Evaluation of the efficacy, safety and pharmacokinetic profile of oral recombinant human parathyroid hormone [rhPTH(1-31)NH(2)] in postmenopausal women with osteoporosis

Cardiovascular Safety of Romosozumab Compared to Commonly Used Anti-osteoporosis Medications in Postmenopausal Osteoporosis: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

INTRODUCTION

The aim of this study was to investigate the cardiovascular safety of romosozumab in postmenopausal women with osteoporosis. Romosozumab, a monoclonal antibody targeting sclerostin, has been shown to increase bone mineral density and reduce the risk of osteoporotic fractures. However, in previous studies, romosozumab therapy was identified as a potential risk factor for cardiovascular events, particularly in patients with predisposing cardiovascular disease.

METHODS

A systematic literature search was performed in the Cochrane Library, Embase, PubMed, and Web of Science databases to identify randomized controlled trials (RCTs) comparing the safety and efficacy of romosozumab versus alendronate, teriparatide, denosumab, or placebo in postmenopausal women with osteoporosis. Contrast-based network meta-analysis was performed using a random-effects model. The pooled estimates are presented as risk ratios with 95% confidence intervals.

RESULTS

Of the 5282 articles retrieved, 25 RCTs were included in this review (n = 24,942), and 18 randomized controlled trials (n = 16,777) were included in the network meta-analysis. The results indicated no significant differences in cardiovascular mortality rate between romosozumab and placebo. Regarding the risk of major cardiovascular events, no significant differences were found in the direct evidence or the network meta-analysis with placebo as the reference.

CONCLUSION

Romosozumab might be a safe option for treating postmenopausal women with osteoporosis. The cardiovascular concerns associated with this treatment seem less significant than previously suggested, although additional real-world data are required to confirm this conclusion.

Gastrointestinal Permeation Enhancers Beyond Sodium Caprate and SNAC - What is Coming Next?

Oral peptide delivery is trending again. Among the possible reasons are the recent approvals of two oral peptide formulations, which represent a huge stride in the field. For the first time, gastrointestinal (GI) permeation enhancers (PEs) are leveraged to overcome the main limitation of oral peptide delivery-low permeability through the intestinal epithelium. Despite some success, the application of current PEs, such as salcaprozate sodium (SNAC), sodium caprylate (C8), and sodium caprate (C10), is generally resulting in relatively low oral bioavailabilities (BAs)-even for carefully selected therapeutics. With several hundred peptide-based drugs presently in the pipeline, there is a huge unmet need for more effective PEs. Aiming to provide useful insights for the development of novel PEs, this review summarizes the biological hurdles to oral peptide delivery with special emphasis on the epithelial barrier. It describes the concepts and action modes of PEs and mentions possible new targets. It further states the benchmark that is set by current PEs, while critically assessing and evaluating emerging PEs regarding translatability, safety, and efficacy. Additionally, examples of novel PEs under preclinical and clinical evaluation and future directions are discussed.

Acute catabolic bone metabolism response to exercise in young and older adults: A narrative review

Exercise is recommended for cardiometabolic benefits and to preserve or improve bone health, especially for older adults at increased risk of fracture. However, exercise interventions have modest benefits on areal bone mineral density (aBMD), and exercise can lead to bone loss in young athletes under certain conditions. In this narrative review, we discuss evidence for a disruption in calcium homeostasis during exercise that may diminish the skeletal benefits of exercise. Topics include 1) a general overview of the effects of exercise on aBMD; 2) discussion of the exercise-induced disruption in calcium homeostasis; 3) factors that influence the magnitude of the exercise-induced disruption in calcium homeostasis, including age, sex, and exercise mode, intensity, and duration; 4) oral calcium supplementation to minimize the exercise-induced disruption in calcium homeostasis; and 5) potential for exercise-induced increase in parathyroid hormone to be both catabolic and anabolic to bone.

Formulation strategies to improve the efficacy of intestinal permeation enhancers. Adv Drug Deliv Rev 2021;177:113925. [PMID: 34418495 DOI: 10.1016/j.addr.2021.113925]

The use of chemical permeation enhancers (PEs) is the most widely tested approach to improve oral absorption of low permeability active agents, as represented by peptides. Several hundred PEs increase intestinal permeability in preclinical bioassays, yet few have progressed to clinical testing and, of those, only incremental increases in oral bioavailability (BA) have been observed. Still, average BA values of ~1% were sufficient for two recent FDA approvals of semaglutide and octreotide oral formulations. PEs are typically screened in static in vitro and ex-vivo models where co-presentation of active agent and PE in high concentrations allows the PE to alter barrier integrity with sufficient contact time to promote flux across the intestinal epithelium. The capacity to maintain high concentrations of co-presented agents at the epithelium is not reached by standard oral dosage forms in the upper GI tract in vivo due to dilution, interference from luminal components, fast intestinal transit, and possible absorption of the PE per se. The PE-based formulations that have been assessed in clinical trials in either immediate-release or enteric-coated solid dosage forms produce low and variable oral BA due to these uncontrollable physiological factors. For PEs to appreciably increase intestinal permeability from oral dosage forms in vivo, strategies must facilitate co-presentation of PE and active agent at the epithelium for a sustained period at the required concentrations. Focusing on peptides as examples of a macromolecule class, we review physiological impediments to optimal luminal presentation, discuss the efficacy of current PE-based oral dosage forms, and suggest strategies that might be used to improve them.

