By Nick Triggle
Health reporter, BBC News
There are more than 20,000 care homes in the UK
Elderly people living in care homes are being put at risk because of sub-standard systems for handing out medicine, according to a report.
University of London researchers found seven in 10 residents were victims of drug errors, having carried out half-day snapshot inspections of 55 homes.
They blamed inadequate information, over-worked staff, poor teamwork and often complex courses of medication.
The government said a review was focusing on medication "weaknesses".
Nurses are part of some of the workforces in specialist units caring for people with severe problems, such as late stage dementia.
But the majority of teams working in more than 20,000 care homes across the UK do not include people with clinical training.
Instead, they rely on pharmacists and GPs signing-off repeat prescription requests without any or little face-to-face contact with residents.
The report, published in the journal Quality and Safety in Health Care, said the system meant vulnerable residents were put at risk.
During the inspections, which took place in the mornings when two-thirds of the daily drug courses would be taken, researchers gathered data on 256 residents.
In total, mistakes were made in 178 cases with many the victims of more than one error.
The most common mistakes involved wrong dosages, insufficient monitoring of residents after medication had been taken and people being given the drug at the wrong time.
But rather than blaming the care home staff, the researchers said they were often not given enough training or information about handing out medication.
The report said part of the problem was that care home residents were increasingly being given complex courses of medication - each resident was taking eight different pills on average a day.
Lead researcher Professor Nick Barber said: "It is a cause for concern. Residents are usually taking a cocktail of medicines and are more susceptible to drug side-effects as a consequences of ageing.
"I think care homes need more help. Pharmacists and GPs should be taking more responsibility and visiting care homes more than they do."
The researchers also collated information on the consequences of the mistakes.
Most were only minor, although one resident did suffer a thyroid complication.
Sheila Scott, of the National Care Association, agreed care homes needed help.
"Mistakes are always indefensible, but this is a problem we keep hearing about," she said.
"We need to face this challenge and find a solution. Staff working in care homes are not medically trained and yet they are being asked to look after people with more and more complex needs."
Andrew Harrop, of the newly merged Age Concern and Help the Aged charity, said the findings were "shocking".
"This is just one of the many flaws in the current care system which can have a huge impact on the quality of life for many older people."
The Department of Health said the government was aware of the issue and was now working with the regulator, the Care Quality Commission, which was carrying out a review of healthcare in care homes.
A spokeswoman added: "The review will take into account the findings of the research and will focus on strengthening weaknesses in the systems involving medication."