Transdermal application of lovastatin to rats causes profound increases in bone formation and plasma concentrations

Effect of simvastatin topical use on alveolar bone after tooth extraction: a scoping review

OBJECTIVES

Conducting a scoping review (SR) to assess scientific evidence for topical simvastatin's impact on alveolar bone regeneration and determine its level of support for clinical applications.

MATERIALS AND METHODS

This SR followed the PRISMA-ScR and OSF registries protocol; systematic searching was conducted on MEDLINE/PubMed, Cochrane, Embase, Scopus, Web of Science, and LILACS, to identify relevant articles until June 2023. Inclusion criteria covered clinical trials, case series, prospective and retrospective studies, along with in vivo investigations, involving participants of any sex and age.

RESULTS

Out of 1312 identified studies, 20 (9 in vivo, 11 RCTs) met inclusion criteria. RCTs focused on third molar extraction, in vivo on mandibular incisor surgery. The majority of RCTs employed a collagen sponge and a simvastatin concentration of 10mg; conversely, most in vivo studies favored polylactide-co-glycolide and a 2 mg simvastatin concentration. RCTs had 3-month follow-ups; in vivo, studies extended to 8 weeks. Seven RCTs assessed pain outcomes, simvastatin did not significantly affect pain in six studies. Among four RCTs on postoperative swelling, only two observed a significant increase in the simvastatin group. In general, positive bone formation and the absence of adverse effects directly linked to topical simvastatin were observed across the study models.

CONCLUSIONS

Intra-alveolar simvastatin post-tooth extraction has been to be shown to be effective and safe for preserving alveolar bone, with varied concentrations and carriers, with no significant adverse effects.

CLINICAL RELEVANCE

This review provides critical insights into the effects of simvastatin on alveolar bone regeneration, informing potential benefits and possible challenges associated with its post-extraction application. OSF REGISTRY PROTOCOL: osf.io/q3bnf.

Alveolar ridge splitting and simvastatin loaded xenograft for guided bone regeneration and simultaneous implant placement: randomized controlled clinical trial

OBJECTIVES

The present study goal was to assess clinically and radiographically using simvastatin (SMV) loaded xenograft for guided bone regeneration (GBR) around simultaneously placed implants with alveolar ridge splitting in patients with horizontally atrophic jaw defect.

MATERIALS AND METHODS

Randomized distribution of the twenty-two patients into two groups (11 patients each) was performed. Group I participants received alveolar ride splitting (ARS) with GBR using SMV gel mixed bone graft and a barrier membrane with simultaneous implant placement. Group II received the same treatment protocol without SMV gel. At the baseline, 6- and 9-months post-surgery, clinical and radiological alterations were assessed.

RESULTS

Six months after therapy, PES records of group I were statistically significantly improved than those of group II (P < .001). Group I exhibited statistically significant expansion of the alveolar ridge over group II after 6 and 9 months (P < .001). When compared to group II over the evaluation interval between 6 and 9 months, group I demonstrated statistically substantially minimal loss of the mean marginal bone level (P < .001). At the 6- and 9-month observation periods, bone density gain was considerably higher in group I than that in group II (P < .001).

CONCLUSION

Alveolar ridge splitting along with GBR-augmented SMV improve the clinical and radiographical outcomes around dental implant over GBR alone.

CLINICAL RELEVANCE

Augmenting GBR with SMV in alveolar ridge splitting could boost implant osseointegration and enhance peri-implant tissue changes.

CLINICAL TRIAL REGISTRATION

NCT05020405.

Therapeutic Effects of Statins: Promising Drug for Topical and Transdermal Administration

Statins are HMG-CoA reductase inhibitors and decrease plasma low-density lipoprotein cholesterol (LDL-C) levels. They are well tolerated, and because of their LDL-C-lowering effect, they are utilized to decrease the risk of atherosclerosis and cardiovascular disease. However, statins have pleiotropic effects, including immunomodulatory, anti-inflammatory, antioxidant, and anticancer. Currently, oral administration is the only Food and Drug Administration (FDA)-approved route of administration for statins. However, other administration routes have demonstrated promising results in different pre-clinical and clinical studies. For instance, statins also seem beneficial in dermatitis, psoriasis, vitiligo, hirsutism, uremic pruritus, and graft-versus-host disease. Topically applied statins have been studied to treat seborrhea, acne, rhinophyma, and rosacea. They also have beneficial effects in contact dermatitis and wound healing in animal studies, (HIV) infection, osseointegration, porokeratosis, and some ophthalmologic diseases. Topical and transdermal application of statins is a non-invasive drug administration method that has shown significant results in bypassing the first-pass metabolism in the liver, thereby reducing possible adverse effects. This study reviews the multifaceted molecular and cellular impacts of statins, their topical and transdermal application, novel delivery systems, such as nanosystems for topical and transdermal administration and the challenges concerning this approach.

Efficacy of simvastatin in bone regeneration after surgical removal of mandibular third molars

PURPOSE

The aim of this study was to assess the efficacy of simvastatin in bone regeneration in extraction sockets of mandibular third molars using cone beam computed tomography (CBCT) at 6th post-operative month.

