Raloxifene pharmacokinetics in males with normal and impaired renal function

AIMS: To compare raloxifene pharmacokinetics between renally impaired and healthy subjects. METHODS: Raloxifene 120 mg was administered to 10 males with renal impairment (creatinine 2-4 mg dl(-1)) and to 10 healthy males. Data were analysed by two noncompartmental and one compartmental nonlinear regression methods. RESULTS: The medians (95% confidence interval) of the area under the curves (AUC) were 35.1 (25.8, 74) and 20.5 (16.8, 28.0) h ng ml(-1) per mg kg(-1), P < 0.01, and of the clearances (CL/F) were 28.5 (13.5, 38.8) and 48.8 (35.8, 59.4) l h(-1) kg(-1), P < 0.01, in renally impaired and healthy subjects, respectively. 95% Confidence intervals on the differences for AUC and CL/F were 6.5-44.1 and -35.1 to -7.9, respectively. CONCLUSION: Exposure to raloxifene was twice as high in males with renal impairment compared with healthy subjects.     

苯并二氢吡喃衍生物抗骨质疏松活性的构效关系研究

目的　研究系列苯并二氢吡喃化合物的构效关系 ,为设计优良的绝经后骨质疏松症防治药物提供理论依据。方法　在综合考察雷洛昔芬和异丙氧基异黄酮的基础上 ,设计合成一系列苯并二氢吡喃化合物 ,从整体水平考察化合物A对去卵巢大鼠骨质疏松的影响 ,从细胞水平研究C单独给药以及与雌二醇联合给药对人成骨细胞株HOSTE85增殖的影响 ,并均在 0 1μmol·L-1水平考察比较化合物BE对HOSTE85增殖的影响。结果　化合物A可一定程度对抗去卵巢大鼠骨质疏松症。C( 1 0nmol·L-1,0 1μmol·L-1)对HOSTE85具有显著增殖作用 ,C与雌二醇联合给药显著拮抗雌二醇对HOSTE85的增殖作用 ,故C可能为雌激素受体的部分激动剂。C、D( 0 1μmol·L-1)对HOSTE85具有显著增殖作用。结论　以A作为母体化合物 ,侧链引入碱性基团 ,对其结构修饰设计抗绝经后骨质疏松症药物是可行的。     

Raloxifene: A Review

women can now expect to live up to one-third of their lives in the post-menopausal state. This low estrogen state is a major risk factor for the development of osteoporosis and cardiovascular disease. The Osteoporosis Society of Canada currently recommends estrogen as the treatment of choice for preventing post-menopausal osteoporosis. Sustained unopposed estrogen use is associated with an increased risk of endometrial hyperplasia and endometrial cancer, necessitating the concomitant use of a progestin in those with an intact uterus. Recent large cohort studies suggest that estrogen and estrogen/progestin therapy may also be associated with an increased risk of breast cancer thus diminishing the beneficial effects of estrogen on overall mortality. Bisphosphonates are also available for the treatment and prevention of osteoporosis. They do not have the other beneficial effects that estrogen may provide. Selective estrogen receptor modulators (SERMs) represent a new therapeutic class of medications that have been developed to act as estrogen agonists in some tissues and estrogen antagonists in others. Raloxifene (Evista®) is a selective estrogen receptor modulator that, in pre-clinical and clinical studies, demonstrates estrogen agonist activity on bone and lipid metabolism, and shows estrogen antagonist activity on uterine and breast tissue. It is the first estrogen receptor active agent that has been shown in adequately powered, placebo-controlled, randomized clinical trials, to reduce the risk of new vertebral fractures in post-menopausal women with osteoporosis.     

Modulation of bone turnover in orchidectomized rats treated with raloxifene and risedronate

Osteoporosis is a reduction in bone mineral density (BMD). It develops less often in men than in women. This study aimed to evaluate the bone protective effects of raloxifene (RAL), risedronate (RIS), and their combination on osteoporotic male rats. Forty male Wister rats (12 weeks) were randomly divided into five groups: sham‐operated group (n = 8), orchidectomized (ORX) group (n = 7), RAL group (n = 9), RIS group (n = 7) and RAL + RIS group (n = 7). RAL was orally administered at 3 mg/kg three times/week, and RIS was given subcutaneously at 5 μg/kg, twice weekly. After 6 weeks of treatment, serum cathepsin‐K, alkaline (ALP) and acid phosphatase activities, serum osteocalcin, serum Ca²⁺, and Pi were determined. Urinary Ca²⁺ and deoxypyridinoline levels, BMD, and Ca²⁺ content of femur ash were estimated. Histochemical localization of ALP activity of tibia and histomorphometry was examined. As compared to sham, ORX rats showed a significant increase in bone turnover markers, and histochemical activity of ALP was increased markedly in proximal tibia of ORX rats, whereas BMD and Ca²⁺ content of femur ash were reduced after ORX. These changes were modulated after treatment with RAL and RIS or both to ORX rats; BMD of femur was improved by each treatment, and bone turnover markers were reduced as compared to ORX vehicle group. We concluded that orchidectomy induced osteoporosis and increased bone turnover in male rats because of withdrawal of sex hormones. Both RAL and RIS could treat osteoporosis in ORX rats; they reduced bone turnover markers and maintained BMD.     

