Age-dependent effects of atorvastatin on biochemical bone turnover markers: a randomized controlled trial in postmenopausal women

Effect of atorvastatin on testosterone levels

BACKGROUND

Statins are one of the most prescribed classes of drugs worldwide. Atorvastatin, the most prescribed statin, is currently used to treat conditions such as hypercholesterolaemia and dyslipidaemia. By reducing the level of cholesterol, which is the precursor of the steroidogenesis pathway, atorvastatin may cause a reduction in levels of testosterone and other androgens. Testosterone and other androgens play important roles in biological functions. A potential reduction in androgen levels, caused by atorvastatin might cause negative effects in most settings. In contrast, in the setting of polycystic ovary syndrome (PCOS), reducing excessive levels of androgens with atorvastatin could be beneficial.

OBJECTIVES

Primary objective To quantify the magnitude of the effect of atorvastatin on total testosterone in both males and females, compared to placebo or no treatment. Secondary objectives To quantify the magnitude of the effects of atorvastatin on free testosterone, sex hormone binding globin (SHBG), androstenedione, dehydroepiandrosterone sulphate (DHEAS) concentrations, free androgen index (FAI), and withdrawal due to adverse effects (WDAEs) in both males and females, compared to placebo or no treatment.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials (RCTs) up to 9 November 2020: the Cochrane Hypertension Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; Embase; ;two international trials registries, and the websites of the US Food and Drug Administration, the European Patent Office and the Pfizer pharmaceutical corporation. These searches had no language restrictions. We also contacted authors of relevant articles regarding further published and unpublished work.

SELECTION CRITERIA

RCTs of daily atorvastatin for at least three weeks, compared with placebo or no treatment, and assessing change in testosterone levels in males or females.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the citations, extracted the data and assessed the risk of bias of the included studies. We used the mean difference (MD) with associated 95% confidence intervals (CI) to report the effect size of continuous outcomes,and the risk ratio (RR) to report effect sizes of the sole dichotomous outcome (WDAEs). We used a fixed-effect meta-analytic model to combine effect estimates across studies, and risk ratio to report effect size of the dichotomous outcomes. We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

We included six RCTs involving 265 participants who completed the study and their data was reported. Participants in two of the studies were male with normal lipid profile or mild dyslipidaemia (N = 140); the mean age of participants was 68 years. Participants in four of the studies were female with PCOS (N = 125); the mean age of participants was 32 years. We found no significant difference in testosterone levels in males between atorvastatin and placebo, MD -0.20 nmol/L (95% CI -0.77 to 0.37). In females, atorvastatin may reduce total testosterone by -0.27 nmol/L (95% CI -0.50 to -0.04), FAI by -2.59 nmol/L (95% CI -3.62 to -1.57), androstenedione by -1.37 nmol/L (95% CI -2.26 to -0.49), and DHEAS by -0.63 μmol/l (95% CI -1.12 to -0.15). Furthermore, compared to placebo, atorvastatin increased SHBG concentrations in females by 3.11 nmol/L (95% CI 0.23 to 5.99). We identified no studies in healthy females (i.e. females with normal testosterone levels) or children (under age 18). Importantly, no study reported on free testosterone levels.

AUTHORS' CONCLUSIONS

We found no significant difference between atorvastatin and placebo on the levels of total testosterone in males. In females with PCOS, atorvastatin lowered the total testosterone, FAI, androstenedione, and DHEAS. The certainty of evidence ranged from low to very low for both comparisons. More RCTs studying the effect of atorvastatin on testosterone are needed.

