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Soluble drug formulations associated with increased CV events

The British Medical Journal has published the results of an observational study that aimed to determine whether patients taking formulations of drugs that contain sodium (soluble, effervescent or dispersible formulations) have a higher incidence of cardiovascular events compared with patients on non-sodium formulations of the same drugs.

The study included data for 1,292,337 UK patients in the Clinical Practice Research Datalink who were prescribed at least two prescriptions of sodium-containing formulations or matched standard formulations of the same drug between January 1987 and December 2010. The primary outcome was a composite of incident non-fatal myocardial infarction, incident non-fatal stroke or vascular death. 61,072 patients who experienced a cardiovascular event were match with controls.

For the primary endpoint the adjusted odds ratio for exposure to sodium-containing drugs was 1.16 (95% confidence interval 1.12 to 1.21). Individually the odds rations were 1.22 (1.16 to 1.29) for incident non-fatal stroke, 1.28 (1.23 to 1.33) for all-cause mortality, 7.18 (6.74 to 7.65) for hypertension, 0.98 (0.93 to 1.04) for heart failure, 0.94 (0.88 to 1.00) for incident non-fatal myocardial infarction, and 0.70 (0.31 to 1.59) for vascular death.

The authors conclude that, "Exposure to sodium-containing formulations of dispersible, effervescent and soluble medicines was associated with significantly increased odds of adverse cardiovascular events compared with standard formulations of those same drugs". They recommend that "Sodium-containing formulations should be prescribed with caution only if the perceived benefits outweigh these risks".

The authors note several limitations in the study including accuracy of information in the database, inability to correct for family history, health behaviours and dietary sodium intake and lack of date on over-the-counter medicine use.

Action: Clinicians should be aware of the association between sodium containing drug formulations and increased cardiovascular events. Use of dispersible, effervescent and soluble medicines should be avoided where this is possible.

Source: Medicines Awareness Weekly email