Treatment of Osteoporosis

Recent advances in oxasteroids chemistry

The continuous interest in the field of oxasteroids mainly arises from the fascinating aspects associated with their peculiar stereochemical features and their promising and sometimes unexpected biological activities. The recent development in the partial and total syntheses of oxasteroids are herein described.

A new synthetic steroid, osaterone acetate (TZP-4238), increases cortical bone mass and strength by enhancing bone formation in ovariectomized rats

A new synthetic steroid, 17 alpha-acetoxy-chloro-2-oxa-4,6-pregnadiene-3,20-dione (osaterone acetate, TZP-4238), has a potent antiandrogenic and gestagenic action with virtually no estrogenic and androgenic activity in their classical target organs. In the present study, the effects of TZP-4238 on the structure, strength, and turnover of the rat long bones were examined. Female Wistar rats at 12 weeks of age were ovariectomized (OVX) and treated with TZP-4238 or 17 beta-estradiol (E2) every day for 12 weeks. TZP-4238 significantly increased the diameters and maintained bone mineral density (BMD) of the femur of OVX rats. Although the BMD of the total femur was higher in E2-treated rats than that in TZP-treated rats, E2 did not increase the diameters of the femurs. To examine the effects of TZP-4238 and E2 on the BMD of different regions of the femur, the BMD was further analyzed by dividing it into 20 regions of equal longitudinal length. E2 increased the BMD of the distal and proximal metaphysis, regions rich in trabecular bone, but had no effect on the BMD of the femoral diaphysis compared with OVX control rats. In contrast, 2.5 and 12.5 mg/kg TZP-4238 increased the BMD of the femoral diaphysis, regions rich in cortical bone, but did not affect the BMD at the distal metaphysis. In agreement with the changes in the BMD of different regions of the femur, TZP-4238 but not E2 increased the physical strength of the femoral diaphysis assessed by a three-point bending test. Histomorphometric analyses of the cross-sections of the tibia revealed that TZP-4238 increased but E2 reduced the periosteal bone formation rate compared with OVX rats. In addition, TZP-4238 caused an increase in serum bone alkaline phosphatase with only a mild and transient decrease in urinary deoxypyridinoline excretion, while E2 reduced both of these parameters. These results demonstrate that TZP-4238 increases the dimension, BMD, and physical strength of the rat long bones by enhancing cortical bone formation, while estrogen maintains trabecular BMD by inhibiting bone resorption. Because the physical strength of long bones is affected by cortical bone mass and geometry, the effect of TZP-4238 on cortical bone may have a potential for the treatment of osteoporosis with reduced cortical bone formation.

Evaluation of bone turnover in type I osteoporosis using biochemical markers specific for both bone formation and bone resorption

The aims of the study were to evaluate the use of bone-specific biochemical markers of turnover in type I osteoporosis, to test for evidence of heterogeneity of bone turnover in this condition, and to attempt to devise an 'uncoupling index' by using the relationship between bone-specific biochemical markers of bone formation and bone resorption. In women with type I osteoporosis (mean age 64 years, SD 5; n = 63) the mean level of serum osteocalcin, a specific biochemical marker of bone formation, was 9.9 ng/ml (SD 2.0), which was higher than the level in normal postmenopausal women (mean age 65 years, SD 6; n = 8.9 ng/ml (SD 2.0; p < 0.01). The variance of serum osteocalcin levels in the two groups was similar. Compared with this 11% increase in the biochemical marker for bone formation, the markers of bone resorption, total urinary deoxypyridinoline (bone-specific), pyridinoline and hydroxyproline were increased by 40% (p < 0.0001), 61% (p < 0.0001) and 25% (p < 0.01), respectively. Furthermore, these biochemical markers of bone resorption had greater variance in women in type I osteoporosis than in the normal postmenopausal women (p < 0.01). The urinary excretion of the free crosslinks deoxypyridinoline, pyridinoline and glycosylated pyridinoline were increased by 26% (p < 0.001), 17% (p < 0.01) and 13% (NS) respectively. An 'uncoupling index' was calculated for the difference between urinary deoxypyridinoline and serum osteocalcin using the results from the normal women and expressed as z-scores. We conclude that the pyridinium crosslinks of collagen enable better discrimination between normal and osteoporotic women than does hydroxyproline.(ABSTRACT TRUNCATED AT 250 WORDS)

Total and regional bone mineral content in relation to menopause

Total body bone mineral content (TBBM) and anatomical region bone mineral content (head, trunk and extremities) were measured using dual-energy X-ray absorptiometry in 188 women aged 60 +/- 6 years, of whom 154 were normal and 34 were osteoporotic. Of the 154 normal subjects, 90 were premenopausal (40 aged 44 +/- 3 years and 50 aged 34 +/- 8 years), the remaining 64 being postmenopausal and aged 58 +/- 7 years. There were no TBBM or regional changes in the premenopausal women, whereas there was a significant reduction in bone mineral content in the postmenopausal as compared with the premenopausal women in all regions. The osteoporotic subjects showed a general decrease (P < 0.001) in all measurements which was more marked in the trunk. The rate of TBBM reduction was 16% in the normal postmenopausal women and 29% in the osteoporotic subjects. All the postmenopausal women (both normal and osteoporotic) showed lower TBBM values than those in the Wisconsin trial, similar results being obtained in the case of the premenopausal group. Such differences can only be explained by hardship experienced by these now postmenopausal women during their childhood and adolescence.

