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Drug Interactions between Chloromycetin and tolvaptan

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

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Interactions between your drugs

Moderate

chloramphenicol tolvaptan

Applies to: Chloromycetin (chloramphenicol) and tolvaptan

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Coadministration with inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of tolvaptan, which is almost exclusively metabolized by the isoenzyme. The interaction has been studied with ketoconazole, a potent CYP450 3A4 inhibitor. When a single 30 mg oral dose of tolvaptan was administered to 19 healthy volunteers following pretreatment with ketoconazole 200 mg/day for 3 days, tolvaptan peak plasma concentration (Cmax) increased by 3.5-fold and systemic exposure (AUC) increased by 5.4-fold, although 24-hour urine output increased by just 1.3-fold due to the saturable nature of tolvaptan's effect on urinary excretion rate. The impact of moderate CYP450 3A4 inhibitors has not been adequately assessed. According to the product labeling, grapefruit juice has been shown to increase tolvaptan exposure by 1.8-fold. However, the potency of grapefruit juice as an inhibitor of CYP450 3A4 depends on its strength, which was not specified.

MANAGEMENT: Concomitant use of tolvaptan with moderate CYP450 3A4 inhibitors should generally be avoided unless no alternatives exist and benefits outweigh potential risks. A lower dosage of tolvaptan should be considered. Serum sodium concentration and neurologic status should be closely monitored during coadministration. Too rapid correction of hyponatremia increases the risk of osmotic demyelination syndrome, which is associated with dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma, and death. Discontinuation or interruption of tolvaptan therapy should be considered in patients who develop too rapid a rise in serum sodium.

References

  1. (2009) "Product Information. Samsca (tolvaptan)." Otsuka American Pharmaceuticals Inc

Drug and food interactions

Moderate

tolvaptan food

Applies to: tolvaptan

You should avoid drinking grapefruit juice during treatment with tolvaptan. Grapefruit juice can cause too much of the medication to be in the blood. Serious nervous system side effects such as difficulty swallowing, trouble speaking, muscle weakness, trouble controlling body movements, confusion, mood changes, seizures, and coma may occur. 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.

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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.


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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.