Chicago—Patients on “drug holidays” from osteoporosis drugs should be carefully monitored because of a heightened risk of risk of bone fractures increases, according to a new study.

The article in Endocrine Practice notes that patients prescribed bisphosphonates for long duration are often advised to temporarily discontinue the drugs to prevent rare but serious side effects to the jaw and thighs.

For example, the American Association of Clinical Endocrinologists and American College of Endocrinology recommend that women at moderate risk for osteoporosis take a drug holiday after 5 years of oral and 3 years of intravenous bisphosphonate treatment.

Those at even higher risk for osteoporosis are urged to temporarily suspend use after 10 years of oral and 6 years of intravenous bisphosphonate treatment.

University of Chicago and Loyola Medicine researchers determined, however, that the drug holidays are not without consequence. Their study found that 15.4% of patients temporarily discontinuing bisphosphonates experienced bone fractures. Over a 6-year follow-up period, the yearly incidence of fractures ranged from 3.7% to 9.9%, with the greatest fracture risk in the fourth and fifth years.

Although bisphosphonates, the most common medications prescribed for osteoporosis, slow down the breakdown of bones and help to maintain density and reduce fracture risks, they also have been linked to adverse events—osteonecrosis of the jaw and atypical femur fracture. Drug holidays are recommended as a way to lessen the risk of those occurrences.

To reach their conclusion, the researchers retrospectively examined the records of 371 women and 30 men with osteoporosis or osteopenia who began drug holidays. The patients had been on bisphosphonates for an average of 6.3 years, with the two most frequently prescribed being alendronate, used by 62% of participants, and risedronate, used by 34% of participants.

Fractures after drug holidays most commonly occurred in the wrist, foot, ribs, and spine, according to the study team, which also pointed out that the patients most likely to have bone breaks were older with lower bone mineral density at the beginning of the study. After suffering fractures, patients were put back on bisphosphonates.

“Patients who begin drug holidays at high risk for fracture based on bone mineral density, age or other clinical risk factors warrant close follow-up during the holiday, especially as its duration lengthens,” study authors write. “Fracture risk needs to be regularly assessed during the drug holiday and treatment resumed accordingly."