Tolvaptan, Oral tol-VAP-tan

What are other names for this medicine?

Type of medicine: vasopressin antagonist

Generic and brand names: tolvaptan, oral; Samsca

What is this medicine used for?

This medicine is taken by mouth to treat hyponatremia (too little sodium in the blood).

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have ever had:

• an allergic reaction to any medicine
• heart failure
• kidney or liver disease
• low blood pressure
• malnutrition
• problems with alcohol abuse

You should not take this medicine if you cannot replace fluids by drinking or you cannot feel if you are thirsty. Talk with your healthcare provider about this.

Females of childbearing age: Tell your healthcare provider if you are pregnant or plan to become pregnant. It is not known whether this medicine will harm an unborn baby. Do not breast-feed while taking this medicine without your healthcare provider's approval.

How do I use it?

A healthcare provider will give you this medicine in the hospital when you first start taking it. You will be watched very closely after you take this medicine.

Read the Medication Guide that comes in the medicine package when you start taking this medicine and each time you get a refill.

If your healthcare provider tells you to keep taking this medicine after you leave the hospital, check the label on the medicine for directions about your specific dose. Take this medicine exactly as your healthcare provider prescribes. Do not take more or less or take it longer than prescribed. Do not stop and re-start taking this medicine without your healthcare provider's approval. You may need to go back to the hospital to re-start this medicine. Talk to your healthcare provider right away if you stop taking this medicine for any reason.

You may take this medicine with or without food. Taking it with meals may lessen the chance the drug will upset your stomach. Drink plenty of water while you are taking this medicine.

What if I miss a dose?

If you miss a dose, use it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and use the next one as directed. Do not use double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

If you or anyone else has intentionally taken too much of this medicine, call 911 or go to the emergency room right away. If you pass out, have seizures, weakness or confusion, or have trouble breathing, call 911. If you think that you or anyone else may have taken too much of this medicine, call the poison control center. Do this even if there are no signs of discomfort or poisoning. The poison control center number is 800-222-1222.

Symptoms of an acute overdose may include: dehydration, increased urination, extreme thirst.

What should I watch out for?

This medicine may make the salt (sodium) level in your blood rise too fast. This can be life threatening. Contact your provider immediately if you have symptoms such as:

• trouble speaking
• trouble swallowing
• drowsiness
• confusion
• mood changes
• trouble controlling body movement and weakness in your arms and legs
• seizures

You will need to have blood tests regularly to see how this medicine affects you. Keep all appointments for these tests.

You may feel dizzy or faint when you get up quickly after sitting or lying down. Getting up slowly may help.

If you need emergency care, surgery, or dental work, tell the healthcare provider or dentist you are taking this medicine.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Life-threatening (Report these to your healthcare provider right away). If you cannot reach your healthcare provider right away, get emergency medical care or call 911 for help): Allergic reaction (hives; itching; rash; trouble breathing; chest pain or tightness in your chest; swelling of your lips, tongue, and throat).

Serious (report these to your healthcare provider right away): unexplained bruising or bleeding; black, tarry stools; vomiting blood or something that looks like coffee grounds; irregular or pounding heartbeat; swelling in hands, feet, or ankles; severe headache; seizures; vomiting or diarrhea; dizziness or fainting; confusion; mood changes; trouble speaking or swallowing; unable to control body movements; trouble urinating.

Other: Constipation, nausea, increased thirst, dry mouth, tiredness, weakness, fever, decreased appetite, increased urination.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

• ACE inhibitors such as benazepril (Lotensin), captopril, enalapril (Vasotec), fosinopril, lisinopril (Prinivil, Zestril), quinapril (Accupril), and ramipril (Altace)
• angiotensin II blockers such as candesartan (Atacand), losartan (Cozaar), and valsartan (Diovan)
• antiarrhythmics (medicines to treat irregular heartbeat) such as amiodarone (Cordarone, Pacerone), dronedarone (Multaq), and quinidine
• antibiotics such as clarithromycin (Biaxin), erythromycin (Ery-Tabs, E.E.S.), isoniazid, metronidazole (Flagyl), telithromycin (Ketek), rifampin (Rifadin, Rimactane), rifabutin (Mycobutin), and norfloxacin (Noroxin)
• antidepressants such as desipramine (Norpramin), nefazodone, and sertraline (Zoloft)
• antifungal medicines such as fluconazole (Diflucan), clotrimazole, itraconazole (Sporanox), ketoconazole (Nizoral), voriconazole (VFEND), and miconazole (Monistat, Micatin)
• anti-HIV medicines such as atazanavir (Reyataz), efavirenz (Sustiva), etravirine (Intelence), indinavir (Crixivan), nelfinavir (Viracept), nevirapine (Viramune), delavirdine (Rescriptor), ritonavir (Norvir), and saquinavir (Invirase)
• antiseizure medicines such as carbamazepine (Tegretol), phenobarbital, phenytoin (Dilantin), and primidone (Mysoline)
• aprepitant (Emend)
• barbiturates such as butabarbital (Butisol), pentobarbital (Nembutal), and secobarbital (Seconal)
• bosentan (Tracleer)
• calcium channel blockers such as nicardipine (Cardene), diltiazem (Cardizem, Dilacor), and verapamil (Calan, Isoptin)
• cimetidine (Tagamet)
• conivaptan (Vaprisol)
• dexamethasone
• digoxin (Lanoxin)
• haloperidol (Haldol)
• imatinib (Gleevec)
• immunosuppressants such as cyclosporine (Sandimmune, Neoral, Gengraf), sirolimus (Rapamune), and tacrolimus (Prograf, Protopic)
• potassium-sparing diuretics such as amiloride, spironolactone (Aldactone), triamterene (Dyrenium), and triamterene/hydrochlorothiazide (Maxzide, Dyazide)
• potassium supplements
• rifapentine (Priftin)
• St. John’s wort

The effects of this medicine may be increased if you drink a lot of grapefruit juice. Talk with your healthcare provider about this.

If you are not sure if your medicines might interact, ask your pharmacist or healthcare provider. Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.

This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Keep all medicines out of the reach of children.