METHODS

This is a prospective randomized split-mouth study involving 15 patients who underwent surgical extraction of bilaterally impacted mandibular third molars with similar morphology on the same day. The efficacy of drug was analyzed by implanting 10 mg of simvastatin into the socket (study site) and observations were made over 6 months to compare the healing with the control site.

RESULTS

The study results demonstrated a statistically significant difference in bone regeneration: mean gray value of 429.133 in study site compared with mean gray value of 310.153 in the control site.

CONCLUSION

These values demonstrate significant change in bone regeneration in simvastatin site as compared to that of control site.

The Effects of Statins on Bone Formation Around Implants Placed in Animal Bones: A Systematic Review and Meta-Analysis

Background

Implants are preferred for replacement of missing teeth by the clinicians as well as the patients. Lesser alveolar bone density doesn't preclude any individual for choosing this option but warrants for extra caution. Preclinical studies have explored the osteoinductive potential of statins, but results should be analyzed vigorously before implementing them in humans. There is no meta-analysis to document effect of statins on bone formation around implants in osteoporotic animals.

Methods and material

PubMed, Embase and Cochrane were searched for studies investigating the effect of statins on bone implant contact (BIC %), bone mineral density (BMD %) and bone volume (BV %) around implants at 2, 4 and 12 weeks. Meta-analysis was performed on subgroups with osteoporotic animals which were administered statins through different routes.

Results

Quantitative data from 12 studies showed favorable effect of statins on bone around implants. Positive difference was observed at 4 weeks in BIC (parenteral [SMD = 4.33 (2.89, 5.77); I 2 = 3%)], BMD (local [SMD = 1.33 (0.51, 2.15); I 2 = 0%] and BV (local [SMD = 1.58 (0.76, 2.40); I 2 = 0%]. BIC [SMD = 1.40 (0.89, 1.90); I 2 = 0%] and BV [SMD = 3.91 (2.33, 5.50); I 2 = 43%] were higher in experimental group after 12 weeks of oral administration.

Conclusions

Statins can be investigated as potential bone graft materials to increase the predictability of osseointegration especially in osteoporotic individuals. Future research should focus to reproduce homogeneous data and conclusive recommendations which can be applied in clinical trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12663-023-01873-z.

Effects of Drugs and Chemotherapeutic Agents on Dental Implant Osseointegration: Narrative Review

BACKGROUND

Dental implants have been one of the most popular treatments for rehabilitating individuals with single missing teeth or fully edentulous jaws since their introduction. As more implant patients are well-aged and take several medications due to various systemic conditions, clinicians should be mindful of possible drug implications on bone remodeling and osseointegration.

OBJECTIVE

The present study aims to study and review some desirable and some unwelcomed implications of medicine on osseointegration.

METHODS

A broad search for proper relevant studies were conducted in four databases, including Web of Science, Pubmed, Scopus, and Google Scholar.

RESULTS

Some commonly prescribed medicines such as nonsteroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, proton pump inhibitors (PPIs), selective serotonin reuptake inhibitors (SSRIs), anticoagulants, metformin, and chemotherapeutic agents may jeopardize osseointegration. On the contrary, some therapeutic agents such as anabolic, anti-catabolic, or dual anabolic and anti-catabolic agents may enhance osseointegration and increase the treatment's success rate.

CONCLUSION

Systemic medications that enhance osseointegration include mineralization promoters and bone resorption inhibitors. On the other hand, medications often given to the elderly with systemic problems might interfere with osseointegration, leading to implant failure. However, to validate the provided research, more human studies with a higher level of evidence are required.

Clinical efficacy of simvastatin gel combined with polypropylene membrane on the healing of extraction sockets: A triple-blind, randomized clinical trial

OBJECTIVES

This study aimed to evaluate dimensional changes, level of soft tissue healing, and pain/discomfort perception in post-extraction sockets filling with 1.2% simvastatin (SIM) gel covered with polypropylene membranes (PPPM).

MATERIAL AND METHODS

Twenty-six post-extraction sockets of posterior teeth were randomly allocated in two groups: (a) socket filling with 1.2% SIM gel and covered with PPPM (n = 13) and (b) socket filling with placebo gel and covered with PPPM (n = 13). Cone-beam computed tomography (CBCT) images before and 90 days after the extraction enabled alveolar bone dimensional changes calculation using horizontal and vertical measurements. The measurements occurred at three different levels for thickness located 1, 3, and 5 mm from the top of the bone crest. The vertical (depth) measure was assessed from the most apical portion of the socket to the bone crest's most coronal portion. Seven days after the extractions, the level of soft tissue healing and pain perception were also analyzed.

RESULTS

After 90 days of extractions, the dimensional changes in thickness in the test group were significantly smaller in sections A (p = .044), B (p = .036) and C (p = .048) when compared to the control group. The test group showed a significantly lower height-dimensional change than the control group (p < .0001). Soft tissue healing index (p = .63), perception of pain (p = .23), and number of analgesics consumed (p = .25) were similar between groups.

