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Dilantin Infatabs and Warfarin

Determining the interaction of Dilantin Infatabs and Warfarin and the possibility of their joint administration.

Check result:

Dilantin Infatabs <> Warfarin

Relevance: 04.07.2023 Reviewer: Shkutko P.M., M.D., in

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Consumer:

Using warfarin together with phenytoin may cause you to bleed more easily. It may also increase phenytoin levels. Phenytoin levels and prothrombin time or International Normalized Ratio (INR) should be monitored whenever the dosage is changed or discontinued. You should notify your doctor promptly if you have any signs of unusual or prolonged bleeding, bruising, vomiting, or change in stool or urine color. Also if you have signs of phenytoin toxicity such as drowsiness, visual problems, change in mental status, or seizures. It is important that you tell your healthcare provider about all other medications that you are using including vitamins and herbs. Do not stop using your medications without first talking to your doctor first.

Professional:

MONITOR: Some oral anticoagulants have been reported to increase phenytoin half-life and serum concentrations, possibly by inhibiting CYP450 metabolism. The addition of phenytoin to warfarin therapy has initially increased prothrombin time, but thereafter reduced anticoagulant effects. The mechanism is not known, but may be due to initial CYP450 metabolic inhibition, followed by isoenzyme induction. Data have been conflicting.

MANAGEMENT: Phenytoin serum concentrations and INR/PT should be monitored in patients receiving this combination and whenever the dosage is changed or discontinued. Patients should be advised to promptly report any signs of bleeding (e.g., pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, nosebleeds, bleeding of gums from brushing, red or brown urine, or red or black stools) or hydantoin toxicity (e.g., drowsiness, visual disturbances, change in mental status, seizures, nausea, or ataxia) to their physician.

References

Wells PS, Holbrook AM, Crowther NR, Hirsh J "Interactions of warfarin with drugs and food." Ann Intern Med 121 (1994): 676-83
Koch-Weser J, Sellers EM "Drug interactions with coumarin anticoagulants (first of two parts)." N Engl J Med 285 (1971): 487-98
Skovsted L, Kristensen M, Hansen M, Siersboek-Nielsen K "The effect of different oral anticoagulants on diphenylhydantoin (DPH) and tolbutamide metabolism." Acta Med Scand 199 (1976): 513-5
Nappi JM "Warfarin and phenytoin interaction." Ann Intern Med 90 (1979): 852
Thijssen HH, Flin ois JP, Beaune PH "Cytochrome P4502C9 is the principal catalyst of racemic acenocoumarol hydroxylation reactions in human liver microsomes." Drug Metab Dispos 28 (2000): 1284-90
Koch-Weser J, Sellers EM "Drug interactions with coumarin anticoagulants (second of two parts)." N Engl J Med 285 (1971): 547-58
Levine M, Sheppard I "Biphasic interaction of phenytoin with warfarin." Clin Pharm 3 (1984): 200-3
Hansen JM, Siersboek-Nielsen K, Skovsted L "Carbamazepine-induced acceleration of diphenylhydantoin and warfarin metabolism in man." Clin Pharmacol Ther 12 (1971): 539-43

Dilantin Infatabs

Generic Name: phenytoin

Brand name: Dilantin, Phenytek, Dilantin Infatabs, Phenytoin Sodium, Prompt

Synonyms: Dilantin

What is Dilantin Infatabs?

Warfarin

Generic Name: warfarin

Brand name: Coumadin, Jantoven

Synonyms: n.a.

What is Warfarin?

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In the course of checking the drug compatibility and interactions, data from the following reference sources was used: Drugs.com, Rxlist.com, Webmd.com, Medscape.com.

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