New anabolic therapies in osteoporosis

Comparison of the Clinical Efficacy of Anabolic Agents and Bisphosphonates in the Patients With Osteoporotic Vertebral Fracture: Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

We investigated the clinical efficacy of anabolic agents compared with bisphosphonates (BPs) for the incidence of new osteoporotic vertebral fracture (OVF) and fracture healing of OVF in the patients with OVF via meta-analyses of randomized controlled trials (RCTs).

METHODS

Electronic databases, including PubMed, Embase, and Cochrane Library were searched for published RCTs till December 2022. The RCTs that recruited participants with osteoporosis at high-/very high-risk of fracture (a history of osteoporotic vertebral or hip fracture) or fresh OVF were included in this study. We assessed the risk of bias on every included RCTs, estimated relative risk (RR) for the incidence of new OVF and fracture healing of OVF, and overall certainty of evidence. Meta-analyses were performed by Cochrane review manager (RevMan) ver. 5.3. Cochrane risk of bias 2.0 and GRADEpro/GDT were applied for evaluating methodological quality and overall certainty of evidence, respectively.

RESULTS

Five hundred eighteen studies were screened, and finally 6 eligible RCTs were included in the analysis. In the patients with prevalent OVF, anabolic agents significantly reduced the incidence of new OVF (teriparatide and romosozumab vs. alendronate and risedronate [RR, 0.57; 95% confidence interval, 0.45-0.71; p < 0.00001; high-certainty of evidence]; teriparatide vs. risedronate [RR, 0.50; 95% confidence interval, 0.37-0.68; p < 0.0001; high-certainty of evidence]). However, there was no evidence of teriparatide compared to alendronate in fracture healing of OVF (RR, 1.23; 95% confidence interval, 0.95-1.60; p = 0.12; low-certainty of evidence).

CONCLUSION

In the patients with prevalent OVF, anabolic agents showed a significant superiority for preventing new OVF than BPs, with no significant evidence for promoting fracture healing of OVF. However, considering small number of RCTs in this study, additional studies with large-scale data are required to obtain more robust evidences.

The efficacy of teriparatide (Cinnopar®) on bone repair in mandibular fractures: A single blinded randomized clinical trial

This study focused on the effects of teriparatide (CinnoPar) on healing and postoperative complications in mandibular bone fractures. In this single-blind randomized controlled trial, 30 patients with a mandibular fracture hospitalized for open reduction internal fixation were randomly assigned to the intervention (I) (n = 15) and control (C) (n = 15) groups. Both groups received daily acetaminophen and cephalexin for 1 week. For 1 month, Group I received daily subcutaneous teriparatide injections. The Radiographic Union Scale of the Mandible (RUSM) was used to assess mandibular bone fusion subjectively, and the Hounsfield unit (HU) was used to objectively assess radiodensity in a computed tomography (CT) scan. In both groups, the visual analog scale (VAS) score was used to assess postoperative complications such as pain, swelling, wound opening, pus secretion, and bitter taste. There was no significant difference in bone repair between the two groups in this study (P > 0.05). Teriparatide also had no effect on the postoperative complication rate in the control group (P > 0.05). Within the limitations of the study it seems that in mandibular fractures, teriparatide did not affect bone fusion or postoperative complications, so its use is not recommended for better bone fusion and fewer postoperative complications of mandibular fracture during the first month.

Osteoporosis therapies and their mechanisms of action (Review)

Osteoporosis is a common disease that affects millions of patients worldwide and is most common in menopausal women. The main characteristics of osteoporosis are low bone density and increased risk of fractures due to deterioration of the bone architecture. Osteoporosis is a chronic disease that is difficult to treat; thus, investigations into novel effective therapeutic methods are required. A number of studies have focused on determining the most effective treatment options for this disease. There are several treatment options for osteoporosis that differ depending on the characteristics of the disease, and these include both well-established and newly developed drugs. The present review focuses on the various drugs available for osteoporosis, the associated mechanisms of action and the methods of administration.

Effectiveness of parathyroid hormone (PTH) analogues on fracture healing: a meta-analysis

This meta-analysis evaluated the evidence for the use of parathyroid hormone (PTH) analogues to improve fracture healing. Eligible studies were prospective randomised controlled trials of adults with acute fractures treated with a PTH analogue. PTH improved functional outcomes but did not affect fracture healing rate or reduce pain.

PURPOSE

This meta-analysis evaluated the evidence of parathyroid hormone (PTH) analogues in fracture healing. The use of PTH analogues to prevent osteoporotic fractures is well investigated, and studies are emerging on extended indications. One such indication receiving increasing attention is the effect of PTH in fracture healing; however, the overall degree of efficacy remains inconclusive.

METHODS

A systematic electronic database search of MEDLINE, EMBASE and the Cochrane Library was conducted for relevant articles in August 2019 with no date restrictions. Randomised controlled trials of adults with acute fractures treated with a PTH analogue were included. PTH was compared with a comparator intervention, placebo or no treatment.

