Clinical trial of fluoride therapy in postmenopausal osteoporotic women: extended observations and additional analysis

Supplementation of Calcium and Fluoride-Free Water Mitigates Skeletal Fluorosis in Fluoride-Intoxicated Rats

Fluorosis is a public health concern in 25 countries around the globe. The present study is about the mitigation of fluoride (F) toxicity by giving F-free water (FFW) and calcium (Ca). A study was conducted by taking 76 Wistar rats in two phases, phase I (6 months), where rats were randomly divided into four groups: normal-Ca diet (NCD) 0.5%; low-Ca diet (LCD) 0.25%; NCD + 100 ppm F and LCD + 100 ppm F in groups 1, 2, 3 and 4, respectively. F and Ca were given through water and diet respectively. Phase II is the reversal of fluorosis for 3 months, where LCD group 2 was treated with NCD. Groups 3 and 4 were divided into two subgroups each: 3X and 3Y, and 4X and 4Y, respectively. Groups 3X and 4X received FFW with NCD. Group 3Y continued as phase I and 4Y NCD and F. The biochemical expression, gene expression, biomechanical properties and DXA were studied by standard methods. The results revealed that in phase I, bone turnover was significantly increased whereas bone mineral content and biomechanical properties of group 4 were significantly decreased (p ≤ 0.05) as compared with that of all other groups. Trabecular separation and total porosity increased in groups 2 and 4. Expression of osteocalcin, osteonectin and osteopontin genes was significantly downregulated in group 4. Bone turnover in group 4X was normalised. Expressions of osteocalcin, osteonectin and osteopontin were upregulated after providing NCD and FFW. In conclusion, low calcium aggravates skeletal fluorosis which could be mitigated on supplementation of Ca and FFW.

THE USE OF VITAMINS AND MINERALS IN SKELETAL HEALTH: AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND THE AMERICAN COLLEGE OF ENDOCRINOLOGY POSITION STATEMENT

ABBREVIATIONS

25(OH)D = 25-hydroxyvitamin D; BMD = bone mineral density; CV = cardiovascular; GI = gastrointestinal; IOM = Institute of Medicine; PTH = parathyroid hormone; RCT = randomized controlled trial; αTF = α-tocopherol; ucOC = undercarboxylated osteocalcin; VKA = vitamin K antagonist; WHI = Women's Health Initiative.

The Prevention and Therapy of Osteoporosis: A Review on Emerging Trends from Hormonal Therapy to Synthetic Drugs to Plant-Based Bioactives

Osteoporosis is one of the major health problems worldwide. It is characterized by increased bone fragility and loss of bone matter due to the action of osteoclast cells, which are associated with modified hormone levels and factors such as aging. Bisphosphonates are the primary treatment for osteoporosis. Apart from bisphosphonates, hormone therapy, calcitonin treatment, selective estrogen receptor modulators (SERMs), and strontium ranelate (SR) are some of the other treatments available for osteoporosis. However, these treatments have some side effects, such as oily skin, fluid retention, nausea, long-term toxicity, and even prostate cancer in males, and thus natural therapies that incur fewer side effects are sought. Phytochemicals, antioxidants, and other plant-based bioactives are important in the human diet. They are abundant in fruits and help against various chronic diseases, including bone disorders. Other providers of these important compounds are the medicinal plant parts. In this article, we highlight the various species of plants and herbs that are useful for the treatment of osteoporosis. The prospect of using these plant-based bioactives in amelioration of osteoporosis as an alternative to hormonal and synthetic drug-based therapy is also discussed.

Calcium Fluoride/Hydroxyfluorapatite Nanocrystals as Novel Biphasic Solid Solution for Tooth Tissue Engineering and Regenerative Dentistry

In this research, a novel biphasic solid solution consisted of Calcium fluoride (CF) and fluorinated-hydroxyapatite (FHAp) was successfully synthesized through a modified precipitation method using buffer solution. The obtained results confirmed the formation of biphasic nanocrystalline powder composed of about 46% CF and 54% (w/w%) FHAp. This product can be considered as an osteoconductive dental filler or implant with the ability of dental carries prevention due to release of fluorine ions. Herein, the usage of buffer solution for this purpose not only can produces biphasic powder but also provides the possibility of establishment of a continuous synthesis method without manual interfere for adjusting pH of the reactor.

Skeletal fluorosis due to excessive tea and toothpaste consumption

We describe the case of a 53-year-old woman who presented with a metatarsal fracture and was found to have a bone mineral density (BMD) T-score of +11 in the lumbar spine and +7.6 in the hip. Subsequent investigation revealed very high serum, urine and tissue fluoride levels, associated with excessive tea and toothpaste consumption. The case emphasises the need to exclude fluorosis in individuals with unexpectedly high BMD levels.

Multifocal nodular periostitis associated with prolonged voriconazole therapy in a lung transplant recipient

We report a case of painful, nodular periostitis in a lung transplant recipient on long-term voriconazole therapy. Symptoms, signs, and laboratory abnormalities resolved quickly after drug withdrawal. The presentation more closely resembles periostitis deformans than hypertrophic osteoarthropathy, suggesting that the fluoride moiety of voriconazole may be pathogenic for this condition. Clinicians should be aware of this association.

Bone quality and osteoporosis therapy

Although BMD measured by DXA is a useful clinical tool for osteoporosis diagnosis, changes resulting from osteoporosis treatment only partially explain the observed reduction in fractures. Several other bone properties that influence its resistance to fractures and explain this discrepancy have been defined as "bone quality". Bone quality is determined by its structural and material properties and orchestrated by bone turnover, a continuous process of renewal through which old or damaged bone is replaced by a mechanically healthy bone and calcium homeostasis is maintained. Bone structural properties include its geometry (size and shape) and microarchitecture (trabecular architecture and cortical porosity), while bone material properties include its mineral and collagen composition as well as microdamage and its repair. This review aims to update concepts surrounding bone quality and how drugs employed to treat osteoporosis might influence them.

Dietary fluoride restriction does not alter femoral biomechanical strength in col1a2-deficient (oim) mice with type I collagen glomerulopathy

Osteogenesis imperfecta (OI) is a clinically and genetically heterogeneous disease due primarily to mutations in the type I procollagen genes, COL1A1 and COL1A2, causing bone deformity and numerous lifetime fractures. OI murine (oim) model mice carry a mutation in the col1a2 gene causing aberrant production of homotrimeric type I collagen [α1(I)(3)], leading to bone fragility and glomerular accumulation of type I collagen. Previous studies demonstrated that heterozygous (+/oim) and homozygous (oim/oim) mice have elevated tibiae fluoride concentrations but reduced femoral biomechanics. However, it is unclear whether these 2 variables are causally related, because impaired renal function could reduce urinary fluoride excretion, thus elevating bone fluoride concentrations regardless of disease status. Our goal in this study was to determine whether dietary fluoride restriction would improve femoral biomechanics in oim mice. Wild-type, +/oim, and oim/oim mice were fed a control (5 mg/kg fluoride) or fluoride-restricted diet (0 mg/kg fluoride) for ∼13 wk, at which time plasma and femora were analyzed for fluoride concentrations and bone biomechanical properties. In wild-type, +/oim, and oim/oim mice, dietary fluoride restriction reduced femoral fluoride burden by 54-74%, respectively (P < 0.05), without affecting glomerular collagen deposition. Oim/oim mice fed the fluoride-restricted diet had reduced material tensile strength (P < 0.05) compared with oim/oim mice fed the control diet. However, dietary fluoride restriction did not affect stiffness or whole bone femoral breaking strength, regardless of genotype. These data suggest that oim mice have reduced bone strength due to homotrimeric type I collagen, independent of bone fluoride content.

