Osseor

Osseor is a medicine that contains the active substance strontium ranelate. It is available as 2 g sachets containing granules that are made up into an oral (by mouth) suspension.

Osseor is used to treat severe osteoporosis (a disease that makes bones fragile) in post-menopausal women and men who have a high risk of fracture and cannot be treated with other medicines approved for osteoporosis. In postmenopausal women, Osseor reduces the risk of vertebral and hip fractures.

The medicine can only be obtained with a prescription.

Treatment should only be started by a doctor with experience of treating osteoporosis. As there has been some data showing an increased risk of heart attack with Osseor, the decision to prescribe Osseor should take into account the patient’s individual heart risk.

Osseor is taken as one sachet once a day. The contents of the sachet are added and mixed into a glass of water to form a suspension, which is drunk just after being prepared. Osseor should be taken at least two hours after food, milk, milk products or calcium supplements, preferably at bedtime. Osseor is intended for long-term use. Patients should also receive calcium or vitamin D supplements if they are not getting enough from their diet.

Osteoporosis happens when not enough new bone grows to replace the bone that is naturally broken down. Gradually, the bones become thin and fragile, and more likely to break. Osteoporosis is more common in women after the menopause, when the levels of the female hormone oestrogen fall, since oestrogen helps to keep bones healthy. Osteoporosis is also observed in men due to gradual bone loss with ageing.

The active substance in Osseor, strontium ranelate, acts on the bone structure. Once in the gut, strontium ranelate releases strontium, which is absorbed into the bone. Exactly how strontium works in osteoporosis is not fully understood, but it is known to stimulate bone formation and reduce bone breakdown.

Osseor has been studied in almost 7,000 elderly women in two large studies. Nearly a quarter of the patients were over 80 years of age. The first study included 1,649 women with osteoporosis who had already had a broken bone in the spine and the second included over 5,000 women whose osteoporosis was affecting the hip. In both studies, Osseor was compared with placebo (a dummy treatment) and the main measure of effectiveness was the reduction in the risk of a new bone break with Osseor. In the first study, this was based on the number of patients who, over three years, developed a new break in the spine, and in the second study, it was based on the number of patients who had a new break due to osteoporosis at any site other than the spine.

Osseor has also been compared with placebo in a main study involving 261 male patients at increased risk of having a broken bone. The study looked at changes in the bone density after one year of treatment.

In the first study, Osseor reduced the risk of new breaks in the spine by 41% over three years: 21% of the 719 women who took Osseor developed a new break in the spine, compared with 33% of the 723 who took placebo.

Overall, the results of the second study taken alone were insufficient to demonstrate a benefit of Osseor in preventing bone breaks. However, when looking only at women of 74 years of age or older with particularly weak thighbones, the results suggested a reduction of the risk of breaks in the hip with Osseor.

When looking at results of the two studies taken together, fewer women in the Osseor group developed breaks at any site outside the spine (including the hip) than in the placebo group (331 out of 3,295 with Osseor compared with 389 out of 3,256 for placebo). This showed that the risk of broken bones is reduced.

In the study in male patients, the bone density in the lower part of the spine increased by 7% after one year of treatment in patients taking Osseor, compared with an increase of 1.7% in patients taking placebo.

The most common side effects with Osseor (which may affect more than 1 in 10 people) are hypersensitivity (allergic) skin reactions (rash, itching, urticaria or itchy rash, and swelling beneath the skin known as angioedema) and pain affecting muscles, bones and joints. For the full list of all side effects reported with Osseor, see the package leaflet.

Osseor must not be used in patients who have or have had venous thromboembolic events (problems due to the formation of blood clots in the veins, such as in the legs or lungs). It must not be used in people who are temporarily or permanently immobilised, such as people on bed rest or recovering from surgery.

In order to reduce the risk of heart attack, Osseor must also not be used in patients with high blood pressure that is not properly controlled or in patients with a current or past history of any of the following:

• ischaemic heart disease (such as angina or a heart attack);
• peripheral arterial disease (obstruction of the blood flow in the arteries, usually in the legs);
• cerebrovascular disease (diseases affecting the blood vessels in the brain, such as stroke).

For the full list of restrictions, see the package leaflet.

The CHMP decided that Osseor’s benefits are greater than its risks and recommended that it be given marketing authorisation.

A risk management plan has been developed to ensure that Osseor is used as safely as possible. Based on this plan, safety information has been included in the summary of product characteristics and the package leaflet for Osseor, including the appropriate precautions to be followed by healthcare professionals and patients.

In addition, education materials are sent to patients and healthcare professionals prescribing Osseor reminding them of the risk of heart and circulatory problems with the medicine and of the need for regular monitoring. These materials will also remind doctors of the approved used of the medicine.

The company will also carry out a study to evaluate the effectiveness of the measures that have been put in place to reduce risk of heart and circulatory problems.

The European Commission granted a marketing authorisation valid throughout the European Union for Osseor on 21 September 2004.

For more information about treatment with Osseor, read the package leaflet (also part of the EPAR) or contact your doctor or pharmacist.