Two of the world's biggest drugs firms are threatening to sue the NHS to stop it using a treatment nearly 70 times cheaper than their medication.
Novartis and Bayer made the threat against 12 health boards in Cumbria and North-East England which have advised doctors to use a different treatment for a devastating eye condition.
Doctors have accused the pharmaceutical giants of trying to 'dictate' which drugs they can use.
Doctors in the North East and Cumbria have been using 'off-licence' drugs to treat patients with age-related macular degeneration, or wet AMD, picture posed by models
Medics have been using Avastin, which costs on average £12 per injection
Eylea, which is produced by Bayer costs the NHS on average £742 per dose
The NHS clinical commissioning groups want to use a drug called Avastin for patients with wet age-related macular degeneration, or wet AMD.
They calculate that at £12 per injection, Avastin would save them £13.5 million a year compared to the current drugs they use – Novartis's Lucentis (£742 a dose) and Bayer's Eylea (£816). They say the saving could pay for an extra 270 nurses in the region.
But Novartis and Bayer have threatened to launch a judicial review, saying the move breaches health rules.
Wet AMD, which affects about 70,000 elderly people in the UK, causes them to rapidly lose their central vision when blood vessels start growing across the retina at the back of the eye.
The treatments, which are injected directly into the eye, stop the growths.
Avastin was initially designed as a breast cancer treatment, and so does not have a licence for use as eye medication. And because its patent expires in 2022, its maker Roche has nothing to gain from an expensive licence application.
Lucentis, pictured, costs on average £742 a dose and is produced by Novartis
But studies have shown it is just as good as Lucentis or Eylea at stopping visual decline, and it is used 'off-label' around the world for elderly eye patients.
If the NHS switched entirely to Avastin, it would save an estimated £500million a year, but off-label use of drugs is permitted only if there is no medical alternative. Novartis and Bayer claim NHS patients have a legal right to be offered drugs that have been approved by drugs watchdog NICE.
David Hambleton, chief officer of