CONCLUSIONS

Simvastatin at 1.2% compared with placebo effectively reduced the dimensional changes in post-extraction sockets covered with PPPM. There was no significant difference in the level of soft tissue healing and postoperative pain between the test and control groups.

Drug Delivery Systems Based on Titania Nanotubes and Active Agents for Enhanced Osseointegration of Bone Implants

TiO2 nanotubes (TNTs) are attractive nanostructures for localized drug delivery. Owing to their excellent biocompatibility and physicochemical properties, numerous functionalizations of TNTs have been attempted for their use as therapeutic agent delivery platforms. In this review, we discuss the current advances in the applications of TNT-based delivery systems with an emphasis on the various functionalizations of TNTs for enhancing osteogenesis at the bone-implant interface and for preventing implant-related infection. Innovation of therapies for enhancing osteogenesis still represents a critical challenge in regeneration of bone defects. The overall concept focuses on the use of osteoconductive materials in combination with the use of osteoinductive or osteopromotive factors. In this context, we highlight the strategies for improving the functionality of TNTs, using five classes of bioactive agents: growth factors (GFs), statins, plant derived molecules, inorganic therapeutic ions/nanoparticles (NPs) and antimicrobial compounds.

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.

Bone union formation in the rat mandibular symphysis using hydroxyapatite with or without simvastatin: effects on healthy, diabetic, and osteoporotic rats

OBJECTIVE

The objective is to compare new bone formation in critical defects in healthy, diabetic, and osteoporotic rats filled with hydroxyapatite (HA) alone and HA combined with simvastatin (SV).

MATERIALS AND METHODS

A total of 48 adult female Sprague-Dawley rats were randomized into three groups (n = 16 per group): Group, 1 healthy; Group 2, diabetics; and Group 3, osteoporotics. Streptozotocin was used to induce type 1 diabetes in Group 2, while bilateral ovariectomy was used to induce osteoporosis in Group 3. The central portion of the rat mandibular symphysis was used as a physiological critical bone defect. In each group, eight defects were filled with HA alone and eight with HA combined with SV. The animals were sacrificed at 4 and 8 weeks, and the mandibles were processed for micro-computed tomography to analyze radiological union and bone mineral density (BMD); histological analysis of the bone union; and immunohistochemical analysis, which included immunoreactivity of vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP-2).

RESULTS

In all groups (healthy, diabetics, and osteoporotics), the defects filled with HA + SV presented greater radiological bone union, BMD, histological bone union, and more VEGF and BMP-2 positivity, in comparison with bone defects treated with HA alone.

CONCLUSIONS

Combined application of HA and SV improves bone regeneration in mandibular critical bone defects compared with application of HA alone in healthy, diabetic, and osteoporotic rats.

CLINICAL RELEVANCE

This study might help to patients with osteoporosis or uncontrolled diabetes type 1, but future studies should be done.

CHILD syndrome: successful treatment of skin lesions with topical lovastatin and cholesterol lotion

CHILD syndrome (Congenital Hemidysplasia, Ichthyosiform erythroderma, Limb Defects) is a rare X-linked dominant disease. The authors report a 2-month-old patient presenting with typical features of CHILD syndrome that was treated with a topical solution containing cholesterol and lovastatin, with complete clearance of her CHILD nevus. The changes in skin lipid metabolism that explain the CHILD ichthyosiform nevus and their correction through topical application of cholesterol and lovastatin are discussed.

The effect of graft application and simvastatin treatment on tibial bone defect in rats. A histological and immunohistochemical study

Purpose:

To evaluate histologically and immunohistochemically the bone regeneration after application of simvastatin on tibial bone defects in rats.

Methods:

Sixty Wistar albino rats were divided into 3 groups as control (6 mm tibial bone defect), defect + graft (allograft treatment), and defect + graft + simvastatin (10 mg/kg/day) for 28 days.

Results:

Histopathological examination revealed inflammation in control group (defect group), congestion in blood vessels, and an increase in osteoclast cells. In defect + graft group, osteoclastic activity was observed and osteocyte cells were continued to develop. In defect + graft + simvastatin group, osteocytes and matrix formation were increased in the new bone trabeculae. Osteopontin and osteonectin expression were positive in the osteclast cells in the control group. Osteoblasts and some osteocytes showed a positive reaction of osteopontin and osteopontin. In defect + graft + simvastatin group, osteonectin and osteopontin expression were positive in osteoblast and osteocyte cells, and a positive expression in osteon formation was also seen in new bone trabeculae.

Conclusion:

The simvastatin application was thought to increase bone turnover by increasing the osteoinductive effect with graft and significantly affect the formation of new bone.

