Aldactone (spironolactone) is an aldosterone inhibitor available by prescription from many pharmaceutical companies. It is approved by the U.S. Food and Drug Administration to treat conditions that cause fluid retention, or edema, such as congestive heart failure, hypertension, and kidney disease. It can also be used as a kidney-protective therapy in Alport syndrome.

How Aldactone works

Alport syndrome is a serious heritable condition in which an essential structural protein called type 4 collagen is faulty, causing the small blood vessels in the kidneys to be formed incorrectly. As a result, the kidneys cannot filter waste and fluid out of the blood efficiently and become scarred over time. All Alport syndrome patients have kidney symptoms, and most men with Alport syndrome will develop end-stage kidney disease in middle-age.

Aldosterone is a signaling hormone that normally binds to a receptor in the kidneys. Once bound to its receptor, aldosterone increases the production of a protein channel that transports water and sodium (a salt) out of urine in the kidneys, before urine reaches the bladder. In this way, aldosterone increases water and sodium retention.

Aldactone competes with aldosterone for its receptor. When Aldactone is bound to the receptor, the receptor is not available to bind to aldosterone. This decreases the number of water and sodium channels produced in the kidneys, ensuring that more water and sodium are excreted. Aldactone also increases the retention of potassium.

Aldactone in clinical trials

A 10-year observational clinical trial (NCT02378805) is recruiting in Germany for a total of 500 Alport syndrome patients to determine whether ACE inhibitors, statins, or Aldactone can delay the time until patients require dialysis and increase life expectancy. Patients records will be analyzed separately based on protein levels in their blood and urine and observed for 10 years with treatment. These will be compared with patients who have not received treatment (primarily older relatives who were not diagnosed prior to the development of kidney failure).

A small study, published in Pediatric Nephrology, described the effect of Aldactone on top of ACE inhibitor treatment with or without an angiotensin-II receptor blocker (ARBs) in 10 children with Alport syndrome. The levels of protein in patients’ blood and urine were measured every month for six months. In eight patients, protein blood and urine levels were also measured after nine and 12 months of treatment. All patients showed a significant decrease in protein levels in the urine following treatment. One obese male experienced gynecomastia (breast development), but no other side effects were reported.

Other information

Aldactone can cause side effects including tiredness, nausea, diarrhea, and stomach cramps.

Aldactone may also cause an increase in the levels of potassium in the blood, so it is recommended that patients using it eat a “renal healthy” diet low in potassium.

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