RESULTS

PTH analogue treatment improved functional outcomes in a range of fracture types but did not affect the fracture healing rate or reduce pain. Most trials included in this review were in elderly patients with osteoporosis. There was no evidence that PTH treatment caused harm or impeded fracture healing.

CONCLUSIONS

Meta-analysis of published data supports the use of PTH analogues to improve functional outcomes but not fracture healing rate or pain for different fracture types. The evidence for PTH analogue use in fracture healing is less clear in younger, non-osteoporotic patient populations. Trial design was heterogeneous and of limited quality, justifying further original trials.

Prior administration of vitamin K2 improves the therapeutic effects of zoledronic acid in ovariectomized rats by antagonizing zoledronic acid-induced inhibition of osteoblasts proliferation and mineralization

Zoledronic acid (ZA) exerts complex influence on bone by suppressing bone resorption, mostly due to the direct osteoclasts inhibition and uncertain influence on osteoblasts. Vitamin K₂ (VK₂, Menaquinone-4) as an anabolic agent stimulates bone formation via anti-apoptosis in osteoblasts and mild osteoclasts inhibition. Based on these knowledge, the therapeutic effect of the combined or sequential therapy of VK₂ and ZA depends on the influence on the osteoblasts, since both cases exert similar inhibitory effect on osteoclasts. In a series of in vitro studies, we confirmed the protective effect of VK₂ in osteoblasts culture, especially when followed by exposure to ZA, and the proliferation and mineralization inhibition induced by ZA towards osteoblasts. For mechanism study, expression of bcl-2/bax, Runx2 and Sost in cells were examined. For in vivo studies, an osteoporosis animal model was established in rats via ovariectomy (OVX) and subjected to sequential treatment, namely VK₂ followed by ZA. Bone mineral density (BMD) was measured by Dual energy X-ray absorptionmetry (DEXA), morphology and mechanical parameters by micro-computed tomography (micro-CT), mechanical strength by an electro-hydraulic fatigue-testing machine. The bone calcium, hydroxyproline content, blood lipids were evaluated using microplate technique, and the bone surface turnover was evaluated using the fluorescence in corporation method. It was found that VK₂ pretreatment partially prevented the inhibition of bone formation caused by ZA, which was reflected by indices like BMD, bone calcium content and bone strength. The underling mechanisms for protection of VK₂ pretreatment, mainly demonstrated via in vitro studies, included inhibiting apoptosis and depressing Sost expression in osteoblasts, which in turn improved the osteoporosis therapeutic effects of ZA. These findings suggested that pretreatment with VK₂ before ZA therapy might serve a new long-term therapy protocol for osteoporosis.

Parathyroid hormone analogues for fracture healing: protocol for a systematic review and meta-analysis of randomised controlled trials

INTRODUCTION

Fracture healing is a complex physiological process. Impaired healing will increase the need for care and cause serious complications. Thus, identifying strategies to accelerate the rate of healing, preventing delayed unions and non-unions, is essential. Parathyroid hormone (PTH) is a key systemic regulator of calcium and phosphate metabolism. It has been determined that intermittent administration of PTH and its analogue can exert anabolic effect on bone, increase bone mass and reduce bone loss, leading to an increase in bone formation. Owing to their anabolic effect, there is an increasing interest in its potential in promoting the process of fracture healing. However, in clinical studies, the results are in conflict. This objective of this study is to determine the role of PTH analogues for fracture healing in adults.

METHODS AND ANALYSIS

MEDLINE, EMBASE and Cochrane databases will be searched to identify all randomised controlled trials (RCTs) and quasi-RCTs that compare the different effects between PTH analogues and any other treatments in adults with any type of fracture. The primary outcome is the functional recovery. And the secondary outcomes are fracture union and adverse events. The meta-analysis will be performed using a random effects model. Heterogeneity will be assessed by the P values and I² statistic. And subgroup analyses and sensitivity analyses will be used to explore the heterogeneity. Risk of bias will be assessed using the Cochrane tool and the quality of evidence will be assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

Ethical approval is not required because this proposed systematic review and meta-analysis is based on published data, without including confidential personal data or data on interventions on patients. The findings of this study will be published in a peer-reviewed journaland presented at a relevant conference.

PROSPERO REGISTRATION NUMBER

CRD42017062093.

Management of bisphosphonate-related osteonecrosis of the jaw: a literature review

Osteonecrosis of the jaw (ONJ) is a serious side effect of bisphosphonate use in patients with osteoporosis, Paget's disease, hypercalcemia of malignancy, metastatic bone disease and multiple myeloma, although recently this complication has also been reported in patients under non-bisphosphonate medication, such as denosumab and bevacizumab. The occurrence of ONJ is higher in oncology patients treated with high-dose iv bisphosphonates than in osteoporosis patients treated with oral bisphosphonates. Although multiple hypotheses have been proposed, the exact pathogenic mechanism of ONJ still remains unclear. As treatment protocols based on randomized controlled trials (RCTs) do not exist, we critically reviewed the existing data concerning the management of bisphosphonate-related osteonecrosis of the jaw, including the most recent data for the use of teriparatide and hyperbaric oxygen.

