Microplastics and Misinformation: What Science Really Says
November 12, 2025
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Brand Name :
Dilantin 125, Dilantin, Phenytek
Synonyms :
phenytoin
Class :
Hydantoins; Anticonvulsants, Antidysrhythmics-Ib
Brand Name :
Dilantin 125, Dilantin, Phenytek
Synonyms :
phenytoin
Class :
Hydantoins; Anticonvulsants, Antidysrhythmics-Ib
Dosage Forms & Strengths
capsule-ER
100mg
200mg
300mg
capsule-IR
30mg
100mg
tablet-chewable
50mg
oral suspension
125mg/5mL
injectable solution
50mg/mL
Dosage Forms & Strengths
capsule-ER
100mg
200mg
300mg
capsule-IR
30mg
100mg
tablet-chewable
50mg
oral suspension
125mg/5mL
injectable solution
50mg/mL
Refer to adult dosing
It may diminish the serum concentration when combined with colesevelam
phenytoin: they may diminish the serum concentration of canagliflozin
may decrease the diagnostic effect when combined with metyrapone
may have an increased arrhythmogenic effect when combined with lamotrigine
trimethoprim: they may enhance the serum concentration of phenytoin
phenytoin lowers the efficacy of norethisterone
it decreases the concentration of rilpivirine in the serum
It may diminish the effect when combined with lumateperone by affecting CYP3A4 metabolism
when both drugs are combined, there may be a decreased level of serum concentration of alpelisib   
phenytoin decreases the effect of ixazomib by altering intestinal/hepatic CYP3A4 enzyme metabolism
phenytoin decreases the effect or level of midostaurin by altering the CYP3A4 enzyme metabolism
phenytoin decreases the effect or level of midostaurin by altering the CYP3A4 enzyme metabolism
may enhance the adverse/toxic effect of antipsychotic agents
may enhance the adverse/toxic effect of antipsychotic agents
may enhance the adverse/toxic effect of antipsychotic agents
may enhance the adverse/toxic effect of antipsychotic agents
may enhance the adverse/toxic effect of antipsychotic agents
may enhance the adverse/toxic effect of antipsychotic agents
may enhance the adverse/toxic effect of antipsychotic agents
may enhance the adverse/toxic effect of antipsychotic agents
may increase the risk of adverse effects of antipsychotic agents
may increase the risk of adverse effects of antipsychotic agents
may increase the risk of adverse effects of antipsychotic agents
may enhance the risk of adverse/toxic effect of antipsychotic agents
may enhance the risk of adverse/toxic effect of antipsychotic agents
may enhance the risk of adverse/toxic effect of antipsychotic agents
may enhance the risk of adverse/toxic effect of antipsychotic agents
may enhance the risk of adverse/toxic effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
may enhance the adverse effect of antipsychotic agents
It may diminish levels when combined with albendazole by enhancing metabolism
it decreases the concentration of thyroid products in serum
it decreases the concentration of thyroid products in serum
it decreases the concentration of thyroid products in serum
it decreases the concentration of thyroid products in serum
The miconazole (oral) has the potential to elevate the levels of phenytoin in the bloodstream
It may diminish the effects when combined with vitamin D
When encainide is used together with phenytoin, this leads to a reduction in the encainide’s metabolism
phenytoin: they may enhance the serum concentration of CYP3A4 Inhibitors
phenytoin: they may enhance the serum concentration of CYP3A4 Inhibitors
phenytoin: they may enhance the serum concentration of CYP3A4 Inhibitors
phenytoin: they may enhance the serum concentration of CYP3A4 Inhibitors
phenytoin: they may enhance the serum concentration of CYP3A4 Inhibitors
dihydroartemisinin/piperaquineÂ
combination of dihydroartemisinin/piperaquine with phenytoin will decrease the levels of DHA/PPQ in blood
the serum concentration of tacalcitol can be reduced when it is linked with phenytoin
when both drugs are combined, there may be a high metabolism of etoposide   
when both drugs are combined, there may be an increased metabolism of vinblastine  
when both the drugs are combined, the serum concentration of phenytoin decreases    
is having an antagonistic impact over brentuximab vedotin by showing altered intestinal/hepatic CYP3A4 enzyme metabolism.