Tissue-selective estrogen complexes for postmenopausal women

Although hormone therapy using estrogens plus progestogens (EPT) is effective for the management of menopausal symptoms (e.g., vasomotor symptoms and vulvar/vaginal atrophy) and prevention/treatment of postmenopausal osteoporosis, EPT is associated with safety and tolerability concerns. A new alternative to EPT is the tissue selective estrogen complex (TSEC), which partners a selective estrogen receptor modulator (SERM) with one or more estrogens and is designed to treat menopausal symptoms and prevent postmenopausal osteoporosis without the tolerability concerns associated with EPT. The first TSEC to reach advanced clinical development is a combination of the SERM bazedoxifene (BZA) with conjugated estrogens (CE). BZA has been shown to inhibit the stimulatory activity of CE on uterine tissue and breast in vitro and in vivo. In clinical studies, BZA/CE treatment has been associated with significant improvements in menopausal symptoms including hot flushes and vulvar/vaginal atrophy and significant increases in bone mineral density, coupled with reductions in bone turnover marker levels and improvements in sleep and health-related quality of life. Additionally, BZA/CE has been shown to have a neutral effect on endometrial and breast tissue because BZA inhibits the stimulatory effects of estrogens in tissue-selective fashion in these 2 organs. Taken together, results of these preclinical and clinical studies indicate that the benefits of estrogens for treating menopausal symptoms are maintained with BZA/CE without endometrial or breast stimulation, resulting in a safe and effective treatment for symptomatic postmenopausal women.     

Raloxifene nanomicelles reduce the growth of castrate-resistant prostate cancer

Background: Castrate-resistant prostate cancer (CRPC) patients are characterised by a 5-year relative survival rate of ～25–33%. Recently, our laboratory encapsulated a selective oestrogen receptor modulator, raloxifene, into poly(styrene-co-maleic acid) (SMA-raloxifene), which demonstrated superior in vitro cytotoxicity compared with free drug against several CRPC cell lines.

Purpose: To validate SMA-raloxifene for the management of CRPC using a mouse xenograft model.

Methods: The internalisation and retention of micellar and free raloxifene in vitro were measured by HPLC. A PC3-CRPC xenograft model was used to compare the biodistribution of both raloxifene formulations, as well as their effect on tumour progression where mice received free raloxifene (1 or 5?mg/kg, i.v.) or SMA-raloxifene (1?mg/kg, i.v.) weekly for 4 weeks.

Results: SMA-raloxifene exhibited 75% higher intracellular content compared to free drug after 48?h in PC3 cells. Biodistribution of raloxifene was 69% higher in tumours following SMA-raloxifene compared with free raloxifene. Weekly administration of 1?mg/kg free raloxifene reduced tumour progression by 20% after 4 weeks, whereas 1?mg/kg SMA-raloxifene and 5?mg/kg free raloxifene reduced progression by 40%.

Conclusion: Encapsulation of raloxifene increased its therapeutic potential for the management of CRPC.     

Alendronate produces greater effects than raloxifene on bone density and bone turnover in postmenopausal women with low bone density: results of EFFECT (Efficacy of FOSAMAX versus EVISTA Comparison Trial) International

