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OSTEOPOROTIC BONES BENEFIT FROM BISPOSPHONATES-MEDICATION SHOULD BE MAINTAINED FOR LASTING BENEFITS

Doctors' role emphasized in ensuring patient compliance

RIO DE JANEIRO, Brazil
May 16, 2004

Benefits lost when therapy is stopped

Bisphophonates, are a major class of bone-specific drug. Several bisphosphonates have been approved worldwide for treatment and prevention of osteoporosis because they have been shown to reduce bone turnover, improve bone mineral density in postmenopausal women, and reduce fracture risk. But this improvement may be rapidly reversed if therapy is halted, reported David Kendler, Providence Health Care Center, Vancouver, Canada. Kendler and colleagues evaluated women completing a two-year clinical trial of the bisphosphonate risedronate (Conference abstract OC34).

The researchers found that within a month of stopping risedronate, bone turnover begins to increase, indicating that the wasting away of bone minerals has resumed. "People who are on risedronate need to know that the positive effect they expect would be rapidly reversed once they stop taking the medication," Kendler said. This is important because patients start and stop taking bisphosphonates at will, without consulting their doctors. In fact, only fifty percent of patients who have been prescribed bisphosphonates are taking them a year later, Kendler noted.

The results were obtained from 88 women who had volunteered for the two-year trial. Half of these women stopped taking risedronate at the end of the trial period and were given placebo, while half continued with the treatment. When Kendler and colleagues measured serum osteocalcin, bone-specific collagen, and bone-specific alkaline phosphatase-all commonly used markers for bone turnover-the trend for each was the same. Samples taken one, two, three and six months after the end of the trial showed that in women who discontinued treatment with risedronate, the levels of these markers increased with time. The authors conclude that reduction in bone turnover is rapidly reversed upon discontinuing treatment.

Physician's role important

Addressing the question of patients stopping medication from another perspective, Pierre Delmas, from INSERM, Lyon, France, and IOF president, reported on the IMPACT study, which was designed to measure how physician reinforcement can influence patients to continue with their medication regimen (conference abstract OC40). Delmas and colleagues found that patients who improved on risedronate, and were informed of that fact, were much more likely to continue with their treatment. In addition, these patients had a concomitant improvement in their bone mineral density. "We found that persistence is improved by over 30% over the course of a year if patients know they are getting better," Delmas said.

Delmas and colleagues evaluated over 2,000 osteoporotic women taking daily risedronate. Bone turnover markers were measured 10 and 22 weeks after starting treatment, and the results were shared with some of the patients. Patients who were not privy to the data served as controls. The researchers found that patients who had the greatest decrease in markers (by over 30%), and hence the best protection against bone loss, were much more likely to maintain their medication if they were informed of the results. In contrast, those who were informed that they had greater than 30% increase in bone markers, indicating worsening of their osteoporosis, dropped their medication fastest.

Importantly, the rate of compliance correlated with changes in bone mineral density (BMD). Those who best maintained their medication improved their BMD, which is commonly used to identify those at highest risk for bone fractures.

Renal Disorders and Paget's Disease

Bisphosphonates are also well tolerated in groups with complicating illnesses, reported Paul Miller from the Colorado Center for Bone Research, Lakewood, Colorado, USA. Miller, an IOF Board member, evaluated risedronate in osteoporosis patients who also have reduced renal function. In a separate study he reported that another bisphosphonate, zoledronic acid, may reduce bone loss more rapidly than risedronate.

In a placebo-controlled phase III clinical trial for risedronate, Miller and colleagues analyzed nearly 9000 patients who had varying degrees of renal insufficiency-ranging from mild, to moderate, to severe renal impairment (conference abstract OC46). Half of these patients took 5mg risedronate daily, while the remaining were placed on placebo. The results showed that all patients with renal insufficiency had significantly reduced fracture risk but without any compromise of renal function. "The data suggests that in patients with chronic reductions in renal function, risedronate in usual therapeutic amounts does not induce any change in renal filtration and therapeutic efficiency is not altered," said Miller.

Measuring the filtration rate of the kidney is standard procedure to gauge kidney fitness and in the US the Food and Drug Adminstration has recommended that bisphosphonates be avoided in patients with filtration rates lower than 35 ml per minute. "It is reassuring," said Miller, that patients taking risedronate and who have filtration rates of less than 30 ml per minute showed no further deterioration of renal function. This is important because physicians rarely measure filtration rates in patients before starting them on bisphosphonates, Miller added. But in women around 70 years old, kidney filtration rates can be as low as 18 ml per minute, he emphasized.

Paget's disease is a rare condition in which bone is rapidly broken down and reformed, but the newly made bone is weak. People suffering from the disease are at increased risk for fractures of the larger bones, including the pelvis, and upper arms and legs. The cause is unknown, though genetics is thought to play a role because many who suffer from the disease have affected family members. About 1.5 to 8 percent of the world's population is affected.

Bisphosphonates have revolutionized the treatment of Paget's disease, write Paul Miller and colleagues, but the need remains for faster onset of action, longer duration of effect, and improved dosing regimens. A single infusion of zoledronic acid rapidly normalizes bone turnover, making this treatment an attractive one for this rare condition.

To test this drug for Paget's disease, Miller and colleagues used a randomized controlled trial to compare the efficacy of a single 5 mg infusion of this zoledronic acid against 60 days of 30 mg/day risedronate given orally (conference abstract OC48). Six months following the start of treatment,

95 percent of patients who received zoledronic acid had at least a 75 percent reduction in serum alkaline phosphatase, a commonly used marker for bone turnover. Only 75 percent of patients in the risedronate group showed a similar response. Patients on zoledronic acid also had greater reductions in serum and urinary osteocalcin compared to those who received risedronate (77 percent versus 46 percent, and 91 percent versus 76 percent, respevtively). "While both risedronate and zoledronic acid can normalisze biochemical markers of bone turnover in patients with Paget's disease, it appears that zoledronic acid may induce a more rapid induction than risedronate, said Miller."

ENDS

The International Osteoporosis Foundation (IOF) is a worldwide organization dedicated to the fight against osteoporosis. It brings together scientists, physicians, patient societies and corporate partners. Working with its 165 member societies in more than 85 locations, and other healthcare-related organizations around the world, IOF encourages awareness and prevention, early detection and improved treatment of osteoporosis.

Osteoporosis, in which the bones become porous and break easily, is one of the world's most common and debilitating diseases. The result: pain, loss of movement, inability to perform daily chores, and in many cases, death. One out of three women over 50 will experience osteoporotic fractures, as will one out of eight men(1). Unfortunately, screening for people at risk is far from being a standard practice. Osteoporosis can, to a certain extent, be prevented, it can be easily diagnosed and effective treatments are available.

1 Melton U, Chrischilles EA, Cooper C et al. How many women have osteoporosis? Journal of Bone Mineral Research, 1992; 7:1005-10

For more information on the IOF World Congress on Osteoporosis, including access to all the abstracts and press releases, please refer to: www.osteofound.org

Find out if you are at risk, take the IOF One Minute Risk Test at: www.osteofound.org

For further information, please contact
Paul Spencer Sochaczewski, Head of Communications,
International Osteoporosis Foundation:

Tel. +41 22 994 0100
Fax. +41 22 994 0101
E-mail: psochaczewski@osteofound.org

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