1. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Introduction to Clinical Pharmacology Chapter 30- Anticonvulsants

2. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Anticonvulsants: Actions Benzodiazepines and barbiturates elevate seizure threshold by decreasing postsynaptic excitation Hydantoins stabilize hyperexcitability postsynaptically in motor cortex of brain Oxazolidinediones decrease repetitive synaptic transmission of nerve impulses Succinimides depress motor cortex creating higher threshold before nerves react to convulsive stimuli

3. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Anticonvulsants: Uses Used prophylactically to prevent seizures following trauma, neurosurgery, or tumor Used in treatment of: –Seizures of all types; neuropathic pain; biopolar disorders; anxiety disorders –Status epilepticus-continual seizure activity. Ativan (lorazepam) is the drug of choice for this condition. The effects of lorazepam last less than 1 hour, may need a longer lasting anticonvulsant such as phenytoin (Dilantin) or phenobarbital to continue to control the seizure

4. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Anticonvulsants: Adverse Reactions Central nervous system reactions: Drowsiness; weakness; dizziness; headache; somnolence; nystagmus; ataxia; slurred speech –*CNS depression with phenobarbital Gastrointestinal reactions: Nausea; vomiting; anorexia; constipation; diarrhea; gingival hyperplasia-phenytoin Other: Skin rashes; pruritus; urticaria; urinary frequency; serious skin reactions; hematologic changes-pancytopenia with administration of carbamazepine (Tegretol), felbamate (Felbatol) and trimethadione (Tridione)

5. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Anticonvulsants: Contraindications Contraindicated in patients : Hypersensitive to the drugs –Phenytoin is contraindicated in patients with sinus bradycardia; sinoatrial block; Adams-Stokes syndrome; second and third-degree atrioventricular (AV) block; during pregnancy and lactation –Ethotoin (Pegatone) is contraindicated in patients with hepatic abnormalities

6. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Anticonvulsants: Contraindications (cont’d) –Succinimides are contraindicated in patients with bone marrow depression or hepatic or renal impairment –Carbamazepine is contraindicated in patients with bone marrow depression or hepatic or renal impairment and during pregnancy –Valproic acid (Depakote) is not administered to patients with renal impairment or during pregnancy

7. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Anticonvulsants: Precautions –Phenytoin is used cautiously in patients with hypotension; severe myocardial insufficiency; hepatic impairment –Trimethadione is used with caution in patients with eye disorders –Miscellaneous anticonvulsants are used cautiously in patients with glaucoma or increased intraocular pressure; a history of cardiac, renal or liver dysfunction; and psychiatric disorders

8. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Anticonvulsants: Interactions Interactant DrugEffect of Interaction Antibiotics/antifungalsIncreased effect of the anticonvulsant Tricyclic antidepressants Increased effect of the anticonvulsant SalicylatesIncreased effect of the anticonvulsant CimetidineIncreased effect of the anticonvulsant Analgesics or alcoholIncreased depressant effect

9. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Assessment Preadministration assessment: –Obtain vital signs at the time of the initial assessment to provide baseline data –Thorough patient history is necessary to identify type of seizure disorder –Primary health care provider may order laboratory and diagnostic tests –**See display 30.1

10. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Assessment Ongoing assessment: –Carefully document each seizure with regard to time of occurrence, duration of seizure, psychic or motor activity occurring before, during, after seizure –Dosage adjustments are based on patient’s response to therapy, as well as occurrence of adverse reactions –Serum plasma levels of anticonvulsant are measured regularly to monitor for toxicity

11. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Planning Expected outcomes for patient depend on the type and severity of the seizure but may include: –optimal response to therapy –Support of patient needs related to management of adverse reactions –Understanding of and compliance with prescribed therapeutic regimen

12. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Promoting an optimal response to therapy: –Make notation on the care plan, as well as informing all health care team members of the importance of the drug –Status epilepticus may result from abrupt discontinuation of the drug, even when it is being administered in small doses-MONITOR RR! –Barbiturates: Monitor patient carefully during administration of barbiturate, taking blood pressure and observing respirations frequently

13. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Promoting an optimal response to therapy (cont’d): –Benzodiazepines: Dosage of benzodiazepines is highly individualized, increase the dosage cautiously to avoid adverse reactions, particularly in elderly and debilitated patient Do not mix diazepam with other drugs

14. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Promoting an optimal response to therapy (cont’d): –Hydantoins: Monitor serum concentrations of drug on regular basis to detect signs of toxicity –Geriatric ALERT! BARBITURATES MAY PRODUCE MARKED EXCITEMENT, DEPRESSION AND CONFUSION IN ELDERLY

15. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Monitoring and managing patient needs: –Risk for injury: The nurse should assist the patient with all ambulatory activities Use caution when giving an oral preparation as aspiration of tablet, capsule, or liquid may occur if patient experiences drowsiness Test swallowing ability of patient by offering small sips of water before giving drug

16. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Alert Phenytoin may cause hematoogic changes MONITOR FOR LEUKOPENIA, SWOLLEN GLANDS When administering phenytoin, monitor the patient for s/s of drug toxicity-slurred speech, ataxia, lethargy, dizziness, nausea, vomiting –Plasma levels between 10-20 mcg/ml give optimal anticonvulsant effect

17. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Educating the patient and family: –When patient receives diagnosis of epilepsy, nurse must assist patient and family to adjust to diagnosis –Instruct family members in care of patient before, during, and after seizure –Explain importance of restricting some activities until seizures are controlled by drugs –Assist patient to look for other modes of transportation in order to continue typical activities or employment –The nurse reviews adverse drug reactions associated with the prescribed anticonvulsant with the patient and family members

18. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Educating the patient and family (cont’d): –Hydantoins: Inform dentist and other primary health care providers of use of this drug Brush and floss teeth after each meal and make periodic dental appointments for oral examination and care

19. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Educating the patient and family (cont’d): Take medication with food to reduce GI upset Thoroughly shake phenytoin suspension immediately before use Do not take capsules that are discolored

20. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Educating the patient and family (cont’d): Notify primary health care provider if any of the following occurs: Skin rash; bleeding; swollen or tender gums; yellowish discoloration of the skin or eyes; unexplained fever; sore throat; unusual bleeding or bruising; persistent headache; malaise; or pregnancy

21. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Educating the patient and family (cont’d): –Succinimides: If GI upset occurs, take drug with food or milk Notify primary health care provider if any of the following occurs: Skin rash; joint pain; unexplained fever; sore throat; usual bleeding or bruising; drowsiness; dizziness, blurred vision; or pregnancy

22. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Implementation Educating the patient and family (cont’d): –Oxazolidinediones: Determine: Protective measures when exposed to ultraviolet light, sunlight Notify primary care provider if following reactions occur: Visual disturbances; excessive drowsiness; dizziness; sore throat; fever; skin rash; pregnancy; malaise; easy bruising; epistaxis; bleeding tendencies

23. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing Process: Evaluation Therapeutic effect is achieved and convulsions are controlled No injury is evident Adverse reactions are identified, reported, and managed successfully through appropriate nursing interventions Patient verbalizes the importance of complying with the prescribed treatment regimen Patient verbalizes an understanding of treatment modalities and the importance of continued follow-up care Patient and family demonstrate an understanding of the drug regimen