In vitro and in vivo evaluation of chitosan scaffolds combined with simvastatin-loaded nanoparticles for guided bone regeneration

The objective of this study was to fabricate and characterize chitosan combined with different amounts of simvastatin-loaded nanoparticles and to investigate their potential for guided bone regeneration in vitro and in vivo. Different SIM-CSN formulations were combined into a chitosan scaffold (SIM-CSNs-S), and the morphology, simvastatin release profile, and effect on cell proliferation and differentiation were investigated. For in vivo experiments, ectopic osteogenesis and the critical-size cranial defect model in SD rats were chosen to evaluate bone regeneration potential. All three SIM-CSNs-S formulations had a porous structure and exhibited sustained simvastatin release. CSNs-S showed excellent degradation and biocompatibility characteristics. The 4 mg SIM-CSNs-S formulation stimulated higher BMSC ALP activity levels, demonstrated significantly earlier collagen enhancement, and led to faster bone regeneration than the other formulations. SIM-CSNs-S should have a significant effect on bone regeneration.

The impact of simvastatin intervention on the healing of bone, soft tissue, and TMJ cartilage in dentistry: a systematic review and meta-analysis

The review aimed at assessing the osteopromotive potential as well as soft tissue and temporomandibular joint (TMJ) cartilage healing properties of simvastatin by summarizing its efficacy on the current dental treatment of periodontal bone and soft tissue defects, and temporomandibular joint (TMJ) arthritis from the available animals and human studies. An electronic search was performed on MEDLINE, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) using a combination of keywords. A hand search was undertaken on seven oral surgery journals. No limitation of publication year in the English language was placed. Controlled randomized animal and human clinical trials, as well as prospective comparative studies, were included. Data on the comparison of topical/systemic simvastatin on bone healing in intrabony and furcation defects, extraction sockets, distraction osteogenesis, as well as soft tissue healing in mucogingival grafting procedures and cartilage protection in TMJ arthritis were extracted from all the eligible studies. Studies with a minimum of ten participants and follow up at least 6 months were included. Ten animal studies and six clinical studies were included in this study. All the animal studies included a minimum of eight sites per group assessed clinically, histologically, and radiographically. All human studies included clinical and radiological evaluation. The results of the review show that simvastatin administration displays positive treatment outcomes in the full range of therapies investigated in the oral regions such as periodontal infection control, periodontal and alveolar bone regeneration, soft tissue grafting, TMJ inflammation reduction, and cartilage repair. Its mechanism includes stimulating bone formation, promoting soft tissue healing, increasing articular and condylar cartilage thickness, as well as reducing inflammation at surgical sites in TMJ disorders. Simvastatin administration is beneficial to the healing of oral bone and cartilage. More studies are desired to determine its potential in soft tissue healing.

Evaluation of the Efficacy of Simvastatin in Bone Regeneration after Surgical Removal of Bilaterally Impacted Third Molars-A Split-Mouth Randomized Clinical Trial

PURPOSE

Simvastatin has been reported to promote osteoblastic activity, inhibit osteoclastic activity, and support osteoblast differentiation induced by bone morphogenetic protein. This split-mouth randomized clinical trial evaluated the effect of local application of simvastatin (10 mg) on bone regeneration after surgical removal of bilaterally impacted mandibular third molars.

MATERIALS AND METHODS

A randomized, split-mouth, single-blinded, single-center trial was performed in 30 patients 18 to 40 years old requiring surgical extraction of bilaterally impacted mandibular third molars. These patients underwent 2 surgical sessions, with extraction of 1 third molar during each session. Each participant was randomly assigned to receive Gelfoam soaked with normal saline or with the drug simvastatin (10 mg) at the first session and were blinded to the use of drug for that particular socket. The alternate regimen was used during the second session. The study was conducted over a period of 3 months. Patients were evaluated for pain, postoperative swelling, and bone density measurement and analysis using intraoral periapical radiographs at the end of 1, 4, 8 and 12 weeks, respectively. In addition, cone-beam computed tomographic (CBCT) images were obtained for every fifth patient at the end of 12 weeks.

RESULTS

Mean gray-level histographic values were significantly higher for the study sockets at the end of 1, 4, 8, and 12 weeks (P = .001) compared with the control sockets (30 sockets each). CBCT analysis further substantiated accelerated bone regeneration in the study sockets.

CONCLUSION

The study was statistically and radiographically in favor of the drug, indicating that local application of simvastatin could be a cost-effective and simple way to stimulate and hasten osseous regeneration.

Maxillary sinus lift using osteoinductive simvastatin combined with β-TCP versus β-TCP - a comparative pilot study to evaluate simvastatin enhanced and accelerated bone formation

PURPOSE

The aim of this study was to evaluate available bone quality and quantity after performing sinus augmentation using simvastatin/β-TCP combination versus β-TCP alone.

MATERIALS AND METHODS

This study included eight sinus lift procedures conducted on six patients. The sinuses were divided into two equal groups. The patients were recalled one, two weeks two, five, nine months post-operatively for post-operative evaluation. Radiographic evaluation involved cone beam computed tomography (CBCT) radiographs taken for every patient one week and nine months post-operatively to evaluate the changes in bone height, while histomorphometric evaluation involved transcortical bone biopsies taken after nine months during the second-stage surgery for implant placement.

RESULTS

The histomorphometric results showed that the amount of newly formed bone was higher in the simvastatin group when compared to the β-TCP group nine months after the surgery; the difference between the two groups was statistically significant. On the other hand, the radiographic evaluation showed that the rate of resorption of the simvastatin group was found to be higher than the control group; however, the difference between both groups was statistically insignificant.

