Novel drug improves breathing and appears to extend life.
It may be hard to imagine that a drug derived from a hormone associated with pregnancy could improve the symptoms of heart failure, but that’s what serelaxin appears to do. In clinical trials of people hospitalized with new onset of sudden (acute) heart failure, the drug significantly improved shortness of breath (a condition doctors call dyspnea), one of the most frightening and persistent symptoms of the disease. It also reduced organ damage caused by poor blood flow and reduced deaths.
How serelaxin works
Both men and women produce a hormone called relaxin. Just what it does in men is unclear, but it is thought to help sperm cells swim more easily in semen. In women, relaxin plays several roles during ovulation and pregnancy. As its name implies, relaxin has a relaxing effect, loosening the tissues in the female reproductive organs and pelvic ligaments to help prepare for childbirth. Serelaxin is a chemically engineered form of relaxin.
The hormone also relaxes blood vessels, allowing them to expand. During pregnancy, this allows more blood to reach the placenta and kidneys without raising blood pressure. In people with heart failure, it increases blood flow throughout the body. This helps a poorly functioning heart to be more effective.
Relaxin is also an anti-inflammatory. Inflammation associated with heart failure can damage the kidneys, liver, and heart, but serelaxin appears to help prevent this from occurring.
In the Relaxin for the Treatment of Acute Heart Failure (RELAX-AHF) trial, researchers gave a single infusion of serelaxin or placebo to 1,138 people with heart failure admitted to the hospital in deteriorating condition. For two weeks after treatment, blood was drawn periodically and tested for the presence of proteins that indicate organ damage is occurring. Compared with placebo, serelaxin seemed to protect the function of the heart, kidneys, and liver in the majority of patients. Moreover, fluid buildup in the lungs (the congestion in “congestive heart failure”) resolved more quickly in the individuals taking serelaxin, and with it, shortness of breath and other symptoms of heart failure decreased. After six months, there had been 37% fewer deaths in the serelaxin group than in the placebo group.
No drug is perfect for everyone, however, and some clinical trial participants on serelaxin experienced worsening kidney or liver function.
Serelaxin will continue to be tested in clinical trials. Doctors hope results will continue to be encouraging.