phenytoin vs voriconazole
Side-by-side comparison of phenytoin and voriconazole. 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
Carbamazepine (CYP450 Induction) Not Studied In Vivo or In Vitro , but Likely to Result in Significant Reduction Contraindicated Long Acting Barbiturates (e.g., phenobarbital, mephobarbital) (CYP450 Induction) Not Studied In Vivo or In Vitro , but Likely to Result in Significant Reduction Contraindicated Phenytoin (CYP450 Induction) Significantly Reduced Increase voriconazole maintenance dose from 4 mg/kg to 5 mg/kg IV every 12 hours or from 200 mg to 400 mg orally every 12 hours (100 mg to 200 mg orally every 12 hours in patients weighing less than 40 kg). Phenytoin (CYP2C9 Inhibition)...
Recommendation: Your doctor will need to increase your voriconazole dose and monitor your phenytoin blood levels very closely.
Dilantin
Vfend
Phenytoin injection is used to treat certain types of seizures. It can also prevent seizures during or after neurosurgery.
Voriconazole (Vfend) is an antifungal medicine. It is used to treat serious fungal infections in adults and children 2 years and older.
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.
This medicine treats several types of fungal infections. It is used for invasive aspergillosis, a lung infection. It also treats candidemia (a blood infection) and other Candida infections in the skin, abdomen, kidney, bladder, and wounds. Voriconazole can also treat esophageal candidiasis (a throat infection) and serious infections caused by Scedosporium and Fusarium fungi.
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.
Voriconazole belongs to a class of drugs called azole antifungals. It works by stopping the growth of fungi. It does this by interfering with the production of the fungal cell membrane.
No common side effects listed.
- • Visual disturbances
- • Fever
- • Nausea
- • Rash
- • Vomiting
- The medicine is reacting with another medicine 1,547
- Seizure 1,382
- Poisoning from different substances 1,353
- Convulsion 1,260
- Prolonged seizure 790
- The medicine is interacting with another medicine 2,315
- Death 1,460
- Fever 1,411
- Lung infection 1,322
- The condition is getting worse 1,093
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.
Voriconazole can cause serious liver problems. Your doctor will check your liver function with blood tests before and during treatment. This medicine can also cause heart rhythm problems. Make sure your potassium, magnesium, and calcium levels are normal before starting. Voriconazole can also cause severe skin reactions and make you sensitive to sunlight. Avoid sunlight and wear protective clothing. This medicine can harm an unborn baby, so women who can get pregnant should use effective birth control.
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.
Voriconazole can cause harm to an unborn baby. If you are pregnant or could become pregnant, talk to your doctor. It is not known if voriconazole passes into breast milk. Talk to your doctor about the risks and benefits of breastfeeding while taking this medicine.
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How to Read This phenytoin vs voriconazole Comparison
phenytoin is classified in the Anticonvulsant (Hydantoin) drug class, while voriconazole 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 voriconazole has 7,601. 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 speeds up how fast the body gets rid of voriconazole, while voriconazole slows down the breakdown of phenytoin. this means the antifungal may not work well, and the seizure medicine could reach toxic levels.. 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 voriconazole - 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.