Download Roach: Introductory Clinical Pharmacology

Introductory Clinical
Pharmacology
Chapter 31
Anticonvulsants
Copyright © 2008 Lippincott Williams & Wilkins.
Anticonvulsants: Actions
• Benzodiazepines and barbiturates inhibit
uptake of GABA at receptors
• Hydantoins stabilize hyperexcitability
postsynaptically in motor cortex of brain
• Oxazolidinediones decrease repetitive
synaptic transmission of nerve impulses
• Succinimides depress motor cortex creating
higher threshold before nerves react to
convulsive stimuli
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Anticonvulsants: Uses
• Used prophylactically to prevent seizures
following trauma, neurosurgery, or tumor
• Used in treatment of:
– Seizures of all types; neuropathic pain;
biopolar disorders; anxiety disorders
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Anticonvulsants: Adverse Reactions
• Central nervous system reactions:
Drowsiness; weakness; dizziness; headache;
somnolence; nystagmus; ataxia; slurred
speech
• Gastrointestinal reactions: Nausea;
vomiting; anorexia; constipation; diarrhea;
gingival hyperplasia
• Other: Skin rashes; pruritus; urticaria;
urinary frequency; serious skin reactions;
hematologic changes
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Anticonvulsants: Contraindications
• Contraindicated in patients hypersensitive to
the drugs
– Phenytoin is contraindicated in patients
with sinus bradycardia; sinoatrial block;
Adams-Stokes syndrome; second and
third-degree atrioventricular (AV) block;
during pregnancy and lactation
– Ethotoin (Pegatone) is contraindicated in
patients with hepatic abnormalities
Copyright © 2008 Lippincott Williams & Wilkins.
Anticonvulsants: Contraindications
(cont’d)
– Succinimides are contraindicated in
patients with bone marrow depression or
hepatic or renal impairment
– Carbamazepine is contraindicated in
patients with bone marrow depression or
hepatic or renal impairment and during
pregnancy
– Valproic acid (Depakote) is not
administered to patients with renal
impairment or during pregnancy
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Anticonvulsants: Precautions
• Used cautiously in patients with liver or
kidney disease or neurologic disorders
– Barbiturates are used with caution in
patients with pulmonary disease and in
hyperactive children
– Benzodiazepines are used cautiously
during pregnancy and in patients with
psychoses; acute narrow-angle
glaucoma; elderly or debilitated patients
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Anticonvulsants: Precautions (cont’d)
– Phenytoin is used cautiously in patients
with hypotension, severe myocardial
insufficiency, hepatic impairment
– Trimethadione is used with caution in
patients with eye disorders
– Miscellaneous anticonvulsants are used
cautiously in patients with glaucoma or
increased intraocular pressure; a history
of cardiac, renal, or liver dysfunction; and
psychiatric disorders
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Anticonvulsants: Interactions
Interactant Drug
Effect of Interaction
Antibiotics/antifungals
Increased effect of the
anticonvulsant
Tricyclic antidepressants
Increased effect of the
anticonvulsant
Salicylates
Increased effect of the
anticonvulsant
Cimetidine
Increased effect of the
anticonvulsant
Theophylline
Decreased serum levels of
the anticonvulsant
Copyright © 2008 Lippincott Williams & Wilkins.
Anticonvulsants: Interactions (cont’d)
Interactant Drug
Effect of Interaction
Antiseizure medications
May increase seizure activity
Protease inhibitors
Increased carbamazepine
levels resulting in toxicity
Oral contraceptives
Decreased effectiveness of
birth control, resulting in
breakthrough bleeding or
pregnancy
Increased depressant effect
Analgesics or alcohol
Antidiabetic medications
Increased blood glucose
levels
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Nursing Process: Assessment
• Preadministration assessment
– Obtain vital signs at the time of the initial
assessment to provide baseline data
– Thorough patient history is necessary to
identify type of seizure disorder
– Primary health care provider may order
laboratory and diagnostic tests
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Nursing Process: Assessment
• Ongoing assessment
– Carefully document each seizure with
regard to time of occurrence, duration of
seizure, psychic or motor activity occurring
before, during, after seizure
– Dosage adjustments are based on patient’s
response to therapy, as well as occurrence
of adverse reactions
– Serum plasma levels of anticonvulsant are
measured regularly to monitor for toxicity
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Nursing Process: Planning
• Expected outcomes for patient depend on
the type and severity of the seizure but may
include:
– Optimal response to therapy
– Support of patient needs related to
management of adverse reactions
– Understanding of and compliance with
prescribed therapeutic regimen
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Nursing Process: Implementation
• Promoting an optimal response to therapy
– Make notation on the care plan, as well
as informing all health care team
members of the importance of the drug
– Barbiturates
•Monitor patient carefully during
administration of barbiturate, taking
blood pressure and observing
respirations frequently
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Nursing Process: Implementation
