01 Mar 2010
It was hailed as a miracle drug when it came on the market more than a decade ago. Alendronate offered new hope for patients suffering from osteoporosis. But according to one local study, this bone-building drug, able to reduce the risk of fractures, may also weaken the bones if used long term.
Although the study showed dangerous side effects when the drug has been in prolonged use, there are still clear benefits when using it to treat patients with established osteoporosis.
The concern was raised following a study published in 2008 by orthopaedic surgeons from Singapore General Hospital (SGH) who discovered a trend developing in a particular group of patients. Dr Howe Tet Sen, Senior Consultant, Trauma Service, Department of Orthopaedic Surgery, SGH, said: “It was around 2004 when we started noticing peculiar stress fractures on the upper thigh bones of several post-menopausal patients we were treating for osteoporosis. We decided to put a team together and study this pattern more closely.”
In the three years after, the five-member team analysed numerous x-rays, combed through medical reports and tabulated data of former and existing patients who qualified for the retrospective study. The study was concluded in 2007, and the findings surprised the team. One team member, Dr JoyceKoh, Consultant, Department of Orthopaedic Surgery, SGH, said: “Seventeen of these patients with a mean age of 66 years had low-trauma fractures. What was most striking was that all of them were on alendronate therapy for an average of almost five years.”
Alendronate belongs to a class of drugs known as bisphosphonates, which slow the loss of bone mass. It has since become a common prescription medication for patients with osteoporosis and osteopenia, a milder form of bone thinning.
The way the fractures reported in the study occurred and appeared were also unique. Dr Goh Seo Kiat, Associate Consultant, Department of Orthopaedic Surgery, SGH, and another member of the team, said: “Unlike trauma fractures where people trip, fall and break their bones, these patients mostly sustained fractures whilst going about their daily tasks. Most of the patients in this group had minimal trauma, and a small number of them recall hearing a cracking sound before falling down.” He added that the fractures show up in images as “a clean horizontal cut, which is very unusual because normally, fractures tend to be a little more jagged in nature. And they’re also located lower on the thigh bone compared to typical breaks.”
“A large majority of these patients reported feeling pain in their thighs for several months before their fractures occurred. We also noticed that some of these cracks were developing on the opposite leg,” said Dr Ernest Kwek Beng Kee, another author who is currently with Tan Tock Seng Hospital.
Since the study involved the largest collection of fractures attributed to alendronate therapy, the team decided to submit their report to several international medical journals. Its published impact was impressive judging by the numerous peer citations that followed. But ultimately, what mattered most for the team were the implications for the medical community and patients.
Dr Howe said: “We hope that through this study, other doctors will know what to look out for when they encounter such patients. The aim is really to empower themto take measures for their patients before the fracture occurs.”
The results of the study could lead to a change in the way many doctors are treating patients with osteopenia. Since most patients diagnosed with the condition do not develop osteoporosis, Dr Howe feels there is no longer a need to put them on aggressive alendronate therapy, unless they are at a high risk.
“Alendronate therapy is still an important component in the management of osteoporosis. What we are suggesting is a need for cautious administration of the drug,” Dr Koh said. It is hoped that more patients will now discuss with their doctors the right medication and ways to minimise their risk of sustaining osteoporotic fractures. “Different medications have different side effects. So those with osteoporosis should not avoid proper treatment because of the fear of rare complications,” said Dr Howe.
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