CONCLUSION

These results showed that Simvastatin is safe to be used in sinus lift with promising osteoinductive capacity, yet further studies using larger sample size is needed.

Healing of extraction socket following local application of simvastatin: A split mouth prospective study

BACKGROUND

The role of simvastatin in lowering serum cholesterol level is well described. However, recent findings suggest they have a role in bone formation as well.

AIM AND OBJECTIVES

The present prospective study was conducted to evaluate the efficacy of simvastatin on bone formation in extraction sockets.

MATERIALS AND METHODS

15 patients undergoing all four first premolar extraction were selected based on inclusion and exclusion criteria. Extraction sockets of left premolars (24 and 34) were considered as cases and right premolars (14 and 44) as controls. Overall 30 extraction sites were assigned to each group. Atraumatic extraction was done in all cases following which simvastatin mixed with gelatin sponge was placed in extraction socket of 24 and 34 while only gelatin sponge was placed in 14 and 44. All sockets were then closed with 3-0 vicryl. The patients were kept on follow-up and complications such as dry socket, pain, and swelling were recorded. Intra oral peri apical radiographs were taken immediately after extraction and at 2nd month and 4th month to record changes in the density of alveolar bone. The radiographic measurements were compared and the differences were statistically analyzed.

RESULT

Percent increase in bone density at the end of 8th week and 16th week was significantly high in case as compared to the control group.

CONCLUSION

Local application of simvastatin induces bone formation in extraction sockets. Application is very simple and provides a very cost effective way of faster bone regeneration following tooth extraction.

The Effect of Local Rosuvastatin on Mandibular Fracture Healing

Mandibular fracture is the most common injury seen in facial fractures and plays an important role for oral and maxillofacial surgery department. The purpose of this study is to investigate the potential of the local administration of rosuvastatin (RSV) on mandibular fracture healing in rats. Thirty-two rats were divided into 4 groups: group C-14 (control), group R-14, group C-28 (control), and group R-28. A unilateral standard vertical osteotomy was performed right side of the mandibula extending from the tooth to the mandibular basis for each animal. In groups C-14 and C-28 sterile saline treated absorbable collogen sponge was applied to the fracture area, in groups R-14 and R-28 absorbable collogen sponge with saline solution containing 1 mg RSV was applied to the fracture area. Animals in groups C-14 and R-14 were euthanized on the 14th day, groups C-28 and R-28 were euthanized on the 28th day after operation. Stereologic analyses were performed. New bone area and connective tissue volumes were measured. Stereologic analysis showed that group R-14 had significantly more new bone at 2 weeks compared with group C-14. Connective tissue volumes were also significantly higher in R-14. New bone and connective tissue volume differences were not statistically significant between groups C-28 and R-28. Locally administered RSV enhances early bone regeneration on mandibular fracture in rats.

Localized rosuvastatin via implantable bioerodible sponge and its potential role in augmenting bone healing and regeneration

OBJECTIVE

Statins proved potential bone healing properties. Rosuvastatin is a synthetic, hydrophilic, potent and highly efficacious statin. In the current work, an attempt was investigated to develop, evaluate various bioerodible composite sponges enclosing rosuvastatin and explore their potential in augmenting bone healing and regeneration.

METHOD

Twelve lyophilized sponge formulae were prepared adapting a 4¹.3¹ full factorial design. Xanthan gum, polycarbophil, Carbopol® and sodium alginate were investigated as anionic polymers, each at three chitosan:anionic polymer ratios (1:3, 1:1, 3:1). The formula of choice was implanted in fractured rat femora.

RESULTS

Visual and microscopic examination showed flexible homogenous porous structures with considerable bending ability. Polyelectrolyte complex formation was proved by DSC and FT-IR for all chitosan/anionic combinations except with xanthan gum where chitosan probably bound to the drug rather than xanthan gum. Statistical analysis proved that anionic polymer type and chitosan: polymer ratio, as well as, their interactions, exhibited significant effects on the release parameters at p ≤ 0.05. The optimum chitosan/anionic polymer complexation ratios were 3:1 for polycarbophil and 1:1 for Carbopol and alginate. The release at these ratios followed Fiction diffusion while other ratios had anomalous diffusion. Imwitor® 900K and HPMC K100M were added as release retarardants for further release optimization. The formula of choice was implanted in fractured rat femora. Histopathological examination revealed advanced stages of healing in treated femora compared to control ones.

CONCLUSION

Biodegradable sponges for local rosuvastatin delivery proved significantly enhanced wound healing and regeneration properties to fractured bones.