Sex differences in the acquisition of total bone mineral mass peak assessed through dual-energy X-ray absorptiometry

Dual energy X-ray absorptiometry evaluation of total body bone mineral content (TBBM), total bone mineral density (TBMD), and regional bone mineral content (BMC) (head, trunk, arms, and legs) was carried out in order to assess sex differences of bone in 120 women and 121 men aged 15-29 years. Subjects from both sexes were divided into 5-year groups (15 through 19, 20 through 24, and 25 through 29 years old, respectively). Significantly higher values for TBBM, TBMD, and regional BMC were observed in males compared with females in the 20 to 24 and 25 to 29-year-old groups (P less than 0.001), but not in the group aged 15-19. After adjusting TBBM for lean body mass (LBM), we observed significantly lower values of TBBM/LBM in the males compared with females in all the age groups. A positive and significant correlation was observed between TBBM and age in the males of all the groups (r = 0.624, P less than 0.001), but not in the females. These data suggest that total bone mass peak acquisition takes place earlier in women than in men, leading to more reduced bone mass value, which in turn may be an osteoporosis predisposing factor.

Total and regional bone mineral content in normal premenopausal women

In the present, cross-section study, a total of 185 normal premenopausal females--aged 15 through 19 years (n = 40), 20 to 29 years (n = 60), 30 through 39 years (n = 40) and 40 to 49 years (n = 45)--were assessed in order to observe and evaluate the total body bone mineral content and the regional body mineral content of different anatomical regions (head, trunk, arms and legs), when the bone mass peak is established in women and its course during premenopause. All subjects underwent bone densitometry with dual energy X-ray absorptiometry with a Norland XR-26 bone densitometer. No differences between groups were found in total body bone mineral and regional bone mineral content values. Total body bone mineral values (mean +/- SD) were 2546 +/- 461 g and 2691 +/- 499 g in the 15-19 year-old group and 40-49 year-old group respectively. The regional bone mineral content values for the same age group were 495 +/- 75 g and 499 +/- 89 g for the head, 1007 +/- 254 g and 1043 +/- 212 g for the trunk, 327 +/- 74 g and 336 +/- 81 for the arms, and 860 +/- 167 g and 811 +/- 146 g for the legs. The results of this study indicate that the peak bone mass is reached at the age of 20 years and that it remains stable in the premenopausal eugonadal females.

Water-borne fluoride and cortical bone mass: a comparison of two communities

This study investigated the relationship between cortical bone mass in an older female population and their ingestion of fluoride from community water supplies. The study was conducted among lifelong female residents in Lordsburg (3.5 ppm fluoride) and Deming (0.7 ppm fluoride), NM. A total of 151 postmenopausal women ranging in age from 39 to 87 years took part; 69 were residents of the optimal-fluoride community, while the remaining 82 were residents of the high-fluoride community. Although bivariate analyses showed no difference in cortical bone mass between women in the two communities, with multiple regression analyses, significant predictors of bone mass (p less than 0.05) were weight, years since menopause, current estrogen supplementation, diabetes, and fluoride exposure status. Based on a model containing all of these variables, women living in the high-fluoride community had a bone mass ranging from 0.004 to 0.039 g/cm2 less than that of similar women living in the optimum-fluoride community. These results suggest that lifelong ingestion of water containing 3.5 ppm fluoride, compared with water containing 0.7 ppm fluoride, does not increase cortical bone mass in women of similar age, weight, and menopausal status. Under the conditions of this study, cortical bone mass might be reduced in a high-fluoride area.

Estrogen-progestogen replacement and cancer risk

The increasing popularity of hormone replacement has focused renewed attention on the issue of whether certain sex steroids predispose to--or exert a protective effect against--various forms of carcinoma. In particular, the impact of the sex hormones on the pathogenesis of breast cancer remains highly controversial. Published reports have failed to demonstrate a clear relationship.

Effect of intermittent therapy with a slow-release fluoride preparation

Long-term clinical effects of intermittent sodium fluoride (slow-release) therapy were assessed in 71 patients with primary osteoporosis. In Group I (receiving 1,25-(OH)2D3 2 micrograms/day for 2 weeks before 3 months of sodium fluoride treatment 25 mg twice a day, in each 5-month cycle), vertebral (L2-L4) bone mineral content did not change significantly. However, the L2-L4 bone mineral content significantly increased by 3.1% in Group II (those who did not receive 1,25-(OH)2D3 during 5-month cycle), 3.5% per patient year in Group III (combined NaF 25 mg twice a day with 1,25-(OH)2D3 0.5 micrograms/day for 12 months in each 13-month cycle), and by 7.8% per patient year in Group IV (combined NaF with calcium citrate for 12 months in each 13-month cycle). The rise in vertebral bone mineral content was sustained, with an annual increment of 4.2% during the third year compared with 4.4% during the first year. The vertebral fracture rate declined significantly from the pretreatment value in all groups, but comparison with a placebo control group was not available. There was no significant change in the bone density of the radial shaft or of the proximal femur. The rate of hip fracture (nontraumatic) during treatment was 1.8% per patient year, the same as before treatment. The drug was well tolerated with only minor infrequent gastrointestinal and rheumatic side effects. Thus, intermittent slow-release sodium fluoride treatment with adequate calcium supplementation augments spinal bone mass and apparently inhibits vertebral fractures, with a satisfactory safety of usage; however, it has no effect on appendicular bone mass or on hip fracture rate.(ABSTRACT TRUNCATED AT 250 WORDS)