Tolvaptan/Moderate CYP3A4 Inhibitors
How the interaction occurs:
Some medicines may slow down how quickly your liver processes tolvaptan.
What might happen:
The amount of tolvaptan in your blood may increase. If you have just started taking tolvaptan, this may increase the risk of a serious condition called osmotic demyelination syndrome (ODS), which can lead to coma and death. It may also increase your risk of dehydration.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. Let your doctor know right away if you experience any symptoms of ODS such as: trouble speaking, trouble swallowing or feeling like food/liquid is getting stuck when you swallow, drowsiness, confusion, mood changes, trouble controlling body movements, weakness in the arms and/or legs, seizures, loss of consciousness, and/or any other new symptoms. Also let your doctor know if you experience vomiting and/or diarrhea and cannot drink normally and/or if you feel dizzy or faint.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Samsca (tolvaptan) US prescribing information. Otsuka Pharmaceutical Co., Ltd. May, 2013.
2.US Food and Drug Administration (FDA). Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers. Available at: http://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/D rugInteractionsLabeling/ucm093664.htm. Updated 08/05/2011.