Influence of simvastatin-loaded implants on osseointegration in an ovariectomized animal model

The success of bone implants in the presence of osteoporosis is limited by lack of osseointegration between the implant and the natural bone. This study applied an electrochemical process to deposit simvastatin-nanohydroxyapatite (HA) coatings on porous implant surfaces and investigated the effects of these simvastatin-HA coatings on implant surfaces in an animal model of osteoporosis. In this study, simvastatin-HA coated implants were inserted into the tibia of osteoporotic rats. After 2, 4, and 12 weeks, tissue was retrieved for histomorphometric evaluation. The results indicated that the simvastatin-HA coatings increased bone-implant contact and new bone formation around implant surfaces. In conclusion, implants loaded with simvastatin by an electrochemical process improved implant osseointegration in osteoporotic rats. Furthermore, the increased concentration of simvastatin could affect the osseointegration, but the dose-effects also need further investigation.

Simvastatin prodrug micelles target fracture and improve healing

Simvastatin (SIM), a widely used anti-lipidemic drug, has been identified as a bone anabolic agent. Its poor water solubility and the lack of distribution to the skeleton, however, have limited its application in the treatment of bone metabolic diseases. In this study, an amphiphilic macromolecular prodrug of SIM was designed and synthesized to overcome these limitations. The polyethylene glycol (PEG)-based prodrug can spontaneously self-assemble to form micelles. The use of SIM trimer as the prodrug's hydrophobic segment allows easy encapsulation of additional free SIM. The in vitro studies showed that SIM/SIM-mPEG micelles were internalized by MC3T3 cells via lysosomal trafficking and consistently induced expression of both BMP2 and DKK1 mRNA, suggesting that the prodrug micelle retains the biological functions of SIM. After systemic administration, optical imaging suggests that the micelles would passively target to bone fracture sites associated with hematoma and inflammation. Furthermore, flow cytometry study revealed that SIM/SIM-mPEG micelles had preferred cellular uptake by inflammatory and resident cells within the fracture callus tissue. The treatment study using a mouse osteotomy model validated the micelles' therapeutic efficacy in promoting bone fracture healing as demonstrated by micro-CT and histological analyses. Collectively, these data suggest that the macromolecular prodrug-based micelle formulation of SIM may have great potential for clinical management of impaired fracture healing.

The use of delta-tocotrienol and lovastatin for anti-osteoporotic therapy

AIMS

Statins are competitive inhibitors of HMGCoA reductase and are commonly used as antihypercholesterolemic agents. Experimental studies clearly demonstrate the beneficial effects of statins on bone. Tocotrienols have also been shown to have anti-osteoporotic effects on the skeletal system. This study was conducted to observe the effect of a combination of delta-tocotrienol and lovastatin on structural bone histomorphometry and bone biomechanical strength in a postmenopausal rat model at clinically tolerable doses, and to compare it with the effect of delta-tocotrienol or lovastatin.

MAIN METHODS

Forty-eight female Sprague Dawley rats were randomly divided into six groups: baseline control; sham-operated control; ovariectomised control; ovariectomised+11mg/kg lovastatin; ovariectomised+60mg/kg delta-tocotrienol and ovariectomised+60mg/kg delta-tocotrienol+11mg/kg lovastatin. These treatments were given via oral gavage daily for eight weeks. After sacrificing the rats, the left and right femurs were dissected and processed for bone histomorphometric analysis and a bone biomechanical test, respectively.

KEY FINDINGS

Delta-tocotrienol in combination with lovastatin significantly improved the trabecular volume, trabecular number, trabecular thickness and trabecular separation; and it significantly increased bone strength in oestrogen-deficient rats. Delta-tocotrienol alone enhanced bone formation and maintained bone strength in ovariectomised rats. Delta-tocotrienol plus lovastatin treatment promoted better trabecular volume and trabecular number and received higher load than delta-tocotrienol alone. Lovastatin alone was not effective.

SIGNIFICANCE

Thus, the combination of delta-tocotrienol and lovastatin has the potential to be used for anti-osteoporotic therapy in postmenopausal women.

Bone anabolics in osteoporosis: Actuality and perspectives

Vertebral and nonvertebral fractures prevention is the main goal for osteoporosis therapy by inhibiting bone resorption and/or stimulating bone formation. Antiresorptive drugs decrease the activation frequency, thereby determining a secondary decrease in bone formation rate and a low bone turnover. Bisphosphonates are today's mainstay among antiresorptive treatment of osteoporosis. Also, oral selective estrogen receptor modulators and recently denosumab have a negative effect on bone turnover. Agents active on bone formation are considered a better perspective in the treatment of severe osteoporosis. Recombinant-human parathyroid hormone (PTH) has showed to increase bone formation and significantly decrease vertebral fractures in severe patients, but with a modest effect on nonvertebral fractures. The study of Wnt signaling pathway, that induces prevalently an osteoblastic activity, opens large possibilities to antagonists of Wnt-inhibitors, such as sclerostin antibodies and dickkopf-1 antagonists, with potential effects not only on trabecular bone but also on cortical bone.

Assessment of vascular endothelial growth factor and matrix metalloproteinase-9 in the periodontium of rats treated with atorvastatin

BACKGROUND

The aim of this study is to examine, for the first time, the role of systemic and local atorvastatin application on periodontium using histomorphometric and immunohistochemical analysis during and after experimental periodontitis induction with or without the presence of microbial dental biofilm.