The effect of parathyroid hormone and teriparatide on fracture healing

INTRODUCTION

Daily subcutaneous injections of parathyroid hormone (PTH), and its synthetic peptide fragment, teriparatide (PTH 1-34, TPTD), have a net anabolic effect on bone and prevent osteoporotic fractures. TPTD is currently approved for this indication worldwide. Because of the anabolic effect, there is an interest in a role for TPTD (and, where available, human PTH 1-84) in improving bone healing after a fracture. PTH has been studied in animal fracture healing models and in a limited number of human trials. We have reviewed current literature regarding possible mechanisms and efficacy for PTH and TPTD to improve the healing process in the setting of various types of fractures.

AREAS COVERED

Our review focuses first on the role of PTH in normal bone. We then discuss mechanisms of normal bone healing as well as delayed and impaired fracture healing. We summarize pertinent animal data and then review human studies utilizing PTH or TPTD for fracture healing. In particular, we examine unique situations including osteoporotic fractures, diabetes, stress fractures, delayed or poor healing and combination with bisphosphonate therapy.

EXPERT OPINION

Available data indicate there is likely an important role for TPTD and PTH in promoting fracture healing in selected patients, but more clinical trial data are needed.

In vitro anti-osteoporosis properties of diverse Korean Drynariae rhizoma phenolic extracts

Drynariae rhizoma has been used to prevent bone loss that occurs with increasing age. However, the chemical compounds in extracts that act on bone metabolism in herbal medicine are poorly understood. This study aimed to investigate and compare the extraction efficacy of polyphenolic compounds, antioxidant activity, and in vitro anti-osteoporosis properties of water extract (DR-DW) and ethanol extract (DR-EtOH) from D. rhizoma. Total phenolics and flavonoids were better extracted with 70% EtOH, and this extraction method also resulted in higher antioxidant activity and in vitro anti-osteoporosis properties in these extracts. In particular, the contents of phloroglucinol, protocatechuic acid ethyl ester, 2-amino-3,4-dimethyl-benzoic acid, 3-(3,5-dimethyl-pyrazol-1-yl)-benzoic acid, chlorogenic acid, syringic acid, trans-ferulic acid, (−)-epigallocatechin, epigallocatechin gallate, quercetin dehydrate, luteolin and emodin in DR-EtOH were higher than those in DR-DW. These results indicated that DR-EtOH could be a good source of natural herbs with anti-osteoporosis properties.

Chemical, target, and bioactive properties of allosteric modulation

Allosteric modulators are ligands for proteins that exert their effects via a different binding site than the natural (orthosteric) ligand site and hence form a conceptually distinct class of ligands for a target of interest. Here, the physicochemical and structural features of a large set of allosteric and non-allosteric ligands from the ChEMBL database of bioactive molecules are analyzed. In general allosteric modulators are relatively smaller, more lipophilic and more rigid compounds, though large differences exist between different targets and target classes. Furthermore, there are differences in the distribution of targets that bind these allosteric modulators. Allosteric modulators are over-represented in membrane receptors, ligand-gated ion channels and nuclear receptor targets, but are underrepresented in enzymes (primarily proteases and kinases). Moreover, allosteric modulators tend to bind to their targets with a slightly lower potency (5.96 log units versus 6.66 log units, p<0.01). However, this lower absolute affinity is compensated by their lower molecular weight and more lipophilic nature, leading to similar binding efficiency and surface efficiency indices. Subsequently a series of classifier models are trained, initially target class independent models followed by finer-grained target (architecture/functional class) based models using the target hierarchy of the ChEMBL database. Applications of these insights include the selection of likely allosteric modulators from existing compound collections, the design of novel chemical libraries biased towards allosteric regulators and the selection of targets potentially likely to yield allosteric modulators on screening. All data sets used in the paper are available for download.

The physicochemistry and topography of ligand binding sites is generally conserved amongst related proteins, however, comparisons of the pharmacology of related targets (and even the same target) are often confounded by the existence of multiple, distinct, binding sites within the same protein. Importantly, these multiple binding sites can have ‘druggability’ or selectivity properties, and can therefore offer attractive novel approaches to develop new therapeutic agents. In this paper, sets of known ligands binding to the same target are classified as being either allosteric (binding at a site that is non-competitive for a natural ligand/substrate) or non-allosteric (binding at the same site as a natural substrate), it is demonstrated that there are differences in the profiles of ligands discovered empirically against these sites. Finally predictive models are developed with several useful applications in drug discovery.

