Antiepileptic drugs.pptx

Antiepileptic drugs Done by: Dr. Rawan AL-Gharaibeh  A seizure: is a brief episode of abnormal electrical active in the nerve cells of the brain, which may or may not lead to a convulsion. A convulsion is a more severe seizure characterized by involuntary spasmodic contractions of any or all vol...

Antiepileptic drugs Done by: Dr. Rawan AL-Gharaibeh  A seizure: is a brief episode of abnormal electrical active in the nerve cells of the brain, which may or may not lead to a convulsion. A convulsion is a more severe seizure characterized by involuntary spasmodic contractions of any or all voluntary muscles throughout the body.  Epilepsy: is the most common chronic neurologic illness. It results from excessive electrical activity of neurons located in the superficial area of the brain known as the cerebral cortex.  is chronic, recurrent pattern of seizures. These excessive electrical discharges can often be detected by an electroencephalogram (EEG), which is commonly obtained to help diagnose epilepsy.  Because up to 50% of patients with epilepsy have normal EEGs, a careful history is important for accurate diagnosis. Other applicable diagnostic tests include skull radiography, computed tomography, and magnetic resonance imaging.  Primary (idiopathic) epilepsy: Epilepsy without an identifiable cause Secondary epilepsy: Epilepsy has a distinct cause, such as trauma, infection, cerebrovascular disorder, or other illness, also some drugs can cause epilepsy. Febrile seizure:  occurs in children aged 6 months to 5 years It is be caused by fever. Children usually outgrow the tendency to have such seizures, These seizures do not constitute a chronic illness.  Status epilepticus: Two or more seizures occur without recovery of full consciousness in between episodes. These may be focal or primary generalized, convulsive or nonconvulsive. Status epilepticus is life threatening and requires emergency treatment In these cases the therapy is the administration of a fast-acting medication typically diazepam ( the drug of choice). Once status epilepticus is controlled, long-term drug therapy is begun with other drugs such as phenytoin for the prevention of future seizures. Antiepileptic drugs: The goal of antiepileptic drug therapy is to control or prevent seizures while maintaining a reasonable quality of life. In most cases, the therapeutic goal is to maximally reduce the incidence of seizures while minimizing drug-induced toxicity. Sometimes, a combination of drugs must be given to control the disorder. Single-drug therapy must fail before two-drug or multidrug therapy is attempted. Antiepileptic drugs should never be stopped abruptly unless a severe adverse effect occurs. Therapeutic drug monitoring of serum drug concentrations provides a useful guideline in assessing the effectiveness of therapy. Each patient should be monitored individually, and the dosages adjusted based on the individual case. Successful control of a seizure disorder hinges on selection of the appropriate drug class and drug dosage, avoidance of drug toxicity, and patient compliance with the treatment regimen. Mechanism of action: The exact mechanism of action of the antiepileptic drugs is not known with certainty strong evidence indicates that they alter the movement of sodium, potassium, calcium, and magnesium. Regardless of mechanism, however, the overall effect is that antiepileptics stabilize neurons and keep them from becoming hyper excited and generating excessive nerve impulses to adjacent neurons. Some work by enhancing the effects of the inhibitory neurotransmitter gamma- aminobutyric acid (GABA). Indications: Antiepileptic drugs are chiefly used for the long-term maintenance treatment of epilepsy. they are also useful for the acute treatment of convulsions and status epilepticus. Drug profiles: A. Benzodiazepines Benzodiazepines bind to GABA inhibitory receptors to reduce firing rate. Most benzodiazepines are reserved for emergency or acute seizure treatment due to tolerance. However, clonazepam and clobazam may be prescribed as adjunctive therapy for types of seizures. Diazepam is also available for rectal administration when oral administration is not possible. B. Carbamazepine (Tegretol): It was marketed in the late 1960s for the treatment of epilepsy in adults after its efficacy and safety for the treatment of trigeminal neuralgia was proved. Carbamazepine blocks sodium channels, thereby inhibiting the generation of repetitive action potentials in the epileptic focus and preventing their spread. Carbamazepine is effective for treatment of focal seizures and, additionally generalized tonic–clonic seizures, trigeminal neuralgia, and bipolar disorder. Carbamazepine is associated with autoinduction of hepatic enzymes. Hyponatremia may be noted in some patients, especially the elderly, and may necessitate a change in medication. C.Gabapentin: Gabapentin is a chemical analogue of GABA Its precise mechanism of action is not known. It is indicated as an adjunct drug for the treatment of partial seizures and for prophylaxis of partial seizures. Gabapentin is effective as a single-drug therapy for the new-onset epilepsy. It is also commonly used to treat neuropathic pain. Adverse effects include CNS and GI symptoms. D. Phenobarbital: It is used primarily in the treatment of status epilepticus when other agents fail. It is an effective prophylactic drug for the control of febrile seizures In developing countries, oral phenobarbital is often the drug of choice for routine seizure prophylaxis because of its lower cost compared with the newer drugs. Phenobarbital associated with physical dependence and withdrawal syndrome. Phenobarbital interacts with many drugs because it is a major liver enzyme inducer.  Phenobarbital is available in oral and injectable forms. The most common adverse effect is sedation. Contraindications include:  known drug allergy  liver or kidney impairment respiratory illness. E. Phenytoin: Phenytoin is primarily indicated for the management of tonic-clonic and partial seizures. Most often it is taken orally. It can also be given intravenously if needed.  Contraindications include:  known drug allergy heart conditions that involve bradycardia. The most common adverse effects are:  lethargy abnormal movements mental confusion. Long-term phenytoin therapy can cause: gingival hyperplasia Acne  hirsutism.  Phenytoin can interact with other medications for two reasons: First, it is highly bound to plasma proteins and competes with other highly protein-bound medications for binding sites. Second, it induces hepatic enzymes. Phenytoin is generally well tolerated, highly effective, and relatively inexpensive. F. Valproic acid: It is used primarily in the treatment of generalized seizures. It has also been shown to be effective in controlling partial seizures. The main reason for the drug interactions with valproic acid are protein binding and liver metabolism. The drug is available in both oral and injectable.  The most serious adverse effects are:  hepatotoxicity pancreatitis. Contraindications include:  known drug allergy  liver impairment urea cycle disorders.  Common adverse effects include: Drowsiness GI disturbances (nausea, vomiting) Tremor weight gain transient hair loss. Nursing Implications:  Oral drugs  Take regularly, same time each day with meals to reduce GI upset  Do not crush, chew, or open extended-release forms  Intravenous forms  Follow manufacturer’s recommendations for IV delivery—usually given slowly and monitor vital signs during administration  Avoid extravasation of fluids  Teach patients to keep a journal to monitor:  Response to AED  Seizure occurrence and descriptions  Adverse effects  Instruct patients to wear a medical alert tag or ID  AEDs should not be discontinued abruptly  Driving may be impaired until drug levels stabilize  Teach patients that therapy is long term and possibly lifelong (not a cure)  Monitor for therapeutic effects: Decreased or absent seizure activity  Monitor for adverse effects Mental status changes, mood changes, changes in level of consciousness. Eye problems, visual disorders, Sore throat, fever (blood dyscrasias may occur with hydantoins) Many others