The Effect of Space Travel on Bone Metabolism: Considerations on Today's Major Challenges and Advances in Pharmacology

Microgravity-induced bone loss is currently a significant and unresolved health risk for space travelers, as it raises the likelihood for irreversible changes that weaken skeletal integrity and the incremental onset of fracture injuries and renal stone formation. Another issue related to bone tissue homeostasis in microgravity is its capacity to regenerate following fractures due to weakening of the tissue and accidental events during the accomplishment of particularly dangerous tasks. Today, several pharmacological and non-pharmacological countermeasures to this problem have been proposed, including physical exercise, diet supplements and administration of antiresorptive or anabolic drugs. However, each class of pharmacological agents presents several limitations as their prolonged and repeated employment is not exempt from the onset of serious side effects, which limit their use within a well-defined range of time. In this review, we will focus on the various countermeasures currently in place or proposed to address bone loss in conditions of microgravity, analyzing in detail the advantages and disadvantages of each option from a pharmacological point of view. Finally, we take stock of the situation in the currently available literature concerning bone loss and fracture healing processes. We try to understand which are the critical points and challenges that need to be addressed to reach innovative and targeted therapies to be used both in space missions and on Earth.

The efficacy of teriparatide on lumbar spine bone mineral density, vertebral fracture incidence and pain in post-menopausal osteoporotic patients: A systematic review and meta-analysis

Objective

Teriparatide has been increasingly utilized in the management of osteoporosis. The efficacy of low and high dose teriparatide on lumbar spine bone mineral density, vertebral fracture incidence and pain is unknown. We sought to determine the efficacy of teriparatide on these patient-important outcomes using a systematic review and meta-analysis.

Methods

A systematic search of electronic databases (MEDLINE, EMBASE, CENTRAL, CINAHL) was performed to identify randomized controlled trials (RCTs) that evaluate teriparatide to any comparator for the treatment of osteoporosis in postmenopausal women. The Grades of Recommendation Assessment, Development and Evaluation (GRADE) criteria were used by two independent reviewers to assess the strength and quality of evidence.

Results

A total of 20 studies (n = 6024) were included in this review, with 2855 patients receiving teriparatide and 3169 patients receiving placebo or control treatment. A teriparatide dose of 20 μg/day increased lumbar spine bone mineral density (BMD) (standardized mean difference (SMD) 0.34 standard deviation (SD) units higher (95% CI 0.19–0.48 SDs higher) in comparison to placebo. Relative to anti-resorptive agents, 20 μg/day of teriparatide had a range from 0.14 SD units to 0.96 SD units higher (95% CI, 0.08 SDs lower to 0.36 SDs higher, CI, 0.33–1.59 SDs higher, respectively). 20 μg/day teriparatide had a significant effect on pain severity to placebo or control (SMD 0.80, 95% CI, 1.16–0.43 SDs lower) and also decreased the incidence of vertebral fractures compared to placebo (relative risk 0.31, 95% CI 0.21 to 0.46). Arthralgia and extremity pain incidence were also calculated; there were 15 and 8 fewer events per 1000 patients with the use of 20 μg/day of teriparatide compared to placebo or control, respectively.

Conclusion

High quality evidence supports the utilization of teriparatide 20 μg/day dose to significantly improve lumbar spine BMD and decrease incidence of vertebral fractures and pain severity relative to all comparators. 40 μg/day dose of teriparatide demonstrated significantly better results with prolonged treatment. This data is valuable for clinicians involved in the care of this growing demographic of patients. Further investigation on the safety and efficacy of teriparatide in higher doses for the long-term treatment of osteoporosis in postmenopausal women should be conducted through high-quality clinical trials.

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Teriparatide (20 μg/day) significantly improves lumbar spine bone mineral density.

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Teriparatide (20 μg/day) reduces vertebral fracture incidence and pain.

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Increased teriparatide dose (40 μg/day) may have even greater clinical efficacy.

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Further investigation on safety profiles for longer-term treatment is warranted.

Intestinal permeation enhancers to improve oral bioavailability of macromolecules: reasons for low efficacy in humans

INTRODUCTION

Intestinal permeation enhancers (PEs) are substances that transiently alter the intestinal epithelial barrier to facilitate permeation of macromolecules with low oral bioavailability (BA). While a number of PEs have progressed to clinical testing in conventional formulations with macromolecules, there has been only low single digit increases in oral BA, irrespective of whether the drug met primary or secondary clinical endpoints.

AREAS COVERED

This article considers the causes of sub-optimal BA of macromolecules from PE dosage forms and suggests approaches that may improve performance in humans.

EXPERT OPINION

Permeation enhancement is most effective when the PE is co-localized with the macromolecule at the epithelial surface. Conditions in the GI tract impede optimal co-localization. Novel delivery systems that limit dilution and spreading of the PE and macromolecule in the small intestine have attempted to replicate promising enhancement efficacy observed in static drug delivery models.

Oral administration of bovine lactoferrin accelerates the healing of fracture in ovariectomized rats

INTRODUCTION

Lactoferrin has recently been reported for its potent bone growth effects. However, the effects of lactoferrin on the healing process of fragility fracture have not yet been studied, so the purpose of this study is to investigate whether oral administration of lactoferrin can promote the fracture healing in an OVX animal model.

MATERIALS AND METHODS

Three months after bilateral ovariectomy, all rats underwent unilateral tibial osteotomy and were then randomly divided into control group and bovine lactoferrin (bLF) group. At 4 and 8 weeks post-fracture, animals were sacrificed, and the fractured tibiae and serum samples were collected for evaluation.

RESULTS

Our results showed that bLF treatment not only accelerated the bone growth at an early stage of OPF healing but also shortened the remolding process of OPF healing. When compared to control group, bLF treatment induced a significant rise in callus BMD (by 35.0% at 4 weeks and by 39.7% at 8 weeks; both p < 0.05) consistent with enhanced biomechanical strength of the callus, with ultimate force increased by 3.39-fold at 4 weeks (p < 0.05) and 1.95-fold at 8 weeks (p < 0.05). Besides, bLF administration resulted in a substantial increase in serum levels of BALP and a significant decrease in serum levels of TRAP 5b and TNF-α. Moreover, both the RANKL/OPG mRNA ratio and the expression of TNF-α in the callus of bLF-treated group were markedly lower than those in the control group.

