Anticonvulsant Drugs Overview

Anticonvulsant Drugs

• Used to treat various seizure types, neuropathic pain, bipolar disorders, anxiety, and status epilepticus (continuous seizures).
• Valium (diazepam) is the drug of choice for status epilepticus.
• Anticonvulsants are CNS depressants, reducing seizure-inducing stimuli.
• Combining anticonvulsants with other CNS depressants (including alcohol) is dangerous, worsening CNS depression.
• A link exists between anticonvulsant use during pregnancy and birth defects.
• Common adverse reactions include:
  • CNS: Drowsiness, headache, somnolence, nystagmus, ataxia, slurred speech, diplopia.
  • GI: Nausea, vomiting, diarrhea, anorexia, constipation, gingival hyperplasia (most common with Dilantin/phenytoin).
  • Cardiovascular: Dysrhythmias.
  • Skin: Rashes (especially with Lamictal), Stevens-Johnson syndrome.
  • Hematologic: Pancytopenia (leukopenia, aplastic anemia, thrombocytopenia).

Anticonvulsant Drug Classes

• Barbiturates (e.g., Phenobarbital):
  • Depress the respiratory system, requiring frequent vital sign monitoring and resuscitation equipment.
  • Not for severe respiratory illnesses.
  • Diazepam (Valium) is given IV for rapid seizure control, with a very short duration of action.
  • Safety precautions regarding driving are necessary post-dosing.
• Hydantoins (e.g., Phenytoin/Dilantin):
  • Common anticonvulsants, available orally or IV.
  • Administered with meals to prevent GI upset.
  • IV preferred over IM due to erratic absorption and pain.
  • Gingival hyperplasia (gum overgrowth) is a significant side effect, necessitating meticulous oral hygiene.
  • Patients should report skin rash, bleeding gums, jaundice, fever, sore throat, bleeding, persistent headache, malaise, and pregnancy to their doctor.
• Carbamazepines (e.g., Tegretol/carbamazepine):
  • Used for bipolar disorder and neuralgia.
  • Prompts ADH secretion, potentially causing fluid overload and heart failure.
  • Monitor sodium levels, blood pressure, and edema.
• Iminostilbenes (e.g., Gabapentin/Neurontin):
  • Used for neuralgia.
  • Can cause hematologic toxicity, including thrombocytopenia, leukopenia, pancytopenia.
• Valproic Acid Derivatives (e.g., Depakote/divalproex sodium):
  • Used for migraine headaches and mania.
  • Hepatotoxic, potentially leading to pancreatitis with nausea, vomiting, and abdominal pain.
• Other (examples): Lyrica (pregabalin), Ativan (lorazepam), Magnesium sulfate (for seizures in eclampsia and acute nephritis).

Contraindications and Precautions

• General: Heart block, pregnancy, lactation.
• Specific:
  • Phenytoin: Pregnancy, lactation, heart block.
  • Carbamazepine: Pregnancy, lactation, within 14 days of MAOIs.
  • Valproic Acid: Pregnancy, renal impairment.
  • Depakote: Pregnancy.
• Drug Interactions:
  • Increased anticonvulsant effect: Antibiotics, antifungals, CNS depressants, salicylates, cimetidine.
  • Decreased anticonvulsant effect: Phenobarbital.
  • Oral contraceptive interference.
  • Increased blood glucose with antidiabetic medications.
  • Frequent dosage adjustments during initial therapy are essential for achieving therapeutic levels.

Key Points

• Anticonvulsants reduce nerve cell excitability in the brain, treating seizures.
• Used in other conditions like neuropathic pain, bipolar disorder, and anxiety.
• Avoid combining with other CNS depressants.
• Careful monitoring and dosage adjustments for optimal seizure control and minimal risks are crucial.

