Anticonvulsants

Commonly Prescribed Drugs

See Mechanism of Action of Select Anticonvulsants table.

Pharmacologic Profile

General Use

Anticonvulsants are used to ↓ the incidence and severity of seizures due to various etiologies. Some anticonvulsants are used parenterally in the immediate treatment of seizures. It is not uncommon for patients to require more than one anticonvulsant to control seizures on a long-term basis. Several anticonvulsants are evaluated with serum level monitoring. Several anticonvulsants also are used to treat neuropathic pain.

General Action and Information

MECHANISM OF ACTION OF SELECT ANTICONVULSANTS

DRUG	MECHANISM
Brivaracetam and levetiracetam	Bind to synaptic vesicle protein 2A, modulating neurotransmitter release
Carbamazepine, fosphenytoin, lacosamide, lamotrigine, phenytoin, and oxcarbazepine	Inhibit voltage-gated sodium channels to ↓ neuronal excitability
Diazepam, clonazepam, midazolam, phenobarbital, and valproates	Potentiate the effects of GABA (an inhibitory neurotransmitter)
Gabapentin and pregabalin	Inhibit voltage-gated calcium channels to ↓ neuronal excitability
Topiramate	Inhibits voltage-gated sodium channels; potentiates effects of GABA; glutamate antagonist; carbonic anhydrase inhibitor

Contraindications

Previous hypersensitivity.

Precautions

Use cautiously in patients with severe hepatic or renal impairment; dose adjustment may be required. Choose agents carefully in pregnant and lactating women. Fetal hydantoin syndrome may occur in offspring of patients who receive phenytoin during pregnancy.

Interactions

Barbiturates, carbamazepine, and phenytoin stimulate the metabolism of other drugs that are metabolized by the liver, ↓ their effectiveness. Phenytoin is highly protein-bound and may displace or be displaced by other highly protein-bound drugs. Lamotrigine, tiagabine, and topiramate are capable of interacting with several other anticonvulsants. Many drugs are capable of lowering seizure threshold and may ↓ the effectiveness of anticonvulsants, including tricyclic antidepressants and phenothiazines. For more specific interactions, see individual drugs.

Nursing Implications

Assessment

Assess location, duration, and characteristics of seizure activity.
Toxicity and Overdose: Monitor serum drug levels routinely throughout anticonvulsant therapy, especially when adding or discontinuing other medications.

Implementation

Administer anticonvulsants around the clock. Abrupt discontinuation may precipitate status epilepticus.
Implement seizure precautions.

Patient/Family Teaching

Instruct patient to take medication every day, exactly as directed.
May cause drowsiness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known. Do not resume driving until physician gives clearance based on control of seizures.
Advise patient to avoid taking alcohol or other CNS depressants concurrently with these medications.
Advise patient to carry identification describing disease process and medication regimen at all times.

Evaluation/Desired Outcomes