CONCLUSIONS

At a dose of 85mg/kg/day orally administrated bLF potently promoted the bone healing following tibial fracture in OVX rats.

Effects of Injected Antiosteoporotic Medication Versus Oral Bisphosphonates on Rates of Repeated Vertebroplasty or Kyphoplasty

PURPOSE

Vertebral compression fractures can recur within a few years after percutaneous vertebroplasty (PVP) or kyphoplasty.

METHODS

We conducted a population-based study using data from the Taiwan National Health Insurance Research Database to investigate the efficacy of various antiosteoporotic treatments in reducing the prevalence rate of repeated PVP or kyphoplasty in patients hospitalized from January 1, 1997, to December 31, 2004. We included patients with vertebral compression fractures after PVP or kyphoplasty who received oral bisphosphonates (OB group; n = 6141) or injected drug therapies (injection group; n = 4308).

FINDINGS

The incidence rate of repeated PVP or kyphoplasty was significantly lower in the I/Z/D (denosumab monotherapy or ibandronate or zoledronate with or without denosumab) group than in the OB group (crude subdistribution hazard ratio [sHR], 0.79; 95% CI, 0.70-0.90; P < 0.05; adjusted sHR, 0.77; 95% CI, 0.68-0.87; P < 0.0001). The analysis revealed a significantly lower incidence rate of repeated PVP or kyphoplasty in the I/Z group compared with that in the OB group (crude sHR, 0.82; 95% CI, 0.72-0.94; P = 0.0038; adjusted sHR, 0.80; 95% CI, 0.70-0.91; P = 0.0011). The denosumab group also exhibited a significantly lower incidence rate of repeated PVP or kyphoplasty than did the OB group (crude sHR, 0.61; 95% CI, 0.46-0.80; P = 0.0005; adjusted sHR, 0.58; 95% CI, 0.44-0.77; P = 0.0001). Although the teriparatide group had higher fracture frequency than did the OB group, the analysis revealed no significant difference between the OB and teriparatide groups with respect to the incidence rate of repeated PVP or kyphoplasty (adjusted sHR, 1.08; 95% CI, 0.92-1.26; P = 0. 3747).

IMPLICATIONS

Injected antiosteoporotic medication was associated with lower rates of repeated vertebroplasty and kyphoplasty than was OB application.

No impact of anti-Rank ligand and PTH analogs on cardiovascular risk in postmenopausal osteoporosis: a systematic literature review and meta-analysis

The mutual effects of drugs used in osteoporosis and cardiovascular diseases are a point of interest. A literature review and meta-analysis were conducted to address the impact of PTH analogs and anti-Rank ligand on cardiovascular events and overall mortality in individuals with idiopathic osteoporosis; these treatments do not appear to have any effect.

INTRODUCTION

Two meta-analyses have been conducted to explore the cardiovascular effects of bisphosphonates. There is no review for other osteoporosis treatments. A literature review and meta-analysis were conducted to address the impact of PTH analogs and anti-Rank ligand on cardiovascular events and overall mortality in individuals with idiopathic osteoporosis.

METHODS

A systematic review was conducted in December 2017 in the PubMed, Embase, and Cochrane databases and updated on PubMed in July 2019, selecting trials with a treatment and a control group. We also conducted a search for abstracts of the French Rheumatology Society, American College of Rheumatology, and European League Against Rheumatism's annual meetings over the past 4 years. The main endpoint was the occurrence of cardiovascular events; the secondary was mortality (all causes).

RESULTS

Of the 2782 reports initially found, 16 articles were used for the meta-analysis (6 for the anti-Rank ligand and 10 for the PTH analog group). After meta-analysis, there was no significant difference between the placebo group and the anti-Rank ligand group for overall mortality (p = 0.13), the combined endpoint (overall mortality, coronary artery disease, and stroke; p 0.77), and the individual risk of coronary artery disease (p 0.53), arrhythmia (p 0.95), and stroke (p 0.62). After meta-analysis, there was no significant difference between the placebo group and the PTH analogs group for overall mortality (p 0.77), the combined endpoint (p = 0.95), and the individual risk of coronary artery disease (p = 0.74), arrhythmia (p = 0.28), and stroke (p = 0.61).

CONCLUSIONS

The anti-Rank ligand and PTH analogs have no impact on cardiovascular risk and overall mortality in idiopathic osteoporosis. To better answer the question whether these treatments can reduce the long-term cardiovascular risk, further comparative studies with longer duration are required.

New Targets and Emergent Therapies for Osteoporosis

The 11 existing FDA-approved osteoporosis drug treatments include hormone replacement therapy, 2 SERMs (raloxifene and bazedoxifene), 5 inhibitors of bone-resorbing osteoclasts (4 bisphosphonates and anti-RANKL denosumab), 2 parathyroid hormone analogues (teriparatide and abaloparatide), and 1 WNT signaling enhancer (romosozumab). These therapies are effective and provide multiple options for patients and physicians. As the genomic revolution continues, potential novel targets for future drug development are identified. This review takes a wide perspective to describe potentially rewarding topics to explore, including knowledge of genes and pathways involved in bone cell metabolism, the utility of animal models, targeting drugs to bone, and ongoing advances in drug design and delivery.