Antiparkinsonian Drugs

• Parkinson's disease results from dopamine deficiency and acetylcholine excess in the CNS.
• No cure; medications manage symptoms.
• "On-off" phenomenon (alternating improved/lost effect) is common in long-term use.
• Dopamine-related drugs (e.g., Sinemet/carbidopa/levodopa):
  • Most common Parkinson's treatment.
  • Side effects include dyskinesias, mental changes, GI disturbances, swallowing difficulties, increased hand tremors, headache, and dizziness.
  • Contraindications: Narrow-angle glaucoma, MAOIs.
• Amantadine: Used for Parkinson's and drug-induced extrapyramidal reactions.
  • Side effects: Orthostatic hypotension, depression, heart failure, psychosis, urinary retention, seizures, leukopenia, neutropenia, confusion, anxiety, anorexia, nausea, and constipation.
• Anticholinergics (adjunctive therapy):
  • Inhibit acetylcholine. Used in all Parkinsonism cases, including drug-induced extrapyramidal disorders; pre-op medication, ulcers, biliary colic, urinary problems and vagal nerve stimulation also utilize these therapies.
  • Side effects: Dry mouth, constipation, urinary retention, blurred vision, dizziness, nausea, nervousness, dysuria, tachycardia, confusion.
  • Important Interventions to help manage these side-effects: frequent fluids, mouth care, hard candy, ice chips.
  • Contraindications: Glaucoma, pyloric/duodenal obstruction, prostatic hypertrophy, achalasia, myasthenia gravis, megacolon.
  • Drug interactions include increased anticholinergic effects with amantadine; digoxin increases, and psychosis/antipsychotic effects with haloperidol and phenothiazines.
• COMT Inhibitors: Adjunct to carbidopa-levodopa, crosses the blood-brain barrier more efficiently than levodopa. Hepatotoxic, requiring liver function monitoring for jaundice. Smooths and prolongs levodopa effects.
• Dopamine Agonists (e.g., Requip/ropinirole, pramipexole): Used for Parkinson's, restlessness and potentially other symptoms.
  • Side effects: Nausea, vomiting, dizziness, hallucinations, confusion, visual issues, postural hypotension, involuntary movements, headaches.
  • Interactions: Increased effectiveness with paroxetine, ranitidine, and quinidine; decreased with estrogen, finasteride, and phenothiazines. Increased levodopa effect and hallucinations with levodopa.

Nursing Considerations for Parkinson's Disease

• Assess baseline motor function.
• Evaluate tremor, facial expression, gait, speech, muscular rigidity, drooling, eating/swallowing, and mental function before/after medication.
• Monitor response to therapy.
• Consider safety precautions for patients with dizziness, weakness, ataxia, or orthostatic hypotension.
• Safe environment to prevent falls is crucial.
• Monitor on/off periods.
• Discontinuing antiparkinsonian medications abruptly can result in neuroleptic malignant syndrome.

Patient Teaching for Parkinson's Medications

• Adhere to prescribed dosage regimen.
• Take with meals to prevent GI issues.
• Avoid driving if symptoms present (dizziness, drowsiness, blurred vision).
• Avoid alcohol unless advised.
• Report specific side effects (dry mouth, swallowing difficulty, urinary problems, depression, severe dizziness, drowsiness, rapid/irregular heartbeat, abdominal pain, new abnormal movements).
• Avoid vitamin B6.
• Urine glucose tests may be affected.
• MAO-B Inhibitors (selegiline, rasagiline): First-line with carbidopa-levodopa to reduce "wearing-off" effect. Monitor for hypertensive crisis with tyramine-containing foods, meperidine, fluoxetine, MAOIs, sympathomimetics.

Other Anticholinergic Drugs

• Atropine: Reduces secretions, used for vehicle spread cardia or uri neural and biliary colic.
• Dicyclomine (Bentyl): IBS, reduces peristalsis.
• Scopolamine: Motion sickness, pre-anesthetic sedation.
• Trihexyphenidyl: Nausea, vomiting.