Do drugs work better if taken by the clock?
A new analysis published in The Lancet journal’s eClinicalMedicine suggests: Yes, they do — if you consider the patient’s individual body clock. The study is the first to find that timing blood pressure drugs to a person’s personal “chronotype” — that is, whether they are a night owl or an early bird — may reduce the risk for a heart attack.
The findings represent a significant advance in the field of circadian medicine or “chronotherapy” — timing drug administration to circadian rhythms. A growing stack of research suggests this approach could reduce side effects and improve the effectiveness of a wide range of therapies, including vaccines, cancer treatments, and drugs for depression, glaucoma, pain, seizures, and other conditions. Still, despite decades of research, time of day is rarely considered in writing prescriptions.
“We are really just at the beginning of an exciting new way of looking at patient care,” said Kenneth A. Dyar, PhD, whose lab at Helmholtz Zentrum München’s Institute for Diabetes and Cancer focuses on metabolic physiology. Dr. Dyar is co-lead author of the new blood pressure analysis.
“Chronotherapy is a rapidly growing field,” he said, “and I suspect we are soon going to see more and more studies focused on ‘personalized chronotherapy,’ not only in hypertension but also potentially in other clinical areas.”
The ‘Missing Piece’ in Chronotherapy Research
Blood pressure drugs have long been chronotherapy’s battleground. After all, blood pressure follows a circadian rhythm, peaking in the morning and dropping at night.
That healthy overnight dip can disappear in people with diabetes, kidney disease, and obstructive sleep apnea. Some physicians have suggested a bed-time dose to restore that dip. But studies have had mixed results, so “take at bedtime” has become a less common recommendation in recent years.
But the debate continued. After a large 2019 Spanish study found that bedtime doses had benefits so big that the results drew questions, an even larger, 2022 randomized, controlled trial from the University of Dundee in Dundee, Scotland — called the TIME study — aimed to settle the question.
Researchers assigned over 21,000 people to take morning or night hypertension drugs for several years and found no difference in cardiovascular outcomes.
“We did this study thinking nocturnal blood pressure tablets might be better,” said Thomas MacDonald, MD, professor emeritus of clinical pharmacology and pharmacoepidemiology at the University of Dundee and principal investigator for the TIME study and the recent chronotype analysis. “But there was no difference for heart attacks, strokes, or vascular death.”
So, the researchers then looked at participants’ chronotypes, sorting outcomes based on whether the participants were late-to-bed, late-to-rise “night owls” or early-to-bed, early-to-rise “morning larks.”
Their analysis of these 5358 TIME participants found the following results: Risk for hospitalization for a heart attack was at least 34% lower for “owls” who took their drugs at bedtime. By contrast, owls’ heart attack risk was at least 62% higher with morning doses. For “larks,” the opposite was true. Morning doses were associated with an 11% lower heart attack risk and night doses with an 11% higher risk, according to supplemental data.
The personalized approach could explain why some previous chronotherapy studies have failed to show a benefit. Those studies did not individualize drug timing as this one did. But personalization could be key to circadian medicine’s success.
“Our ‘internal personal time’ appears to be an important variable to consider when dosing antihypertensives,” said co-lead author Filippo Pigazzani, MD, PhD, clinical senior lecturer and honorary consultant cardiologist at the University of Dundee School of Medicine. “Chronotherapy research has been going on for decades. We knew there was something important with time of day. But researchers haven’t considered the internal time of individual people. I think that is the missing piece.”
The analysis has several important limitations, the researchers said. A total of 95% of participants were White. And it was an observational study, not a true randomized comparison. “We started it late in the original TIME study,” Dr. MacDonald said. “You could argue we were reporting on those who survived long enough to get into the analysis.” More research is needed, they concluded.