GI Tolerability for Risedronate Better Than for Alendronate

Laurie Barclay, MD

May 20, 2003

May 20, 2003 — Compared with alendronate (Fosamax), risedronate (Actonel) is associated with fewer clinically severe adverse gastrointestinal (GI) events in the elderly, according to the results of two retrospective studies presented at the American Academy of Clinical Endocrinology annual meeting.

"The major finding of this study was that the cost of GI-related medical events related to Fosamax was about three times higher than the cost of GI-related medical events related to Actonel in patients over age 65 who were receiving osteoporosis treatment, " second author Joseph J. Doyle, RPH, MBA, told Medscape.

Of 2,957 adults older than 65 years receiving new prescriptions for osteoporosis between Nov. 1, 2000, and Aug. 31, 2001, 16% were treated with risedronate daily, 28% with alendronate daily, and 56% with alendronate weekly. Mean age was 76 years, and 93% were women.

During the first four months of treatment in subjects with no GI history, the average GI-related direct medical per-member-per-month cost was $2.52 for risedronate, $7.40 for daily alendronate ( P = .049), and $7.50 for weekly alendronate ( P < .01 compared with risedronate). Average number of inpatient visits per 100 patients per month was 0.2 for risedronate, 1.2 for daily alendronate ( P < .01), and 1.6 for weekly aledronate ( P = .01).

"Patients treated with Actonel averaged three times less GI-related costs than the patients on Fosamax. This is not only important to managed care companies making formulary decisions but also to physicians in clinical practice treating osteoporosis," Andrea B. Klemes, DO, FACE, told Medscape. She is the senior regional medical director for the South Region of Procter & Gamble Pharmaceuticals and a coauthor of both studies.

In patients with a history of GI disease, costs were still lower for those treated with risedronate than for those treated with alendronate. Because the main source of the GI-related cost difference between risedronate and alendronate was inpatient utilization, the authors suggest that alendronate-treated patients were experiencing clinically more severe GI adverse effects.

The second study used the Protocare Sciences database, an integrated medical and pharmaceutical claims database, to evaluate data from 3,947 adults older than 65 years receiving bisphosphonate prescriptions between November 2000 and August 2001, excluding those with a bisphosphonate prescription during the preceding six months.

Patients started on risedronate were 23% more likely than patients started on daily alendronate and 15% more likely than patients started on weekly alendronate to have a prior history of GI diagnoses, which the authors interpret as a possible preference among clinicians for prescribing risedronate among high-risk GI patients.

After adjusting for prior GI history, frequency of experiencing a GI event after beginning therapy was 7.8% for daily alendronate, 8.4% for weekly alendronate, and 5.2% for risedronate. Compared with risedronate, relative risk of experiencing a GI event was 1.57 for daily alendronate ( P = .021) and 1.66 for weekly alendronate ( P = .004).

"In a real-world setting similar to what most physicians encounter in clinical practice, risk of GI events was 66% higher for weekly Fosamax, and 57% higher for daily Fosamax, compared with Actonel," coauthor Karen Worley, PhD, told Medscape.

Procter & Gamble, the maker of risedronate, Aventis, and the Alliance for Better Bone Health (a group represented by both Procter & Gamble and Aventis) supported both these studies and employ all study authors.

AACE 12th Annual Meeting: Abstracts 28, 29. Presented May 14-18, 2003.

Reviewed by Gary D. Vogin, MD

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