Tolvaptan (Jinarc®) is a new treatment available in Australia for adults with ADPKD, that can help slow the progression of ADPKD.
Clinical trials have shown Tolvaptan can slow the rate at which your kidneys become enlarged by cysts and can help to slow the speed at which your kidney function declines. Tolvaptan is taken orally (as a tablet).
How does Tolvaptan/ Jinarc® work?
Our bodies depend on a hormone called vasopressin to regulate fluid balance. When our bodies are not hydrated more vasopressin is produced. High vasopressin levels (which occur when we don’t get enough fluid) have been linked to cyst growth in ADPKD. Tolvaptan works by blocking vasopressin in your body and may help to slow the speed at which your kidney function declines.
Jinarc/ Tolvaptan Q&A
- Who is eligible to receive Jinarc®?
- Who would most benefit from treatment with Jinarc®?
- How do I obtain treatment?
- Will Jinarc® delay the need for dialysis or renal transplant?
- What are the common side effects of taking Jinarc®?
- Are clinical trials for other treatment therapies currently underway?
- Would increased water intake serve as a substitute for taking Jinarc®?
- If I am currently enrolled in a clinical trial will I be able to take Jinarc®?
The information provided here is an overview of Jinarc® and does not contain all the available information nor does it take the place of talking to your doctor or pharmacist. All medicines have risks and benefits and your doctor will weigh the risks of you taking this medicine against the benefits they expect it will have for you.
- To qualify for Jinarc, a person with ADPKD must have either Stage 2 or Stage 3 chronic kidney disease (CKD), and have declining kidney function. This is defined as a fall in eGFR of greater than 2.5ml/min/yr averaged over 5 years, or greater than 5.0 ml/min/yr over one year.
- In the trial of approximately 1500 ADPKD patients (REPRISE), the impact was greatest in CKD Stage 3a, where the rate of decline in the untreated patients was 4.4ml/min/yr, and in the group prescribed Jinarc it slowed to 2.1ml/min/yr. There was a similar impact in CKD Stage 2. With worsening levels of renal function the benefit gets smaller.
- Jinarc can only be prescribed by a Nephrologist. You should discuss the use of Jinarc with your nephrologist who can the discuss the use of Jinarc, taking into account your kidney function when considering potential benefit, as well as the side effects of this treatment.
- Jinarc will delay dialysis or transplantation. It is important to note a significant proportion of people cannot tolerate Jinarc, mainly because it leads to people passing up to 5 litres of urine a day. However, there have been two major trials of Jinarc in ADPKD. The investigators have extrapolated from this data and have suggested that Jinarc may delay dialysis or transplantation for between 6 to 9 years. This is likely to be restricted to patients starting at the time of CKD Stage 2 or early Stage 3a.
- There are two important side effects to be aware of when taking Jinarc. The first of these is that on Jinarc, one can pass up to 5 litres of urine a day. This is not so much a side effect, but arises directly from the way the drug works. To be effective Jinarc block sufficient Antidiuretic hormone (ADH) to make you pass a lot of urine. Studies in animals suggest that taking a low dose won’t be of benefit. Unfortunately around 12-15% of ADPKD patients could not take Jinarc long term because of this. The other important side effect involves the liver. In the first major study of Jinarc, three individuals out of approximately 700 on Jinarc got serious changes in the blood tests monitoring liver function. They all got better when Jinarc was stopped. However approximately 5% of patients on Jinarc developed less serious abnormalities in the tests of their lIver function. In all cases the drug was ceased and the changes resolved. Putting these together, around 20% of patients will not be able to Jinarc long term.
- There is currently a study underway looking at whether suppressing ADH by drinking excessive water can be of benefit in ADPKD. It is also likely there will trials of potential agents in the future, although there are none currently. Any future trial would have to first be registered, so searching on www.australianclinicaltrials.gov.au would keep you up to date.
- There is enough evidence to say that adequate suppression of ADH will be of benefit and we know drinking excessive water does suppress ADH. The current study running in Australia will help answer this question. Some individuals drinking excessive amounts of water or other liquids can develop a low blood sodium which can be dangerous. If you are thinking of drinking large volumes of liquid this should only be done after discussion with a doctor and with ongoing supervision.
- If you are currently in another clinical trial, it is likely that you will not be able to take Jinarc but each trial is different, and you would need to discuss this with the medical staff monitoring the trial you are in.
If you are currently in another clinical trial, it is likely that you will not be able to take Jinarc but each trial is different, and you would need to discuss this with the medical staff monitoring the trial you are in.