Phenytoin

Definition

Phenytoin is an anticonvulsant medication primarily used to control seizures, particularly in epilepsy. It works by stabilizing the neuronal membrane and reducing the frequency of seizure activity through modulation of sodium channels. Its effectiveness and safety profile make it a mainstay in the treatment of various seizure disorders.

5 Must Know Facts For Your Next Test

1. Phenytoin is often given as a first-line treatment for generalized tonic-clonic seizures and focal seizures.
2. The drug exhibits nonlinear pharmacokinetics, meaning that small changes in dosage can lead to disproportionately large changes in drug levels in the blood.
3. Common side effects of phenytoin include dizziness, drowsiness, and gingival hyperplasia, which is an overgrowth of gum tissue.
4. It is important to monitor serum drug levels of phenytoin regularly to avoid toxicity, especially since it has a narrow therapeutic index.
5. Phenytoin can interact with numerous medications, leading to altered efficacy or increased toxicity, so it's vital for patients to inform healthcare providers about all medications they are taking.

Review Questions

• How does phenytoin's mechanism of action contribute to its effectiveness as an anticonvulsant?
  • Phenytoin works by stabilizing neuronal membranes and inhibiting the excessive firing of neurons that occurs during seizure activity. It achieves this by blocking voltage-gated sodium channels, which decreases the influx of sodium ions into neurons. By reducing this excitability, phenytoin effectively helps to control and prevent seizures in patients with epilepsy.
• Discuss the significance of monitoring phenytoin levels in patients and the implications of its nonlinear pharmacokinetics.
  • Monitoring phenytoin levels is crucial due to its nonlinear pharmacokinetics, where small changes in dose can lead to significant fluctuations in drug concentration. This characteristic increases the risk of toxicity if levels rise above therapeutic ranges. Regular serum monitoring helps ensure that drug levels remain within the effective range while minimizing potential adverse effects. Consequently, understanding these dynamics is key to achieving optimal treatment outcomes.
• Evaluate the impact of side effects associated with phenytoin on patient compliance and management strategies for these effects.
  • The side effects of phenytoin, such as dizziness, drowsiness, and particularly gingival hyperplasia, can significantly affect patient compliance with the treatment regimen. Patients may become discouraged or uncomfortable with their medication due to these adverse effects. Effective management strategies include educating patients about potential side effects beforehand, implementing good oral hygiene practices to minimize gum overgrowth, and considering alternative therapies if side effects are intolerable. A proactive approach in addressing these issues is essential for maintaining adherence and ensuring effective seizure control.

Related terms

Antiepileptic drugs: Medications used to prevent or reduce the frequency of seizures in people with epilepsy and other seizure disorders.

Sodium channels: Proteins in neuronal membranes that allow sodium ions to enter the cell, playing a critical role in the generation and propagation of action potentials.

Seizure types: Different classifications of seizures, including generalized and focal seizures, which are important for determining appropriate treatment options.