Adjunct teriparatide therapy with monitoring of bone turnover markers and bone scintigraphy for bisphosphonate-related osteonecrosis of the jaw

The management of bisphosphonate-related osteonecrosis of the jaw (BRONJ) is still difficult in many cases that do not respond to conservative treatments. We report a case of BRONJ treated by adjunctive teriparatide therapy for 6 months with monitoring of bone turnover markers (at baseline, at 1, 3, and 6 months of treatment, and after 9 months off therapy) and bone scintigraphy (at baseline, 3 and 6 months, and after 9 months off therapy). The patient was a 78-year-old woman with osteoporosis and BRONJ. She had not responded to previous conventional treatment. Teriparatide was added for resolution of BRONJ. The pain disappeared after 1 month, and remarkable bone regeneration was obtained after 6 months, with significantly increasing bone formation and resorption markers. Bone scintigraphy showed regression of the uptake area. This case suggests the usefulness of monitoring bone turnover markers and using bone scintigraphy to increase the effectiveness of teriparatide therapy.

Ronacaleret, a calcium-sensing receptor antagonist, has no significant effect on radial fracture healing time: results of a randomized, double-blinded, placebo-controlled Phase II clinical trial

BACKGROUND

Fractures cause significant morbidity, mortality, and use of health care resources. An oral agent that enhances fracture healing could reduce costs and prevent future disabilities. In Phase I studies, ronacaleret, a novel calcium-sensing receptor antagonist, stimulated parathyroid hormone (PTH) release and increased bone formation markers, suggesting that it may act as an effective oral anabolic agent to enhance fracture healing.

METHODS

This was a randomized, double-blind, placebo-controlled, parallel-group, clinical trial in 85 male and female subjects who had sustained a closed, unilateral, extra-articular fracture of the distal radius and were receiving conservative treatment. Subjects were randomly assigned in a double-blind manner to ronacaleret 200 mg twice daily, ronacaleret 400 mg once daily or matching placebo and followed for 12 weeks. Fracture healing was assessed by radiographs and quantitative computed tomography (CT), and bone turnover markers were measured. The study was terminated early for futility based on the results of an unplanned interim analysis.

RESULTS

There were no significant differences between treatment groups in time to radiographic fracture healing (74, 65 and 68 days for placebo, 200 mg twice daily and 400 mg once daily dose groups, respectively), cortical bridging, grip strength, pain and swelling, time to cast removal, or range of motion. Markers of bone formation and levels of whole PTH, intact PTH and serum calcium increased following treatment with ronacaleret.

CONCLUSION

Ronacaleret had no significant effect on duration of healing by radiograph or CT scan, time to cast removal, clinical symptoms, grip strength, or range of motion.

Parathyroid hormone and its effects on dental tissues

In the current era, various pharmacological agents exist for osteoporosis management, and synthetic parathyroid hormone (PTH) (Teriparatide, Forteo) is one of the treatment options. Depending on the timing of administration, PTH has a unique ability to cause both bone apposition and bone resorption. This review focuses on the effects of PTH on the bone, specifically the jaw bones mandible and maxilla. The article briefly describes the fundamental mechanism of PTH action at the molecular level, as well as in experimental animals and in humans. It differentiates intermittent administration of PTH, especially at doses tolerated by humans that increase bone strength and prevent bone fractures, from continuous use that may lead to bone loss. In particular, it shows how intermittent administration of PTH can play a significant role in periodontal repair and implant success via stimulation of bone mineral content especially in the pre-alveolar region.

Management of age-related osteoporosis and prevention of associated fractures

Osteoporosis and related fractures are a significant concern for the global community. As the population continues to age, morbidity and mortality from fractures due to low bone mineral density (BMD) will likely continue to increase. Efforts should be made to screen those at risk for osteoporosis, identify and address various risk factors for falls and associated fractures, ensure adequate calcium and vitamin D intake, and institute pharmacological therapy to increase BMD when indicated. Agents which increase BMD and have been shown to decrease fractures, particularly at the hip, should be considered preferentially over those for which only BMD data are available. Drugs which have been shown to decrease the risk of age-related osteoporotic fractures include oral bisphosphonates (alendronate, ibandronate, and risedronate), intranasal calcitonin, estrogen receptor stimulators (eg, estrogen, selective estrogen receptor modulators [raloxifene]), parathyroid hormone (teriparatide), sodium fluoride, and strontium ranelate. Data are beginning to emerge supporting various combination therapies (eg, bisphosphonate plus an estrogen receptor stimulator), though more data are needed to identify combinations which are most effective and confer added fracture protection. In addition, further research is needed to identify ideal regimens in special populations such as nursing home patients and men.

New approaches to the treatment of osteoporosis

Although safe and effective agents are currently available to treat osteoporosis, fragility fractures remain a significant problem worldwide. Recent improvements in the understanding of the cellular, biochemical, and molecular pathways of bone biology have led to the development of newer agents to treat osteoporosis, which may lead to further improvements in outcomes. In this review, we summarize the most recent advances in the field, including new modes of administration of existing drug classes, various approaches to combination therapy, and drugs with novel mechanisms of action to treat osteoporosis.