Advances in oral peptide therapeutics

Protein and peptide therapeutics require parenteral administration, which can be a deterrent to medication adherence. For this reason, there have been extensive efforts to develop alternative delivery strategies, particularly for peptides such as insulin that are used to treat endocrine disorders. Oral delivery is especially desirable, but it faces substantial barriers related to the structural organization and physiological function of the gastrointestinal tract. This article highlights strategies designed to overcome these barriers, including permeation enhancers, inhibitors of gut enzymes, and mucus-penetrating and cell-penetrating peptides. It then focuses on the experience with oral peptides that have reached clinical trials, including insulin, calcitonin, parathyroid hormone and vasopressin, with an emphasis on the advances that have recently led to the landmark approval of an oral formulation of the glucagon-like peptide 1 receptor agonist semaglutide for the treatment of type 2 diabetes.

Nasal Administration and Plasma Pharmacokinetics of Parathyroid Hormone Peptide PTH 1-34 for the Treatment of Osteoporosis

Nasal delivery of large peptides such as parathyroid 1-34 (PTH 1-34) can benefit from a permeation enhancer to promote absorption across the nasal mucosa into the bloodstream. Previously, we have published an encouraging bioavailability (78%), relative to subcutaneous injection in a small animal preclinical model, for a liquid nasal spray formulation containing the permeation enhancer polyethylene glycol (15)-hydroxystearate (Solutol^® HS15). We report here the plasma pharmacokinetics of PTH 1-34 in healthy human volunteers receiving the liquid nasal spray formulation containing Solutol^® HS15. For comparison, data for a commercially manufactured teriparatide formulation delivered via subcutaneous injection pen are also presented. Tc-99m-DTPA gamma scintigraphy monitored the deposition of the nasal spray in the nasal cavity and clearance via the inferior meatus and nasopharynx. The 50% clearance time was 17.8 min (minimum 10.9, maximum 74.3 min). For PTH 1-34, mean plasma C_max of 5 pg/mL and 253 pg/mL were obtained for the nasal spray and subcutaneous injection respectively; relative bioavailability of the nasal spray was ≤1%. Subsequently, we investigated the pharmacokinetics of the liquid nasal spray formulation as well as a dry powder nasal formulation also containing Solutol^® HS15 in a crossover study in an established ovine model. In this preclinical model, the relative bioavailability of liquid and powder nasal formulations was 1.4% and 1.0% respectively. The absolute bioavailability of subcutaneously administered PTH 1-34 (mean 77%, range 55-108%) in sheep was in agreement with published human data for teriparatide (up to 95%). These findings have important implications in the search for alternative routes of administration of peptides for the treatment of osteoporosis, and in terms of improving translation from animal models to humans.

An Adiponectin Receptor Agonist Reduces Type 2 Diabetic Periodontitis

Periodontitis is twice as prevalent in diabetics as in nondiabetics, and type 2 diabetes (T2D)-associated periodontitis is severe in many cases due to the altered and aberrant functions of bone cells in hyperglycemic conditions. Therefore, developing an effective method to halt the disease process, as well as restore and regenerate lost alveolar bone to reserve the natural teeth in diabetics, is critically important. In the current study, we applied a newly discovered adiponectin receptor agonist AdipoRon (APR) in experimental periodontitis in diabetic animal models and demonstrated the underlying molecular mechanisms. We found that when APR systemically quenched the blood sugar level in diet-induced obesity (DIO) diabetic mice, it reduced osteoclast numbers and alveolar bone loss significantly due to APR's inhibition on osteoclast differentiation shown in our in vitro studies. APR also decreased the production of proinflammatory molecules CC chemokine ligand 2 and interleukin 6 in diseased gingival tissues. On the other hand, APR promoted alveolar bone regeneration through enhancing osteogenic differentiation and decreasing stromal cell-derived factor 1 in the bone marrow that facilitates stem cell migration. Same results were achieved by APR treatment of periodontitis induced in adiponectin (APN) knockout mice, indicating the ability of APR to activate the endogenous APN receptors to exert osteoanabolic effects. In summary, our study supports the notion that APR could be used as an effective multipronged approach to target T2D-associated periodontitis.

The Discovery and Development of Liraglutide and Semaglutide

The discovery of glucagon-like peptide-1 (GLP-1), an incretin hormone with important effects on glycemic control and body weight regulation, led to efforts to extend its half-life and make it therapeutically effective in people with type 2 diabetes (T2D). The development of short- and then long-acting GLP-1 receptor agonists (GLP-1RAs) followed. Our article charts the discovery and development of the long-acting GLP-1 analogs liraglutide and, subsequently, semaglutide. We examine the chemistry employed in designing liraglutide and semaglutide, the human and non-human studies used to investigate their cellular targets and pharmacological effects, and ongoing investigations into new applications and formulations of these drugs. Reversible binding to albumin was used for the systemic protraction of liraglutide and semaglutide, with optimal fatty acid and linker combinations identified to maximize albumin binding while maintaining GLP-1 receptor (GLP-1R) potency. GLP-1RAs mediate their effects via this receptor, which is expressed in the pancreas, gastrointestinal tract, heart, lungs, kidneys, and brain. GLP-1Rs in the pancreas and brain have been shown to account for the respective improvements in glycemic control and body weight that are evident with liraglutide and semaglutide. Both liraglutide and semaglutide also positively affect cardiovascular (CV) outcomes in individuals with T2D, although the precise mechanism is still being explored. Significant weight loss, through an effect to reduce energy intake, led to the approval of liraglutide (3.0 mg) for the treatment of obesity, an indication currently under investigation with semaglutide. Other ongoing investigations with semaglutide include the treatment of non-alcoholic fatty liver disease (NASH) and its use in an oral formulation for the treatment of T2D. In summary, rational design has led to the development of two long-acting GLP-1 analogs, liraglutide and semaglutide, that have made a vast contribution to the management of T2D in terms of improvements in glycemic control, body weight, blood pressure, lipids, beta-cell function, and CV outcomes. Furthermore, the development of an oral formulation for semaglutide may provide individuals with additional benefits in relation to treatment adherence. In addition to T2D, liraglutide is used in the treatment of obesity, while semaglutide is currently under investigation for use in obesity and NASH.