Regulation of Osteoclast Differentiation and Activity by Lipid Metabolism

Bone is a dynamic tissue and is constantly being remodeled by bone cells. Metabolic reprogramming plays a critical role in the activation of these bone cells and skeletal metabolism, which fulfills the energy demand for bone remodeling. Among various metabolic pathways, the importance of lipid metabolism in bone cells has long been appreciated. More recent studies also establish the link between bone loss and lipid-altering conditions—such as atherosclerotic vascular disease, hyperlipidemia, and obesity—and uncover the detrimental effect of fat accumulation on skeletal homeostasis and increased risk of fracture. Targeting lipid metabolism with statin, a lipid-lowering drug, has been shown to improve bone density and quality in metabolic bone diseases. However, the molecular mechanisms of lipid-mediated regulation in osteoclasts are not completely understood. Thus, a better understanding of lipid metabolism in osteoclasts can be used to harness bone cell activity to treat pathological bone disorders. This review summarizes the recent developments of the contribution of lipid metabolism to the function and phenotype of osteoclasts.

Adjuvant drug-assisted bone healing: Part III - Further strategies for local and systemic modulation

In this third in a series of reviews on adjuvant drug-assisted bone healing, further approaches aiming at influencing the healing process are discussed. Local and systemic modulation of bone metabolism is pursued with use of a number of drugs with completely different indications, which are characterized by a pleiotropic spectrum of action. These include drugs used to treat lipid disorders (HMG-CoA reductase inhibitors), hypertension (ACE inhibitors), osteoporosis (bisphosphonates), cancer (proteasome inhibitors) and others. Potential applications to enhance bone healing are discussed.

Efficacy of statins for osteoporosis: a systematic review and meta-analysis

Our meta-analysis assessed the efficacy of statins on the risk of fracture, bone mineral density (BMD), and the markers of bone metabolism by collecting data from 33 clinical trials. We found that statin treatment was associated with bone metabolism. And statins seemed to be more effective on male patients with osteoporosis. The efficacy of statins for the treatment of osteoporosis has been controversial in previous studies and meta-analyses. Our meta-analysis was conducted to examine in detail the efficacy of statins on osteoporosis. We searched PubMed, Embase, and the Cochrane Library databases for clinical trials from inception to May 2016. We included studies that described the effect of statins on the risk of fracture, BMD, or bone turnover markers. Moreover, we also conducted subgroup analyses according to the skeleton site, patient gender, and length of follow-up. A total of 33 studies which included 23 observational studies (16 cohort studies and 7 case-control studies) and 10 randomized controlled trials (RCTs) were evaluated. These 33 studies included 314,473 patients in statin group and 1,349,192 patients in control group. Statins decreased the risk of overall fractures (OR = 0.81, 95% CI 0.73-0.89) and hip fractures (OR = 0.75, 95% CI 0.60-0.92). Furthermore, the use of statins was associated with increased BMD at the total hip (standardized mean difference (SMD) = 0.18, 95% CI 0.00-0.36) and lumbar spine (SMD = 0.20, 95% CI 0.07-0.32) and improved the bone formation marker, osteocalcin (OC) (SMD = 0.21, 95% CI 0.00-0.42). However, there was no positive effect on vertebral fractures, upper extremity fractures, BMD at the femoral neck, bone-specific alkaline phosphatase (BALP), and serum C-terminal peptide of type I collagen (S-CTX). Also, compared with male subgroups, the effect on female subgroups was only slightly positive or of no statistical significance. Our meta-analysis indicates that statin treatment may be associated with a decreased risk of overall fractures and hip fractures, an increased BMD at the total hip, BMD at the lumbar spine, and OC. Moreover, our results also show that statin treatment may have a greater effect on male patients than on female patients.

Wheelchair use and lipophilic statin medications may influence bone loss in chronic spinal cord injury: findings from the FRASCI-bone loss study

We identified a protective bone effect at the knee with lipophilic statin use in individuals with chronic spinal cord injury. Lipophilic statin users gained bone at the knee compared to non-users and wheelchair users lost bone compared to walkers. Ambulation and or statins may be effective osteogenic interventions in chronic spinal cord injury (SCI).

INTRODUCTION

SCI increases the risk of osteoporosis and low-impact fractures, particularly at the knee. However, during the chronic phase of SCI, the natural history and factors associated with longitudinal change in bone density remain poorly characterized. In this study, we prospectively assessed factors associated with change in bone density over a mean of 21 months in 152 men and women with chronic SCI.

