Anticonvulsants: Interactions and Therapeutic Levels

CNS Depression and Interactions

• CNS depressants worsen the effects of anticonvulsants, increasing CNS depression.
• Salicylates and cimetidine increase the effects of anticonvulsants.
• Opioids decrease anticonvulsant effectiveness, potentially causing seizures.
• Oral contraceptives can interfere with anticonvulsant efficacy.
• Alcohol increases the depressant effects of anticonvulsants.
• Antidiabetic medications can raise blood glucose levels in patients taking anticonvulsants.

Therapeutic Levels and Adjustments

• Therapeutic levels for anticonvulsants must be established, requiring frequent adjustments initially.
• Plasma levels are monitored via blood tests for therapeutic ranges and to prevent toxicity.
• Therapeutic ranges ensure effective seizure control without toxicity.

Abrupt Discontinuation and Status Epilepticus

• Abrupt discontinuation of anticonvulsants can lead to status epilepticus, a dangerous, life-threatening condition of continuous seizures.
• Status epilepticus can cause respiratory arrest.

Common Adverse Effects

• Drowsiness is a common adverse effect of anticonvulsants, typically decreasing over time.
• Safety is compromised by the potential for drowsiness and impaired coordination.

Geriatric Considerations

• Geriatric patients may need lower diazepam doses to prevent oversedation.
• Decreased kidney and liver function in the elderly can affect drug metabolism, necessitating dosage adjustments.

Serious Adverse Effects

• Cardiac arrest and apnea are possible with anticonvulsants.
• A severe, potentially fatal rash can occur with lamotrigine (Lamictal).
• Suicidal ideation should be monitored in patients taking lamotrigine (Lamictal).
• Pancytopenia (a drop in all blood cell counts) can occur with anticonvulsants.
• Thrombocytopenia (low platelets) causes bleeding (e.g., nosebleeds, easy bruising, petechiae).
• Leukopenia (low white blood cells) increases infection risk (e.g., sore throat, fever, cough).
• Anemia (low red blood cells) causes fatigue and malaise.
• Use soft toothbrushes to prevent bleeding gums.

Monitoring and Administration

• Plasma levels are periodically monitored to maintain therapeutic levels.
• Monitoring frequency varies by doctor and patient needs.
• Do not put anything in the mouth of a seizing person.
• Avoid alcohol, as it's a CNS depressant.

Barbiturates: Respiratory Depression and Other Effects

• Barbiturates depress the respiratory system, requiring frequent vital signs, especially in new patients.
• Resuscitation equipment should be available.
• Barbiturates should not be used in patients with severe respiratory issues.
• Drowsiness, sedation, and depression are common barbiturate side effects.
• Elderly patients may experience paradoxical excitement and agitation instead of sedation.

Diazepam: IV Administration and Short Duration

• Diazepam is given intravenously (IV) to quickly control seizures.
• Diazepam is the preferred drug for status epilepticus.
• Diazepam has a short duration of action.

Overview of anticonvulsant drug interactions, focusing on CNS depressants, salicylates, and opioids, in the presence of anticonvulsants. Discusses the importance of monitoring therapeutic levels via plasma levels to balance efficacy and toxicity and the risks associated with abrupt discontinuation, including status epilepticus.