving Antiseizure Drug
Therapy
Nursing Process Focus: Patients Receiving Antiseizure Drug
Therapy
Nursing Process Focus: Patients Receiving Antiseizure Drug
Therapy
Nursing Process Focus: Patients Receiving Antiseizure Drug
Therapy
Nursing Process Focus: Patients Receiving Antiseizure Drug
Therapy