Tolvaptan is used to treat hyponatraemia (low sodium levels in the blood) associated with heart failure and syndrome of inappropriate antidiuretic hormone secretion (a condition in which the body makes too much antidiuretic hormone).
This medicine may also be used to treat polycystic kidney disease, an inherited disorder characterized by the growth of numerous cysts in the kidneys.
Take Tolvaptan exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor. Treatment with Tolvaptan should be initiated in a hospital, with the supervision of your doctor. Your doctor need to monitor your sodium levels closely.
You may take this medicine with or without food. Try to take it at the same time each day.
Tolvaptan must be taken regularly for it to be effective. Continue taking this medicine even when you feel better. Do not stop taking it suddenly as this may worsen your condition.
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.
DO NOT double a dose under any circumstances.
If you often forget to take your medicine, let your doctor and pharmacist know.
Alert your doctor if you have the following conditions:
- hypovolemic or euvolemic hyponatremia (total body water increases but
body’s sodium content stays the same)
- unable to pass urine
- cannot tell when you are thirsty
as Tolvaptan may not be suitable for you.
Do not take Tolvaptan with certain antibiotics, medicines for fungal infection, medicines for HIV infection, and medicines for depression. Please see the section “Can I take this with other medicines?” below for more information.
Inform your doctor if you have the following conditions:
- fluid restriction (water/other fluid intake is limited to a specific amount per day)
- electrolyte imbalance e.g. high levels of potassium in the blood
- bladder obstruction e.g. enlarged prostate
- liver disease
- kidney disease
Let your doctor know if you are pregnant or breastfeeding.
If you are going for an operation, including minor surgery and dental work, inform your doctor or dentist that you are taking this medicine.
Be sure to check with your doctor or pharmacist before giving Tolvaptan to a child or elderly person. Children and elderly people may be more sensitive to the side effects.
As Tolvaptan may cause water loss, you may develop fever or heat stroke in hot weather, or when participating in activities such as exercising, taking hot baths, or using the saunas. Discuss with your doctor if you frequently need to participate in such activities or you are required to work in a hot environment. Drink more water or other fluids to prevent dehydration.
Tolvaptan may cause dizziness or weakness. If affected, do not drive or take part in any activity in which you need to be alert or need to see clearly.
You may also feel dizzy when getting up from a sitting or lying down position, especially if you are taking this medicine for the very first time. This is common and should improve gradually as you get used to Tolvaptan. It will help if you get up slowly from a sitting or lying down position.
Other side effects include any of the following: thirst, constipation, dry mouth, nausea, fever, loss of appetite and frequent urination.
Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
- swelling of the face, lips, mouth, tongue or throat with difficulty in breathing
- fainting or loss of consciousness
- yellowing of the skin or eyes
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Do not take Tolvaptan with the following medicines:
- certain antibiotics e.g. clarithromycin, telithromycin
- medicines for fungal infection e.g. ketoconazole, itraconazole
- medicines for HIV infection e.g. indinavir, nelfinavir, ritonavir, saquinavir
- medicines for depression e.g. nefazodone
Inform your doctor and pharmacist if you are taking any of these medicines:
- medicine for heart disease e.g. digoxin
- medicines for epilepsy (fits or seizures) e.g. phenytoin, carbamazepine
- medicines to treat TB (lung infection known as tuberculosis) e.g. rifampicin, rifabutin
- medicine for excessive production or passage of urine e.g. desmopressin
- herbal medicines e.g. St John’s wort
This list does not include all medicines that may interact with Tolvaptan.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements and medicines that you buy without a prescription.
Avoid alcohol and grapefruit juice.
Cut down on your salt intake -- this may help lower your blood pressure and improve your overall health. Speak to your doctor or dietitian about ways to cut down on your salt intake.
Store in a cool, dry place away from the reach of children. Protect from light and moisture.
Medicines must not be used past the expiry date.