METHODS

A mixed model procedure with repeated measures was used to assess predictors of change in bone mineral density (PROC MIXED) at the distal femur and proximal tibia. Factors with a p value of <0.10 in the univariate mixed models, as well as factors that were deemed clinically significant (gender, age, and walking status), were assessed in multivariable models. Factors with a p value of ≤0.05 were included in the final model.

RESULTS

We found no association between bone loss and traditional osteoporosis risk factors, including age, gender, body composition, or vitamin D level or status (normal or deficient). In both crude and fully adjusted models, wheelchair users lost bone compared to walkers. Similarly, statin users gained bone compared to nonusers.

CONCLUSIONS

The statin finding is supported by reports in the general population where statin use has been associated with a reduction in bone loss and fracture risk. Our results suggest that both walking and statins may be effective osteogenic therapies to mitigate bone loss and prevent osteoporosis in chronic SCI. Our findings also suggest that loss of mechanical loading and/or neuronal factors contribute more to disuse osteoporosis than traditional osteoporosis risk factors.

Lipid-lowering efficacy of atorvastatin

BACKGROUND

This represents the first update of this review, which was published in 2012. Atorvastatin is one of the most widely prescribed drugs and the most widely prescribed statin in the world. It is therefore important to know the dose-related magnitude of effect of atorvastatin on blood lipids.

OBJECTIVES

Primary objective To quantify the effects of various doses of atorvastatin on serum total cholesterol, low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol and triglycerides in individuals with and without evidence of cardiovascular disease. The primary focus of this review was determination of the mean per cent change from baseline of LDL-cholesterol. Secondary objectives • To quantify the variability of effects of various doses of atorvastatin.• To quantify withdrawals due to adverse effects (WDAEs) in placebo-controlled randomised controlled trials (RCTs).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 11, 2013), MEDLINE (1966 to December Week 2 2013), EMBASE (1980 to December Week 2 2013), Web of Science (1899 to December Week 2 2013) and BIOSIS Previews (1969 to December Week 2 2013). We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled and uncontrolled before-and-after trials evaluating the dose response of different fixed doses of atorvastatin on blood lipids over a duration of three to 12 weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility criteria for studies to be included and extracted data. We collected information on withdrawals due to adverse effects from placebo-controlled trials.

MAIN RESULTS

In this update, we found an additional 42 trials and added them to the original 254 studies. The update consists of 296 trials that evaluated dose-related efficacy of atorvastatin in 38,817 participants. Included are 242 before-and-after trials and 54 placebo-controlled RCTs. Log dose-response data from both trial designs revealed linear dose-related effects on blood total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides. The Summary of findings table 1 documents the effect of atorvastatin on LDL-cholesterol over the dose range of 10 to 80 mg/d, which is the range for which this systematic review acquired the greatest quantity of data. Over this range, blood LDL-cholesterol is decreased by 37.1% to 51.7% (Summary of findings table 1). The slope of dose-related effects on cholesterol and LDL-cholesterol was similar for atorvastatin and rosuvastatin, but rosuvastatin is about three-fold more potent. Subgroup analyses suggested that the atorvastatin effect was greater in females than in males and was greater in non-familial than in familial hypercholesterolaemia. Risk of bias for the outcome of withdrawals due to adverse effects (WDAEs) was high, but the mostly unclear risk of bias was judged unlikely to affect lipid measurements. Withdrawals due to adverse effects were not statistically significantly different between atorvastatin and placebo groups in these short-term trials (risk ratio 0.98, 95% confidence interval 0.68 to 1.40).

AUTHORS' CONCLUSIONS

This update resulted in no change to the main conclusions of the review but significantly increases the strength of the evidence. Studies show that atorvastatin decreases blood total cholesterol and LDL-cholesterol in a linear dose-related manner over the commonly prescribed dose range. New findings include that atorvastatin is more than three-fold less potent than rosuvastatin, and that the cholesterol-lowering effects of atorvastatin are greater in females than in males and greater in non-familial than in familial hypercholesterolaemia. This review update does not provide a good estimate of the incidence of harms associated with atorvastatin because included trials were of short duration and adverse effects were not reported in 37% of placebo-controlled trials.

