第一種用於停經婦女的注射型骨質疏鬆藥物

作者：Laurie Barclay, MD  
出處：WebMD醫學新聞

　　June 2, 2010 — 美國食品藥物管理局(FDA)日前核准denosumab (商品名Prolia；Amgen藥廠製造)，這是一種用於高骨折風險之骨質疏鬆停經婦女的注射藥物，這是核准多年的新一類停經骨質疏鬆治療藥品中的第一項藥物。
　　
　　對於停經骨質疏鬆，denosumab注射劑可以由健康照護者每6個月以皮下方式給藥一次，以減少骨骼破壞以及改善骨密度和強度。
　　
　　根據國家關節炎與肌肉骨骼及皮膚疾病研究中心，女性佔美國骨質疏鬆病患的80%之多，50歲以上女性有一半在一生中發生過骨質疏鬆骨折。
　　
　　FDA的Drug Evaluation III辦公室主任Julie Beitz醫師在新聞稿中表示，因為此病的發生率，骨質疏鬆是公共衛生的一個嚴重考量，而核准Prolia可提供另一種治療選項給那些容易發生骨折的停經骨質疏鬆婦女。
　　
　　被視為高骨折風險的骨質疏鬆婦女，包括那些曾發生過骨質疏鬆骨折、或有多種骨折風險因素、或對其他現有的骨質疏鬆治療無法耐受或治療失敗者。
　　
　　為期3年的隨機雙盲安慰劑控制試驗(Fracture REduction Evaluation of Denosumab in Osteoporosis every six Months [FREEDOM])納入了7808名年紀60-91歲的停經婦女，denosumab和骨質疏鬆婦女的脊椎、非脊椎與髖骨骨折發生率較低有關。
　　
　　每6個月以皮下注射方式給予60 mg的注射劑或安慰劑，為期3年。該試驗減少了68%的脊椎骨折、40%的髖骨骨折、20%的非脊椎骨折，腰椎、總髖骨和股骨頸的骨密度顯著增加。
　　
　　背痛、手足痛、肌肉骨骼疼痛、高膽固醇血症、泌尿膀胱感染是denosumab最常見的副作用。嚴重副作用包括低鈣血症、嚴重皮膚與其他感染、皮膚炎、皮疹和濕疹等皮膚狀況。
　　
　　Denosumab禁用於低血鈣病患，特別是嚴重腎功能不佳病患會惡化，這些病患應補充鈣質和維他命D。
　　
　　因為denosumab明顯抑制骨代謝，可能會增加上下頜骨頭壞死、非典型骨折、延遲骨折癒合等風險。FDA因此要求進行風險評估與降低計劃(REMS)，包括病患藥物指引以及給健康照護者的denosumab相關風險與利益的資訊。


FDA Approves First-in-Class Injectable Osteoporosis Drug for Postmenopausal Women

By Laurie Barclay, MD
Medscape Medical News

June 2, 2010 — The US Food and Drug Administration (FDA) yesterday approved denosumab (Prolia; Amgen), an injectable drug for postmenopausal women with osteoporosis who are at high risk for fractures. This is the first new class of medicine for treating postmenopausal osteoporosis that has been approved in many years.

For postmenopausal osteoporosis, an injection of denosumab may be administered subcutaneously by a healthcare provider once every 6 months to reduce bone destruction and to improve bone mass and strength.

Women make up 80% of those with osteoporosis in the United States, and 1 of 2 women older than 50 years will have an osteoporotic fracture during their lifetime, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases.

"Due to its prevalence, osteoporosis is a serious concern to public health," Julie Beitz, MD, director of the FDA's Office of Drug Evaluation III, said in a news release. "The approval of Prolia provides another treatment option for postmenopausal women with osteoporosis who are susceptible to fractures."

Women with osteoporosis who are considered to be at high risk for fracture include those with previous osteoporotic fracture or multiple risk factors for fracture or those who have failed or are intolerant to other available treatment of osteoporosis.

In a 3-year, randomized, double-blind, placebo-controlled trial (Fracture REduction Evaluation of Denosumab in Osteoporosis every six Months [FREEDOM]) enrolling 7808 postmenopausal women aged 60 to 91 years, denosumab was associated with lower incidence of vertebral, nonvertebral, and hip fractures in women with osteoporosis.

The drug was administered as a 60-mg subcutaneous injection every 6 months vs placebo at 3 years. The trial resulted in a 68% reduction in vertebral fractures, 40% reduction in hip fractures, 20% reduction in nonvertebral fractures, and significant increases in bone density at the lumbar spine, total hip, and femoral neck.

Back pain, limb pain, musculoskeletal pain, hypercholesterolemia, and urinary bladder infections were the most common adverse effects reported with denosumab. Serious adverse events included hypocalcemia, serious skin and other infections, and dermatologic conditions including dermatitis, rashes, and eczema.

Denosumab is contraindicated in patients with hypocalcemia and may worsen particularly in patients with severe renal impairment. These patients should receive a supplement of calcium and vitamin D.

Because denosumab significantly suppresses bone turnover, it may increase risk for osteonecrosis of the jaw, atypical fractures, and delayed fracture healing. The FDA therefore requires a risk evaluation and mitigation strategy (REMS), including a medication guide for patients and information for healthcare providers regarding the risks and benefits of denosumab.