phenytoin sodium

How long does Phenytoin Sodium stay in your body?

The elimination half-life of phenytoin sodium is About 22 hours on average, ranging from 7 to 42 hours — but phenytoin does NOT have a single fixed half-life. It follows nonlinear, saturable (Michaelis-Menten) kinetics, so the half-life lengthens as the dose and blood level rise; the label warns that "small incremental doses may increase the half-life and produce very substantial increases in serum levels" once levels are in the upper range. — the time it takes the body to clear about half of it. As a rule of thumb, a medicine is mostly gone after roughly 4 to 5 half-lives, though this varies from person to person with age and kidney or liver function. Because phenytoin is hydroxylated by a liver enzyme system that becomes saturated at higher plasma levels, clearance is dose- and concentration-dependent — this is why one number can't describe it. There is no active metabolite that outlasts the parent: the label states the drug is metabolized in the liver and "most of the drug is excreted in the bile as inactive metabolites." Phenytoin itself is not a prodrug, but fosphenytoin (given IV/IM) is a prodrug the body rapidly converts to phenytoin. Since elimination depends on those saturable liver enzymes, liver disease, low serum albumin, genetically slow metabolizers, and interacting drugs can prolong the half-life substantially. The Clinical Pharmacology section does not give fixed half-life figures for specific age, kidney, or liver groups. This is pharmacokinetic information, not a drug-test detection window or dosing guidance.

This is general information, not medical advice. It doesn’t tell you when a drug test would read negative (tests detect substances for different, often longer, windows) or when it’s safe to take another dose — ask your pharmacist or prescriber. Source: DILANTIN (extended phenytoin sodium capsule) — FDA label, Clinical Pharmacology: Pharmacokinetics (DailyMed SPL).

Frequently asked questions

What does Phenytoin Sodium treat?

Phenytoin Sodium (Phenytoin Sodium) may be used to treat tonic-clonic epilepsy, temporal lobe epilepsy, status epilepticus, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.

How does Phenytoin Sodium work?

Phenytoin Sodium is a anti-epileptic agent. Anti-epileptic (anticonvulsant) drugs calm the abnormal, excessive electrical activity that triggers seizures. They do this by stabilizing overactive sodium or calcium channels in nerve cells, boosting the brain's natural calming chemical GABA, or dampening excitatory signals, which makes nerves less likely to fire uncontrollably.

How much does Phenytoin Sodium cost?

Nobody can tell you what you will pay — your price is set by your insurer's formulary, your deductible and the pharmacy's markup, and none of those are published. What IS published is what the pharmacy paid to acquire it: about $0.18 per ml, per the CMS NADAC survey. Treat that as the floor, not the quote — ask the pharmacist for the cash price as well as your copay, because for cheap generics the cash price often wins.

Is there a coupon or discount for Phenytoin Sodium?

pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Phenytoin Sodium. To pay less, Phenytoin Sodium is already a generic — usually the lowest-cost version — so the main levers are comparing cash prices between pharmacies and using a pharmacy discount-card service. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.

Who makes Phenytoin Sodium?

Phenytoin Sodium is marketed by Marsam Pharms LLC. You can see Marsam Pharms LLC's full profile, rating, and other products on pharmaranks.

Is Phenytoin Sodium a brand-name or generic drug?

Phenytoin Sodium is a generic medication; its active ingredient is Phenytoin Sodium. Generics contain the same active ingredient as the brand-name original and are usually lower cost.

Is Phenytoin Sodium available over the counter?

No. Phenytoin Sodium is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.

What forms does Phenytoin Sodium come in?

Phenytoin Sodium is currently marketed as capsule and injectable, per the FDA's National Drug Code Directory.

What class of drug is Phenytoin Sodium?

Phenytoin Sodium is classified as anti-epileptic agent, per the FDA's Established Pharmacologic Class.

Is Phenytoin Sodium FDA-registered?

Phenytoin Sodium is on record with the U.S. FDA under application number ANDA089779. You can verify this on its official FDA label.