What is the mechanism of action for carbamazepine (Tegretol)?
Blocking sodium channels in neurons, which blocks propagation of impulses
What is carbamazepine (Tegretol) known for?
Highly effective for simple and complex partial seizures
What are some other clinical uses for carbamazepine (Tegretol) and why is it of special interest in the field of dentistry?
- Bipolar depression
- Chronic pain
- Treatment of trigeminal neuralgia
What are the adverse drug reactions of Tegretol?
- Hematologic - causes aplastic anemia (wipes out bone marrow)
- Liver toxicity (potential)
- Congestive heart failure, altered blood pressure
What are the drug interactions of Tegretol?
- It's a classic "inducer"
- Decreases effectiveness of warfarin, doxycycline, theophylline, oral contraceptives
- Erythromycin-type antibiotics
- Carbamazepine may increase hepatotoxicity of acetaminophen
What is the mechanism of action for phenytoin (Dilantin)?
Stabilizes neuronal membranes by decreasing the neuronal membrane passage of sodium ions.
Reduces propagation of abnormal impulses in the brain to reduce the frequency of seizures
What is characteristic of all anticonvulsants, with just about the very first dose?
What are some characteristics of phenytoin (Dilantin)?
- Highly effective for all partial seizures
- Highly effective for tonic-clonic seizures
- Effective for status epilepticus
- NOT effective for absence seizures (petit mal)
- Dental use - trigeminal neuralgia
What are some adverse effects of phenytoin (Dilantin)?
- Loss of taste
- Oral mucosal ulceration or glossitis associated with Vitamin D and folate deficiencies
- Gingival hyperplasia
What can reduce the extent/severity of the adverse effects of phenytoin (Dilantin)?
Good oral hygiene
What anticonvulsant is known to cause gingival hyperplasia?
phenytoin (Dilantin) -
50-60% of people that take it will experience it
How is phenytoin (Dilantin) rated the FDA category?
- Category D
- Fetal syndrome - cleft lip, cleft palate, congenital heart disease
What drug interactions does phenytoin (Dilantin) have and why?
- Many drug interactions
- Increases metabolism of many drugs
- Cytochrome P450 "inducer"
What do GABAmimetic agents cause?
Release of GABA from presynaptic interneurons
They encourage GABA fusion with presynaptic neuron - inhibit the release of acetylcholine
What is GABA?
Inhibitory neurotransmitter (presynaptically)
What does phenobarbital (Luminal) do?
- General depressent to CNS
- Limits the spread of seizure discharge in the brain
What is the mechanism of action of phenobarbital (Luminal)?
Reduces Na and K tranport along axonal membranes, potentiates the inhibitory effects of GABA-mediated neurons (GABAmimetic)
What is the most common barbituate used as an anticonvulsant?
phenobarbital (Luminal sodium)
What is phenobarbital (Luminal) indicated for?
- Tonic-clonic and partial seizure types
What are some side effects of phenobarbital (Luminal)?
- Most common - sedation
- Rare - stomatitis may indicate onset of cutaneous reactions, some of which have been fatal
What do you do if a patient develops a skin reaction while taking phenobarbital (Luminal)?
Discontinue drug - may be fatal
What are the drug interactions of Luminal?
- Strong inducer
- Additive CNS effects
- Enhances hepatoxicity of acetaminophen
What is chemically related to phenobarbital that is metabolized in liver to phenobarbtial (precursor to phenobarbital)?
What drugs fall under the family name Valproates?
- valproic acid (Depakene)
- valproate sodium (Depacon)
- divalproex sodium (Depakote)
What is the mechanism of action for valproates?
Causes increased availability of GABA to neurons - enhances action of or mimics the effects of GABA presynaptically
What is valproic acid (Depakene) used for?
- Tonic-clonic seizures (grand mal)
- Generalized seizures
- Absence (petit mal)
- Absence (petit mal)
What are the adverse reactions of valproates?
- Hepatotoxicity - not used as often as other drugs, monitor liver function
- Increases bleeding time - inhibition of platelet aggregation
What are the drug reactions to valproates?
- Macrolide antibiotics - inhibit metabolism of valproic acid
- Aspirin and other salicylates - displace valproic acid from protein-binding sites, leading to acute toxicity
What is the first choice in absence seizures (petit mal)?
What's a main side effect of Zarontin?
Oral gingival hyperplasia - swelling of tongue