phenytoin vs posaconazole
Side-by-side comparison of phenytoin and posaconazole. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
major Known Drug Interaction
Interaction Drug Interaction Rifabutin, phenytoin, efavirenz, cimetidine, esomeprazole* Avoid coadministration unless the benefit outweighs the risks ( 7.6 , 7.7 , 7.8 , 7.9 ) Other drugs metabolized by CYP3A4 Consider dosage adjustment and monitor for adverse effects and toxicity ( 7.1 , 7.10 , 7.11 ) Digoxin Monitor digoxin plasma concentrations ( 7.12 ) Fosamprenavir, metoclopramide* Monitor for breakthrough fungal infections ( 7.6 , 7.13 ) *The drug interactions with esomeprazole and metoclopramide do not apply to posaconazole tablets. 7.8 Phenytoin Phenytoin induces UDP-glucuronidase...
Recommendation: Avoid using these medicines at the same time unless your doctor decides it is necessary and monitors you closely.
Dilantin
Noxafil
Phenytoin injection is used to treat certain types of seizures. It can also prevent seizures during or after neurosurgery.
Posaconazole is an antifungal medicine. It helps prevent certain fungal infections in people with weakened immune systems.
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.
Posaconazole prevents Aspergillus and Candida infections. You may need this medicine if you have a high risk of getting these infections. This often includes people who had a stem cell transplant or have certain blood cancers and are on chemotherapy.
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.
Posaconazole belongs to a class of drugs called azole antifungals. It works by stopping the growth of fungi. This helps your body fight off the infection.
No common side effects listed.
- • Diarrhea
- • Nausea
- • Fever
- • Vomiting
- • Headache
- The medicine is reacting with another medicine 1,547
- Seizure 1,382
- Poisoning from different substances 1,353
- Convulsion 1,260
- Prolonged seizure 790
- Fever with low white blood cell count 1,018
- The medicine is interacting with another medicine 930
- Death 928
- Fever 850
- Low white blood cell count 705
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.
Posaconazole can interact with many other medicines. It can cause heart rhythm problems (QT prolongation). It can also cause liver problems. Tell your doctor about all the medicines you take.
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.
Posaconazole may harm an unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if posaconazole passes into breast milk, so talk to your doctor if you are breastfeeding.
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How to Read This phenytoin vs posaconazole Comparison
phenytoin is classified in the Anticonvulsant (Hydantoin) drug class, while posaconazole sits within the Azole Antifungal 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, phenytoin has 6,332 submissions while posaconazole has 4,431. 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 major interaction flagged in FDA labeling, attributed to phenytoin causes the body to break down posaconazole much faster than usual, which can make the antifungal medicine less effective.. 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 phenytoin and posaconazole - 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.