Bone turnover markers in statin users: a population-based analysis from the Camargo Cohort Study

OBJECTIVE

To analyze the effects of statin use on bone turnover markers (BTM), in participants from a large population-based cohort.

SUBJECTS AND METHODS

Cross-sectional study that included 2431 subjects (1401 women and 930 men) from the Camargo Cohort. We analyzed the differences in serum BTM between statin or non-statin users, by means of a generalized linear model, adjusted for a wide set of covariates and stratified by diabetes status. We also studied the effect of the type of statin, dose, pharmacokinetic properties, and length of treatment, on BTM.

RESULTS

Five hundred subjects (21%) were taking statins (273 women and 227 men). Overall, they had lower levels of aminoterminal propeptide of type I collagen (PINP) and C-terminal telopeptide of type I collagen (CTX) than non-users (p<0.0001). BTM levels were significantly lower in diabetic women using statins, than in female non-statin users with diabetes. In men, we found similar results, but only for CTX. All the statins users had lower levels of BTM than non-users, except subjects taking fluvastatin that showed slightly higher values. In the whole sample, no differences between dose or drug-potency were noted regarding BTM. When comparing with non-statin users, only subjects taking lipophilic statins had lower BTM levels (p<0.0001). Serum CTX levels were lower in women using statins for more than 3 vs. 1-3 years (p=0.006).

CONCLUSIONS

In a large population-based cohort, serum BTM were lower in participants taking statins than in non-users, and this effect was modulated by diabetes status. Overall, this decrease in BTM was more evident in subjects receiving the more lipophilic statins, especially when using for more than 3 years.

Lipid lowering efficacy of atorvastatin

BACKGROUND

Atorvastatin is one of the most widely prescribed drugs and the most widely prescribed statin in the world. It is therefore important to know the dose-related magnitude of effect of atorvastatin on blood lipids.

OBJECTIVES

To quantify the dose-related effects of atorvastatin on blood lipids and withdrawals due to adverse effects (WDAE).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library Issue 4, 2011, MEDLINE (1966 to November 2011), EMBASE (1980 to November 2011), ISI Web of Science (1899 to November 2011) and BIOSIS Previews (1969 to November 2011). No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled and uncontrolled before-and-after trials evaluating the dose response of different fixed doses of atorvastatin on blood lipids over a duration of 3 to 12 weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. WDAE information was collected from the placebo-controlled trials.

MAIN RESULTS

Two hundred fifty-four trials evaluated the dose-related efficacy of atorvastatin in 33,505 participants. Log dose-response data revealed linear dose-related effects on blood total cholesterol, low-density lipoprotein (LDL)-cholesterol and triglycerides. Combining all the trials using the generic inverse variance fixed-effect model for doses of 10 to 80 mg/day resulted in decreases of 36% to 53% for LDL-cholesterol. There was no significant dose-related effects of atorvastatin on blood high-density lipoprotein (HDL)-cholesterol. WDAE were not statistically different between atorvastatin and placebo for these short-term trials (risk ratio 0.99; 95% confidence interval 0.68 to 1.45).

AUTHORS' CONCLUSIONS

Blood total cholesterol, LDL-cholesterol and triglyceride lowering effect of atorvastatin was dependent on dose. Log dose-response data was linear over the commonly prescribed dose range. Manufacturer-recommended atorvastatin doses of 10 to 80 mg/day resulted in 36% to 53% decreases of LDL-cholesterol. The review did not provide a good estimate of the incidence of harms associated with atorvastatin because of the short duration of the trials and the lack of reporting of adverse effects in 37% of the placebo-controlled trials.

