Tolvaptan Not Yet Approved to Treat PKD
May 19, 2009 |
Research & Medicine
Ronald D. Perrone, M.D.
Chairman, Scientific Advisory Committee, PKD Foundation
The FDA approved Tolvaptan (Samsca®) for use as a treatment for hyponatremia (low level of salt in the blood) on May 19, 2009. Tolvaptan works by blocking the receptor for vasopressin (anti-diuretic hormone) which results in the production of very dilute urine leading to correction of low levels of salt in the blood.
Results of Tolvaptan therapy in animal PKD models are very promising; however, the effect of Tolvaptan in humans with ADPKD is only presently being tested in the Tempo ¾ study (ClinicalTrials.gov NCT00428948).
As someone interested in treatments for polycystic kidney disease, you should be aware that the use of Tolvaptan for polycystic kidney disease is not presently approved by the FDA and is not appropriate for the treatment of polycystic kidney disease for the following reasons:
• Neither its safety nor effectiveness have been established for polycystic kidney disease.
• Despite the promising results in animal studies, it is possible that Tolvaptan may be ineffective or even harmful in human ADPKD.
• The product labeling indicates that Tolvaptan should be initiated in a hospital setting (http://www.accessdata.fda.gov/drugsatfda_docs/label/2009/022275lbl.pdf ).
• Because of its potent effect on urine output, the very real possibility exists that profound dehydration and impaired kidney function could result from inappropriate use of this medication.
PKD experts and the PKD Foundation strongly discourage the off-label use of Tolvaptan for polycystic kidney disease until the results of ongoing clinical studies provide definitive information regarding safety and effectiveness.