Osteoporosis treatment: marine algal compounds

Osteoporosis is one of the most common bone diseases that occur due to imbalance during bone formation and bone resorption. About half of all women over the age of 50 will have a fracture on the hip, wrist, or vertebra. Research and treatment of osteoporosis are challenging for researchers and physicians. There are several types of treatments for osteoporosis including most famous bisphosphonates, estrogen agonists/antagonists, parathyroid hormone, estrogen therapy, hormone therapy, and recently developed RANKL inhibition. In the recent days, much attention has been paid for marine algal extracts and compounds for osteoporosis treatment. In this chapter, we extensively deal with marine algae compounds and their rich mineral constituents for osteoporosis treatment.

The regulation of parathyroid hormone secretion and synthesis

Secondary hyperparathyroidism classically appears during the course of chronic renal failure and sometimes after renal transplantation. Understanding the mechanisms by which parathyroid hormone (PTH) synthesis and secretion are normally regulated is important in devising methods to regulate overactivity and hyperplasia of the parathyroid gland after the onset of renal insufficiency. Rapid regulation of PTH secretion in response to variations in serum calcium is mediated by G-protein coupled, calcium-sensing receptors on parathyroid cells, whereas alterations in the stability of mRNA-encoding PTH by mRNA-binding proteins occur in response to prolonged changes in serum calcium. Independent of changes in intestinal calcium absorption and serum calcium, 1α,25-dihydroxyvitamin D also represses the transcription of PTH by associating with the vitamin D receptor, which heterodimerizes with retinoic acid X receptors to bind vitamin D-response elements within the PTH gene. 1α,25-Dihydroxyvitamin D additionally regulates the expression of calcium-sensing receptors to indirectly alter PTH secretion. In 2°HPT seen in renal failure, reduced concentrations of calcium-sensing and vitamin D receptors, and altered mRNA-binding protein activities within the parathyroid cell, increase PTH secretion in addition to the more widely recognized changes in serum calcium, phosphorus, and 1α,25-dihydroxyvitamin D. The treatment of secondary hyperparathyroidism by correction of serum calcium and phosphorus concentrations and the administration of vitamin D analogs and calcimimetic agents may be augmented in the future by agents that alter the stability of mRNA-encoding PTH.

Anti-inflammatory glucocorticoid drugs: reflections after 60 years

This review considers the problem of the serious concomitant side effects of powerful anti-inflammatory drugs modelled upon the principal human glucocorticoid hormone, cortisol. The very nature of the original bio-assays to validate their cortisol-like hormonal and anti-inflammatory activities ensured that pleiotropic toxins were selected for clinical studies. Other complicating factors have been (1) considerable reliance on bio-assays conducted in laboratory animals that primarily secrete corticosterone, not cortisol, as their principal anti-inflammatory adrenal hormone; (2) some differences in the binding of xenobiotic cortisol analogues (vis á vis cortisol) to transport proteins, detoxifying enzymes and even some intra-cellular receptors; (3) the "rogue" properties of these hormonal xenobiotics, acting independently of--but still able to suppress--hormonal mechanisms regulating endogenous cortisol; and (4) problems of intrinsic/acquired "steroid resistance", diminishing their clinical efficacy, but not necessarily all their toxicities. The rather gloomy conclusion is that devising new drugs to reproduce the effect of multi-potent hormones may be a recipe for disaster, in contexts other than simply remedying an endocrine deficiency. Promising new developments include "designed" combination therapies that allow some reduction in total steroid doses (and hopefully their side effects); sharpening strategies to limit the actual duration of steroid administration; and resurgent interest in searching for more selective analogues (both steroidal and non-steroid) with less harmful side effects. Some oversights and neglected areas of research are also considered. Overall, it now seems timely to engage in some drastic rethinking about (retaining?) these "licensed toxins" as fundamental therapies for chronic inflammation.

Investigational anabolic therapies for osteoporosis

IMPORTANCE OF THE FIELD

Anabolic therapy, or stimulating the function of bone-forming osteoblasts, is the preferred pharmacological intervention for osteoporosis.

AREAS COVERED IN THIS REVIEW

We reviewed bone anabolic agents currently under active investigation. The bone anabolic potential of IGF-I and parathyroid hormone-related protein is discussed in the light of animal data and human studies. We also discuss the use of antagonists of the calcium-sensing receptor (calcilytics) as orally administered small molecules capable of transiently elevating serum parathyroid hormone (PTH). Further, we reviewed novel anabolic agents targeting members of the wingless tail (Wnt) signaling family that regulate bone formation including DKK-1, sclerostin, Thp1, and glycogen synthase kinase 3beta. We have also followed up on the promise shown by beta-blockers in modulating the activity of sympathetic nervous system, thus affecting bone anabolism. We give critical consideration to neutralizing the activity of activin A, a negative regulator of bone mass by soluble activin receptor IIA, as a strategy to promote bone formation.

WHAT THE READER WILL GAIN

Update on various strategies to promote osteoblast function currently under evaluation.

TAKE HOME MESSAGE

In spite of favorable results in experimental models, none of these strategies has yet achieved the ultimate goal of providing an alternative to injectable PTH, the sole anabolic therapy in clinical use.