Skeletal fluorosis from instant tea

INTRODUCTION

Skeletal fluorosis (SF) can result from prolonged consumption of well water with >4 ppm fluoride ion (F(-); i.e., >4 mg/liter). Black and green teas can contain significant amounts of F(-). In 2005, SF caused by drinking 1-2 gallons of double-strength instant tea daily throughout adult life was reported in a 52-yr-old woman.

MATERIALS AND METHODS

A 49-yr-old woman developed widespread musculoskeletal pains, considered fibromyalgia, in her mid-30s. Additionally, she had unexplained, increasing, axial osteosclerosis. She reported drinking 2 gallons of instant tea each day since 12 yr of age. Fluoxetine had been taken intermittently for 5 yr. Ion-selective electrode methodology quantitated F(-) in her blood, urine, fingernail and toenail clippings, tap water, and beverage.

RESULTS

Radiographs showed marked uniform osteosclerosis involving the axial skeleton without calcification of the paraspinal, intraspinal, sacrotuberous, or iliolumbar ligaments. Minimal bone excrescences affected ligamentous attachments in her forearms and tibias. DXA Z-scores were +10.3 in the lumbar spine and +2.8 in the total hip. Her serum F(-) level was 120 microg/liter (reference range, 20-80 microg/liter), and a 24-h urine collection contained 18 mg F(-)/g creatinine (reference value, <3). Fingernail and toenail clippings showed 3.50 and 5.58 mg F(-)/kg (control means, 1.61 and 2.02, respectively; p(s) < 0.001). The instant tea beverage, prepared as usual extra strength using tap water with approximately 1.2 ppm F(-), contained 5.8 ppm F(-). Therefore, the tea powder contributed approximately 35 mg of the 44 mg daily F(-) exposure from her beverage. Fluoxetine provided at most 3.3 mg of F(-) daily.

CONCLUSIONS

SF from habitual consumption of large volumes of extra strength instant tea calls for recognition and better understanding of a skeletal safety limit for this modern preparation of the world's most popular beverage.

Role of genetic background in determining phenotypic severity throughout postnatal development and at peak bone mass in Col1a2 deficient mice (oim)

Osteogenesis imperfecta (OI) is a genetically and clinically heterogeneous disease characterized by extreme bone fragility. Although fracture numbers tend to decrease post-puberty, OI patients can exhibit significant variation in clinical outcome, even among related individuals harboring the same mutation. OI most frequently results from mutations in type I collagen genes, yet how genetic background impacts phenotypic outcome remains unclear. Therefore, we analyzed the phenotypic severity of a known proalpha2(I) collagen gene defect (oim) on two genetic backgrounds (congenic C57BL/6J and outbred B6C3Fe) throughout postnatal development to discern the phenotypic contributions of the Col1a2 locus relative to the contribution of the genetic background. To this end, femora and tibiae were isolated from wildtype (Wt) and homozygous (oim/oim) mice of each strain at 1, 2 and 4 months of age. Femoral geometry was determined via muCT prior to torsional loading to failure to assess bone structural and material biomechanical properties. Changes in mineral composition, collagen content and bone turnover were determined using neutron activation analyses, hydroxyproline content and serum pyridinoline crosslinks. muCT analysis demonstrated genotype-, strain- and age-associated changes in femoral geometry as well as a marked decrease in the amount of bone in oim/oim mice of both strains. Oim/oim mice of both strains, as well as C57BL/6J (B6) mice of all genotypes, had reduced femoral biomechanical strength properties compared to Wt at all ages, although they improved with age. Mineral levels of fluoride, magnesium and sodium were associated with biomechanical strength properties in both strains and all genotypes at all ages. Oim/oim animals also had reduced collagen content as compared to Wt at all ages. Serum pyridinoline crosslinks were highest at two months of age, regardless of strain or genotype. Strain differences in bone parameters exist throughout development, implicating a role for genetic background in determining biomechanical strength. Age-associated improvements indicate that oim/oim animals partially compensate for their weaker bone material, but never attain Wt levels. These studies indicate the importance of genetic background in determining phenotypic severity, but the presence of the proalpha2(I) collagen gene defect and age of the animal are the primary determinants of phenotypic severity.

Clinical perspectives on bone quality in osteoporosis: effects of drug therapy

Treatment of primary osteoporosis has advanced dramatically during the past decade, with more therapeutic options being available now than at any other time. Anti-resorptive (anti-catabolic) drugs have been prominent in the treatment of osteoporosis for decades. However, over time, several clinical observations made during use of these agents have challenged the prevailing dogma about mechanisms of drug action, changes in bone density and fracture reduction during treatment. It has become clear that changes in bone density are only a small part of the explanation for the dramatic reduction of fractures with treatment. From this paradox developed the notion of 'bone quality'- an operational term describing a number of characteristics that enable bone to resist fracturing. This article reviews this concept from a clinical perspective. It discusses the historical paradoxes found in clinical practice that have led to this notion, identifies the major areas of bone physiology circumscribed by the concept and focuses on present therapies and their effects on bone quality.

Addition of monofluorophosphate to estrogen therapy in postmenopausal osteoporosis: a randomized controlled trial

INTRODUCTION

Treatment of osteoporosis with high-dose fluoride alone does not reduce fracture risk. We hypothesized that the antifracture efficacy of fluoride could be optimized by its use in low doses combined with an antiresorptive agent.

EXPERIMENTAL SUBJECTS

Subjects included 80 women with postmenopausal osteoporosis who had been taking estrogen for at least 1 yr.

METHODS

Subjects were randomized to receive monofluorophosphate (MFP) (fluoride content of 20 mg/d) or placebo over 4 yr in a double-blind trial.