• Promoting an optimal response to therapy
(cont’d)
– Benzodiazepines
•Dosage of benzodiazepines is highly
individualized; increase the dosage
cautiously to avoid adverse reactions,
particularly in elderly and debilitated
patient
•Do not mix diazepam with other drugs
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Nursing Process: Implementation
• Promoting an optimal response to therapy
(cont’d)
– Hydantoins
•Monitor serum concentrations of drug
on regular basis to detect signs of
toxicity
– Oxazolidinediones
•Used when less-toxic drugs are not
effective in controlling seizure disorder
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Nursing Process: Implementation
• Promoting an optimal response to therapy
(cont’d)
– Succinimides
•Effective in controlling partial seizures,
these drugs are given with food to
prevent GI upset
– Miscellaneous anticonvulsants
•Drug is absorbed rapidly when taken
orally; should not be chewed but
swallowed whole
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Nursing Process: Implementation
• Monitoring and managing patient needs
– Risk for injury
• The nurse should assist the patient with all
ambulatory activities
• Use caution when giving an oral preparation,
as aspiration of tablet, capsule, or liquid may
occur if patient experiences drowsiness
• Test swallowing ability of patient by offering
small sips of water before giving drug
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Nursing Process: Implementation
• Monitoring and managing patient needs (cont’d)
– Risk for impaired skin integrity
• Carefully examine all affected areas and
provides an accurate description
• Be alert for signs of pancytopenia, such as
sore throat, fever, general malaise, bleeding
of the mucous membranes, epistaxis, easy
bruising
• Routine laboratory tests, such as complete
blood counts and differential counts, should
be performed periodically
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Nursing Process: Implementation
• Monitoring and managing patient needs (cont’d)
– Impaired oral mucous membranes
• Periodically inspect mouth, teeth, gums of
patients in a hospital or long-term clinical
setting
– Disturbed sensory perception: Visual
• Patient should stay out of sun if possible and
wear sunscreens and protective clothing as
needed until individual effects of drug are
known
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Nursing Process: Implementation
• Educating the patient and family
– Nurse must assist patient and family to adjust to
diagnosis of epilepsy
– Instruct family members in care of patient before,
during, and after seizure
– Explain importance of restricting some activities until
seizures are controlled by drugs
– Assist patient in looking for other modes of
transportation in order to continue typical activities
or employment
– Review adverse drug reactions associated with the
prescribed anticonvulsant with the patient and family
members
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Nursing Process: Implementation
• Educating the patient and family (cont’d)
– Hydantoins
•Inform dentist and other primary health
care providers of use of this drug
•Brush and floss teeth after each meal
and make periodic dental appointments
for oral examination and care
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Nursing Process: Implementation
• Educating the patient and family (cont’d)
•Take medication with food to reduce GI
upset
•Thoroughly shake phenytoin suspension
immediately before use
•Do not take capsules that are
discolored
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Nursing Process: Implementation
• Educating the patient and family (cont’d)
•Notify primary health care provider if
any of the following occur: Skin rash;
bleeding; swollen or tender gums;
yellowish discoloration of the skin or
eyes; unexplained fever; sore throat;
unusual bleeding or bruising; persistent
headache; malaise; pregnancy
Copyright © 2008 Lippincott Williams & Wilkins.
Nursing Process: Implementation
• Educating the patient and family (cont’d)
– Succinimides
• If GI upset occurs, take drug with food or
milk
• Notify primary health care provider if any
of the following occurs: Skin rash; joint
pain; unexplained fever; sore throat;
unusual bleeding or bruising;
drowsiness; dizziness, blurred vision;
pregnancy
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Nursing Process: Implementation
• Educating the patient and family (cont’d)
– Oxazolidinediones
• Determine protective measures when exposed
to ultraviolet light, sunlight
• Notify primary care provider if following occur:
Visual disturbances; excessive drowsiness;
dizziness; sore throat; fever; skin rash;
pregnancy; malaise; easy bruising; epistaxis;
bleeding tendencies
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Nursing Process: Evaluation
• Therapeutic effect is achieved and convulsions are
controlled
• No injury is evident
• Adverse reactions are identified, reported, and managed
successfully through appropriate nursing interventions
• Patient verbalizes the importance of complying with the
prescribed treatment regimen
• Patient verbalizes understanding of treatment modalities
and the importance of continued follow-up care
• Patient and family demonstrate an understanding of the
drug regimen
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End of Presentation
Copyright © 2008 Lippincott Williams & Wilkins.