The Pharmaceutical Journal
Vol 268 No 7188 p311-320
9 March 2002

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New England Journal of Medicine (www.nejm.org)

One dose of zolendronic acid per year is effective

An annual infusion of zolendronic acid might be an effective treatment for postmenopausal osteoporosis, researchers suggest. The effects on bone turnover and bone density are as great as those achieved with daily oral dosing with bisphosphonates with proven efficacy against fractures, they say.

Dr Ian Reid, University of Auckland, New Zealand, and colleagues randomly assigned 351 postmenopausal women, with low bone mineral density and who had had no more than one vertebral fracture, to receive one of six treatment regimens: zolendronic acid 0.25mg, 0.5mg or 1mg every three months, zolendronic acid 4mg given as a single dose at the start of the trial, zolendronic acid 2mg given at the start of the trial and again at six months, or placebo.

The researchers say that similar increases in bone mineral density were seen for all zolendronic acid groups and that these were higher than for those treated with placebo. Administering treatment for osteoporosis at intervals of six to 12 months or more might be more acceptable to patients than daily dosing and could also reduce costs of treatment, they say. They add that infrequent dosing may also increase tolerance of side effects, although zolendronic acid was generally well tolerated for all regimens.

The researchers suggest that a longer interval between doses could also be effective, particularly if larger doses are used. However, a maximal dosing interval was not established since bone turnover remained suppressed at 12 months. How a single infusion of zolendronic acid suppresses bone turnover for so long remains to be determined, they say.

Studies that demonstrate an effect on the rate of fractures are needed before any recommendation can be made (New England Journal of Medicine 2002;346:653).