Detection of the misuse of steroids in doping control

The list of prohibited substances of the World Anti-Doping Agency (WADA) classifies the administration of several steroids in sports as doping. Their analysis is generally performed using urine specimen as matrix. Lots of the steroids are extensively metabolised in the human body. Thus, knowledge of urinary excretion is extremely important for the sensitive detection of steroid misuse in doping control. The methods routinely used in steroid screening mainly focus on substances, that are excreted unconjugated or as glucuronides. Common procedures include deconjugation using a beta-glucuronidase enzyme. Following extraction and concentration the analytes are submitted to LC-MS(/MS) analysis and/or GC-MS(/MS) analyses. Besides the classical steroids, more and more products appear on the market for "dietary supplements" containing steroids that have never been marketed as approved drugs, mostly without proper labelling of the contents. To cover the whole range of potential products comprehensive screening tools have to be utilised in addition to the classical methods. Endogenous steroids, e.g. testosterone, represent a special group of compounds. As classical chemical methodology is incapable of discriminating synthetic hormones from the biosynthesised congeners, the method of steroid profiling is used for screening purpose. Additionally, based on isotope signatures a discrimination of synthetic and natural hormones can be achieved.

Allosteric modulators of class B G-protein-coupled receptors

Class B GPCR’s are activated by peptide ligands, typically 30-40 amino acid residues, that are involved in major physiological functions such as glucose homeostasis (glucagon and glucagon-like peptide 1), calcium homeostasis and bone turnover (parathyroid hormone and calcitonin), and control of the stress axis (corticotropin-releasing factor). Peptide therapeutics have been developed targeting these receptors but development of nonpeptide ligands, enabling oral administration, has proved challenging. Allosteric modulation of these receptors provides a potential route to developing nonpeptide ligands that inhibit, activate, or potentiate activation of these receptors. Here the known mechanisms of allosteric modulators targeting Class B GPCR’s are reviewed, particularly nonpeptide antagonists of the corticotropin-releasing factor 1 receptor and allosteric enhancers of the glucagon-like peptide-1 receptor. Also discussed is the potential for antagonist ligands to operate by competitive inhibition of one of the peptide binding sites, analogous to the Charniere mechanism. These mechanisms are then used to discuss potential strategies and management of pharmacological complexity in the future development of allosteric modulators for Class B GPCR’s.

Higher habitual sodium intake is not detrimental for bones in older women with adequate calcium intake

Based on the calciuric effect of sodium (Na), it has been speculated, although not proven, that higher Na intake might have a detrimental effect on bone health. The objective was to determine the relationship between Na intake (expressed as urinary Na) and bone mineral density/content (BMD/BMC) during a 3-year study. Participants were healthy, postmenopausal, Caucasian women (n = 136 at baseline) with no medications affecting bone. After baseline screening, half were instructed to reduce sodium intake to approximately 1,500 mg/day (intervention). The other half remained on habitual intake of approximately 3,000 mg/day (control). All subjects were given calcium and vitamin D supplements to achieve recommended levels. Anthropometries, densitometry, blood and 24-h urine analyses, and dietary and activity records were assessed every 6 months. Data were analyzed as a continuum, irrespective of the initial assignment to a control or intervention group, using random effects regressions with repeated measures analysis of variance to examine changes over time. Results showed that subjects with higher Na intake had higher BMD in the forearm and spine at baseline and all subsequent time-points (p < 0.01). In the forearm, time and higher urinary calcium modified results, producing a curvilinear decrease in BMD (p < 0.01). In the spine, more active individuals had higher BMD at all time-points. We conclude that higher sodium intake, within the range consumed, had a positive effect on some skeletal sites and no adverse effect on bone in women who had adequate calcium and vitamin D intake.

The use of PTH in the treatment of osteoporosis

Anabolic drugs have recently widened therapeutic options in osteoporosis treatment, as they influence processes associated with bone formation to a greater extent and earlier than bone reabsortion. They positively affect a number of skeletal properties besides bone density, as intermittent administration of parathyroid hormone (PTH) results in an increase in the number and activity of osteoblasts leading to an increase in bone mass and improvement in skeletal architecture at both the trabecular and cortical bone. Human recombinant parathyroid hormone (hrPTH 1-84) and human recombinant PTH peptide 1-34 (teriparatide) belong to this group. The objective of this paper is to review PTH actions, benefits and adverse effects, action on biochemical markers, combination therapy with antiresorptive agents, impact of antiresorptive therapy prior to anabolic treatment, sequential treatment, and effect on glucocorticoid-induced osteoporosis.

Parathyroid hormone (1-34) augments spinal fusion, fusion mass volume, and fusion mass quality in a rabbit spinal fusion model

STUDY DESIGN

The posterolateral rabbit spinal fusion model was used to assess the effect of intermittent parathyroid hormone on spinal fusion outcomes.

OBJECTIVE

To test the hypothesis that intermittent parathyroid hormone (PTH) improves spinal fusion outcomes in the rabbit posterolateral spinal fusion model.