RESULTS AND DISCUSSION

There were progressive increases in lumbar spine bone density over the duration of the study (MFP, 22%; placebo, 6%; P < 0.0001). In the trabecular bone of L3, these increases were even greater (MFP, 49%; placebo, 2.5%; P < 0.0001). In the proximal femur, there were smaller but significant treatment effects (P = 0.015). Total body scans and their subregions also showed significantly greater increases in the MFP group. Bone formation markers increased significantly in the MFP group at yr 1. Hyperosteoidosis was present in biopsies from five of seven MFP subjects, with osteomalacia in two of seven. The hazards ratio for vertebral fractures was 0.20 (95% confidence interval, 0.05-1.30), and the incidence rate ratio was 0.12 (95% confidence interval, 0.06-0.23; P < 0.01). The hazards ratio for nonvertebral fractures was 3.3 (95% confidence interval, 0.8-12.0).

CONCLUSIONS

We conclude that fluoride at 20 mg/d produces substantial increases in bone mineral density but still interferes with bone mineralization. This indicates that most previous studies with this ion have used toxic doses and that much lower doses should be assessed to find a safe dose window for the use of this powerful anabolic agent.

Synthesis of fluoride-releasing carbonate apatites for bone substitutes

Fluoride (F-)-substituted B-type carbonate hydroxyapatite (CHAP) powders were prepared for application as bone substitute materials having the ability to enhance bone formation and to suppress bone resorption due to the therapeutic effect of F-. F- was adsorbed on CHAP in a sodium fluoride solution followed by heating at 700 degrees C in carbon dioxide flow to substitute F- for the hydroxyl ion in the CHAP structure. The F- contents in the F-substituted CHAP powders were 16-22 times greater than that in normal adult human bones. The carbonate ion contents in the F-substituted CHAP powders corresponded to or were higher than that in normal adult human bones. F-substituted CHAP powder with CO3(2-) and F- contents of 11.03 and 0.66 wt%, respectively, slowly released F- in a physiological salt solution to a sufficiently high F- level. The F- concentration slowly increased and reached 67.20 +/- 4.81 microg l(-1), which was 1.5-9.3 times higher than that in the body fluid of normal adult humans, near the therapeutic window of F-, and far lower than the estimated toxic level. Therefore, the F-substituted CHAP can promote bone formation. The present F-substituted CHAP has the advantage of slow F- release over sodium fluoride and sodium monofluorophosphate which are highly soluble salts and cannot be sintered into a ceramic body.

Advances in the diagnosis and treatment of osteoporosis

Although severely low bone density is relatively rare in the pediatric population, it can be a significant problem in many patients with chronic illness. As peak bone formation occurs during adolescence, it is crucial that pediatricians and other care providers for this patient population recognize the significance of attainment of adequate bone. Dietary intake of vitamin D and calcium should be optimized, and correction of underlying causes of poor bone density should occur whenever possible. Assessment of bone density is difficult, as each technology available has problems, and none of the technologies are well-associated with fracture risk in pediatric patients. Once diagnosis of severely low bone density is established, treatment options are limited and poorly studied. The benefits of bisphosphonate therapy appear to outweigh the risks in patients with low bone density and frequent fragility fractures, and it appears that most improvement with bisphosphonates occurs within the first 2 to 4 years. Evidence, however, is emerging that once off therapy, bone turnover remains decreased for at least several years. During that time, improvements in bone density are decreased. Many questions remain regarding duration of therapy with bisphosphonate therapy and the long-term effects on the children who receive this medication. Anabolic therapies may become important in the future, but there is currently extremely limited information regarding their use in pediatrics.

Recovery from skeletal fluorosis (an enigmatic, American case)

A 52-year-old man presented with severe neck immobility and radiographic osteosclerosis. Elevated fluoride levels in serum, urine, and iliac crest bone revealed skeletal fluorosis. Nearly a decade of detailed follow-up documented considerable correction of the disorder after removal of the putative source of fluoride (toothpaste).

INTRODUCTION

Skeletal fluorosis, a crippling bone disorder, is rare in the United States, but affects millions worldwide. There are no data regarding its reversibility.

MATERIALS AND METHODS

A white man presented in 1996 with neck immobility and worsening joint pains of 7-year duration. Radiographs revealed axial osteosclerosis. Bone markers were distinctly elevated. DXA of lumbar spine (LS), femoral neck (FN), and distal one-third radius showed Z scores of +14.3, +6.6, and -0.6, respectively. Transiliac crest biopsy revealed cancellous volume 4.5 times the reference mean, cortical width 3.2 times the reference mean, osteoid thickness 25 times the reference mean, and wide and diffuse tetracycline uptake documenting osteomalacia. Fluoride (F) was elevated in serum (0.34 and 0.29 mg/liter [reference range: <0.20]), urine (26 mg/liter [reference range: 0.2-1.1 mg/liter]), and iliac crest (1.8% [reference range: <0.1%]). Tap and bottled water were negative for F. Surreptitious ingestion of toothpaste was the most plausible F source.

RESULTS

Monitoring for a decade showed that within 3 months of removal of F toothpaste, urine F dropped from 26 to 16 mg/liter (reference range: 0.2-1.1 mg/liter), to 3.9 at 14 months, and was normal (1.2 mg/liter) after 9 years. Serum F normalized within 8 months. Markers corrected by 14 months. Serum creatinine increased gradually from 1.0 (1997) to 1.3 mg/dl (2006; reference range: 0.5-1.4 mg/dl). Radiographs, after 9 years, showed decreased sclerosis of trabeculae and some decrease of sacrospinous ligament ossification. DXA, after 9 years, revealed 23.6% and 15.1% reduction in LS and FN BMD with Z scores of +9.3 and +4.8, respectively. Iliac crest, after 8.5 years, had normal osteoid surface and thickness with distinct double labels. Bone F, after 8.5 years, was 1.15% (reference range, <0.1), which was a 36% reduction (still 10 times the reference value). All arthralgias resolved within 2 years, and he never fractured, but new-onset nephrolithiasis occurred within 9 months and became a chronic problem.

CONCLUSIONS

With removal of F exposure, skeletal fluorosis is reversible, but likely impacts for decades. Patients should be monitored for impending nephrolithiasis.

A biomechanical perspective on bone quality

Observations that dual-energy X-ray absorptiometry (DXA) measures of areal bone mineral density cannot completely explain fracture incidence after anti-resorptive treatment have led to renewed interest in bone quality. Bone quality is a vague term but generally refers to the effects of skeletal factors that contribute to bone strength but are not accounted for by measures of bone mass. Because a clinical fracture is ultimately a mechanical event, it follows then that any clinically relevant modification of bone quality must change bone biomechanical performance relative to bone mass. In this perspective, we discuss a framework for assessing the clinically relevant effects of bone quality based on two general concepts: (1) the biomechanical effects of bone quality can be quantified from analysis of the relationship between bone mechanical performance and bone density; and (2) because of its hierarchical nature, biomechanical testing of bone at different physical scales (<1 mm, 1 mm, 1 cm, etc.) can be used to isolate the scale at which the most clinically relevant changes in bone quality occur. As an example, we review data regarding the relationship between the strength and density in excised specimens of trabecular bone and highlight the fact that it is not yet clear how this relationship changes during aging, osteoporosis development, and anti-resorptive treatment. Further study of new and existing data using this framework should provide insight into the role of bone quality in osteoporotic fracture risk.

