Common pain reliever may increase kidney risk when taken with blood pressure medicines

Using ibuprofen together with two specific types of blood pressure medication can increase the chance of a sudden drop in kidney function. To understand why some people are more vulnerable than others, researchers built a computer model.

The drug combination includes a diuretic, often called a water pill, and a medicine that works on the body’s renin-angiotensin system. That category includes ACE inhibitors and angiotensin receptor blockers, which are widely prescribed for blood pressure and other conditions.

Ibuprofen is one of several nonsteroidal anti-inflammatory drugs, or NSAIDs. Since it is available over the counter in many places, people may take it briefly without realizing it can interact with medicines they are already using.

The research, published in Mathematical Biosciences in 2022, was led by scientists at the University of Waterloo and partner institutions. Their model examined how the heart, blood vessels and kidneys work together to manage blood pressure and regulate salt and water balance.

The kidneys filter blood through countless tiny units, and that function depends on pressure inside small blood vessels. Normally, the body adjusts the vessels leading into and out of each filter to help maintain filtration when blood pressure or fluid levels change.

A diuretic can lower the amount of fluid circulating in the body. An ACE inhibitor or a similar drug affects how the vessels leaving the filters respond, while an NSAID can weaken the signals that help keep the vessels supplying those filters open.

This interaction reflects the close link between blood pressure control and kidney injury.

The model indicated that these effects can work together to reduce the pressure driving filtration. Lower water intake, differences in how kidney vessels respond and sensitivity to the drugs all helped determine how much filtration declined in the simulations.

The researchers also found that blood pressure measurements in the model could appear similar with two drugs or with all three, even while kidney filtration changed. That suggests blood pressure readings alone may not reveal a developing kidney problem.

Because the study was a simulation, it could test possible mechanisms without estimating how many patients might be affected. Separate research using medical records has reported a higher rate of acute kidney injury when the three types of medicines are used together.

Acute kidney injury refers to a rapid decline in kidney function. How severe it becomes, and how likely recovery is, depends on the underlying cause and a person’s health before the episode. A blood test can help detect a sudden change in filtration.

The practical issue is whether a pain medicine fits safely with an individual’s prescribed drugs. A pharmacist or doctor can review the active ingredients, consider kidney function and suggest pain relief options that do not interfere with blood pressure treatment.

Source: University of Waterloo.