Over the past 20 years, the development of new prescription drugs and their use in clinical practice have improved cardiovascular mortality rates. Despite that progress, cardiovascular disease still accounts for one in three deaths among Americans.

And now fewer drugs are being produced.

The American College of Cardiology recently published findings in JACC: Basic to Translational Science that show the pace of innovation and investment in developing new cardiovascular therapeutics has decreased over the past 22 years.

Researchers analyzed data from a large commercial database of drug development activity that tracks the pipeline of pharmaceutical research and development projects. The study included all products that had entered Phase 1 clinical trials from 1990 through 2012, focusing on drugs intended to treat cardiovascular disorders.

The trial observed a total of 347 drugs that entered testing. Each year, the number of drugs entering Phase 1 testing declined steadily. Between 1990 and 1995, 16 percent of drugs entering the trail were cardiovascular. That number dropped to 5 percent from 2005 to 2012. For comparison, the number of cancer drugs increased over those same intervals.

The study found that this is due, in part, to the increasing cost of conducting large cardiovascular outcome trials and the availability of low-cost generic medications.  

While the total number of cardiovascular drugs in trials decreased, the number targeted at unique biological pathways increased. According to Aaron S. Kesselheim, MD, JD, MPH, associate professor of medicine at Brigham and Women's Hospital and Harvard Medical School and the senior author of the study, the increase offers a possible explanation for why fewer cardiovascular drugs are making it to market.

Half of cardiovascular drugs entering Phase 3 trials targeted a novel biological pathway or one for which the FDA had not yet approved a therapeutic agent. The rate of novel drugs entering Phase 3 increased from 27 percent in 1990 and 1991 to 57 percent in 2012.

“Most cardiovascular drugs fail in Phase 3 clinical trials due to inadequate efficacy or safety concerns, but cardiovascular drugs do not appear to be more likely to fail than drugs for other disease,” the study’s authors wrote.

As a result, they suggest that policymakers focus their efforts on supporting research aimed at improving gaps in understanding of cardiovascular disorders so that more drugs can gain approval.