Hydantoins
乙内酰脲类药 Indications适应症
The hydantoins stabilize nerve membranes throughout the CNS directly by influencing ionic channels in the cell membrane, thereby decreasing excitability and hyperexcitability to stimulation. By decreasing conduction through nerve pathways, they reduce the tonic–clonic, muscular, and emotional responses to stimulation.
Contraindications禁忌症
Hydantoins are generally contraindicated in the presence of allergy to any of these drugs to avoid hypersensitivity reactions. Many of these agents are associated with specific birth defects and should not be used in pregnancy or lactation unless the risk of seizures outweighs the potential risk to the fetus. In such cases the mother should be informed of the potential risks. The risk of taking a woman with a seizure disorder off an antiepileptic drug that has stabilized her condition may be greater than the risk of the drug to the fetus. Discontinuing the drug could result in status epilepticus, which has a high risk of hypoxia for the mother and the fetus. Research has not been able to show the effects of even a minor seizure during pregnancy on the fetus, making it important to prevent seizures during pregnancy if at all possible. Women of childbearing age should be urged to use barrier contraceptives while taking these drugs. If a pregnancy does occur, the woman should receive educational materials and counseling.
Cautions注意事项
Caution should be used with elderly or debilitated patients, who may respond adversely to the CNS depression, and with patients who have impaired renal or liver function that may interfere with drug metabolism and excretion. Patients with hepatic impairment are at risk for increased toxicity from phenytoin. Caution should be used when giving ethotoin to diabetic patients and patients with severe cardiovascular problems. Patients receiving fosphenytoin intravenously require careful monitoring of their cardiovascular status during the infusion period. Some potentially serious name confusion has occurred with fosphenytoin (see prior Focus on Safe Medication Administration). Other contraindications include coma, depression, or psychoses, which could be exacerbated by the generalized CNS depression.
★Test ★ 1. John suddenly experiences a seizure, and Nurse Gina notice that John exhibits uncontrollable jerking movements. Nurse Gina documents that John experienced which type of seizure?
A. Tonic seizure
B. Absence seizure
C. Myoclonic seizure
D. Clonic seizure 2. A child is admitted to the hospital with an uncontrolled seizure disorder. The admitting physician writes orders for actions to be taken in the event of a seizure. Which of the following actions would NOT be included?
A. Notify the physician.
B. Restrain the patient’s limbs.
C. Position the patient on his/her side with the head flexed forward.
D. Administer rectal diazepam.
Answer 答案 1. C. Myoclonicseizure Rationale: Myoclonic seizure is characterized by sudden uncontrollable jerking movements of a single or multiple muscle group. 2. B. Restrain the patient’s limbs. Rationale: During a witnessed seizure, nursing actions should focus on securing the patient’s safely and curtailing the seizure. Restraining the limbs is not indicated because strong muscle contractions could cause injury. A side-lying position with head flexed forward allows for drainage of secretions and prevents the tongue from falling back, blocking the airway. Rectal diazepam may be a treatment ordered by the physician, who should be notified of the seizure.
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