Physiologic aspects of aging: impact on cancer management and decision making, part II

In this second article of our two-part review, we focus on age-associated physiologic changes involving the nervous, endocrine, hematologic, immune, and musculoskeletal systems, with close attention to the interconnected nature of these systems. There is a well-known connection between the neuroendocrine and immune systems via the hypothalamic-pituitary-adrenal axis and via interaction by means of cytokines, hormones, and neurotransmitters. These changes may lead to a loss of integration and resiliency with age, thus decreasing the ability of the elderly patient with cancer to adapt to stressful circumstances. Prominent changes include decline in memory and cognition, and increased susceptibility to peripheral neuropathy. Hematologic and immune changes like reduced bone marrow reserve and increased susceptibility to infections have far reaching implications for cancer care in the elderly. Gradual decline in hormone levels, and changes in muscle and body composition, can lead to functional decline and frailty. Use of the clinical interventions suggested in this article, along with an appreciation of the interplay of these age-related physiologic changes and their consequences, allows oncology professionals to customize therapy and minimize side effects in the geriatric oncology patient.

Effects of cyclic versus daily hPTH(1-34) regimens on bone strength in association with BMD, biochemical markers, and bone structure in mice

We developed a cyclic PTH regimen with repeated cycles of 1-week on and off daily PTH injection and explored its effects on bone strength, BMD, bone markers, and bone structure in mice. Cyclic protocols produced 60-85% of the effects achieved by daily protocols with 57% of the total PTH given, indicating more economic use of PTH. The study supports further exploration of cyclic PTH regimens for the treatment of osteoporosis.

INTRODUCTION

To minimize the cost and the catabolic action of hPTH(1-34), a cyclic PTH regimen with repeated 3-month cycles of on-and-off daily injection of hPTH(1-34) was developed in humans and shown to be as effective as a daily regimen in increasing vertebral BMD. However, changes in BMD may not adequately predict changes in bone strength. A murine model was developed to explore the efficacy of a cyclic PTH regimen on bone strength in association with other bone variables.

MATERIALS AND METHODS

Twenty-week-old, intact, female C57BL/J6 mice (n = 7/group) were treated with (1) daily injection with vehicle for 7 weeks (control); (2) daily injection with hPTH(1-34) (40 microg/kg/day) for 7 weeks (daily PTH); and (3) daily injection with hPTH(1-34) and vehicle alternating weekly for 7 weeks (cyclic PTH). BMD was measured weekly by DXA, and serum bone markers, bone structure, and strength were measured at 7 weeks.

RESULTS

Daily and cyclic PTH regimens increased BMD at all sites by 16-17% and 9-12%, respectively (all p < 0.01). The most dramatic effect of cyclic PTH occurred during the second week of treatment when PTH was off, with femoral and tibial BMD continuing to increase to the same extent as that produced by daily PTH. Both daily and cyclic PTH regimens significantly increased osteocalcin (daily, 330%; cyclic, 260%), mTRACP (daily, 145%; cyclic, 70%), femoral cortical width (daily, 23%; cyclic, 13%), periosteal circumference (daily, 5%; cyclic, 3.5%), and bone strength (max load: daily, 48%; cyclic, 28%; energy absorbed: daily, 103%; cyclic, 61%), respectively. Femoral bone strength was positively correlated with BMD, bone markers, and cortical structure. Neither regimen had an effect on vertebral bone strength. Although actual effects of cyclic PTH were 60-85% of those produced by daily PTH, the effects of cyclic PTH per unit amount administered were slightly greater than those of daily PTH for most measures.

CONCLUSIONS

PTH-enhanced femoral bone strength is positively correlated with its effects on femoral BMD, bone markers, and bone structure. Cyclic PTH regimens represent a potential economic use of PTH and warrant further study.

Tratamiento anabólico en la osteoporosis

Pharmacological treatment of osteoporosis is based mainly on antiresorptive agents. However, there have been recently developed a group of drugs whose mechanism of action is the direct stimulation of bone formation: these drugs are named bone anabolic therapies. Among these compounds are fluoride, growth hormone (GH), insulin-like growth factor type I (IGF-I) and statins. Two further agents with major evidences of efficacy include strontium ranelate and parathyroid hormone (PTH) and its fragments. The present work reviews the current evidences of anabolic agents used in the treatment of osteoporosis.

The Effect of Tamoxifen and Fluoride on Bone Mineral Density, Biomechanical Properties and Blood Lipids in Ovariectomized Rats

The most important aspect of therapy with fluoride and tamoxifen concerns its influence on bone tissue and lipid metabolism. The aim of the study was to evaluate the effect of tamoxifen and natrium fluoride (NaF) on bone metabolism, biochemical properties and blood lipids levels in ovariectomized rats. The study was performed in Wistar rats divided into 5 subgroups: ovariectomized controls, rats treated with NaF 20 mg/kg/24 hr, rats treated with NaF 20 mg/kg/24 hr+tamoxifen 2 mg/kg/24 hr, rats treated with NaF 20 mg/kg/24 hr plus tamoxifen 4 mg/kg/24 hr, and sham-operated controls. In ovariectomized rats the increase of total cholesterol, low-density lipoproteins cholesterol (LDL-cholesterol) as well as the decrease of bone mineral content, bone mineral density and biomechanical properties was observed. The therapy with NaF increased the level of total cholesterol, LDL-cholesterol, triglycerides, bone mineral density, bone mineral content. In this group the decrease of bone strength and stiffness was observed. The administration of tamoxifen reduced the changes in plasma lipid levels, but did not improve the biomechanical properties of bone tissue.

Bone as an effect compartment : models for uptake and release of drugs

"Bone-seeking agents" are drugs characterised by high affinity for bone, and are disposed in bone for prolonged periods of time while maintaining remarkably low systemic concentrations. As a consequence, the bone becomes a reservoir for bone-seeking agents, and a site of both desirable and adverse effects, depending on the pharmacological activities of the specific agent. For some agents, significant systemic effects may also be produced following their prolonged release from bone, a process that is governed mostly by the rate of bone remodelling. This review covers the pharmacokinetic and pharmacodynamic features of bone-seeking agents with different pharmacological properties, including drugs (bisphosphonates, drug-bisphosphonate conjugates, radiopharmaceuticals and fluoride), bone markers (tetracycline, bone imaging agents) and toxins (lead, chromium, aluminium). In addition, drugs that do not possess bone-seeking properties but are used for therapy of bone diseases (such as antibacterials for treatment of osteomyelitis) are discussed, along with targeting of these drugs to the bone by conjugation to bone-seeking agents, local delivery systems, and other approaches. The pharmacokinetic and pharmacodynamic behaviour of bone-seeking agents is extremely complex due to heterogeneity in bone morphology and physiology. This complexity, accompanied by difficulties in human bone research caused by ethical and other limitations, gave rise to modelling approaches to study bone drug disposition. This review describes the pharmacokinetic models that have been proposed to describe the pharmacokinetic behaviour of bone-seeking agents and predict bone concentrations of these agents for different doses and patient populations. Models of different types (compartmental and physiologically based) and of different complexity have been applied, but their relevance to drug effects in the bone tissue is limited since they describe the behaviour of the "average" drug molecule. Understanding of the cellular and molecular processes responsible for the heterogeneity of bone tissue will provide better comprehension of the influence of microenvironment on drug bone disposition and the resulting pharmacological response.

