NEUROLOGIC & NEUROMUSCULAR DRUGS 2

NEUROLOGIC & NEUROMUSCULAR DRUGS 2 9/26/2024 Anticonvulsant drugs Anticonvulsant drugs inhibit neuromuscular transmission. They can be prescribed for: • long-term management of chronic epilepsy (recurrent seizures) • short-term management of acute isolated seizures not caused by epilepsy, such as seizures after trauma or brain surgery. In addition, some anticonvulsants are used in the emergency treatment of status epilepticus (a continuous seizure state). Try one, then another, before together Treatment of epilepsy should begin with a single drug, increasing the dosage until seizures are controlled or adverse effects become problematic. Generally, a second alternative should be tried as monotherapy before considering combination therapy. Choice of drug treatment depends on the seizure type, the drug’s characteristics, and the patient’s preferences. Class discussion Anticonvulsants can be categorized into several major classes: • hydantoins • barbiturates • iminostilbenes • benzodiazepines • carboxylic acid derivatives • 1-(aminomethyl) cyclohexane acetic acid • phenyltriazine • carboxamide • sulfamate-substituted monosaccharides • succinimides • sulfonamides. Hydantoins The two most commonly prescribed anticonvulsant drug phenytoin and phenytoin sodium belong to the hydantoin class. Other hydantoins include fosphenytoin and ethotoin. Pharmacokinetics The pharmacokinetics of hydantoins varies from drug to drug. Phenytoin is absorbed slowly after oral and IM administration. It’s distributed rapidly to all tissues and is highly (90%) protein bound. Phenytoin is metabolized in the liver. Inactive metabolites are excreted in bile and then reabsorbed from the GI tract. Eventually, however, they’re excreted in urine. Pharmacotherapeutics Because of its effectiveness and relatively low toxicity, phenytoin is the most commonly prescribed anticonvulsant and one of the drugs of choice to treat: • complex partial seizures (also called psychomotor or temporal lobe seizures) • tonic-clonic seizures. The enzyme system responsible for the metabolism of phenytoin is saturable. A change in dose can result in disproportional changes in serum concentration. Phenytoin Actions • Stabilizes neuronal membranes and limits seizure activity by either increasing efflux or decreasing influx of sodium ions across cell membranes in the motor cortex during generation of nerve impulses Indications • Control of tonic-clonic and complex partial seizures • Status epilepticus • Prevention of and treatment for seizures during neurosurgery Nursing considerations • Monitor the patient for adverse effects, such as ataxia, slurred speech, mental confusion, nystagmus, blurred vision, gingival hyperplasia, nausea, vomiting, hematologic disorders, hepatitis, Stevens- Johnson syndrome, and hirsutism. • Don’t withdraw the drug suddenly; seizures may occur. • Monitor drug levels as ordered; therapeutic levels range from 10 to 20 mcg/mL