Sodium in Effervescent Painkillers, Vitamins Ups CVD Risk

Marlene Busko

November 27, 2013

DUNDEE, SCOTLAND — Effervescent or readily soluble formats of common medications, such as painkillers and vitamin supplements, contain high levels of "hidden" sodium, which was linked with an increased risk of cardiovascular events, researchers report [1].

In an observational study of UK adults followed for about seven years, being prescribed a readily soluble formulation as opposed to a regular formulation of a drug was associated with a 22% increased risk of stroke and a sevenfold increased risk of hypertension.

Sodium carbonate or bicarbonate in effervescent, dispersible, and soluble medications and vitamins makes them release carbon dioxide in water, so that they are more readily absorbed, lead author Dr Jacob George (University of Dundee, Scotland) explained to heartwire in an email. These formats may be prescribed to patients who have difficulty swallowing or need a drug with a rapid onset of action (such as for migraine).

However, according to the authors, the study suggests that "sodium-containing formulations should be prescribed with caution only if the perceived benefits outweigh [the] risks . . . and patients . . . should be carefully monitored for the emergence of hypertension."

The study also showed that "the public should be warned about the potential hazards of high sodium consumption in prescribed medicine, and these should be clearly labeled with the sodium content in the same way as foods are labeled." The findings can likely be extrapolated to include over-the-counter formulations, which were not studied, they add.

The study was published November 26, 2013 in BMJ.

Surprising Source of Sodium: Fizzy Pills and Vitamins

The negative impact on health from consuming too much dietary sodium is a worldwide concern. However, "curiously, unlike foods, pharmaceutical manufacturers are not placed under any restrictions or obligations with regards to sodium content or labeling of these sodium-containing formulations," write George and colleagues.

The authors hypothesized that taking medication formulations that contain sodium might lead to increased cardiovascular events. They performed a nested case-control study of patients aged 18 and older who were part of the UK Clinical Practice Research Datalink database and received at least two prescriptions for any of 24 sodium-containing formulations of drugs or vitamin or mineral supplements or 116 standard formulations of those products from 1987 to 2010.

Sodium-containing medications included acetaminophen (paracetemol, Tylenol), effervescent aspirin, and soluble ibuprofen for pain; calcium carbonate (Alka-Seltzer) for acid indigestion; and metoclopramide plus aspirin for migraine. Vitamin and mineral supplements included ascorbic acid and zinc sulfate.

Of more than 1.29 million patients, 61 072 had an incident cardiovascular event and were matched with controls. After adjustment for multiple variables, patients who took sodium-containing formulations had a 1.16-fold increased odds of the primary outcome (nonfatal MI, nonfatal stroke, or vascular death) compared with controls.

Risk of outcome, sodium-containing vs standard formulations group

Outcome Adjusteda odds ratio (95% CI)
Composite outcomeb 1.16 (1.12–1.21)
Incident nonfatal stroke 1.22 (1.16–1.29)
Hypertension 7.18 (6.74–7.65)
All-cause mortality 1.28 (1.23–1.33)

a. Adjusted for age, sex, body mass index, smoking, alcohol, chronic illness, and use of other medications.
b. Nonfatal MI, nonfatal stroke, vascular death.

George explained that the average consumption of sodium from the preparations was 106.7 mmol/day, which is higher than the recommended UK dietary intake (104 mmol/day) or US dietary intake (approximately 100 mmol/day). For example, a 500-mg tablet of soluble acetaminophen contains 18.6 mmol of sodium, and the maximum daily dosage contains 148.8 mmol of sodium.

"We would like to see more discussion between regulators—like the [US Food and Drug Administration] and [UK Medicines and Healthcare Products Regulatory Agency]—and industry on the sodium content of medications, and hopefully newer innovations that might enable a reduction in the sodium content of these preparations," he concluded.

The study was funded by Tenovus Scotland. The authors had no conflicts of interest.

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