Heart drugs that affect bone

There have been important developments in our understanding of the mechanisms underlying the development of osteoporosis, and several of these mechanisms also underlie atherosclerosis. Drugs given to treat cardiovascular disease may impact on bone health in either a beneficial or a harmful way. There is evidence that nitrates are beneficial to bone, but evidence for the benefit of statins, thiazide diuretics, and β-blockers is weaker. By contrast, it is likely to be that some drugs such as loop-acting diuretics are harmful to bone, whereas evidence for harm caused by drugs such as warfarin is weaker. These observations point towards opportunities for new drug development for bone diseases, and possibly the development of treatments that will benefit more than one disease.

A systems approach to bone pathophysiology

With evolving interest in multiscalar biological systems one could assume that reductionist approaches may not fully describe biological complexity. Instead, tools such as mathematical modeling, network analysis, and other multiplexed clinical- and research-oriented tests enable rapid analyses of high-throughput data parsed at the genomic, proteomic, metabolomic, and physiomic levels. A physiomic-level approach allows for recursive horizontal and vertical integration of subsystem coupling across and within spatiotemporal scales. Additionally, this methodology recognizes previously ignored subsystems and the strong, nonintuitively obvious and indirect connections among physiological events that potentially account for the uncertainties in medicine. In this review, we flip the reductionist research paradigm and review the concept of systems biology and its applications to bone pathophysiology. Specifically, a bone-centric physiome model is presented that incorporates systemic-level processes with their respective therapeutic implications.

Effect of atorvastatin on chronic periodontitis: a randomized pilot study

AIM

We studied the effect of atorvastatin (ATV) treatment on bone loss prevention in subjects with chronic periodontitis.

MATERIAL AND METHODS

In this controlled double-blind study, 38 subjects with chronic periodontitis were randomized into two groups, paired by age to receive ATV (20 mg) or placebo daily for 3 months. Periodontal mechanical treatment was carried out in both groups at baseline. Clinical and radiographic parameters and bone turnover markers were assessed at baseline and at 3 months.

RESULTS

Periodontal disease conditions improved in both groups. After comparing the figures of change, significant improvements were observed in cholesterol levels (Δ=-58.5 ± 37.6 versusΔ=5.4 ± 41.2 mg/dl, p<0.0002), low-density lipoprotein levels (Δ=-48.1 ± 31.7 versusΔ=1.9 ± 42.8 mg/dl, p<0.002), dental mobility (Δ=-0.17 ± 0.11 versusΔ=-0.06 ± 0.11%, p<0.04), and the distance from the crestal alveolar bone to the cemento-enamel junction (Δ=-0.75 ± 0.7 versusΔ=0.09 ± 0.4 mm, p<0.0006) in the ATV group.

CONCLUSIONS

The results suggest that ATV might have beneficial effects on bone alveolar loss and tooth mobility in subjects with periodontal disease.

Biochemical markers of bone turnover: potential use in the investigation and management of postmenopausal osteoporosis

INTRODUCTION

The aim was to analyse data on the use of biochemical bone turnover markers (BTM) in postmenopausal osteoporosis.

METHODS

We carried out a comparative analysis of the most important papers concerning BTM in postmenopausal osteoporosis that have been published recently.

RESULTS

The BTM levels are influenced by several factors. They are moderately correlated with BMD and subsequent bone loss. Increased levels of bone resorption markers are associated with a higher risk of fracture. Changes in the BTM during the anti-osteoporotic treatment (including combination therapy) reflect the mechanisms of action of the drugs and help to establish their effective doses. Changes in the BTM during the anti-resorptive treatment are correlated with their anti-fracture efficacy.

CONCLUSION

Biological samples should be obtained in a standardised way. BTM cannot be used for prediction of the accelerated bone loss at the level of the individual. BTM help to detect postmenopausal women who are at high risk of fracture; however, adequate practical guidelines are lacking. BTM measurements taken during the anti-resorptive therapy help to identify non-compliers. They may improve adherence to the anti-resorptive therapy and the fall in the BTM levels that exceeds the predefined threshold improves patients' persistence with the treatment. There are no guidelines concerning the use of BTM in monitoring anti-osteoporotic therapy in postmenopausal women.