SUMMARY OF BACKGROUND DATA

Spinal fusion is the definitive management for spinal deformity or instability, yet despite current technology, 5% to 40% of lumbar fusions result in pseudarthrosis. Animal studies have demonstrated enhanced fracture healing with the use of PTH, but the effect of PTH on spinal fusion is poorly described.

METHODS

Forty-four male New Zealand white rabbits underwent bilateral posterolateral spine fusion (L5-L6 level). Twenty-two rabbits received daily subcutaneous injections of PTH (1-34) (10 microg/kg) and 22 received an injection of saline fluid. All were killed 6 weeks after surgery. L5-L6 vertebral segments were removed and analyzed with manual bending, faxitron radiography, microCT, and histomorphometry.

RESULTS

Manual bending identified fusion in 30% (control) versus 81% (PTH) animals (P < 0.001). A radiographic scoring system ("0" = no bone formation, "5" = full fusion) resulted in an average score of 3.36 (control) versus 4.51 (PTH) (P < 0.001). MicroCT analysis demonstrated a median mass of 3.5 cc (control) (range, 2.25-5.40 cc) versus 6.03 cc (PTH) (range, 4.34-10.58 cc) (P < 0.001). Histology showed a median percentage bone area of 14.3% (control) (n = 12) versus 29.9% (PTH) (n = 15) (P < 0.001). The median percentage cartilage was 2.7% (control) (n = 5) versus 26.6% (PTH) (n = 5) (P < 0.01). Osteoclast quantification revealed median values of 140.5 (control) (n = 6) and 345.0 (PTH) (n = 8) (P < 0.001) respectively, and the percentage of osteoblasts revealed a median value of 31.4% (control) (n = 6) versus 64.4% (PTH) (n = 8) (P < 0.001).

CONCLUSION

Intermittent PTH administration increased posterolateral fusion success in rabbits. Fusion bone mass and histologic determinants were also improved with PTH treatment. PTH has promise for use as an adjunctive agent to improve spinal fusion in clinical medicine.

Combination anabolic and antiresorptive therapy for osteoporosis: opening the anabolic window

Antiresorptive agents for osteoporosis are a cornerstone of therapy, but anabolic drugs have recently increased our options. By stimulating bone formation, anabolic agents reduce fracture incidence by improving bone qualities in addition to increasing bone mass. The only anabolic agent currently approved for osteoporosis by the US Food and Drug Administration, teriparatide (recombinant human parathyroid hormone ), has emerged as a major approach to selected patients with osteoporosis. Recombinant human parathyroid hormone (1-84) is also available in Europe. Teriparatide increases bone density and bone turnover, improves microarchitecture, and changes bone size. The incidence of vertebral and nonvertebral fractures is reduced. A current concept in the mechanism of teriparatide action is related to its effect to stimulate processes associated with bone formation before it stimulates processes associated with bone resorption. This sequence of events has led to the concept of the anabolic window, the period of time when teriparatide is maximally anabolic. Newer approaches to the use of teriparatide alone and in combination with antiresorptive agents have led to ways in which the anabolic window can be expanded.

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.

Bone Remodeling in Health and Disease: Lessons From Mathematical Modeling

Parathyroid hormone is the single anabolic treatment for osteoporosis currently approved by U.S. Food and Drug Administration. The physiology underlying anabolic actions of parathyroid hormone remains mysterious, since only when applied intermittently, does it increase bone mass. This study employs mathematical modeling to consider multiple concomitant effects of parathyroid hormone and local regulators on bone turnover. Remarkably, due to coupling between osteoclasts and osteoblasts, anabolic effects of parathyroid hormone emerged from a single action-stimulation of osteoclastic bone resorption. This study provides a novel conceptual framework for the development of highly desirable anabolic treatments for bone diseases.

Evaluation of bone mineral density at different phases of therapy of childhood all

In the present study the authors evaluated the status of spinal bone mineral density (BMD) using dual-energy X-ray absorptiometry in a group of 31 children with acute lymphoblastic leukemia, treated by ALL-BFM protocols without irradiation, at different phases of their treatment. These patients were studied (1) within 2 months of diagnosis (group 1, n = 17, median time postdiagnosis 17 days), (2) during chemotherapy (group 2, n = 16, median time on treatment 22 months), and (3) shortly after completion of therapy (group 3, n = 10, median time postchemotherapy 13 months). Twelve patients underwent serial measurements in either of the groups they entered (6 patients of group 1 and 6 patients of group 2). The mean cumulative prednisone dose was 0.8, 4.3, and 5 g/m2 in groups 1, 2, and 3, respectively. A gradual decline of BMD from group 1 through group 3 was observed. The mean value of age- and sex-specific BMD z-score was -0.74 (+/-0.32) in group 1, -1.59 (+/-0.24) in group 2, and -2.03 (+/-0.27) in group 3; there was a statistically significant difference between groups 1 and 3 (p = .022). A BMD z-score < -2 was found in 3 (17%), 4 (25%), and 5 (50%) patients of groups 1, 2, and 3, respectively. In conclusion, a high incidence of reduced bone mass was observed during and shortly after treatment. These findings could have significant consequences in long-term survivors.

