28 November 2013
Salting It Away
Doctors have known for years that soluble (effervescent) preparations of drugs such as paracetamol contain quite high levels of salt. They assumed, wrongly as it turns out, that patients did not take enough of the drugs to cause a problem.
According to an article in the Daily Telegraph yesterday, researchers at the University of Dundee have now shown that people taking these preparations are 7 times more likely to develop hypertension and, therefore, 22% more likely to suffer a stroke and 28% more likely to die over a period of seven years.
But are the numbers straight up?
Well they seem to be. Quoting odds like this make the cynical doctor think of relative risk, so maybe the numbers were very small. For example, if the number taking non-soluble preparations who had a stroke was, say, 10 then a 22% excess is still only 12.
But this doesn’t seem to be the case. The researchers examined the records of no fewer than 1,300,000 people. Now that’s a lot and quite sufficient to show statistically significant results.
Ah, but this is obviously an observational trial, not a randomised controlled trial. We remember the famous American Nurses Trial, which was later discredited (although it has to be said that its findings have been vindicated more recently) on the grounds that the people not taking HRT were more at risk of coronary heart disease than the treated group for other reasons.
In other words, people taking soluble drugs rather than plain tablets may be more at risk of hypertension for other reasons. However, there is no reason to suspect that this might be the case.
So this is momentous stuff; and the researchers only examined those who were taking these drugs prescribed on NHS prescriptions. Many more are buying these drugs over the counter. Half the population of the UK have a higher than recommended level of sodium (salt) in the blood.
So this is a really important topic. We must remember not to prescribe soluble drugs containing high levels of sodium unless there are compelling reasons to do so, such as difficulty in swallowing pills, and the drugs should be given for as short a period as possible.
Just one final reminder when you are trying to work out the salt content of substances but the label gives the sodium content. Just multiply the sodium content by 2½ to get the salt content. 1g of sodium = 2½g salt. And the recommended maximum daily intake is 6g salt.