the levels of phenytoin are increased by fluorouracil due to an unknown mechanism
may reduce serum levels of docetaxel by affecting MDR1/PG-P efflux transporter
may reduce serum levels of erdafitinib by affecting MDR1/PG-P efflux transporter
phenytoin decreases the effect of gefitinib by altering the intestinal/ hepatic CYP3A4 enzyme metabolism
antiseizure agents may diminish the diagnostic effect of metyrapone
may alter the level by affecting CYP450 enzyme metabolism
may have an increased hepatotoxic effect when combined with phenytoin
seizure lowering agents increase the toxic or adverse effects of other antipsychotic agents
seizure lowering agents increase the toxic or adverse effects of other antipsychotic agents
seizure lowering agents increase the toxic or adverse effects of other antipsychotic agents
seizure lowering agents increase the toxic or adverse effects of other antipsychotic agents
seizure lowering agents increase the toxic or adverse effects of other antipsychotic agents
metronidazole/tetracycline/bismuth subsalicylateÂ
by altering CYP2C9/10 metabolism, the levels of phenytoin may be increased with metronidazole
sulfamethoxazole increases the effect of phenytoin by reducing the metabolism
it decreases the concentration of perampanel in the serum
seizure lowering agents increase the toxic or adverse effects of iopamidol
Actions and Spectrum:
phenytoin is an antiepileptic drug that is used to treat various types of seizures. It works by stabilizing the electrical activity in the brain. The actions and spectrum of phenytoin can be described as follows:
Anti-Seizure Action: phenytoin primarily exerts its action by blocking voltage-gated sodium channels in neurons. By doing so, it reduces the excessive and abnormal firing of neurons that can lead to seizures. This makes it effective in preventing and controlling seizures.
Narrow Therapeutic Range: phenytoin has a narrow therapeutic range, which means that the difference between a therapeutic dose and a toxic dose is relatively small. Maintaining the right blood levels of phenytoin is crucial to ensure its effectiveness while avoiding side effects.
Spectrum of Activity: phenytoin is primarily used in the treatment of partial seizures and tonic-clonic (grand mal) seizures. It is less effective for certain types of seizures like absence seizures. It may also be used in the management of status epilepticus, a life-threatening emergency seizure condition.
Non-Epileptic Uses: phenytoin may be occasionally used for conditions other than epilepsy, such as certain types of neuropathic pain and cardiac arrhythmias. However, its use for these purposes is less common and may require careful monitoring due to its side effects.
Metabolism and Drug Interactions: Phenytoin is metabolized in the liver, and its metabolism can be affected by various factors, including other medications. It has a potential for drug interactions, so it’s important for healthcare providers to be aware of all medications a patient is taking when prescribing phenytoin.
Side Effects: Common side effects of phenytoin can include dizziness, drowsiness, coordination problems, and gum hyperplasia (enlargement of the gums). Long-term use may also affect bone health. Serious side effects, such as skin rashes and liver problems, can occur but are less common.
Monitoring: Regular monitoring of blood levels of phenytoin is essential to ensure that the drug is within the therapeutic range. This helps to minimize the risk of seizures and reduce the likelihood of side effects.
Frequency Not Defined
Irritability
Fatigue
Drowsiness
Ataxia
Headache
Slurred speech
Restlessness
Nervousness
Dizziness
Nystagmus
Vertigo
Rash
Dysarthria
Black Box Warning:
Black Box Warnings for phenytoin is related to its potential for causing severe skin reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis.
Pregnancy consideration: pregnancy category: N/A
Lactation: excreted into human milk is known
Pregnancy category:
Category N: There is no data available for the drug under this category.
Patient information leaflet
Generic Name: phenytoin
Why do we use phenytoin?
phenytoin is a medication primarily used to treat seizures. It belongs to a class of drugs called antiepileptic or anticonvulsant medications. Here are some of the primary reasons why phenytoin is used:
phenytoin is commonly prescribed to individuals with epilepsy. It helps prevent or reduce the frequency and severity of seizures. It’s often used for focal (partial) seizures and generalized tonic-clonic seizures. It may be used in emergency situations like status epilepticus, a prolonged and life-threatening seizure activity that requires immediate medical intervention.
After certain types of brain surgery or traumatic brain injury, phenytoin may be prescribed to prevent post-operative or post-injury seizures. In some cases, phenytoin can be used to treat certain types of irregular heart rhythms, particularly ventricular arrhythmias.
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