Genetics may decide whether certain heart medications are effective.
Genes dictate the color of our hair and eyes. They factor into whether we get cancer or heart disease. And, scientists increasingly recognize, they also ensure some patients will benefit from a prescription drug, while others develop adverse reactions or simply fail to respond at all.
Julie Johnson, an expert in pharmacogenomics and cardiovascular drug therapy, is part of a team of researchers who have discovered that patients with heart failure can harbor genetic variations that determine whether they will tolerate the common heart drugs known as beta-blockers. In a separate study, they have also determined certain genes influence whether beta-blockers successfully restore the heart to a more normal shape and size in these patients.
Although diet, age, health status and the environment also shape how people respond to medications, personalizing drugs based on genetic makeup instead of taking a trial-and-error approach could lead to safer, more effective treatments, she says. The findings highlight the need to individualize therapy, as opposed to treating all people with a certain disease generally the same.
Because of hereditary factors, some patients break down drugs more slowly, so the amount of a certain medication may soar to toxic levels in the body. Others metabolize drugs quickly, and never accumulate enough in the bloodstream to ease what ails them.
“In the past five to 10 years, there’s really been an increased interest in understanding the role of genetics in determining how people respond to drugs,” Johnson said. “The reason for that is that we know that in a group of individuals, a certain portion will have side effects, or toxicity from a drug, a certain portion will derive the benefits we want, and some won’t derive any benefit. The long-term goal is to try to be able to determine that before we actually have to give them the drug.”
A clearer understanding of who would benefit from beta-blocker therapy also would ensure more patients would be helped, Johnson says, citing a serious international problem with both underuse and underdosing of the drugs.
“Our data suggest that you might be able to use genetic information to identify, before therapy, those people who are going to have difficulty,” Johnson said. “That would allow the physician to really focus in on those patients and monitor them very closely.”