Anti-seizure drugs

• The type of seizure will determine what drug is prescribed
• Seizures are caused by a sudden electrical disturbance in the brain due to a group (focus) of hyperexcitable neurons; electrical discharge will the spread to other areas of the brain and cause normal neurons to fire abnormally
• Anti-seizure drugs will either suppress electrical discharge from the focus or stop the spread of discharge
• seizure treatment is usually life-long and patients need to be educated on how seizure control is highly dependent on medication adherence
• All anti-seizures drugs increase the risk of suicidal thoughts and behavior
• Phenytoin is a traditional anti-seizure drug that is used to treat all major forms of seizures; only exception is absence seizures
• The therapeutic range of phenytoin is 10-20 mcg/mL
• IV phenytoin is contraindicated for patients with sinus bradycardia, SA or AV node block, and Stoke's syndrome; use with caution for patients with the HLA gene mutation
• Phenytoin works by selectively inhibiting sodium channels in hyperactive neurons; preventing sodium from entering the neuron and thus decreasing the ability of the neuron to fire at high frequency
• Adverse effects of Phenytoin include CNS depression (nystagmus, diplopia, ataxia, sedation), gingival hyperplasia (overgrowth of gums), morbilliform rash (which can turn into Stevens-Johnson syndrome), teratogen, and Purple glove syndrome (IV)
• Patients must be educated on taking Phenytoin exactly as prescribed, as small dose deviations can cause toxicity or loss of seizure control
• For gingival hyperplasia, the patient should look into Folic acid (0.5 mg daily), teach proper oral hygiene techniques, and follow up with a dentist
• Phenytoin should never be abruptly stopped
• Warn patient that Phenytoin interacts with other CNS depressant medications, alcohol, warfarin, and oral contraceptives
• Phenytoin will decrease the effectiveness of warfarin and oral contraceptives
• If Phenytoin has to be taken during pregnancy, educate the patient on taking vitamin K supplements before and during delivery
• Phenytoin decreases the production of vitamin K based clotting factors
• Carbamazepine is a traditional anti-seizure drug used to treat epilepsy; 1st choice focal seizures
• Carbamazepine is contraindicated for patients with a history of bone marrow depression or blood disorders
• The therapeutic range for Carbamazepine is 4-12 mcg/mL
• Carbamazepine works by suppressing sodium channel activation, which decreases high-frequency neuron discharge
• Adverse effects of Carbamazepine include CNS depression (sedation/dizziness, ataxia), visual disturbances (diplopia, blurred vision, nystagmus), headaches, vertigo, morbilliform rash, and bone marrow suppression (leukopenia, anemia, thrombocytopenia)
• Phenytoin can increase the metabolism of carbamazepine
• Carbamazepine increases the metabolism of oral contraceptives and Warfarin (will reduce their effectiveness )
• Grapefruit will inhibit the metabolism of Carbamazepine and increase the risk of toxicity
• Patients on Carbamazepine should be educated on the signs of blood disorders like fever, weakness, activity intolerance, easy bruising, and petechiae
• Before starting Carbamazepine, a CBC should be done to establish the patient's baseline and to monitor for any changes during treatment.
• Status epileptics is a severe form of epilepsy that occurs when there are continuous seizures that last for 20-30 minutes or more
• Intervene if seizures have lasted for more than 5 minutes
• Treatment for status epilepticus is IV benzodiazepine (lorazepam) followed by long-term anti-seizure drugs