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Drug Interactions between fosphenytoin and V-Gan-25

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

promethazine fosphenytoin

Applies to: V-Gan-25 (promethazine) and fosphenytoin

MONITOR: Concurrent use of phenothiazines and phenytoin may increase the effect of phenytoin and decrease the effect of the phenothiazine. The mechanism is unknown and clinical data have been inconsistent.

MANAGEMENT: Close monitoring for clinical and laboratory evidence of phenytoin toxicity is indicated. Patients should be advised to notify their physician if they experience symptoms of possible hydantoin toxicity, including drowsiness, visual disturbances, change in mental status, seizures, nausea, or ataxia.

References

  1. Houghton GW, Richens A (1975) "Inhibition of phenytoin metabolism by other drugs used in epilepsy." Int J Clin Pharmacol, 12, p. 210-6
  2. Vincent FM (1980) "Phenothiazine-induced phenytoin intoxication." Ann Intern Med, 93, p. 56-7
  3. Haidukewych D, Rodin EA (1985) "Effect of phenothiazines on serum antiepileptic drug concentrations in psychiatric patients with seizure disorder." Ther Drug Monit, 7, p. 401-4
  4. Linnoila M, Viukari M, Vaisanen K, Auvinen J (1980) "Effect of anticonvulsants on plasma haloperidol and thioridazine levels." Am J Psychiatry, 137, p. 819-21
  5. Sands CD, Robinson JD, Salem RB, Stewart RB, Muniz C (1987) "Effect of thioridazine on phenytoin serum concentration: a retrospective study." Drug Intell Clin Pharm, 21, p. 267-72
View all 5 references

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Drug and food interactions

Moderate

promethazine food

Applies to: V-Gan-25 (promethazine)

GENERALLY AVOID: Concurrent use of ethanol and phenothiazines may result in additive CNS depression and psychomotor impairment. Also, ethanol may precipitate dystonic reactions in patients who are taking phenothiazines. The two drugs probably act on different sites in the brain, although the exact mechanism of the interaction is not known.

MANAGEMENT: Patients should be advised to avoid alcohol during phenothiazine therapy.

References

  1. Lutz EG (1976) "Neuroleptic-induced akathisia and dystonia triggered by alcohol." JAMA, 236, p. 2422-3
  2. Freed E (1981) "Alcohol-triggered-neuroleptic-induced tremor, rigidity and dystonia." Med J Aust, 2, p. 44-5

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

See also

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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