What is the Difference Between Phenytoin and Phenytoin Sodium?

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Phenytoin and phenytoin sodium are both anti-seizure medications, but they have different solubility in water and distinct formulations.

  • Phenytoin: This is the active ingredient in some oral pharmaceutical products and is practically insoluble in water. It is soluble in acetone, ethanol, and alkali hydroxides.
  • Phenytoin Sodium: This is the sodium salt of phenytoin and is highly water-soluble. It is used in liquid formulations, such as suspensions and injections.

Both phenytoin and phenytoin sodium have similar chemical and physical properties, but their solubility in water differs. Phenytoin sodium is more water-soluble than phenytoin, which is practically insoluble in water. Due to the difference in bioavailability, dosage adjustments may be required when converting patients from one formulation to another.

Comparative Table: Phenytoin vs Phenytoin Sodium

Phenytoin and Phenytoin Sodium are both anticonvulsant drugs used to treat patients with tonic-clonic epilepsy and other seizure disorders. Here is a table summarizing the differences between the two:

Property Phenytoin Phenytoin Sodium
Chemical Structure Phenytoin is a white, odorless powder at room temperature. Phenytoin Sodium is the sodium salt of phenytoin, a hydantoin derivate and non-sedative antiepileptic agent with anticonvulsant activity.
Solubility Practically insoluble in water, but soluble in acetone, ethanol, and alkali hydroxides. Soluble in water and alcohol.
Form Phenytoin is available in various forms, including immediate and extended-release oral capsules. Phenytoin Sodium is available in various forms, including oral capsules and intravenous injections.
Brand Name Dilantin is a brand name for Phenytoin Sodium. Dilantin is also used as a brand name for Phenytoin Sodium.

Changing the dosage forms or salt forms (phenytoin sodium versus phenytoin base) and/or interchanging brands may lead to changes in bioavailability.