METHODS

One hundred ten male Wistar rats were used. Silk ligatures were placed around the cervical area of the mandibular first molars; rats in the healthy control group received no ligatures (n = 10). In experimental periodontitis groups (n = 90), systemic and local atorvastatin and saline were administered in three different periods; the control periodontitis group (n = 10) received no treatment. Histomorphometric analysis, which included alveolar bone area, alveolar bone level, and attachment loss, and immunohistochemical analysis, which included immunoreactivity of vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9, were performed after the rats were sacrificed at the end of the experimental procedure.

RESULTS

There was a greater increase in alveolar bone area and VEGF immunoreactivity, as well as a greater decrease in alveolar bone and attachment loss and MMP-9 immunoreactivity, with systemic and local atorvastatin application during and after induction of experimental periodontitis. Local atorvastatin application showed better results on periodontium with regard to alveolar bone findings.

CONCLUSIONS

Systemic and local atorvastatin application showed beneficial effects on periodontium during and after induction of experimental periodontitis. Within the limits of this study, it can be concluded that atorvastatin, which is used for hypercholesterolemia treatment, can also be used as a protective and therapeutic agent for periodontal disease.

The effect of local simvastatin application on critical size defects in the diabetic rats

OBJECTIVES

To evaluate bone-healing effects of local simvastatin application to critical size defects (CSDs) in the experimental diabetes mellitus (DM) rat model.

MATERIALS AND METHODS

A total of 35 male Sprague-Dawley rats with an average weight of 350 g and aged 3 months were used in this study. The rats were divided into five groups of seven animals each: passive control (group A), active control (group B), 0.5 mg simvastatin (group C), 1.0 mg simvastatin (group D), and 1.5 mg simvastatin (group E). Streptozotocin was used to induce Type 1 diabetes in all rats. Eight mm CSDs were created under anesthesia in each rat calvarium. CSDs were left empty in group A. Defects in group B were grafted alone with a gelatin sponge mixed with normal saline. Defects in the experimental groups (groups A, B, and C) were grafted with gelatin sponge mixed saline solutions contain 0.5, 1.0, 1.5 mg simvastatin. Rats were sacrificed after 1 month, and the defects were prepared for radiologic and histomorphometric assessment of regenerated bone.

RESULTS

None of the specimens exhibited complete closure of new bone across the 8-mm defect. A correlation between computed tomography and histomorphometric analysis was not determined. Both amount of volume and area of regenerated bone were found higher in the experimental groups than in the control groups. However, these values were not found statistically significant degree (P < 0.05) for each groups. The density of regenerated bone in the region of interest was higher in the control groups in contrast to in the experimental groups. However, statistical significance was just found between groups C and A and between groups C and B (P < 0.05).

CONCLUSION

The local simvastatin application enhanced healing of the bone defects in the diabetic rat model CSDs.

Influence of statins locally applied from orthopedic implants on osseous integration

Background

Simvastatin increases the expression of bone morphogenetic protein 2 (BMP-2) in osteoblasts, therefore it is important to investigate the influence of statins on bone formation, fracture healing and implant integration. The aim of the present study was to investigate the effect of Simvastatin, locally applied from intramedullary coated and bioactive implants, on bone integration using biomechanical and histomorphometrical analyses.

Methods

Eighty rats received retrograde nailing of the femur with titanium implants: uncoated vs. polymer-only (poly(D,L-lactide)) vs. polymer plus drug coated (either Simvastatin low- or high dosed; “SIM low/ high”). Femurs were harvested after 56 days for radiographic and histomorphometric or biomechanical analysis (push-out).

Results

Radiographic analysis revealed no pathological findings for animals of the control and SIM low dose group. However, n=2/10 animals of the SIM high group showed osteolysis next to the implant without evidence of bacterial infection determined by microbiological analysis. Biomechanical results showed a significant decrease in fixation strength for SIM high coated implants vs. the control groups (uncoated and PDLLA). Histomorphometry revealed a significantly reduced total as well as direct bone/implant contact for SIM high- implants vs. controls (uncoated and PDLLA-groups). Total contact was reduced for SIM low vs. uncoated controls. Significantly reduced new bone formation was measured around SIM high coated implants vs. both control groups.

Conclusions

This animal study suggests impaired implant integration with local application of Simvastatin from intramedullary titanium implants after 8 weeks when compared to uncoated or carrier-only coated controls.

'Old drugs for new applications': can orthopedic research benefit from this strategy?

New drug exploration is difficult in a clinical setting and the development of new drugs may be costly and time consuming. With further research into the pathological mechanisms and etiology of diseases as well as the rapid development of biological techniques, many 'old drugs' that have been applied in clinics may have new therapeutic functions which may shed light on clinical management. Based on this, we have investigated the 'old drugs for new applications' strategy in pharmacology which may be less expensive and more efficient in the clinical setting. In this paper we have explored and illustrated the potential applications of 'old drugs' for the treatment of orthopedic diseases, especially in arthritis and osteoporosis therapy.

