In this study, tirzepatide’s impact on blood pressure reduction, during both the day and night, was impressive, says the lead study author, James A. de Lemos, MD, who serves as the chair of cardiology and a professor of medicine at UT Southwestern Medical Center in Dallas. Though studied as a weight loss drug, the blood pressure reduction achieved by tirzepatide is about what would be expected from a blood pressure lowering drug, says Dr. de Lemos.
Tirzepatide is sold as Mounjaro when prescribed for type 2 diabetes.
The efficacy of Zepbound in lowering blood pressure (also called hypertension) has important implications for treating obesity, says Michael E. Hall, MD, a volunteer expert with the American Heart Association (AHA), a cardiologist, and the chair of the school of medicine at the University of Mississippi Medical Center in Jackson.
“Hypertension is the most attributable risk factor for cardiovascular diseases, thus, effective treatments for common causes of hypertension such as obesity are needed. Effectively, this is treating the root cause of hypertension — obesity — rather than treating the secondary high blood pressure,” says Dr. Hall, who was not involved in the study.
What Is Hypertension?
Systolic Blood Pressure Went Down 7.4 to 10.6 mmHg in People on Zepbound
In the original study, participants who were overweight or obese (meaning they had a body mass index of 27 or greater) taking once-weekly tirzepatide injections of 5 milligrams (mg), 10 mg, or 15 mg for 72 weeks led to average weight reductions of 15 percent, 19.5 percent and 20.9 percent, respectively, compared with placebo.
About one-third of participants reported they had high blood pressure at the beginning of the study and were taking one or more hypertension medications.
At the start of the substudy, all participants had blood pressure levels that were less than 140/90 mmHg, and if they used blood pressure medications, they had to have been taking them for at least three months. The substudy included both participants who had hypertension and those who had normal blood pressure.
Subjects were split 70 to 30 percent female and male, and 67 percent were white, 12 percent were Black, and 25 percent were Hispanic.
The average age was 45 years old, and the average BMI was 37, which meets the criteria for obesity (obesity is a BMI at or above 30).
The 600 subgroup participants were divided into four nearly equal groups: those taking a placebo dose or Zepbound in 5 mg, 10 mg, or 15 mg doses.
The study was conducted from December 2019 to April 2022, and key findings at 8 months on participants taking Zepbound included:
- Those on 5 mg of tirzepatide had an average reduction in systolic blood pressure of 7.4 mmHg.
- Subjects taking 10 mg of tirzepatide had an average reduction in systolic blood pressure of 10.6 mmHg.
- People taking the highest dose at 15 mg of tirzepatide had an average reduction in systolic blood pressure of 8.0 mmHg.
The blood-pressure lowering effects of tirzepatide were found in blood pressure measures taken during both the day and night. Nighttime systolic blood pressure is a stronger predictor for cardiovascular death and all-cause death than daytime blood pressure readings, according to the authors.
The reductions in systolic blood pressure were consistent among all genders, races, BMIs, and hypertension-related risk factors.
People on a GLP-1 Often Need Their BP Meds Adjusted or Stopped
Zepbound works by mimicking two metabolic hormones in the body that stimulate insulin secretion and sensitivity after a person eats. The drug regulates the body’s blood sugar levels, slows down digestion, and reduces appetite, which makes a person feel fuller, eat less, and lose weight.
These findings confirm what is often observed in people taking Zepbound or other GLP-1 drugs like Ozempic, says de Lemos. “Patients on these drugs do experience drops in blood pressure, and if blood pressure gets low enough, they may be able to come off some of their other blood pressure medications,” he says.
Overall, these data show that novel weight loss medications are effective at reducing body weight, and they are also effective at improving many of the cardiometabolic complications of obesity, including hypertension, type 2 diabetes, and high cholesterol, among others, says Hall.
Would Improvements in Blood Pressure Remain if People Stopped Taking Zepbound?
“Because the blood pressure lowering is mostly related to weight loss, like most drugs for hypertension, this one will require people to take it regularly to keep up the improvements,” he says.
Dan Azagury, MD, an associate professor of surgery and the section chief of minimally invasive bariatric surgery at Stanford University in California, agrees. “A significant proportion of the blood pressure lowering effect (70 percent per this study) is related to the weight loss itself,” he says.
If patients are able to keep the weight off, then their blood pressure may remain lower, but that is the exception rather than the rule. Most patients will regain weight upon discontinuation of treatment, says Dr. Azagury.
But future studies are needed to confirm what happens to blood pressure if the weight is regained, says Hall. More studies are also needed to determine the long-term impact of GLP-1 drugs on cardiovascular events such as heart attack and heart failure, he says.
Could Improvements in Blood Pressure Help With GLP-1 Insurance Coverage?
Experts aren’t sure whether these latest findings will increase insurance coverage for weight loss drugs like Zepbound and Wegovy.
“I don’t think this alone would do that, given that there are much cheaper options for blood pressure and cholesterol lowering. However, if as expected, these drugs lower long-term heart disease risks, then that will help with the insurance arguments,” says de Lemos.
While Hall agrees that there are cheaper meds for high blood pressure, “these [other] drugs are not treating the actual cause: obesity,” he says. “If these drugs are shown to reduce hard cardiovascular events or mortality, then this may help with insurance coverage,” says Hall.
Whether studies like this will encourage insurance coverage for GLP-1s for weight loss is a difficult question, says Azagury. In the United States, the system isn’t set up to encourage long-term prevention, he says.
“The private insurance groups have no incentive, because if they pay for prevention and patients enjoy better health later in life, CMS [Medicare] reaps the benefits, not them. It’s a huge flaw in the current system,” he says.