Fears over premature baby medicine

The medicines contain substances that are sometimes above the level recommended for adults and could cause nerve damage, they added.

One of the problems is that medicines are routinely tested in adults but very rarely in children. This means little evidence exists about their safety for younger people.

The study, led by researchers at Leicester Royal Infirmary, followed 38 babies born between June 2005 and July 2006 at under 30 weeks' into pregnancy and who weighed less than 1,500g (3.3lb) each.

The babies were in hospital for between 2.5 and nine weeks and were given a range of treatments, from iron and vitamin drops to furosemide (a diuretic used to lessen fluid retention or treat congestive heart failure or lung disease) and dexamethasone (a steroid).

Researchers found that the babies were regularly exposed to more than 20 different excipients, which are substances used to ease the administration, absorption or preservation of a medicine or improve its taste and appearance. The excipients noted included sorbitol (in dexamethasone and iron), ethanol (alcohol used in iron and furosemide) and propylene glycol (found in dexamethasone).

The authors wrote: "During their in-patient stay, infants were exposed to over 20 excipients including ethanol and propylene glycol, chemicals associated with neurotoxicity. Infants with CLD (chronic lung disease) were exposed to higher concentrations of these toxins."

The authors noted that the babies' exposure to ethanol ranged from 0.2ml to 1.8ml per week, equivalent to an estimate of one to seven units of alcohol, while exposure to sorbitol ranged from 0.1 to 3.5g per kg per week.

The recommended maximum intake of sorbitol for adults is 20g a day. When calculated according to the baby's weight, this level was exceeded in 18 babies for at least one week. While all babies given dexamethasone exceeded the recommended levels of propylene glycol, which is about two thirds as strong as ethanol.

The study was published online in the journal Archives of Disease in Childhood. The authors said: "We feel it is important that the EMEA/Medicines and Healthcare Products Regulatory Agency not only ensures that all manufacturers provide detailed labelling of the excipient content of their products, but also leads action to determine whether existing practice constitutes a risk and, if so, how this might be dealt with."