New anabolic therapies in osteoporosis

Anabolic agents represent an important new advance in the therapy of osteoporosis. Their potential might be substantially greater than the anti-resorptives. Because the anti-resorptives and anabolic agents work by completely distinct mechanisms of action, it is possible that the combination of agents could be significantly more potent than either agent alone. Recent evidence suggests that a plateau in BMD might occur after prolonged exposure to PTH. Anti-resorptive therapy during or after anabolic therapy might prevent this skeletal adaptation. Protocols to consider anabolic agents as intermittent recycling therapy would be of interest. Of all the anabolics, PTH is the most promising. However, there are unanswered questions about PTH. More studies are needed to document an anabolic effect on cortical bone. More large-scale studies are needed to further determine the reduction in nonvertebral fractures with PTH, especially at the hip. In the future, PTH is likely to be modified for easier and more targeted delivery. Oral or transdermal delivery systems may become available. Recently, Gowen et al have described an oral calcilytic molecule that antagonizes the parathyroid cell calcium receptor, thus stimulating the endogenous release of PTH. This approach could represent a novel endogenous delivery system for intermittent PTH administration. Rising expectations that anabolic therapies for osteoporosis will soon play a major role in treating this disease are likely to fuel further studies and the development of even more novel approaches to therapy.

New anabolic therapies in osteoporosis

While antiresorptive drugs have been the cornerstone of osteoporosis therapy, anabolic drugs are an important new advance in the treatment of osteoporosis. By directly stimulating bone formation, anabolic agents might have greater potential than the antiresorptives to increase bone mass and to decrease fractures. It is also possible that the combination of an antiresorptive agent with an anabolic agent could be more potent than either agent alone. Potential anabolic therapies for osteoporosis, including fluoride, growth hormone, insulin-like growth factor-I, strontium, and parathyroid hormone, are reviewed here. Of these, parathyroid hormone has clearly emerged as the most promising treatment at this time.

Osteoporosis in inflammatory bowel disease: effect of calcium and vitamin D with or without fluoride

BACKGROUND

Previous data have indicated low bone formation as a mechanism of osteoporosis in inflammatory bowel disease. Fluoride can stimulate bone formation.

AIM

To assess the effect of fluoride supplementation on lumbar spine bone mineral density in osteoporotic patients with inflammatory bowel disease treated in parallel with calcium and vitamin D.

METHODS

In this prospective, randomized, double-blind, parallel and placebo-controlled study, 94 patients with inflammatory bowel disease (lumbar spine T score below - 2 standard deviations, normal serum 25OH vitamin D), with a median age of 35 years, were included. Bone mineral density was measured by dual-energy X-ray absorptiometry. Patients were randomized to receive daily either sodium monofluorophosphate (150 mg, n=45) or placebo (n=49) for 1 year, and all received calcium (1 g) and vitamin D (800 IU). The relative change in bone mineral density from 0 to 12 months was tested in each group (fluoride or placebo) and compared between the groups.

RESULTS

Lumbar spine bone mineral density increased significantly in both groups after 1 year: 4.8 +/- 5.6% (n=29) and 3.2 +/- 3.8% (n=31) in the calcium-vitamin D-fluoride and calcium-vitamin D-placebo groups, respectively (P < 0.001 for each group). There was no difference between the groups (P=0.403). Similar results were observed according to corticosteroid intake or disease activity.

CONCLUSIONS

Calcium and vitamin D seem to increase lumbar spine density in osteoporotic patients with inflammatory bowel disease; fluoride does not provide further benefit.

Position of the American Dietetic Association: the impact of fluoride on health

Fluoride is an important element for mineralization of body tissues. The use of topical and systemic fluoride for oral health has resulted in major reductions in dental caries and its associated disability. Fluoridation of public water supplies has been endorsed by over 90 professional health organizations as the most effective dental public health measure in existence. Still, about half of the US population fails to receive the maximum benefits possible from community water fluoridation and the use of fluoride products. Fluoride also plays a role in bone health. The role of high doses of fluoride for prevention of osteoporosis is undergoing active study and is considered experimental at this point. Dietetics professionals should routinely monitor and promote the use of systemic and topical fluorides, especially in children and adolescents. The American Dietetic Association strongly reaffirms its endorsement of the use of systemic and topical fluorides, including water fluoridation, at appropriate levels of intake, as an important public health measure. However, clients should be cautioned that experimental use of high intakes of fluoride should be avoided unless they are participating in clinical trials.

Position of the American Dietetic Association: the impact of fluoride on health

Fluoride is an important element for mineralization of body tissues. The use of topical and systemic fluoride for oral health has resulted in major reductions in dental caries and its associated disability. Fluoridation of public water supplies has been endorsed by over 90 professional health organizations as the most effective dental public health measure in existence. Still, about half of the US population fails to receive the maximum benefits possible from community water fluoridation and the use of fluoride products. Fluoride also plays a role in bone health. The role of high doses of fluoride for prevention of osteoporosis is undergoing active study and is considered experimental at this point. Dietetics professionals should routinely monitor and promote the use of systemic and topical fluorides, especially in children and adolescents. The American Dietetic Association strongly reaffirms its endorsement of the use of systemic and topical fluorides, including water fluoridation, at appropriate levels of intake, as an important public health measure. However, clients should be cautioned that experimental use of high intakes of fluoride should be avoided unless they are participating in clinical trials.

