At Last a Drug for Genetic Kidney Disease

Polycystic kidney disease patients taking Samsca had slower progression of kidney disease

(RxWiki News) Researchers have known about polycystic kidney disease for more than a century. However, they have had trouble coming up with an effective treatment for this common disease. That is, until now.

In a recent study, Samsca (tolvaptan) seemed to slow the progression of polycystic kidney disease. However, the risks of the drug may keep some patients from taking effective doses.

Over the total 3-year research period, kidney size increased 2.8 percent among Samsca patients versus 5.5 percent among placebo patients.

This study means there is a new drug that may help with a specific type of kidney disease.

"Get screened for kidney disease."

The study by Vicente E. Torres, MD, PhD, of Mayo Clinic, and colleagues showed that Samsca can reduce kidney growth and slow the decline in kidney function.

Polycystic kidney disease is one of the most common genetic diseases. As many as 10 percent of dialysis patients worldwide have the condition.

The condition occurs when cysts form in the kidneys, causing the kidneys to become enlarged. When these cysts develop, patients with polycystic kidney disease may experience pain, high blood pressure and eventually kidney failure.

According to Dr. Torres and colleagues, "Effective treatment for [polycystic kidney disease] has been lacking." Samsca may be the new drug option for patients living with this disease.

From their phase III clinical trial, the researchers found that patients who took Samsca for 3 years had slower kidney growth than those who took placebo. While kidney size increased 5.5 percent per year among patients who took placebo, kidneys grew only 2.8 percent per year among patients who took Samsca.

Patients taking Samsca also had lower rates of worsening kidney function and kidney pain.

"The study achieved its goal," said Olivier Devuyst, MD, PhD, of the University of Zurich and a researcher in the trial.

Still, the side effects of the Samsca led a number of patients to quit taking the drug. While 14 percent of patients in the placebo group quit treatment, 23 percent in the Samsca group stopped taking their drug.

Patients taking Samsca had fewer adverse events related to polycystic kidney disease itself but more events likely caused by the drug. The side effects of the drug included:

  • thirst
  • polyuria (excessive amounts of urine)
  • nocturia (the need to wake up to urinate more than once a night)
  • polydipsia (excessive thirst and fluid intake)

"Whether [Samsca] is a helpful long-term treatment in patients with [polycystic kidney disease] will depend on a balance between benefits and risks," the authors wrote.

The average cost per day for a Samsca prescription is $300 per day.

The study included 1,445 patients between 18 and 50 years of age. The research was funded by Otsuka Pharmaceuticals, the distributor and marketer of Samsca.

A number of the researchers report receiving fees from or other potential conflicts of interest with Otsuka. The study was published November 3 in the New England Journal of Medicine.

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Review Date: 
November 5, 2012
Last Updated:
June 27, 2013