How does this medication work? What will it do for me?
Tolvaptan belongs to the class of medications called vasopressin receptor antagonists. It is used to correct low blood levels of sodium, an electrolyte that has a number of roles in the body. Tolvaptan is used to correct sodium levels for people with conditions such as heart failure, liver disease, and certain hormone imbalances.
Low blood levels of sodium are often a result of too much fluid being retained by the kidneys. Vasopressin regulates the amount of water in the body. When vasopressin is active in the body, it causes less water to be removed by the kidneys. Tolvaptan blocks this action and causes the kidneys to excrete more water, resulting in an acceptable balance between sodium and water in the body.
This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.
Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.
Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.
What form(s) does this medication come in?
Each non-scored, bevelled-edged, shallow-convex, blue, triangular tablet debossed with "OTSUKA" and "15" on one side contains 15 mg of tolvaptan. Nonmedicinal ingredients: corn starch, hydroxypropyl cellulose, lactose monohydrate, low-substituted hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, and FD&C Blue No. 2 Aluminum Lake as colorant.
Each non-scored, bevelled-edged, shallow-convex, blue, round tablet debossed with "OTSUKA" and "30" on one side contains 30 mg of tolvaptan. Nonmedicinal ingredients: corn starch, hydroxypropyl cellulose, lactose monohydrate, low-substituted hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, and FD&C Blue No. 2 Aluminum Lake as colorant.
Each non-scored, bevelled-edged, blue, modified rectangular, shallow-convex, tablet, debossed with “OTSUKA” and “60” on one side, contains 60 mg of tolvaptan. Nonmedicinal ingredients: corn starch, hydroxypropyl cellulose, lactose monohydrate, low-substituted hydroxypropyl cellulose, magnesium stearate, microcrystalline cellulose, and FD&C Blue No. 2 Aluminum Lake as colorant.
How should I use this medication?
The recommended starting dose of tolvaptan is 15 mg taken once daily. This dose may be gradually increased to a maximum of 60 mg taken once daily, based on the amount of sodium in the blood.
Tolvaptan may be taken with food or on an empty stomach. If you become thirsty, fluids may be consumed. Avoid grapefruit or grapefruit juice while you are taking tolvaptan.
Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.
It is important to take this medication exactly as prescribed by your doctor.
If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.
Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.
Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.
Who should NOT take this medication?
Do not take tolvaptan if you:
- are allergic to tolvaptan or any ingredients of the medication
- are not producing urine
- are using certain other medications, such as ketoconazole, clarithromycin, HIV protease inhibitors, nefazodone
- have low blood sodium combined with excessive loss of body water
- urgently need to increase sodium in the body
- cannot sense or respond to thirst
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.
The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- dry mouth
- loss of appetite
- more frequent urination
Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- signs of dehydration (e.g., dry or sticky mouth, decreased urine production, decreased tear production, dizziness, thirst, nausea, vomiting)
- signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
- symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
Stop taking the medication and seek immediate medical attention if any of the following occur:
- signs of bleeding in the stomach (e.g., bloody, black, or tarry stools, spitting up of blood, vomiting blood or material that looks like coffee grounds)
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Dehydration: Tolvaptan causes an increase in the amount of urine produced as it causes the body to eliminate fluid. As a result, it is possible for dehydration to occur. Drink fluids when you feel thirsty and be aware of other signs of dehydration such as muscle cramps, nausea and vomiting, rapid pounding heart beat as well as a feeling of dry stickiness in the mouth.
Fluid and electrolyte balance: Tolvaptan may cause the levels of electrolytes such as potassium, magnesium, chloride, and calcium in the blood to change while taking this medication. If you experience symptoms of fluid and electrolyte imbalance such as muscle pains or cramps; dry mouth; numb hands, feet, or lips; or racing heartbeat, contact your doctor as soon as possible. Your doctor will do blood tests regularly to monitor the levels of these electrolytes in your blood while you are taking this medication.
Grapefruit juice: Grapefruit juice affects how tolvaptan is removed from the body and may cause too much of the medication to build up in the body and cause possibly harmful side effects. Do not drink grapefruit juice or eat grapefruit at anytime while taking this medication for treatment.
Liver function: Tolvaptan may reduce liver function and can cause liver failure. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.
Tolvaptan may increase the risk of bleeding in the stomach when it is taken by people with liver disease. If you experience signs of bleeding in the digestive system, such as blood in the stools, vomiting blood or a substance that looks like coffee grounds, or black and tarry stools get immediate medical help.
Rapid correction of sodium levels: Correcting the blood levels of sodium too quickly can be as dangerous as having too little sodium in the body. This may be more likely to occur if you consume large amounts of alcohol, are severely malnourished, or have advanced liver disease. If you experience difficulty speaking, confusion, drowsiness, mood changes, difficulty swallowing, or weakness in the arms and legs, contact your doctor immediately.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if tolvaptan passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children.
What other drugs could interact with this medication?
There may be an interaction between tolvaptan and any of the following:
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.