Cyclical etidronate versus sodium fluoride in established postmenopausal osteoporosis: a randomized 3 year trial

To compare the effects of sodium fluoride and etidronate in severe postmenopausal osteoporosis, we conducted a 3 year, prospective, trial in 118 postmenopausal osteoporotic women with at least one vertebral fracture, who were randomly assigned to receive sodium fluoride (25 mg twice daily, as enteric-coated tablets) plus calcium (1000 mg/day) or intermittent etidronate (400 mg/day for 14 days) followed by calcium (1000 mg/day for 76 days). Lateral spine X-ray films and dual-energy X-ray absorptiometry (DXA) measurements of the lumbar spine and proximal femur were performed at enrollment and yearly. Nonvertebral fractures were recorded every 6 months. Thirty-one women in the fluoride group and 47 in the etidronate group completed the trial. At 36 months, the mean change from baseline of the lumbar bone density in the fluoride group was 8.5 +/- 2.04% (p = 0.001) and in the etidronate group was of 3.6 +/- 0. 84% (p < 0.001). The changes in the fluoride group were significantly higher than in the etidronate group (p = 0.01). Both groups showed nonsignificant changes in femoral neck bone density. There was no significant difference between groups in the cumulative proportion of women with new vertebral fractures, with an incidence in the fluoride group of 16% vs. 17% in the etidronate group. However, the number of new vertebral fractures was significantly lower in the fluoride group (6 fractures) than in the etidronate group (19 fractures) (p = 0.05). The number of patients with nonvertebral fractures was similar in both groups. A high incidence of side effects, mainly gastrointestinal symptoms and lower extremity pain syndrome, was observed in the fluoride group. Etidronate was well tolerated. We conclude that, in women with severe osteoporosis, although sodium fluoride is more favorable than cyclical etidronate for increasing lumbar bone mass, no differences were observed in the incidence of fractures.

Fluoride for treating postmenopausal osteoporosis

OBJECTIVES

To assess the efficacy of fluoride therapy on bone loss, vertebral and non-vertebral fractures and side effects in postmenopausal women.

SEARCH STRATEGY

We searched Medline, Current Contents and the Cochrane Controlled Trial Registry up to December 1998.

SELECTION CRITERIA

Two independent reviewers selected RCTs which met predetermined inclusion criteria.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data using predetermined forms and assessed the methodological quality of the trials using a validated scale. For dichotomous outcomes, relative risks (RR) were calculated and for continuous outcomes, weighted mean differences (WMD) of percentage change from baseline were calculated. Where heterogeneity existed (determined by a chi-square test) a random effects model was used.

MAIN RESULTS

Eleven studies (1429 subjects) met the inclusion criteria. The increase in lumbar spine bone mineral density (BMD) was found to be higher in the treatment group than in the control group with a WMD 8.1% (95%CI: 7.15,9.09) after two years of treatment and 16.1%(95%CI: 14.65,17.5) after four years. The RR for new vertebral fractures was not significant at two years [0.87 (95%CI: 0.51,1.46)] or at four years [0.9(95%CI: 0.71,1.14)]. The RR for new non-vertebral fractures was not significant at two years 1.2(95%CI: 0.68,2.1) but was increased at four years in the treated group 1.85(95%CI: 1.36,2.5), especially if used at high doses and in a non slow release form. The RR for gastrointestinal side effects was not significant at two years 2.18(95%CI: 0.86,1.21) but was increased at four years in the treated group 2.18(95%CI: 1.69,4.57) especially if fluoride was used at high doses and in a non slow release form. The number of withdrawals and dropouts was not different between treated and control groups at two and four years.

REVIEWER'S CONCLUSIONS

Although fluoride has an ability to increase BMD at lumbar spine, it does not result in a reduction of vertebral fractures. In increasing the dose of fluoride, one increases the risk of non-vertebral fracture and gastrointestinal side effects without any effect on the vertebral fracture rate.

Osteoporosis: current modes of prevention and treatment

The most common metabolic bone disorder is osteoporosis, which affects 25 million Americans, of whom 80% are women. Bone loss in women occurs most commonly after menopause, when the rate of loss may be as high as 2% per year. Bone mass can be determined with dual-energy x-ray absorptiometry. The rate of active loss can be assayed by the detection of bone collagen breakdown products (e.g., N-telopeptide, pyridinoline) in the urine. Although it has been suggested that white women are most commonly affected, Hispanic and Asian women are also affected. Strategies for the prevention and treatment of osteoporosis are directed at maximizing peak bone mass by optimizing physiologic intake of calcium, vitamin D therapy, exercise, and maintenance of normal menstrual cycles from youth through adulthood. Coupled with drug therapy should be a comprehensive approach to exercise and fall prevention. Stretching, strengthening, impact, and balance exercises are effective. Of the balance exercises, tai chi chuan has proved to be the most successful in decreasing falls. Prevention of bone loss is obviously preferable to any remedial measures, but new therapeutic strategies provide a means of restoring deficient bone.

Molecular mechanism of action of fluoride on bone cells

Fluoride is an effective anabolic agent to increase spinal bone density by increasing bone formation, and at therapeutically relevant (i.e., micromolar) concentrations, it stimulates bone cell proliferation and activities in vitro and in vivo. However, the fluoride therapy of osteoporosis has been controversial, in large part because of a lack of consistent antifracture efficacy. However, information regarding the molecular mechanism of action of fluoride may improve its optimum and correct usage and may disclose potential targets for the development of new second generation drugs that might have a better efficacy and safety profile. Accordingly, this review will address the molecular mechanisms of the osteogenic action of fluoride. In this regard, we and other workers have proposed two competing models, both of which involve the mitogen activated protein kinase (MAPK) mitogenic signal transduction pathway. Our model involves a fluoride inhibition of a unique fluoride-sensitive phosphotyrosine phosphatase (PTP) in osteoblasts, which results in a sustained increase in the tyrosine phosphorylation level of the key signaling proteins of the MAPK mitogenic transduction pathway, leading to the potentiation of the bone cell proliferation initiated by growth factors. The competing model proposes that fluoride acts in coordination with aluminum to form fluoroaluminate, which activates a pertussis toxin-sensitive Gi/o protein on bone cell membrane, leading to an activation of cellular protein tyrosine kinases (PTKs), which in turn leads to increases in the tyrosine phosphorylation of signaling proteins of the MAPK mitogenic signal transduction pathway, ultimately leading to a stimulation of cell proliferation. A benefit of our model, but not the other model, is that it accounts for all the unique properties of the osteogenic action of fluoride. These include the low effective fluoride dose, the skeletal tissue specificity, the requirement of PTK-activating growth factors, the sensitivity to changes in medium phosphate concentration, the preference for undifferentiated osteoblasts, and the involvement of the MAPK. Unlike fluoride, the mitogenic action of fluoroaluminate is not specific for skeletal cells. Moreover, the mitogenic action of fluoroaluminate shows several important, different characteristics than that of fluoride. Thus, it is likely that our model of a fluoride-sensitive PTP represents the actual molecular mechanism of the osteogenic action of fluoride.