Challenges in oral peptide delivery: lessons learnt from the clinic and future prospects

Therapeutic peptides have become very successful drugs due to their specificity, potency and low toxicity, but they show challenges for their delivery, due to their short half-life and rapid plasma clearance. For these reasons, peptides are usually administered using injectable sustained-release formulations. Oral peptide route is highly compelling from a patient and commercial point of view. However, poor peptide stability and low permeability across the intestinal epithelium still make it very challenging to effectively deliver peptides by the oral route. In this paper, biopharmaceutical and formulation features of oral peptides, as well as key clinical outcomes, are reviewed and discussed in the perspective of designing next generation of oral peptide formulations for a true paradigm shift.

Optimal dosing and delivery of parathyroid hormone and its analogues for osteoporosis and hypoparathyroidism - translating the pharmacology

In primary hyperparathyroidism (PHPT), bone loss results from the resorptive effects of excess parathyroid hormone (PTH). Under physiological conditions, PTH has actions that are more targeted to homeostasis and to bone accrual. The predominant action of PTH, either catabolic, anabolic or homeostatic, can be understood in molecular and pharmacokinetic terms. When administered intermittently, PTH increases bone mass, but when present continuously and in excess (e.g. PHPT), bone loss ensues. This dual effect of PTH depends not only on the dosing regimen, continuous or intermittent, but also on how the PTH molecule interacts with various states of its receptor (PTH/PTHrP receptor) influencing downstream signalling pathways differentially. Altering the amino-terminal end of PTH or PTHrP could emphasize the state of the receptor that is linked to an osteoanabolic outcome. This concept led to the development of a PTHrP analogue that interacts preferentially with the transiently linked state of the receptor, emphasizing an osteoanabolic effect. However, designing PTH or PTHrP analogues with prolonged state of binding to the receptor would be expected to be linked to a homeostatic action associated with the tonic secretory state of the parathyroid glands that is advantageous in treating hypoparathyroidism. Ideally, further development of a drug delivery system that mimics the physiological tonic, circadian, and pulsatile profile of PTH would be optimal. This review discusses basic, translational and clinical studies that may well lead to newer approaches to the treatment of osteoporosis as well as to different PTH molecules that could become more advantageous in treating hypoparathyroidism.

G protein-coupled receptors as anabolic drug targets in osteoporosis

Osteoporosis is a progressive bone disorder characterised by imbalance between bone building (anabolism) and resorption (catabolism). Most therapeutics target inhibition of osteoclast-mediated bone resorption, but more recent attention in early drug discovery has focussed on anabolic targets in osteoblasts or their precursors. Two marketed agents that display anabolic properties, strontium ranelate and teriparatide, mediate their actions via the G protein-coupled calcium-sensing and parathyroid hormone-1 receptors, respectively. This review explores their activity, the potential for improved therapeutics targeting these receptors and other putative anabolic GPCR targets, including Smoothened, Wnt/Frizzled, relaxin family peptide, adenosine, cannabinoid, prostaglandin and sphingosine-1-phosphate receptors.

Development of Potent, Protease-Resistant Agonists of the Parathyroid Hormone Receptor with Broad β Residue Distribution

The parathyroid hormone receptor 1 (PTHR1) is a member of the B-family of GPCRs; these receptors are activated by long polypeptide hormones and constitute targets of drug development efforts. Parathyroid hormone (PTH, 84 residues) and PTH-related protein (PTHrP, 141 residues) are natural agonists of PTHR1, and an N-terminal fragment of PTH, PTH(1-34), is used clinically to treat osteoporosis. Conventional peptides in the 20-40-mer length range are rapidly degraded by proteases, which may limit their biomedical utility. We have used the PTHR1-ligand system to explore the impact of broadly distributed replacement of α-amino acid residues with β-amino acid residues on susceptibility to proteolysis and agonist activity. This effort led us to identify new PTHR1 agonists that contain α → β replacements throughout their sequences, manifest potent agonist activity in cellular assays, and display remarkable resistance to proteolysis, in cases remaining active after extended exposure to simulated gastric fluid. The strategy we have employed suggests a path toward identifying protease-resistant agonists of other B-family GPCRs.

The efficacy and safety of vertebral fracture prevention therapies in post-menopausal osteoporosis treatment: Which therapies work best? a network meta-analysis

Objectives

Osteoporosis has become an increasing concern for older people as it may potentially lead to osteoporotic fractures. This study is designed to assess the efficacy and safety of ten therapies for post-menopausal women using network meta-analysis.

Methods

We conducted a systematic search in several databases, including PubMed and Embase. A random-effects model was employed and results were assessed by the odds ratio (OR) and corresponding 95% confidence intervals (CI). Furthermore, with respect to each outcome, each intervention was ranked according to the surface under the cumulative ranking curve (SUCRA) value.

Results

With respect to preventing new vertebral fractures (NVF), all ten drugs outperformed placebo, and etidronate proved to be the most effective treatment (OR 0.24, 95% CI 0.14 to 0.39). In addition, zoledronic acid and parathyroid hormone ranked higher compared with the other drugs. With respect to preventing clinical vertebral fractures (CVF), zoledronic acid proved to be the most effective drug (OR = 0.25, 95% CI 0.08 to 0.92), with denosumab as a desirable second option (OR = 0.48, 95% CI 0.22 to 0.96), when both were compared with placebo. As for adverse events (AE) and severe adverse events (SAE), no significant difference was observed. According to SUCRA, etidronate ranked first in preventing CVF; parathyroid hormone and zoledronic acid ranked highly in preventing NVF and CVF. Raloxifene was safe with a high rank in preventing AEs and SAEs though performed unsatisfactorily in efficacy.

