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aprepitant vs phenytoin

Side-by-side comparison of aprepitant and phenytoin. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.

moderate Known Drug Interaction

Intervention Avoid concomitant use of aprepitant Examples rifampin, carbamazepine, phenytoin 7.1 Effect of Aprepitant on the Pharmacokinetics of Other Drugs Aprepitant is a substrate, a weak-to-moderate (dose-dependent) inhibitor, and an inducer of CYP3A4. Intervention Avoid concomitant use of aprepitant Examples rifampin, carbamazepine, phenytoin

Recommendation: You should avoid taking these two medications together. Ask your doctor for an alternative treatment.

Drug Class
aprepitant NK1 Receptor Antagonist (Antiemetic)
phenytoin Anticonvulsant (Hydantoin)
Type
aprepitant Prescription
phenytoin Prescription
Summary
aprepitant

Aprepitant (Emend) is a medicine that helps prevent nausea and vomiting. It belongs to a class of drugs called NK1 receptor antagonists.

phenytoin

Phenytoin injection is used to treat certain types of seizures. It can also prevent seizures during or after neurosurgery.

What It Treats
aprepitant

Aprepitant is used to prevent nausea and vomiting caused by chemotherapy. It can be used for both strong and moderate chemotherapy treatments. It is also used to prevent nausea and vomiting after surgery in adults.

phenytoin

This medicine treats generalized tonic-clonic status epilepticus, a type of prolonged seizure. It also helps prevent and treat seizures that may happen during or after brain surgery. Sometimes, it can be used for a short time instead of the oral form of phenytoin when you cannot take the medicine by mouth.

How It Works
aprepitant

Aprepitant blocks a substance in your body called substance P. Substance P can trigger nausea and vomiting. By blocking it, aprepitant helps reduce these side effects.

phenytoin

Phenytoin works by slowing down the signals in the brain that cause seizures. It stabilizes nerve cell membranes, reducing excessive electrical activity. This helps to prevent seizures from starting or spreading.

Common Side Effects
aprepitant
  • Tiredness
  • Diarrhea
  • Weakness
  • Upset stomach
  • Stomach pain
phenytoin

No common side effects listed.

FAERS Reports
aprepitant
  • Feeling sick to your stomach 2,147
  • Tiredness 1,769
  • Fever 1,589
  • Diarrhea 1,543
  • Difficulty breathing 1,508
phenytoin
  • The medicine is reacting with another medicine 1,547
  • Seizure 1,382
  • Poisoning from different substances 1,353
  • Convulsion 1,260
  • Prolonged seizure 790
Serious Warnings
aprepitant

Aprepitant can interact with other medicines. It can affect how well warfarin (a blood thinner) and hormonal birth control work. If you take warfarin, your doctor will check your blood. If you use hormonal birth control, use a backup method while taking aprepitant and for 28 days after your last dose.

phenytoin

This medicine can cause serious heart problems if given too quickly. The injection rate should not be faster than 50 mg per minute for adults, and 1 to 3 mg/kg/min (or 50 mg per minute, whichever is slower) for children. Your heart will be monitored closely during and after the injection.

Pregnancy
aprepitant

There is not enough information about the safety of aprepitant during pregnancy. Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if aprepitant passes into breast milk, so discuss breastfeeding with your doctor.

phenytoin

Taking phenytoin during pregnancy may increase the risk of birth defects. If you are pregnant or plan to become pregnant, talk to your doctor about the risks and benefits of this medicine.

Also Compare, Nearby Drugs

Compare aprepitant with

How to Read This aprepitant vs phenytoin Comparison

aprepitant is classified in the NK1 Receptor Antagonist (Antiemetic) drug class, while phenytoin sits within the Anticonvulsant (Hydantoin) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.

Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, aprepitant has 8,556 submissions while phenytoin has 6,332. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known moderate interaction flagged in FDA labeling, attributed to phenytoin can speed up how your body processes aprepitant, which may make the aprepitant not work as well.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.

A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between aprepitant and phenytoin - always consult your physician or pharmacist first.

Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.