A new study has found a link between the amount of sodium in certain medications and the risk of cardiovascular problems, including hypertension and stroke – and says normal use of some medicines can expose patients to sodium levels well above the recommended maximum.
The paper, published in the British Medical Journal, describes how many effervescent, dispersible and soluble medicines contain very high levels of sodium – high enough to significantly raise consumers’ chances of developing a range of serious health conditions. For example, the maximum recommended dose of dispersible paracetamol delivers almost 1.5 times an adult’s recommended sodium intake.
It is well known that excess sodium consumption carries health risks, and there has been growing concern about the levels that people are routinely ingesting. High-salt diets are the most publicised problematic sodium intake, but the level of sodium in medicines has until now received scant attention.
Sodium is added to medicines for various reasons, such as to aid absorption into the body. Many effervescent tablets use sodium bicarbonate to make them fizz; other medications use sodium compounds to aid their dispersal, or to help them dissolve in water. This means these medicines can contain very high quantities of sodium, even though sodium is not one of their active medical ingredients.
The team of researchers tracked more than 1.2 million UK patients for a period of seven years, and compared the risk of cardiovascular events – non-fatal heart attack, non-fatal stoke, or vascular death – in patients taking sodium-containing effervescent, dispersible and soluble medications with those taking non-sodium versions of the same drugs.
They found that those taking the sodium-containing drugs had a 16% increased risk of a heart attack, stroke or vascular death compared with patients taking sodium-free versions of the same medications.
The patients who took sodium-containing drugs were seven times more likely to develop high blood pressure. Their death rate was also 28% higher than that of the non-sodium patients, a number the researchers say was driven by the increased risk of hypertension and stroke.
Lead author Dr Jacob George, Senior Clinical Lecturer and Honorary Consultant in Clinical Pharmacology at the University of Dundee, said a problem with many medicines’ sodium content is not just the quantity of it, but the fact that people just don’t know about it.
“These medications contain quite a lot more sodium than a lot of people are aware. In fact, if you take the full dose of certain medications, you’re elevating your risk of sodium-related health problems even before you take into account dietary factors.”
Dr George emphasised that the elevated risks shown in the study were attributable to normal doses of sodium-containing medicines, not excessive use.
“The average sodium consumption by these medications alone was already exceeding the recommended dietary allowance of sodium,” he said. “The average person taking these medications was already exceeding that. If you add a western diet on top of that, they are far in excess of what they should be consuming.”
The study refers to high-sodium medications delivered in specific forms, among them most effervescent tablets. “It’s the sodium, usually in the form of sodium bicarbonate, that makes the tablet fizz. We’re not talking about all effervescent tablets; some contain potassium or calcium as the salt, and we’re talking specifically about the sodium-containing ones.”
The authors argue that sodium-containing medications should be labelled as such, allowing patients to weigh up the risks of taking them. In particular, they write that those at high risk of hypertension and stroke, or with risk factors for them, should be made aware of the presence of sodium in medicines they take.