Conclusions

This study suggests that, taking efficacy and safety into account, parathyroid hormone and zoledronic acid had the highest probability of satisfactory performance in preventing osteoporotic fractures.

Cite this article: G. Wang, L. Sui, P. Gai, G. Li, X. Qi, X. Jiang. The efficacy and safety of vertebral fracture prevention therapies in post-menopausal osteoporosis treatment: Which therapies work best? a network meta-analysis. Bone Joint Res 2017;6:452–463. DOI: 10.1302/2046-3758.67.BJR-2016-0292.R1.

New Target Sites for Treatment of Osteoporosis

In the last few years, much progress has been achieved in the discovery of new drug target sites for treatment of osteoporotic disorders, one of the main challenging diseases with a large burden for the public health systems. Among these new agents promoting bone formation, shifting the impaired equilibrium between bone anabolism and bone catabolism in the direction of bone synthesis are inorganic polymers, in particular inorganic polyphosphates that show strong stimulatory effects on the expression of bone anabolic marker proteins and hydroxyapatite formation. The bone-forming activity of these polymers can even be enhanced by combination with certain small molecules like quercetin, or if given as functionally active particles with certain divalent cations like strontium ions even showing by itself biological activity. This chapter summarizes recent developments in the search and development of novel anti-osteoporotic agents, with a particular focus on therapeutic approaches based on the potential application of inorganic polymers and combinations.

Current status of selected oral peptide technologies in advanced preclinical development and in clinical trials

The development of oral dosage forms that allows absorption of therapeutic peptides to the systemic circulation is one of the greatest challenges for the pharmaceutical industry. Currently, a number of technologies including either mixtures of penetration enhancers or protease inhibitors and/or nanotechnology-based products are under clinical development. Typically, these formulations are presented in the form of enteric-coated tablets or capsules. Systems undergoing preclinical investigation include further advances in nanotechnology, including intestinal microneedle patches, as well as their combination with regional delivery to the colon. This review critically examines four selected promising oral peptide technologies at preclinical stage and the twelve that have progressed to clinical trials, as indicated in www.clinicaltrials.gov. We examined these technologies under the criteria of peptide selection, formulation design, system components and excipients, intestinal mechanism of action, efficacy in man, and safety issues. The conclusion is that most of the technologies in clinical trials are incremental rather than paradigm-shifting and that even the more clinically advanced oral peptide drugs examples of oral bioavailability appear to yield oral bioavailability values of only 1-2% and are, therefore, only currently suitable for a limited range of peptides.

Teriparatide as a systemic treatment for lower extremity nonunion fractures: a case series

OBJECTIVE

To investigate the effect of teriparatide (parathyroid hormone [1-34]) on the healing of long bone nonunion fractures.

METHODS

We performed a retrospective chart review of patients with fracture nonunion, aged 10 to 99 years who were treated with teriparatide at the Children's Hospital of Philadelphia or the Hospital of the University of Pennsylvania between November 2002 and January 2013. The primary endpoints were radiographic evidence of callus formation and fracture union, ability to bear weight without affected limb limp, and normal range of motion and strength.

RESULTS

Six patients aged 19 to 64 years with tibial or femoral fractures that had not healed for 3 to 36 months were treated with teriparatide 20 μg/day. Accelerated healing of fracture nonunion was confirmed in 5 of 6 patients with time to complete union of 3 to 9 months. The shortest time to recovery was observed in younger patients without comorbidities. Treatment was well tolerated.

CONCLUSION

Teriparatide is a promising treatment for nonunion fractures, but its response depends on associated comorbidities. The potential benefit of teriparatide as an adjunct to treat nonunion justifies randomized placebo-controlled trials to determine its efficacy and safety in broader populations.

Safety concerns over the use of intestinal permeation enhancers: A mini-review

Intestinal permeation enhancers (PEs) are key components in ∼12 oral peptide formulations in clinical trials for a range of molecules, primarily insulin and glucagon-like-peptide 1 (GLP-1) analogs. The main PEs comprise medium chain fatty acid-based systems (sodium caprate, sodium caprylate, and N-[8-(2-hydroxybenzoyl) amino] caprylate (SNAC)), bile salts, acyl carnitines, and EDTA. Their mechanism of action is complex with subtle differences between the different molecules. With the exception of SNAC and EDTA, most PEs fluidize the plasma membrane causing plasma membrane perturbation, as well as enzymatic and intracellular mediator changes that lead to alteration of intestinal epithelial tight junction protein expression. The question arises as to whether PEs can cause irreversible epithelial damage and tight junction openings sufficient to permit co-absorption of payloads with bystander pathogens, lipopolysaccharides and its fragment, or exo- and endotoxins that may be associated with sepsis, inflammation and autoimmune conditions. Most PEs seem to cause membrane perturbation to varying extents that is rapidly reversible, and overall evidence of pathogen co-absorption is generally lacking. It is unknown however, whether the intestinal epithelial damage-repair cycle is sustained during repeat-dosing regimens for chronic therapy.

The safety and tolerability profile of therapies for the prevention and treatment of osteoporosis in postmenopausal women

At a time when the prevalence of osteoporosis and related fractures is increasing, initiation and continuation of pharmacologic therapies for prevention and treatment of postmenopausal osteoporosis have declined. This decline has been at least in part attributable to concerns about safety of these agents, such as atypical fractures with bisphosphonates and breast cancer with estrogen/progestin therapy, particularly when they are used long term by older women. However, in many cases, absolute risk of serious adverse effects is small and should be balanced against the larger potential for fracture reduction. Here, we review the safety and tolerability of available therapies for postmenopausal osteoporosis. Taking into consideration their relative efficacy, we also provide strategies for optimization of the risk:benefit ratio.

