In this Article

• What is tolvaptan (Samsca)?
• What are the possible side effects of tolvaptan (Samsca)?
• What is the most important information I should know about tolvaptan (Samsca)?
• What should I discuss with my health care provider before taking tolvaptan (Samsca)?
• How should I take tolvaptan (Samsca)?
• What happens if I miss a dose (Samsca)?
• What happens if I overdose (Samsca)?
• What should I avoid while taking tolvaptan (Samsca)?
• What other drugs will affect tolvaptan (Samsca)?
• Where can I get more information?

What should I discuss with my health care provider before taking tolvaptan (Samsca)?

You should not use this medication if you are allergic to tolvaptan, if you are unable to urinate, if you are unable to tell that you are thirsty, or if you are severely dehydrated and feel like you might pass out.

You should not take tolvaptan if you are taking any of the following medications:

• conivaptan (Vaprisol);
• an antibiotic such as clarithromycin (Biaxin), dalfopristin/quinupristin (Synercid), erythromycin (E.E.S., EryPed, Ery-Tab, Erythrocin), or telithromycin (Ketek);
• antifungal medication such as fluconazole (Diflucan), itraconazole (Sporanox), ketoconazole (Nizoral), or voriconazole (Vfend);
• an antidepressant such as nefazodone;
• heart or blood pressure medication such as diltiazem (Cardizem, Dilacor, Tiazac), nicardipine (Cardene), quinidine (Quinaglute, Quinidex, Quin-Release), or verapamil (Calan, Covera, Isoptin, Verelan); or
• HIV/AIDS medicine such as amprenavir (Agenerase), atazanavir (Reyataz), delavirdine (Rescriptor), fosamprenavir (Lexiva), indinavir (Crixivan), nelfinavir (Viracept), saquinavir (Invirase), or ritonavir (Norvir).

Your doctor will tell you if any of your medications need to be changed while taking tolvaptan.

If you have any of these other conditions, you may need a dose adjustment or special tests to safely take tolvaptan:

• severe liver disease (especially cirrhosis);
• if you are malnourished; or
• if you have been drinking large amounts of alcohol.

FDA pregnancy category C. It is not known whether tolvaptan is harmful to an unborn baby. Before taking this medication, tell your doctor if you are pregnant or plan to become pregnant during treatment.

It is not known whether tolvaptan passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

How should I take tolvaptan (Samsca)?

Take this medication exactly as prescribed by your doctor. Do not take it in larger amounts or for longer than recommended. Follow the directions on your prescription label.

You will receive your first few doses of tolvaptan in a hospital setting where your heart rhythm can be monitored, in case the medication causes serious side effects.

Your doctor may occasionally change your dose to make sure you get the best results from this medication.

Tolvaptan is usually given once per day, with or without food.

Take this medication with a full glass (8 ounces) of water. Drink plenty of fluids during the first 24 hours of treatment with tolvaptan. It is best to drink something as soon as you feel thirsty, but avoid alcoholic drinks. Follow your doctor's instructions about the type and amount of liquids you should drink while treating hyponatremia. In some cases, drinking too much liquid can be as unsafe as not drinking enough.

Call your doctor if you have ongoing vomiting or diarrhea, or if you are sweating more than usual. You can easily become dehydrated while taking this medication, which can lead to serious side effects.

To be sure this medication is helping your condition, your blood will need to be tested on a regular basis. You may not notice any change in your symptoms, but your blood work will help your doctor determine how long to treat you with tolvaptan.

If you stop taking tolvaptan for any length of time, do not start taking it again at home. You will need to be in a hospital under observation any time you start or restart treatment with tolvaptan.

Store tolvaptan at room temperature away from moisture and heat.