Arachidonic acid metabolism by adult human osteoblast-like cells exhibits sexually dimorphic characteristics

The eicosanoids, including prostaglandin E2 (PGE2) and other bioactive arachidonic acid metabolites, are important local mediators of bone remodeling. Presumably, the limited or excessive synthesis of the eicosanoids could compromise bone homeostasis. We have noted that the stimulated release of arachidonic acid by adult male donor derived human osteoblast-like (hOB) cells exceeded the stimulated release measured for female-derived hOB cells by 1.5-fold. Assays of PGE2 biosynthesis by cytokine-stimulated hOB cells also demonstrated a sex-linked difference, such that male hOB cell PGE2 production exceeded female cell production by 1.6-2.2-fold. The calcium-dependent cytoplasmic phospholipase A2 activity in subcellular fractions prepared from hOB cell homogenates was higher in both the cytosolic (1.6-fold) and particulate (1.5-fold) fractions from the male cells than in those prepared from female hOB cells, suggesting a molecular basis for the observed sexually dimorphic characteristics related to arachidonic acid metabolism by hOB cells. The relatively limited capacity of the female cells may limit needed intracellular and intercellular signaling during bone remodeling, thereby contributing to the development of bone pathology.

The role of fluoride in the prevention of osteoporosis

Osteoporosis defined as low bone mass and increased susceptibility to fracture is a reflection of the sum of peak bone mass and any bone that has been lost once peak mass has been attained. Several strategies have been applied to optimize peak bone mass and to prevent bone loss. Fluoride has greatest potential as a therapy for osteoporosis once bone has been lost. It has been demonstrated both experimentally and clinically to stimulate bone formation directly and to increase bone mass in patients who already have osteoporosis. Several bone formation/stimulation therapies are under development, and some of these have reached the stage of clinical trial. None of these therapies has been as extensively studied as fluoride, and none is sufficiently advanced in development to be clinically available in the next 3 to 5 years. Fluoride therapy for osteoporosis is already performed in many countries, and approval for use in osteoporosis in the United States is pending. The first clinical trials of NaF therapy for osteoporosis were reported by Rich and Ensinck in 1961. Since then, hundreds of reports on the successes and failures of fluoride therapy have appeared in the literature. At first glance, it seems disappointing and inexplicable that, after 40 years of research, fluoride is still considered an experimental drug in the United States. One plausible explanation is that much of the early research on this drug was suboptimal, including the author's contributions. Fluoride as a naturally occurring element is difficult to patent, and this has kept major pharmaceutical companies from investing heavily in fluoride therapy despite its obvious potential. As a result, pharmacologic and pharmacokinetics studies of fluoride are limited in scope, as are phase I and phase II human toxicology and dose-finding studies. Most early studies of large doses of plain NaF were unable to demonstrate a consistent effect on fracture rate despite a consistent and dramatic effect on bone density. Once this became obvious and as new technologies for measuring bone density became available, it became equally clear that future clinical trials would have to be performed using different formulations of fluoride and lower doses. This approach has not resulted in uniformly positive clinical trials, and one must look elsewhere for answers. The most compelling explanation is that the trials have included patients with different severity of disease, suggesting that there is point in the bone loss spectrum at which even a potent bone-stimulating agent such as fluoride is ineffective. This possibility should provoke a reappraisal of the earlier negative studies: was the failure a result of the drug or of patient selection? The answer to this question is crucial, because these failures have cast a long shadow over the safety of fluoride and are contributing more to the absence of this drug from the pharmacopoeia than any other factor.

Comparison of rates of change in bone density as measured by dual-energy X-ray absorptiometry and quantitative computed tomography in osteoporotic females treated with fluoride

We conducted a retrospective comparison of the rates of change in vertebral bone density measured by two densitometric techniques: dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) in osteoporotic women treated with fluoride. To compare both densitometric methods, lumbar vertebral bone density was determined before and during fluoride therapy in 104 osteoporotic women. All patients signed an informed consent under a protocol approved by our University Institutional Review Board. All subjects had at least three serial measurements using both densitometric techniques over the studied time period. Linear regression was used to calculate rate of change values for each patient. In agreement with previous published reports, lumbar density increased linearly over time both with DXA and QCT. Rates of change determined by DXA and QCT were significantly correlated (r = 0.88, p < 0.0001) and this relationship was independent of the magnitude of the increase in density. Either densitometric technique may be used to evaluate the axial skeletal response to fluoride therapy.

Influence of fracture criteria on the outcome of a randomized trial of therapy

Based on a presumption that the morphometric approach to vertebral fracture assessment is beset by false positive deformities, it has been suggested that more stringent criteria should be used to asses vertebral fracture outcomes in clinical trials of osteoporosis therapies. We applied a variety of criteria in the reanalysis of a randomized trial of sodium fluoride therapy for women with established osteoporosis. Although progressively more severe criteria reduced the cumulative incidence of a new vertebral fracture in both those receiving a placebo and the fluoride-treated patients, differences between the two groups were not magnified and none of the suggested approaches produced a statistically significant result. These findings indicate that the false positive rate associated with morphometric assessment of vertebral fractures is not so great as supposed from theoretical considerations that assume independence among the measurements. Our findings also provide some reassurance that differences in the criteria used to define a vertebral fracture are not the controlling influence in the likelihood that a particular clinical trial will find a result favoring one treatment over another.

Fluoride potentiates the osteogenic effects of IGF-I in aged ovariectomized rats

The molecular mechanisms whereby fluoride stimulates osteogenic cell proliferation are not clearly established. However, fluoride has been shown to enhance the protein tyrosine phosphorylation of various constituents of intracellular signaling cascades in osteoblastic cells following stimulation of growth factor receptors such as the insulin-like growth factor-I (IGF-I) receptor. Such in vitro findings provided the rationale for testing whether the administration of fluoride could enhance IGF-I effects on bone mass in vivo. Adult ovariectomized osteopenic rats were treated with sodium fluoride at a dose of 6 mg/kg per day in drinking water for 8 weeks in association with IGF-I either at a dose of 2 mg/kg per day, which is capable of increasing bone mass, or at a lower dose without detectable skeletal effects. Bone mineral density (BMD) and content (BMC) were evaluated by dual-energy X-ray absorptiometry at the levels of the lumbar spine and proximal, midshaft, and total tibia before and after 8 weeks of treatment. During this period, fluoride alone did not significantly influence BMD/BMC at any skeletal site. However, it potentiated the effect of the higher dose of IGF-I on bone mass at the level of the proximal tibia. When administered in combination with the lower dose of IGF-I, which per se did not modify bone mass, it appeared to sensitize tibial bone to the effects of IGF-I. These changes were associated with a concomitant increase in osteocalcin, taken as a reflection of bone formation. These results indicate that fluoride could potentiate the osteogenic effects of IGF-I on bone in adult ovariectomized rats.