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.

Serum osteoprotegerin and its relationship with bone mineral density and markers of bone turnover

INTRODUCTION

The purpose of this study was to compare age-related differences in osteoprotegerin (OPG) in relationship with BMD and the serum bone markers osteocalcin (OC), collagen crosslinks (CTX), and tartrate-resistant acid phosphatase 5b (TRACP-5b).

METHODS

Data were derived from a cross-sectional study on bone health in a random sample of community-dwelling adults aged 30 to 85 years in the Reykjavik area in Iceland. All subjects had whole body, hip, and lumbar spine BMD measured (by DXA), gave blood samples, and answered a thorough questionnaire on medications and medical history. We assessed relationships using the Spearman correlation coefficient, partial correlation, and multivariable linear regression. Men and women were analyzed separately.

RESULTS

Of 2,310 subjects invited over 2 years, 1,630 participated. After excluding individuals with diseases and medications affecting bone metabolism, 517 women (age 56.1 +/- 16.9 years) and 491 men (age 58.7 +/- 14.9 years) remained for analysis. OPG increased steadily with age in both genders without a gender difference. In women, BMD at all sites declined steadily after age 50. In men, BMD remained relatively stable until age 70, after which it declined significantly. After controlling for age, BMI, and other confounding variables, OPG showed only a borderline positive relationship with whole body BMD in men (P = 0.10), but the relationship was nonsignificant in women. In multivariable models, OPG was inversely related to TRACP-5b (P = 0.002) and positively with OC (P = 0.007), the OC/TRACP-5b (P = 0.001) and OC/CTX (P = 0.02) ratios in women. Among men, multivariable models showed a positive association between OPG and OC (P = 0.05) and OC/TRACP-5b (P < 0.009).

CONCLUSIONS

We conclude that serum OPG levels are associated with a profile of bone turnover markers favoring bone formation, suggesting that OPG may be protective against age-related bone loss. Longitudinal studies are needed to address that issue.

Teriparatide: A review

BACKGROUND

Traditionally, the management of osteoporosis in men and women has included the use of antiresorptive agents in combination with calcium and vitamin D supplementation. The mechanism of action of teriparatide is unique in that it possesses anabolic properties and therefore builds bone. Since the approval of teriparatide in the United States in 2002, a great deal of interest regarding its use in osteoporosis has developed.

OBJECTIVES

This article reviews the information available on the new recombinant human parathyroid hormone teriparatide (hPTH [1-34]), including its clinical pharmacology, mechanism of action, pharmacokinetic properties, clinical efficacy, safety profile, potential drug interactions, contraindications and warnings, dosage and administration, and pharmacoeconomics.

METHODS

The articles included in this review were identified through searches of PubMed and MEDLINE (1966-December 2003) and International Pharmaceutical Abstracts (1970-December 2003). Search terms included teriparatide, Forteo, recombinant human parathyroid hormone (1-34), and osteoporosis. The references of the identified articles were reviewed for additional publications. Specific product information was also obtained from the manufacturer of teriparatide.

RESULTS

Teriparatide has been studied in postmenopausal women with osteoporosis, drug-induced osteoporosis (specifically, corticosteroid-induced osteoporosis), and men with osteoporosis. The data available from various clinical trials have shown an increase in both bone mineral density (BMD) and bone mineral content (BMC) with the use of teriparatide compared with placebo. One study found that women treated with the 20-microg dose and the 40-microg dose were 35% and 40%, respectively, less likely to have one or more new nonvertebral fractures compared with placebo (P = 0.02). Another study compared the use of daily teriparatide 40-microg injections versus oral daily alendronate. Results showed that the incidence of nonvertebral fractures was significantly lower in the teriparatide group than the alendronate group (P < 0.05). A study using 20- and 40-microg daily injections of teriparatide was performed in men with osteoporosis. There was a statistically significant increase in lumbar spine BMD of 5.9% in the 20-microg group and 9.0% in the 40-microg group (both, P < 0.001). In the femoral neck, a 1.5% increase in BMD occurred in the 20-microg group (P = 0.021) and a 0.9% increase in the 40-microg group (P < 0.001). A limited number of studies are available assessing the combination of antiresorptive medications and teriparatide; however, the available data suggest that the effects of teriperatide do not require prior stimulation of bone resorption.

CONCLUSIONS

Teriparatide has been shown clinically to improve BMD and BMC in postmenopausal women and in men. Because of its anabolic capabilities, teriparatide can be used as an alternative to the traditional therapies that are currently available for the treatment of osteoporosis, with scheduled monitoring for adverse effects such as hypercalcemia and urinary calcium excretion. In 1 study, mild hypercalcemia was seen most often 4 to 6 hours after SC injection of teriparatide before returning to normal. Urinary calcium was observed to increase by 30 mg/d (0.75 mmol/d) with teriparatide.