Drugs Treating Seizure Disorders PDF

DRUGS TREATING SEIZURE DISORDERS Unit 5,Chapter 18 Ms.Fathiya AL-Harrasi OCHS -2024  DRUGS TREATING SEIZURE DISORDERS 1. PHENYTOIN 2. ETHOSUXIMIDE 3. DIAZEPAM Antiepileptic Drugs ❖ Patients who are diagnosed with epilepsy are treated with antiepileptic...

DRUGS TREATING SEIZURE DISORDERS Unit 5,Chapter 18 Ms.Fathiya AL-Harrasi OCHS -2024  DRUGS TREATING SEIZURE DISORDERS 1. PHENYTOIN 2. ETHOSUXIMIDE 3. DIAZEPAM Antiepileptic Drugs ❖ Patients who are diagnosed with epilepsy are treated with antiepileptic drugs. ❖ 3 main ways that antiepileptic drugs work are by: I. Decreasing the rate at which sodium flows into the cell (Prototype: Phenytoin) II. Inhibiting calcium flow rate into the cell through specific channels (Prototype: Ethosuximide) III. Increasing the effect of the neuroinhibitor GABA (Prototype: Benzodiazepines) I. Antiepileptic Drugs that Decrease Sodium Influx ❑ Control seizures by decreasing sodium influx into the cells. ❑ Prototype drug: Phenytoin (Dilantin) ❑ Phenytoin is representative of a class of drugs called the hydantoins. Phenytoin: Core Drug Knowledge ❖ Pharmacotherapeutics: ▪ Used to control partial and generalized (grand mal) and other psychomotor seizures. ▪ Also used to prevent and treat seizures that occur either during or following neurosurgery. ▪ Parenterally used to treat status epilepticus. Phenytoin: Core Drug Knowledge ❖ Pharmacokinetics: ▪ Phenytoin is slowly absorbed when given orally. ▪ Oral phenytoin reaches peak serum levels in 1.5 hours to 3 hours. ▪ Highly protein bound (about 90%). ▪ Metabolism: Liver ▪ Excretion: Urine ▪ Half-life: 6-24 hours at low doses 20-60 hours at therapeutic doses.  Phenytoin: Core Drug Knowledge ❖ Pharmacodynamics: ▪ Primary site of action: Motor Cortex ▪ Reversibly binds to sodium channels while they are in the inactive state. ▪ This binding delays the return of the channel to an active state. ▪ Phenytoin selectively binds to sites with hyperactive neurons. ❑ Explain why phenytoin is effective in treating cardiac arrhythmias from ectopic foci. Phenytoin: Core Drug Knowledge ❖ Contraindications: ▪ Patients with: ✔ Sinus bradycardia ✔ Sinoatrial block ✔ Second- and third-degree atrioventricular (AV) block or Adams-Stokes syndrome. Phenytoin: Core Drug Knowledge ❖ Precautions: Should not be administered with other drugs that cause blood dyscrasias. Patients with diabetes. Phenytoin should not be abruptly stopped because doing so can precipitate status epilepticus. Use of the drug during pregnancy is complicated and confusing issue. Phenytoin: Core Drug Knowledge ❖ Adverse Effects: ▪ Most frequent adverse effects of phenytoin occur in the CNS and include: Nystagmus Ataxia Dysarthria Slurred speech Mental confusion Tremor & Headache Phenytoin: Core Drug Knowledge ❖ Adverse Effects: ▪ Other common adverse include: ✔ Nausea ✔ Gingival hyperplasia. Rare, but potentially life threatening adverse effect is: ✔ Hematopoietic effects. Phenytoin: Core Drug Knowledge ❖ Drug Interactions: ▪ Numerous drugs interact with phenytoin. ❖ Patient and Family Education: ▪ Ensure proper administration of medication. ▪ Take medication with food to decrease GI upset. ▪ Notify the physician of adverse effects. ▪ Pg. No: 304 (Specific for phenytoin) ▪ Pg. No: 305, Box: 18.4 (Common to all antiepileptic drugs) II. Antiepileptic Drugs that Decrease Calcium Influx The prototype antiepileptic drug that inhibits influx of calcium is Ethosuximide (Zarontin).  Ethosuximide: Core Drug Knowledge ❖ Pharmacotherapeutics: Used to treat absence (petit mal) seizures. Available as capsules and as a syrup. Ethosuximide: Core Drug Knowledge ❖ Pharmacokinetics: Readily absorbed from the GI tract. Peak serum level in 3 to 7 hours. Metabolism: Liver. Excretion: Urine (20% excreted unchanged). Half-life: 30 hours in children 60 hours in adults. Ethosuximide: Core Drug Knowledge ❖ Pharmacodynamics: Works by inhibiting the influx of calcium ions into the cells. ❖ Contraindications: Hypersensitivity to succinimides. ❖ Warning: It may increase suicidal thoughts and actions. Ethosuximide: Core Drug Knowledge ❖ Precautions: ❑ Caution should be used if it is used as monotherapy in mixed types of epilepsy because it may increase the frequency of tonic-clonic (grand mal) seizures in some patients. ❑ Caution should be used if the patient has pre-existing renal or liver disease. ❑ Its use during pregnancy can cause complications. Ethosuximide: Core Drug Knowledge ❖ Adverse Effects: ▪ Common adverse effects are: ✔ Drowsiness ✔ Dizziness ✔ Lethargy ✔ Nausea & ✔ Vomiting Serious adverse effect is: ✔ Blood dyscrasias with and without bone marrow suppression Ethosuximide: Core Drug Knowledge ❖ Drug Interactions: Interact with some of the other antiepileptic drugs. ❖ Patient & Family Education: Teach patients to take the drug with milk or food if GI upset occurs. Notify the provider of adverse effects. Teach women of childbearing age to use birth control, because drug therapy carries some risks if they become pregnant. III. Antiepileptic Drugs that Increase the Effects of GABA ❑ Benzodiazepines ❑ Diazepam ❑ Clonazepam III. Antiepileptic Drugs that Increase the Effects of GABA Antiepileptic drugs that affect GABA are designed to increase the supply of GABA by: ✔ lowering GABA metabolism, ✔ reducing reuptake of GABA into the neurons and glia, or ✔ increasing the production of GABA. Other antiepileptic drugs imitate the action GABA or improve GABA’s inhibition of the nervous system. Diazepam Diazepam ❖ Pharmacotherapeutics: Used as an effective adjunctive therapy for: ✔ Myoclonic seizures ✔ Atonic seizures ✔ Partial seizures ✔ Generalized tonic-clonic seizures Administered IV during status epilepticus. Diazepam ❖ Pharmacotherapeutics: ▪ Also used as a: ✔ Muscle relaxant ✔ Preoperative medication to reduce anxiety, tension and recall of events. Diazepam ❖ Pharmacokinetics: Onset of action is very rapid when taken orally. Peak plasma levels are reached in 30 minutes to 2 hours. Highly protein bound. Metabolism: Liver. Excretion: Urine. Half-life: 20-80 hours. Diazepam ❖ Pharmacodynamics: Works by increasing the effectiveness of GABA. ❖ Warning: It may increase suicidal thoughts and actions. Diazepam ❖ Precautions: Patients need to be cautioned when the drug is added to their therapy as CNS depression may occur. It should be injected very slowly, no faster than 5 mg in 1 minute. Diazepam should not be mixed or diluted with other solutions or drugs, either in the syringe or in IV bags of fluid. Drugs treating Seizure disorders THANK YOU