1. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Chapter 16 Anticonvulsants

2. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Epilepsy  A group of functional disorders of the brain characterized by recurrent single or multiple seizures accompanied by motor activity or changes in sensory or emotional behavior 2

3. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Seizure Disorders  About 10% of the population will have one or more seizures at some point in life.  1% to 3% of the population has a chronic seizure disorder called epilepsy.  Most causes of epilepsy are idiopathic but other causes include trauma to the head, neoplasm, drugs, and congenital malformations.  Seizure disorders are classified as either general or partial.  General seizures include generalized tonic-clonic seizures and absence seizures. 3

4. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Therapy of Seizure Disorders  The intent of drug therapy is to reduce the frequency of seizures and reduce potential adverse reactions.  Ideally, the intent is to completely control all seizures.  A single drug at the lowest dose possible is used first.  If single drug therapy fails, then multiple drug therapy at low doses is used. 4

5. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. General Adverse Reactions to Anticonvulsant Agents  CNS depression is probably the most common side effect of anticonvulsants.  CNS depressant effects include dizziness, sedation, impaired learning and cognitive abilities, and excitability.  Gastrointestinal adverse effects include anorexia, nausea, vomiting, and GI upset.  Dermatologic adverse effects range from a mild rash to Stevens-Johnson syndrome, which is rare. 5

6. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Interactions  Many drug interactions can occur with anticonvulsant drugs.  These drugs increase or decrease the metabolism of each other in the liver.  The drug interactions that occur with each other are more significant than other drugs because of their narrow therapeutic indexes.  Plasma monitoring of anticonvulsant drugs is necessary. 6

7. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Dental Management of Patient Taking Anticonvulsant Agents 7

8. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Carbamazepine  Carbamazepine blocks sodium channels which blocks the propagation of nerve impulses.  Adverse reactions unique to carbamazepine Hematologic Hematologic  Agranulocytosis has been reported with carbamazepine therapy.  It usually occurs within 4 months of starting therapy or after an increase in dose. 8

9. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Carbamazepine  Adverse Reactions Unique to Carbamazepine  Dry mouth, glossitis, and stomatitis can sometimes occur.  The pediatric chewable dose form contains 63% sugar. 9

10. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Dental Management of Patient Taking Carbamazepine 10

11. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Valproate  This drug may exert its anticonvulsant effects by increasing the levels of GABA.  This drug has been reported to cause hypersalivation.  Hepatotoxicity has also been reported.  Valproate inhibits the second phase of platelet aggregation. As a result, bleeding time may be prolonged. 11

12. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Valproate 12

13. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Phenytoin  Phenytoin is the most commonly used anticonvulsant drug.  Phenytoin has a very narrow therapeutic index.  Phenytoin demonstrates zero-order kinetics. 13

14. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Phenytoin  Adverse Effects  Phenytoin can cause hirsutism which can lead to noncompliance in young women.  Some patients may experience vitamin D or folate deficiency. Oral mucosal changes such as ulcerations or glossitis are indicative of folate deficiency.  Teratogenicity has also been reported. 14

15. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Phenytoin  Adverse Effects  Gingival Enlargement This occurs in 50% of all chronic users. This occurs in 50% of all chronic users. It can appear in as little as a few weeks after beginning therapy or after several years of therapy. It can appear in as little as a few weeks after beginning therapy or after several years of therapy. Its cause is unknown. Its cause is unknown. The better the oral hygiene, the less likely it will occur or the less severe the lesions will be. The better the oral hygiene, the less likely it will occur or the less severe the lesions will be. 15

16. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Phenytoin  Adverse Effects  Managing Gingival Enlargement Stop phenytoin and change to another drug. Stop phenytoin and change to another drug. Improve and maintain meticulous oral hygiene. Improve and maintain meticulous oral hygiene. A gingivectomy may be necessary. A gingivectomy may be necessary. 16

17. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Phenytoin 17

18. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Other Drugs  Phenobarbital is used alone or in combination with other antidepressants to treat generalized tonic-clonic and partial seizures.  Its most common side effect is sedation.  Ethosuximide is the treatment of choice for absence seizures.  Gingival enlargement and swelling of the tongue have been reported with ethosuximide.  Benzodiazepines are often used to treat status epilepticus. They are used as adjunct to treat other seizures. Oral adverse effects include increased salivation, coated tongue, dry mouth, and sore gums. 18

19. Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc. Newer Anticonvulsants  Gabapentin is unique in that it does not appear to have any drug interactions.  Felbamate is limited to those that are refractory to other anticonvulsants.  Felbamate has been associated with aplastic anemia and acute hepatic failure. 19