Increased bone turnover in patients with hypercholesterolemia

Osteoporosis has been linked with arteriosclerotic vascular diseases, suggesting that hypercholesterolemia or dyslipidemia may be a common pathogenetic factor underlying these diseases. However, little is known about the relationship between osteoporosis and hypercholesterolemia. The purpose of this study was, therefore, to investigate the effects of hypercholesterolemia upon bone metabolism, by measuring bone turnover markers in hypercholesterolemic patients. This study included 281 Japanese patients with hypercholesterolemia, and 267 control subjects. Serum bone-specific alkaline phosphatase (BAP) of the patients was significantly higher than that of the controls in women. Serum N-terminal telopeptide of type I collagen (NTx) of the patients was significantly higher than that of the controls in both men and women. In addition, both BAP and NTx in men showed a significantly negative correlation with high density lipoprotein cholesterol (HDL-C). On the other hand, in women, both BAP and NTx showed a significantly positive correlation with total cholesterol and low density lipoprotein cholesterol (LDL-C). These results indicate increased bone turnover in hypercholesterolemic or dyslipidemic patients regardless of gender, and suggest the importance of treating hypercholesterolemia or dyslipidemia in order to prevent not only arteriosclerotic complications but also osteoporotic bone loss and subsequent fractures.

Short-term effects of atorvastatin on bone turnover in male patients with hypercholesterolemia

No consensus has been reached on whether the 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, known as statins, have beneficial effects on bone health. The purpose of our study was to evaluate the effects of atorvastatin on bone metabolism by means of measuring bone turnover markers in male patients with hypercholesterolemia both at diagnosis and prospectively after 3 months of treatment. Twenty-two Japanese male patients (mean age 62.36 +/- 10.1 years) with untreated hypercholesterolaemeia were selected for this study. After 3-months treatment of atorvastatin, total cholesterol and low density lipoprotein cholesterol significantly decreased as expected (p<0.001 for both parameters). Bone-specific alkaline phosphatase (BAP) did not change significantly (p = 0.444). However, serum N-terminal telopeptide of type I collagen (NTx) significantly decreased by -19.86 +/- 26.4% (p = 0.020). In addition, delta NTx during the course of this study was negatively correlated with NTx at baseline (r = -0.645, p = 0.0008). Although there was a tendency of positive correlations of delta NTx with delta total cholesterol, delta triglycerides, and delta low density lipoprotein cholesterol, and of negative correlations of delta NTx and delta BAP with delta high density lipoprotein cholesterol, none of them reached statistical significance. Our findings suggest that atorvastatin may have potentially beneficial effects on bone metabolism in patients with hypercholesterolemia mostly by reducing bone resorption rather than by stimulating bone formation. Further studies with more patients and longer duration are warranted to evaluate its effects, if any, on prevention of osteoporosis and subsequent fractures.

Simvastatin and atorvastatin enhance gene expression of collagen type 1 and osteocalcin in primary human osteoblasts and MG-63 cultures

To clarify the mechanism of the stimulatory effect of statins on bone formation, we have assessed the effect of simvastatin and atorvastatin on osteoblast activity by analysing cell proliferation, as well as collagen, osteocalcin, and bone morphogenetic protein-2 (BMP2) gene expression in primary human osteoblast (hOB) and MG-63 cell line cultures. Explants of bone from patients without any metabolic disease under orthopedic hip procedures were used to obtain hOB. Cell cultures were established, synchronized, and different concentrations of simvastatin or atorvastatin were added (10(-9) M, 10(-8) M, 10(-7) M, 10(-6) M) during the experiment. Cell proliferation was analyzed after 24 h. Collagen polypeptide alpha1 type 1 (COL1A1) gene expression, osteocalcin, and BMP2 expression levels were quantified by real-time PCR after 24 h incubation with statins. There was a statistically significant decrease in cell proliferation related to simvastatin or atorvastatin addition at all concentrations in primary hOB compared with those not treated. A significant increase in COL1A1, osteocalcin, and BMP2 gene expression was detected when hOB cultures were treated with simvastatin or atorvastatin at different concentrations. Similar but less significant effects were found on MG-63 cells. After statin treatment we observed both an arrest of proliferation in hOB cells and an increase in collagen, osteocalcin, and BMP2 gene expression, consistent with a stimulatory effect towards mature osteoblast differentiation. These findings support the bone-forming effect of statins, probably through the BMP2 pathway.

