A drug taken just once each year may help prevent and treat osteoporosis in people who take corticosteroid medications.

That’s the conclusion of a new study published Thursday in The Lancet medical journal, which compared the benefits of two drugs from the same class, called bisphosphonates, in people who had, or were at risk for, corticosteroid-induced osteoporosis.

Bone loss is a well-known side effect of corticosteroids, which help control inflammation in conditions like lupus and rheumatoid arthritis. 

Previous studies have shown that too few patients taking long-term corticosteroids are monitored or treated for bone loss. One of the latest, which was published in the March 2009 issue of The Journal of Clinical Rheumatology reported that only about 40 percent of long-term corticosteroid users in a large rheumatology practice in Philadelphia, Pa., were treated for bone loss or even given baseline bone density scans.

For the Lancet study, an international team of researchers recruited 833 patients on long-term corticosteroid therapy, defined as at least 7.5 mg of prednisolone (Prelone) daily, or its equivalent, for at least 12 months.

Half the patients were given a standard infusion of zolendronic acid (Reclast), and half were told to take a 5 mg pill of risedronate (Actonel), each day.

To keep participants from knowing which drug they were on, the researchers asked the zolendronic acid group to take a placebo pill every day in addition to their infusion, and the group that was taking daily risedronate tablets was also given a placebo infusion at the start of the study.

At the end of a year, both medications increased bone density and prevented fractures in study participants who were being treated for osteoporosis or who were receiving the drugs to prevent bone loss. But zolendronic acid appeared to be more effective than risdedronate at building bone, increasing bone density in the lower spine by an average of 4.06 percent compared to 2.71 percent in the treatment group, and by an average of 2.60 percent compared to .64 percent in the prevention group. Similar results were also seen for two sites in the hip.

“Both drugs seem to work in that there were virtually no fractures in the trial,” says David M. Reid, MD, a professor of medicine at the University of Aberdeen in the U.K., who led the study. “Fractures start happening pretty quickly in patients who take glucocorticoids,” he adds.

Overall, Dr. Reid notes, the side effects for both drugs were similar and tolerable except in the three days after the zolendronic acid infusion, when participants reported pain and flu-like symptoms that eventually went away.

Since the study, Dr. Reid says the Food and Drug Administration has approved risedronate as a once-a-week, rather than a daily, treatment for osteoporosis, but he does not think the new dosing would have affected the outcome of the trial.

“It’s good news, whichever one people take. I suppose it will come down to convenience or patient choice,” he adds.

At the end of the study, study participants were asked whether they preferred the once-yearly infusion or the daily pills. About 80 percent said they were more satisfied with the intravenous infusion and would be willing to take it long-term. About 10 percent said they preferred taking the daily tablets.

Novartis, the drug company that makes Reclast, funded the study, and Dr. Reid reported receiving both consulting fees and grant support from the drug manufacturer.