Patients can play an important part in reducing medicines wastage by ensuring unused medicines are removed from their repeat prescriptions, says a new study, which estimates that unwanted medicines returned to community pharmacies by patients cost the NHS at least £100 million a year.

The study, which examined the number of medicine packs returned after public education campaigns in Guernsey and Alderney found that the estimated annual cost of prescription drugs returned in 2009 was over £186,000 for a total population of 62,000 in the two islands.

The World Health Organisation (WHO) has estimated that, globally, there is only a 50% adherence rate to medicines prescribed for long-term conditions. Reasons for waste include side-effects, recovery by patients who then do not finish a course of medication and the re-ordering of medications that are not used on repeat prescriptions.

Commenting on the study findings, which were presented at the Royal Pharmaceutical Society of Great Britain’s (RPSGB) annual conference this month, Society spokesman Neal Patel said that “for the NHS, the most expensive medicines are those that aren’t taken by patients.”

“It’s easy to re-order all items on a repeat prescription ‘just in case’ they are needed. If patients find they have packs of medicines building up at home then it’s time to get advice,” he said.

Another new study presented at the conference showed that hospital inpatients are, on average, likely to miss out on almost 10% of their medication doses.

The study, based on research conducted at Bradford Teaching Hospitals, showed that overall, 9.7% of prescribed medicines were omitted. While this could be explained by various reasons - including “nil by mouth” policies after surgery, specific advice from a health professional to withhold doses and, very often, patients refusing to take their medication – the non-availability of drugs was found to account for missed doses in 2.4% of cases.

Not taking medication at the correct time can have serious consequences to health for those with critical conditions or long-term problems such as Parkinson’s disease or epilepsy. Omitting doses of potent antibiotics, for instance, can lead delayed recovery from infection and a prolonged stay in hospital, says the Society. Spokeswoman Nina Barnett added that the Bradford audit is an example of many likely to be taking place in hospitals across the country following a “rapid response report” from the National Patient Safety Agency (NPSA) in February 2010 on the issue of missed medication.

“There is a real need to raise staff awareness around medicines which must not be delayed or omitted,” she said.