Drugs used to treat osteoporosis could have the opposite effect and make you more prone to fractures, study finds

Taking biphosphonates for more than five years alters the composition of bone
Older women were found to be most at risk from taking the pills, experts said
Such drugs, taken by millions worldwide, include Fosamax, Boniva and Reclast

Drugs used to strengthen bones can actually have the opposite effect, scientists have warned.

Taking biphosphonates for more than five years alters the composition of bone – making it more brittle.

Older women were found to be most at risk of taking the cheap pills, which include Fosamax, Boniva and Reclast.

The study of 50 women aged 65 to 93 found using the drugs long-term can make bones more mineralised and harder.

Such pills protect millions of osteoporosis patients from potentially fatal fractures if they are taken daily.

The findings have potential implications for the treatment of the condition which affects more than three million Britons and 44 million in the US.

Taking biphosphonates for more than five years alters the composition of bone – making it more brittle, a study found

Study author Professor Eve Donnelly from Cornell University in New York said: ‘It’s kind of a double-edged sword.

‘It’s extremely good to prevent bone loss but the drugs will also slow this natural process – which allows turnover.

‘That’s one of the cautions I’d like to impart. What we have observed is really the result of long-term treatment.’

How long should you use them?

US health officials recommend that patients use bisphosphonates for no more than three to five years. The NHS says such prescriptions should be re-evaluated after five years of use.

But some of the volunteers in the journal Proceedings of the National Academy of Sciences had used the drugs for up to eight years.

HOW THE DRUGS COULD ALSO BE USED

Thousands of women’s lives could be saved after scientists discovered a way to stop breast cancer spreading into the bones, it was revealed in 2015.

Experts hoped the finding would slash the death rate associated with the disease, which affects more than 50,000 people in the UK every year.

Scientists at Sheffield University said they discovered a way of stopping cancerous cells from burrowing into a patient’s bones by using bisphosphonates.

Secondary tumours in the bones is the cause of roughly 85 per cent of the 12,000 breast cancer deaths seen in the UK every year.

Participants were split into five different groups based on types of fracture and bisphosphonate use to make the findings.

Analysis of biopsies of the outer layer or cortical shaft of the thigh bone obtained during surgery found it was harder and more mineralised.

How do the drugs work?

This is believed down to the main function of bisphosphonates main function – slowing the shredding of old bone.

In healthy adults, cortical bone is constantly being resurfaced – so the entire adult skeleton is overhauled every 10 years or so.

New layers of bone can act as a ‘firewall’ of sorts – stopping a crack from spreading. Mineralised, older bone loses that function.

If the resurfacing process is slowed remodeling is also affected – resulting in existing bone ageing and getting brittle over time.

Are the drugs safe?

Studies have estimated the risk of thigh bone breaks among bisphosphonate users at between one and 10 in 10,000, with their benefit far outweighing this risk.

One study estimated for each reduction of 100 typical hip fractures associated with bisphosphonate use, there was one more thigh bone fracture.

However, bisphosphonates have also been linked to a painful and disfiguring jaw condition and a raised risk of sight problems.