Novel therapies for osteoporosis

Since the identification of osteoporosis as a major health issue in aging populations and the subsequent development of the first treatment modalities for its management, considerable progress has been made in our understanding of the mechanisms controlling bone turnover and disease pathophysiology, thus enabling the pinpointing of new targets for intervention. This progress, along with advances in biotechnology, has rendered possible the development of ever more sophisticated treatments employing novel mechanisms of action. Denosumab, a monoclonal antibody against RANKL, approved for the treatment of postmenopausal and male osteoporosis, significantly and continuously increases bone mineral density (BMD) and maintains a low risk of vertebral, non-vertebral, and hip fractures for up to 8 years. Currently available combinations of estrogens with selective estrogen receptor modulators moderately increase BMD without causing the extra-skeletal adverse effects of each compound alone. The cathepsin K inhibitor odanacatib has recently been shown to decrease vertebral, non-vertebral, and hip fracture rates and is nearing approval. Romosozumab, an anti-sclerosin antibody, and abaloparatide, a PTH-related peptide analog, are at present in advanced stages of clinical evaluation, so far demonstrating efficaciousness together with a favorable safety profile. Several other agents are currently in earlier clinical and preclinical phases of development, including dickkopf-1 antagonists, activin A antagonists, β-arrestin analogs, calcilytics, and Src tyrosine kinase inhibitors.

Challenges in the delivery of peptide drugs: an industry perspective

Due mainly to their poor stability and short plasma half-life, peptides are usually administered by injection, often several times daily. Injectable sustained-release formulations of peptides based on biodegradable polymer microparticles or implants early demonstrated the power of drug delivery technologies to enhance patient adherence and convenience, and increase safety and efficacy. Injectable sustained-release formulations are likely to remain a significant part of new peptide products. However, a new generation of technologies that enable solvent-free formulations and manufacturing processes, injection through narrow gauge needles and ready-to-use presentations will be increasingly used. In addition, the tremendous developments in noninvasive routes of delivery are likely to result in more and more peptides being delivered by the oral, transdermal, nasal or inhalation routes.

Lessons learned from the clinical development of oral peptides

The oral delivery of peptides and proteins has been hampered by an array of obstacles. However, several promising novel oral delivery systems have been developed. This paper reviews the most advanced oral formulation technologies, and highlights key lessons and implications from studies undertaken to date with these oral formulations. Special interest is given to oral salmon calcitonin (CT), glucagon-like peptide-1 (GLP-1), insulin, PYY-(3-36), recombinant human parathyroid hormone (rhPTH(1-31)-NH2) and PTH(1-34), by different technologies. The issues addressed include (i) interaction with water, (ii) interaction with food, (iii) diurnal variation, (iv) inter- and intra-subject variability, (v) correlation between efficacy and exposure and (vi) key deliverables of different technologies. These key lessons may aid research in the development of other oral formulations.

Novel approaches to the treatment of osteoporosis

Despite the availability of efficacious treatments for fracture reduction in patients with osteoporosis, there are still unmet needs requiring a broader range of therapeutics. In particular, agents that are capable of replacing already lost bone and that also drastically reduce the risk of non-vertebral fractures are needed. Studies of rare bone diseases in humans and animal genetics have identified targets in bone cells for the development of therapies for osteoporosis with novel mechanisms of action. Here, we review these new developments, with emphasis on inhibitors of cathepsin K in osteoclasts and sclerostin in osteocytes, which are currently studied in phase 3 clinical trials.

Efficacy and safety of currently marketed anti-osteoporosis medications

During the past 2 decades, many interventions were proven effective in the management of postmenopausal osteoporosis. The objective of an anti-osteoporosis treatment is to reduce fracture rates, ideally at all skeletal sites (i.e. spine, hip, and other non-spine). The armamentarium against osteoporosis includes anti-resorptive agents (i.e. bisphosphonates, selective estrogen receptor modulators and denosumab), bone-forming agents (i.e. peptides from the parathyroid hormone family) and one agent with a dual mechanism of action (i.e. strontium ranelate). All these medications combine antifracture efficacy with a reasonable benefit/risk profile. However, the choice of a particular chemical entity, in one individual patient is based on the knowledge and expertise of the physician. Prioritization of drugs should be based on the individual profile of the patient, the severity of osteoporosis and the specific contraindications, warnings and precautions of use of the various available medications.

Investigational parathyroid hormone receptor analogs for the treatment of osteoporosis

INTRODUCTION

Intermittent parathyroid hormone (PTH) administration, acting through multiple signaling pathways, exerts an osteoanabolic effect on the skeleton that surpasses the effect of other antiosteoporotic agents. However, its efficacy is limited by the coupling effect and relatively common adverse events. Thus, the development of more sophisticated PTH receptor analogs seems imperative.

AREAS COVERED

In this review, the authors summarize the role of PTH signaling pathway in bone remodeling. The authors also summarize investigational analogs targeting this pathway, which may be potential treatments for osteoporosis.

EXPERT OPINION

β-arrestins are multifunctional cytoplasmic molecules that are decisive for regulating intracellular PTH signaling. Recently, in preclinical studies, arrestin analogs have achieved the anabolic bone effect of PTH without an accompanying increase in bone resorption. However, it is not yet known whether these analogs have adverse effects and there are no clinical data for their efficacy to date. On the other hand, several molecules derived either from PTH and PTH-related protein (PTHrP) molecules have been developed. Alternative routes of PTH 1 - 34 delivery (oral, transdermal), the PTH analog ostabolin and the N-terminal PTHrP analogs PTHrP 1 - 36 and abaloparatide, have recently been or are currently being tested in clinical trials and are more likely to become available for use in the near future.