OBJECTIVES: Alendronate and raloxifene are antiresorptive agents with different mechanisms of action, each used to treat osteoporosis in postmenopausal women. This study was undertaken to compare the efficacy and tolerability of alendronate to raloxifene in postmenopausal women with low-bone density. DESIGN: Randomized, double-masked, double-dummy multicentre international study. SETTING: Clinical trial centres in Europe, South America and Asia-Pacific. SUBJECTS: A total of 487 postmenopausal women with low bone density, based on bone mineral density (BMD) of the lumbar spine or hip (T-score < or =-2.0). Interventions. Patients received either alendronate 70 mg once weekly and daily placebo identical to raloxifene or raloxifene 60 mg daily and weekly placebo identical to alendronate for 12 months. MAIN OUTCOME MEASURES: Evaluations included BMD of the lumbar spine and hip and markers of bone turnover at 6 and 12 months and adverse event reporting. RESULTS: Alendronate demonstrated substantially greater increases in BMD than raloxifene at both lumbar spine and hip sites at 12 months. Lumbar spine BMD increased 4.8% with alendronate vs. 2.2% with raloxifene (P < 0.001). The increase in total hip BMD was 2.3% with alendronate vs. 0.8% with raloxifene (P < 0.001). Reductions in bone turnover were significantly larger with alendronate than raloxifene. Overall tolerability was similar, however, the proportion of patients reporting vasomotor events was significantly higher with raloxifene (9.5%) than with alendronate (3.7%, P = 0.010). The proportion of patients reporting gastrointestinal events was similar between groups. CONCLUSION: In postmenopausal women with low bone density, improvements in BMD and markers of bone turnover were substantially greater during treatment with alendronate compared to raloxifene.     

磷酸钙人工骨联合雷洛昔芬修复兔下颌骨缺损

背景：雷洛昔芬是第3代选择性雌激素受体调节剂,可减少骨量的丢失,增加骨组织中的矿物质含量,降低骨折风险。目的：观察雷洛昔芬结合自固化磷酸钙人工骨修复兔下颌骨缺损的效果。方法：在36只新西兰大白兔左侧下颌骨制作8 mm×4 mm×3 mm的缺损模型,随机分组,实验组12只植入自固化磷酸钙人工骨,并给予雷洛昔芬7.5 mg/（kg·d）;药物组12只给予雷洛昔芬7.5 mg/（kg·d）;人工骨组12只植入自固化磷酸钙人工骨。分别于治疗4,8,12周取下颌骨标本,免疫组织化学法观察骨形态发生蛋白2的表达,激光共聚焦显微镜观察转化生长因子β的表达。结果与结论：实验组治疗后4,8周时的骨形态发生蛋白2免疫组织化学染色阳性细胞数明显高于药物组与人工骨组,治疗后12周时实验组骨改建基本完成,骨形态发生蛋白2免疫组织化学染色阳性细胞数目低于其他两组。实验组转化生长因子β免疫荧光染色表达为逐步升高,到第8周时达到峰值,而药物组和人工骨组的转化生长因子β免疫荧光表达从4-12周一直呈上升状态,趋近于最高峰。说明雷洛昔芬能够促进自固化磷酸钙人工骨在骨缺损过程中骨形态发生蛋白的早期表达及早期骨痂的形成,加快骨缺损修复。     

Raloxifene protects endothelial cell function against oxidative stress

Background and purpose:

Maintaining a delicate balance between the generation of nitric oxide (NO) and removal of reactive oxygen species (ROS) within the vascular wall is crucial to the physiological regulation of vascular tone. Increased production of ROS reduces the effect and/or bioavailability of NO, leading to an impaired endothelial function. This study tested the hypothesis that raloxifene, a selective oestrogen receptor modulator, can prevent endothelial dysfunction under oxidative stress.

Experimental approach:

Changes in isometric tension were measured in rat aortic rings. The content of cyclic GMP in aortic tissue was determined by radioimmunoassay. Phosphorylation of endothelial NOS (eNOS) and Akt was assayed by Western blot analysis.

Key results:

In rings with endothelium, ACh-induced relaxations were attenuated by a ROS-generating reaction (hypoxanthine plus xanthine oxidase, HXXO). The impaired relaxations were ameliorated by acute treatment with raloxifene. HXXO suppressed the ACh-stimulated increase in cyclic GMP levels; this effect was antagonized by raloxifene. The improved endothelial function by raloxifene was abolished by ICI 182,780, and by wortmannin or {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002. Raloxifene also protected endothelial cell function against H₂O₂. Raloxifene increased the phosphorylation of eNOS at Ser-1177 and Akt at Ser-473; this effect was blocked by ICI 182,780. Finally, raloxifene was not directly involved in scavenging ROS, and neither inhibited the activity of xanthine oxidase nor stimulated that of superoxide dismutase.

Conclusion and implications:

Raloxifene is effective against oxidative stress-induced endothelial dysfunction in vitro through an ICI 182,780-sensitive mechanism that involves the increased phosphorylation and activity of Akt and eNOS in rat aortae.