Sodium, medicines, and importance for patients

Sodium within medicines

Sodium can be included in medicines as the active ingredient or part of it (e.g. sodium chloride or diclofenac sodium), as part of an excipient (e.g. sodium bicarbonate) or used in the preparation of the medicine. The European Medicines Agency Committee for Human Medicinal Products (CHMP) questions and answers on sodium used as an excipient in medicinal product for human use notes that all sodium salts are soluble and therefore even sodium bound in complex molecules would be expected to dissolve and exert a physiological effect.

Some medicines contain significant amounts of sodium. The European Medicines Agency CHMP questions and answers on sodium used as an excipient in medicinal product for human use document highlights that sodium content may be especially high in effervescent and soluble preparations. Other preparations that might be high in sodium include alginates, other indigestion remedies and  some bowel preparations.

Excipient regulations

In the EU, according to the European Commission Volume 2C Guideline, it is a legal requirement that all excipients in parenteral, eye and topical medicines must appear on the packaging and in the package leaflet. For all other medicines, only those excipients known to have a recognised action or effect must be included on the labelling and in the package leaflet, if this information is essential for safe and effective use of the medicine. According to the MHRA Best practice guidance on the labelling and packaging of medicines (2020) this requirement also applies to all medicines licensed for use in the UK.

Acceptable levels

The European Medicines Agency Committee for Human Medicinal Products (CHMP) questions and answers on sodium used as an excipient in medicinal product for human use document notes there is no evidence to suggest the level of sodium that is acceptable and it is expected to vary between individuals.

Importance for patients

People with conditions associated with sodium retention, such as hypertension, heart failure or renal impairment, or individuals following a salt-restricted diet, should avoid regular use of medicines containing high levels of sodium.

Labelling requirements

According to EU guidance excipients in the labelling and package leaflet of medicinal products for human use (UK guidance not yet available), the following information must be included in the package leaflet:

Less than 1mmol sodium per dose

For medicines containing less then 1mmol sodium per dose, labelling should read:

• This medicine contains less than 1mmol sodium (23mg) per <dosage unit><unit volume>, that is to say essentially ‘sodium-free.’

1mmol sodium or more per dose

For medicines containing 1mmol or more of sodium per dose, labelling should read:

• This medicine contains Xmg sodium (main component of cooking/table salt) in each <dosage unit><unit volume>. This is equivalent to Y% of the recommended maximum daily dietary intake of sodium for an adult.’

17mmol sodium or more in the maximum daily dose

For medicines containing 17mmol sodium or more in the maximum daily dose, labelling should read:

• Talk to your doctor if you need <Z> or more <dosage units> daily for a prolonged period, especially if you have been advised to follow a low salt (sodium) diet

This applies only to products for which the labelled posology allows the product to be taken on a daily basis for more than one month or repeated use for more than 2 days every week. 17mmol (391mg) is approximately 20% of the World Health Organisation adult recommended maximum daily dietary intake of 2g sodium and is considered to represent ‘high’ sodium.

Update history