The osteocyte as a therapeutic target in the treatment of osteoporosis

Osteoporosis is characterized by a low bone-mineral density associated with skeletal fractures. The decrease in bone-mineral density is the consequence of an unbalanced bone-remodeling process, with higher bone resorption than bone formation. The orchestration of the bone-remodeling process is under the control of the most abundant cell in bone, the osteocyte. Functioning as an endocrine cell, osteocytes are also a source of soluble factors that not only target cells on the bone surface, but also target distant organs. Therefore, any drugs targeting the osteocyte functions and signaling pathways will have a major impact on the bone-remodeling process. This review discusses potential advances in drug therapy for osteoporosis, including novel osteocyte-related antiresorptive and anabolic agents that may become available in the coming years.

Postmenopausal osteoporosis

PURPOSE OF REVIEW

The aim of this study is to provide a thorough updated review of the diagnosis and treatment of postmenopausal osteoporosis.

RECENT FINDINGS

There have been several important findings in the field of postmenopausal osteoporosis over the past 1-2 years. Fewer morphometric vertebral fractures were found in women treated for 6 years with zoledronic acid compared with those who stopped treatment after 3 years. Longer duration of bisphosphonate therapy is associated with a higher risk of atypical femur fractures. Combination therapy with teriparatide and denosumab appears to increase bone mineral density to a greater extent than either therapy alone in postmenopausal women at high risk for fracture. There are several novel therapies under investigation for the treatment of osteoporosis, which are in various stages of development. Nonadherence to osteoporosis therapies continues to be a major problem in clinical practice.

SUMMARY

There are numerous effective pharmacologic treatment options for postmenopausal osteoporosis. Bisphosphonate drug holidays continue to be an area of significant debate.

Parathyroid hormone and parathyroid hormone-related protein analogs as therapies for osteoporosis

Osteoporotic fractures result in significant morbidity and mortality. Anabolic agents reverse the negative skeletal balance that characterizes osteoporosis by stimulating osteoblast-dependent bone formation to a greater degree than osteoclast-dependent bone resorption. Parathyroid hormone (PTH) and parathyroid hormone- related protein (PTHrP) are peptide hormones, which have anabolic actions when administered intermittently. The only FDA-approved anabolic bone agent for the treatment of osteoporosis in the United States is PTH 1-34, or teriparatide, administered by daily subcutaneous injections. However, PTH 1-84 is also available in Europe. Synthetic human PTHrP 1-36 and a PTHrP 1-34 analog, BA058, have also been shown to increase lumbar spine bone density. These agents and several other PTH and PTHrP analogs, including some which are not administered as injections, continue to be investigated as potential anabolic therapies for osteoporosis.

In vitro and in vivo evaluation of osteoporosis therapeutic peptide PTH 1-34 loaded pegylated chitosan nanoparticles

Oral formulation of human parathyroid hormone 1-34 (PTH 1-34) is an alternative patient compliant route in treating osteoporosis. PTH 1-34 loaded chitosan nanoparticles were PEGylated (PEG-CS-PTH NPs) and characterized by DLS, SEM, TEM and FTIR. PEG-CS-PTH NP aggregates of 200-250 nm which in turn comprised 20 nm individual nanoparticles were observed in SEM and TEM images respectively. The PEG-CS-PTH NP with 40% encapsulation efficiency was subjected to an in vitro release in simulated rat body fluids. PEG-CS-PTH NP treated human primary osteoblast cells, upon PTH 1-34 receptor activation, produced second messenger-cAMP, which downstream stimulated intracellular calcium uptake, production of bone specific alkaline phosphatase, osteocalcin etc., which substantiates the anabolic effect of the peptide. PEG-CS-PTH NPs showed an oral bioavailability of 100-160 pg/mL PTH 1-34 throughout 48 h, which is remarkable compared to the bare PTH 1-34 and CS-PTH NPs. The NIR image of gastrointestinal transit of ICG conjugated PEG-CS-PTH NPs supports this significant finding.

Effects of different dosages of parathyroid hormone-related protein 1-34 on the bone metabolism of the ovariectomized rat model of osteoporosis

Intermittent and low-dose parathyroid hormone (PTH) injection to stimulate bone formation has been used in the treatment of osteoporosis. The N-terminal fragment 1-34 of PTH is quite similar in structure and function to N-terminal PTH-related protein (PTHrP). PTH(1-34) and PTHrP also share a coreceptor, the PTH/PTHrP receptor. Therefore, some studies have suggested that PTHrP could effectively stimulate bone formation, similar to PTH. We used an ovariectomized (OVX) rat model of osteoporosis to study the effects of PTHrP(1-34) on bone metabolism by measuring bone mineral density (BMD), bone histomorphometrics, and biomechanical parameters. We found that subcutaneous injection of PTHrP(1-34) (40 or 80 μg/kg body weight every day) in OVX rats increased lumbar and femoral BMD, improved bone biomechanical properties, enhanced bone strength, and promoted bone formation. We selected 40 μg/kg as the preferred therapeutic dose of PTHrP(1-34) and investigated the effects of frequency of treatment (per 1, 2, 3, or 7 days) on bone metabolism in OVX rats. We found that injection of PTHrP(1-34) once per day or every other day significantly improved the BMD and strength of OVX rats. Serum calcium and phosphate levels in all treated rats did not vary significantly from control rats. Based on our results, intermittent low-dose PTHrP(1-34) injection promoted bone formation in OVX rats, suggesting a high potential for therapeutic use in osteoporosis patients.