Statins, Fracture Risk, and Bone Remodeling: What Is True?

Besides the action on plasma lipid levels, statins show a series of ancillary effects defined as all of their vascular and nonvascular effects independent from the cholesterol reduction. It has been recently hypothesized that one of these ancillary effects could be the improvement of bone health, due to the interference with bone metabolism. This may potentially represent the rationale for statins' use in the treatment of osteoporosis, the most common disease of the bone. Both experimental observations and clinical studies on this topic generated a number of conflicting results; however, the largest randomized clinical trials, the Scandinavian Simvastatin Survival Study (4S), Long Term Intervention with Pravastatin in Ischemic Disease (LIPID), and Heart Protection Study (HPS), indicate that statins do not prevent or reduce fracture risk.

Statins and tissue mineralization: putative involvement of alkaline phosphatase

Many clinical trials have clearly demonstrated the benefit of statins in the prevention of coronary heart disease. Although other effects have subsequently been described, the so-called pleiotropic effects of statins, there is a tendency to relate all those effects, more or less directly, to inhibition of 3-hydroxy-3-methylglutaryl coenzyme A. Several clinical and laboratory studies show an association between statins and increased bone formation and/or density, but no clear explanation for that statin effect has emerged. We therefore hypothetized that statins may have an effect on alkaline phosphatase activity (ALP), an enzyme with an important role in bone mineralization and that may also contribute to pathological mineralization in other tissues, such as vascular calcification. Our experience with drug effects on ALP lead us to admit the possibility of finding a statin with an ALP increasing effect on bone but not on vascular tissue, or with a more marked effect upon one of the ALP isoforms or isoenzymes. That information would allow the design of clinical trials to confirm the suitability of a specific statin to a specific clinical condition.

Statins and osteoporosis: new role for old drugs

Osteoporosis is the most common bone disease, affecting millions of people worldwide and leading to significant morbidity and high expenditure. Most of the current therapies available for its treatment are limited to the prevention or slowing down of bone loss rather than enhancing bone formation. Recent discovery of statins (HMG-CoA reductase inhibitors) as bone anabolic agents has spurred a great deal of interest among both basic and clinical bone researchers. In-vitro and some animal studies suggest that statins increase the bone mass by enhancing bone morphogenetic protein-2 (BMP-2)-mediated osteoblast expression. Although a limited number of case-control studies suggest that statins may have the potential to reduce the risk of fractures by increasing bone formation, other studies have failed to show a benefit in fracture reduction. Randomized, controlled clinical trials are needed to resolve this conflict. One possible reason for the discrepancy in the results of preclinical, as well as clinical, studies is the liver-specific nature of statins. Considering their high liver specificity and low oral bioavailability, distribution of statins to the bone microenvironment in optimum concentration is questionable. To unravel their exact mechanism and confirm beneficial action on bone, statins should reach the bone microenvironment in optimum concentration. Dose optimization and use of novel controlled drug delivery systems may help in increasing the bioavailability and distribution of statins to the bone microenvironment. Discovery of bone-specific statins or their bone-targeted delivery offers great potential in the treatment of osteoporosis. In this review, we have summarized various preclinical and clinical studies of statins and their action on bone. We have also discussed the possible mechanism of action of statins on bone. Finally, the role of drug delivery systems in confirming and assessing the actual potential of statins as anti-osteoporotic agents is highlighted.