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Isoniazid Tablets and Phenytoin Sodium

Determining the interaction of Isoniazid Tablets and Phenytoin Sodium and the possibility of their joint administration.

Check result:

Isoniazid Tablets <> Phenytoin Sodium

Relevance: 24.07.2022 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 phenytoin together with isoniazid may increase the effects of phenytoin. Contact your doctor if you experience twitching eye movements, slurred speech, loss of balance, tremor, muscle stiffness or weakness, nausea, vomiting, feeling light-headed, fainting, and slow or shallow breathing. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Professional:

MONITOR: Isoniazid frequently increases serum phenytoin levels and may induce phenytoin toxicity in up to 20% of patients receiving the combination. The mechanism is related to inhibition of CYP450 hepatic metabolism by isoniazid. Slow acetylators of isoniazid may be at greater risk for this interaction. Patients should be closely observed for signs of hydantoin toxicity if these drugs must be given concurrently. Other hydantoins may interact similarly.

MANAGEMENT: Serum hydantoin concentrations should be measured if a drug interaction is suspected. Patients should be advised to notify their physician if they experience symptoms of toxicity, including drowsiness, visual disturbances, change in mental status, seizures, nausea, or ataxia. The hydantoin dose may need to be decreased.

References

Miller RR, Porter J, Greenblatt DJ "Clinical importance of the interaction of phenytoin and isoniazid." Chest 75 (1979): 356-8
Witmer DR, Ritschel WA "Phenytoin-isoniazid interaction: a kinetic approach to management." Drug Intell Clin Pharm 18 (1984): 483-6
Cerner Multum, Inc. "Australian Product Information." O 0
Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
Sandyk R "Phenytoin toxicity induced by antituberculosis drugs." S Afr Med J 61 (1982): 382
Yew WW, Lau KS, Ling MH "Phenytoin toxicity in a patient with isoniazid-induced hepatitis." Tubercle 72 (1991): 309-10
Kutt H, Winters W, McDowell FH "Depression of parahydroxylation of diphenylhydantoin by antituberculosis chemotherapy." Neurology 16 (1966): 594-602

Isoniazid Tablets

Generic Name: isoniazid

Brand name: Nydrazid

Synonyms: Isoniazid

What is Isoniazid Tablets?

Phenytoin Sodium

Generic Name: phenytoin

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

Synonyms: n.a.

What is Phenytoin Sodium?

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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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