Patients taking a toxic drug for psoriasis or rheumatoid arthritis have been given safety warnings by a health watchdog.
Prescribing errors to blame
The move by the National Patient Safety Agency follows 25 deaths and 26 cases of serious harm linked to methotrexate in the last 10 years.
Two-thirds of these incidents involved prescribing errors by doctors.
Doctors, pharmacists and patients have been reminded to check the dose and frequency is correct.
Oral methotrexate tablets are taken by thousands of people in the UK for rheumatoid arthritis and psoriasis.
There are 13,000 medicines currently licensed for use in the UK. Oral methotrexate is one of only six medicines that should be taken weekly.
Methotrexate is also used to treat some cancers, such as leukaemia, in daily oral or injectable doses.
Patients taking methotrexate need regular blood tests to check for side effects because of its toxicity.
The NPSA is aware of 137 patient safety incidents over the last decade in England alone.
The bulk of the incidents resulted from the wrong dose being prescribed and a fifth were linked to poor monitoring.
Doctors have incorrectly prescribed methotrexate as a daily dose when it should only be given once a week, the NPSA found.
Patients have also been confused about how often to take the dose.
The similar appearance of the two available strengths, 2.5mg and 10mg, has lead to further dosing errors.
Manufacturers have altered the shape to help avoid confusion and are discussing packaging changes with government watchdogs.
Tablets arrive at pharmacies in large packs of 100 or blister packs of 28.
Re-packaging to smaller quantities in the pharmacy for patients has meant some packs no longer contain the warning information included in the manufacturers
Look alike pharmacy packaging provided has caused further confusion for the patient or carer to identify and distinguish them from others, the NPSA found.
Doctors have been told to make sure patients are given and understand information before they start methotrexate.
Patients will be asked to keep a record of the dose and how often they are taking the medication.
IT systems for prescribing and dispensing the drug will have safety alerts and prompts.
Chief Medical Officer, Sir Liam Donaldson said: "Whilst the vast majority of NHS care is safe, errors do occur. And as this work so clearly demonstrates, in most cases these are not isolated events, but can be traced to weaknesses in systems and processes."
Wendy Harris, Senior Pharmacist at the NPSA, said: "We've had to tackle this complex problem at a number of levels, and have combined forces with industry, and involved patients, clinicians and pharmacists who have given us invaluable feedback about making treatment safer.
"All the evidence tells us that these solutions will help to reduce the risk for those taking oral Methotrexate and ultimately save lives," she said.
Neil Betteridge, Director of Public Affairs at Arthritis Care, said: "It is essential that patients have an understanding of all the risks around the drugs that they are taking, particularly in relation to dosage and frequency.
"We believe that the patient information the NPSA has developed will be crucial in helping people with arthritis to take oral Methotrexate safely and effectively."
Dr Jim Kennedy, prescribing spokesman at the Royal College of GPs, said: "GPs who are supplying oral methotrexate must ensure there is adequate
monitoring and supervision of the condition.
"They must also ensure that patients are fully informed of the beneficial and adverse effects of the drug and that they understand fully how the medication should be taken."
For further information visit the NPSA website.