Phenytoin, sold under the brand name Dilantin, is an anti-seizure medication used to prevent and manage tonic-clonic (grand mal) and focal (partial) seizures. It is not effective for absence seizures. Fosphenytoin, a prodrug of phenytoin, is used in emergency settings for status epilepticus when benzodiazepines fail. Phenytoin works by stabilizing neuronal activity, preventing excessive electrical discharges that cause seizures.
Parent: Diphenhydramine/ Phenytoin/ Dimenhydrinate
Parent: Phenytoin
Parent: Phenytoin
Parent: Phenytoin
Parent: Phenytoin
Parent: Phenytoin
Parent: Phenytoin
Parent: Phenytoin
As with all pharmaceutical drugs, phenytoin can contain impurities that require monitoring and control to ensure safety and efficacy.
Related Substances
These are structurally similar compounds formed during synthesis or degradation. Examples include:
Degradation Products
Phenytoin is prone to hydrolysis and oxidation, especially under humid and high-temperature conditions. This can lead to inactive or toxic degradation products.
Residual Solvents
Trace amounts of organic solvents (e.g., ethanol, acetone, methanol) used during manufacturing may remain in the final product and need to be controlled under regulatory limits.
Heavy Metals and Elemental Impurities
Toxic metals such as lead, arsenic, cadmium, and mercury must be kept within permissible limits to avoid adverse effects.
Analytical Techniques for Impurity Detection
Phenytoin impurities are analyzed using:
Phenytoin is primarily used to prevent and manage tonic-clonic (grand mal) and focal seizures. It is also used for status epilepticus in its intravenous form (fosphenytoin).
Common adverse effects include dizziness, drowsiness, nausea, and gingival hyperplasia. Serious side effects may include ataxia, liver toxicity, Stevens-Johnson syndrome (SJS), and bone marrow suppression. Long-term use may cause osteoporosis and peripheral neuropathy.
Phenytoin works by blocking voltage-gated sodium channels, stabilizing neuronal membranes, and preventing excessive electrical activity in the brain, which helps to control seizures.
Yes, phenytoin is a sodium channel blocker that prevents excessive neuronal firing, making it effective for seizure prevention and management.