Osteoporosis: trials and tribulations

A 30-50% reduction in fracture risk produced by a drug is biologically "worthwhile." The detection of this benefit, when truly present, is a challenge requiring large studies of 3-5 years' duration, because only a small number of women at risk actually sustain a fracture during this time. For example, in any year, fractures occur in 1-2 per 100 women approximately 65 years of age, 6-10 per 100 women approximately 75 years of age, and only 1-2 per 2,000 of the 15% of women < 60 years of age with osteoporosis. An appreciation of this low annual event rate is important because (1) it helps patients to understand their illness, (2) it determines the power of clinical trials, (3) it underscores the large numbers of patients that must be treated to prevent one fracture, and (4) it underscores the need for safety, particularly in groups at low absolute risk of fracture; all are exposed to drug side effects, and the vast majority derive no benefit from treatment because they would not have had a fracture without it, despite being at risk. Few studies have met the design requirements needed to identify the antifracture efficacy of a drug when it really exists, namely, (1) large patient samples randomized to treatment or placebo for 3-4 years, (2) blinding throughout follow-up, (3) statistical analyses of preplanned comparisons using intention to treat, and (4) avoidance of statistical analyses of associations discovered by post hoc analyses. Moreover, (5) few studies have assessed long-term safety and quality of life. Consequently, the uncertainty regarding efficacy and safety of available treatments may be more of a problem of the design, execution, and interpretation of the clinical studies than of the drugs themselves. In the reduction of vertebral fracture risk, the greatest optimism exists for hormone replacement therapy (HRT) and the bisphosphonates. HRT reduces bone turnover, increases bone mineral density (BMD), and decreases vertebral fracture rates by approximately 40%, even in women > 70 years of age. Reduction in hip fracture risk with HRT has been reported in observational studies. Two rigorously conducted studies provide credible evidence that the bisphosphonate alendronate reduces the risk of vertebral and hip fractures by approximately 40-50%. Etidronate, calcitonin, and 1,25-dihydroxyvitamin D3 may reduce risk of vertebral fracture; however, problems in study design leave uncertainty. Although 2 trials using fluoride suggest a reduction in fracture rates, the more rigorously conducted trials do not, despite having adequate power to do so. Calcium supplements are likely to slow bone loss, but reduction in fracture risk is uncertain. Vitamin D and calcium supplementation reduce risk of hip fracture in nursing home residents but not in community residents. There have been no studies of the efficacy of any treatment to prevent hip or vertebral fractures in men or in corticosteroid-related osteoporosis. The treatment of osteoporosis is becoming a reality. HRT and the bisphosphonates, particularly alendronate, appear to be the best options at present.

Is addition of sodium fluoride to cyclical etidronate beneficial in the treatment of corticosteroid induced osteoporosis?

OBJECTIVE

To investigate whether administration of sodium fluoride (NaF) in addition to cyclical etidronate has a positive effect on bone mineral density (BMD) in patients with established osteoporosis during continued treatment with corticosteroids.

PATIENTS AND METHODS

47 patients who were receiving treatment with corticosteroids were included in a two year randomised, double blind, placebo controlled trial. Established osteoporosis was defined as a history of a peripheral fracture or a vertebral deformity, or both, on a radiograph. All patients were treated with cyclical etidronate, calcium, and either NaF (25 twice daily) or placebo. Vitamin D was supplemented in the case of a low serum 25 (OH) vitamin D concentration. BMD of the lumbar spine and hips was measured at baseline and at 6, 12, 18, and 24 months.

RESULTS

After two years of treatment, the BMD of the lumbar spine in the etidronate/NaF group had increased by +9.3% (95% confidence intervals (CI): +2.3% to +16.2%, p < 0.01), while the BMD in the etidronate/placebo group was unchanged: +0.3% (95% CI: -2.2% to +2.8%). The difference in the change in BMD between groups was +8.9% (95% CI: +1.9% to +16.0%, p < 0.01). For the hips, no significant changes in BMD were observed in the etidronate/NaF group after two years: -2.5% (95% CI: -6.8% to +1.8%); in the etidronate/placebo group BMD had significantly decreased: -4.0% (95% CI: -6.6% to -1.4%; p < 0.01). The difference between the groups was not significant: +1.5% (95% CI: -3.4% to +6.4%). No significant differences in number of vertebral deformities and peripheral fractures were observed between the two groups.

CONCLUSION

The effect of combination treatment with NaF and etidronate on the BMD of the lumbar spine in corticosteroid treated patients with established osteoporosis is superior to that of etidronate alone.

Histomorphometric assessment of bone mass, structure, and remodeling: a comparison between healthy black and white premenopausal women

While noninvasive studies of bone mass and turnover in blacks and whites abound, histologic evaluations are very rare. We have performed a comparative bone histomorphometric study of iliac biopsies from 55 healthy, premenopausal women including 21 blacks (mean age 33.4 + 1.2 years) and 34 whites (mean age 32.5 + 0.8 years) of comparable age, weight, body composition, education, and lifestyle. Biochemical indices of mineral metabolism: parathyroid hormone, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, serum ionized calcium, serum phosphorus, and urinary calcium/creatinine were measured in the fasting state. Blacks had lower 25-hydroxyvitamin D (315 +/- 3.36 vs. 63.21 +/- 3.79 nmol/l, p = 0.0001). Histomorphometric indices of bone volume, structure, and connectivity were not different between groups. The following indices of bone remodeling were also similar in both groups: eroded perimeter, osteoid width, mineralizing perimeter, tissue-based bone formation rate, osteoid maturation time, active formation period, and activation frequency. However, osteoid perimeter (black [B] = 15.85 +/- 1.30 vs. white [W] = 9.49 +/- 0.70%, p = 0.0002), osteoid area (B = 2.55 +/- 0.32 vs. W = 1.39 +/- 0.12%, p = 0.003), single-labeled perimeter (B = 5.46 +/- 0.54 vs. W = 4.04 +/- 0.33%, p = 0.03), mineralization lag time (B = 38.18 +/- 4.04 vs. W = 21.83 +/- 1.60 days, p < 0.009), and total formation period (B = 148.15 +/- 19.70 vs. W = 84.04 +/- 7.62 days, p = 0.0056) were higher in blacks than in whites. The quiescent perimeter (B = 76.91 +/- 1.40 vs. W = 84.25 +/- 0.91%, p = 0.0001), mineral apposition rate (B = 0.70 +/- 0.02 vs. W = 0.75 +/- 0.02 micron/day, p = 0.066), mineralizing osteoid perimeter (B = 0.49 +/- 0.04 vs. W = 0.75 +/- 0.04%, p = 0.0001) and adjusted apposition rate (B = 0.35 +/- 0.04 vs. W = 0.58 +/- 0.04 micron3/micron2/day, p = 0.0001) were all lower in blacks than in whites. These results indicate that there are no differences in bone volume, microstructure, or turnover between black and white premenopausal women. However, there are significant differences in the mechanism of bone formation between the two groups, with a lower rate of mineralized matrix apposition within each remodeling unit and a longer total formation period in blacks than in whites. The differences appear to the result of more frequent and/or longer inactive periods in the life span of the bone formation units in blacks. These differences may allow a greater overall deposition of bone mineral in black women and therefore help explain a higher bone mass and perhaps better bone quality in black than white women.