Effect of atorvastatin on the cortical bones of corticosteroid treated rabbits

Osteoporosis ("secondary" osteoporosis) and avascular necrosis (AVN) of the femoral head are well-known adverse effects of corticosteroid therapy. Statins have been reputed to increase bone strength and bone density. In this study, we evaluated the effect of atorvastatin calcium on the flexural properties (3-point bending strength and modulus) of corticosteroid (methylprednisolone acetate) treated rabbit femurs and tibias. Our study hypothesis was that the use of statins would counteract the loss of bone strength caused by corticosteroid treatment. The 40 rabbits were divided into 5 groups: control, corticosteroid alone and corticosteroid combined with oral doses of atorvastatin calcium (2, 10, or 20 mg/day). A daily oral dose of atorvastatin calcium treatment for 70 days weakened the long bones of methylprednisolone acetate treated rabbits irrespective of the dosage (2, 10, or 20 mg). Cortical bone strength was assessed using the 3-point bending test at the end of the study period. A daily oral dose of atorvastatin calcium did not attenuate the loss of cortical bone strength caused by corticosteroid treatment in rabbits. It appeared to decrease that bone strength. If these results hold true in humans, they would have wide applicability given the frequent combined use of corticosteroids and statins in many patients.

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.

The effects of direct inhibition of geranylgeranyl pyrophosphate synthase on osteoblast differentiation

Statins, drugs commonly used to lower serum cholesterol, have been shown to stimulate osteoblast differentiation and bone formation. These effects have been attributed to the depletion of geranylgeranyl pyrophosphate (GGPP). In this study, we tested whether specific inhibition of GGPP synthase (GGPPS) with digeranyl bisphosphonate (DGBP) would similarly lead to increased osteoblast differentiation. DGBP concentration dependently decreased intracellular GGPP levels in MC3T3-E1 pre-osteoblasts and primary rat calvarial osteoblasts, leading to impaired Rap1a geranylgeranylation. In contrast to our hypothesis, 1 µM DGBP inhibited matrix mineralization in the MC3T3-E1 pre-osteoblasts. Consistent with this, DGBP inhibited the expression of alkaline phosphatase and osteocalcin in primary osteoblasts. By inhibiting GGPPS, DGBP caused an accumulation of the GGPPS substrate farnesyl pyrophosphate (FPP). This effect was observed throughout the time course of MC3T3-E1 pre-osteoblast differentiation. Interestingly, DGBP treatment led to activation of the glucocorticoid receptor in MC3T3-E1 pre-osteoblast cells, consistent with recent findings that FPP activates nuclear hormone receptors. These findings demonstrate that direct inhibition of GGPPS, and the resulting specific depletion of GGPP, does not stimulate osteoblast differentiation. This suggests that in addition to depletion of GGPP, statin-stimulated osteoblast differentiation may depend on the depletion of upstream isoprenoids, including FPP.

Anabolic agents and bone quality

BACKGROUND

The definition of bone quality is evolving particularly from the perspective of anabolic agents that can enhance not only bone mineral density but also bone microarchitecture, composition, morphology, amount of microdamage, and remodeling dynamics.

QUESTIONS/PURPOSES

This review summarizes the molecular pathways and physiologic effects of current and potential anabolic drugs.

METHODS

From a MEDLINE search (1996-2010), articles were identified by the search terms "bone quality" (1851 articles), "anabolic agent" (5044 articles), "PTH or parathyroid hormone" (32,229 articles), "strontium" or "strontium ranelate" (283 articles), "prostaglandin" (77,539 articles), and "statin" or "statins" (14,233 articles). The search strategy included combining each with the phrase "bone quality." Another more limited search aimed at finding more novel potential agents.

RESULTS

Parathyroid hormone is the only US Food and Drug Administration-approved bone anabolic agent in the United States and has been the most extensively studied in in vitro animal and human trials. Strontium ranelate is approved in Europe but has not undergone Food and Drug Administration trials in the United States. All the studies on prostaglandin agonists have used in vivo animal models and there are no human trials examining prostaglandin agonist effects. The advantages of statins include the long-established advantages and safety profile, but they are limited by their bioavailability in bone. Other potential pathways include proline-rich tyrosine kinase 2 (PYK2) and sclerostin (SOST) inhibition, among others.

CONCLUSIONS

The ongoing research to enhance the anabolic potential of current agents, identify new agents, and develop better delivery systems will greatly enhance the management of bone quality-related injuries and diseases in the future.

Red yeast rice stimulates osteoblast proliferation and increases alkaline phosphatase activity in MC3T3-E1 cells

Red yeast (Monascus purpureus) is used as a traditional hypocholesterolemic dietary food component in Asia due to its bioactive component, lovastatin. Recently, new evidence suggesting that the statins in red yeast enhance bone formation has been reported, but more research is still needed in order to support these claims of osteogenic effects. Therefore, in this study, we hypothesized that red yeast rice (in which red yeast is fermented) can improve osteogenic function through osteoblast cell proliferation and differentiation. We studied the effect of methanol extract of red yeast rice powder (RYRP) on osteoblast proliferation and differentiation by measuring mitochondrial enzyme activity and bone marker alkaline phosphatase (ALP) activity, respectively. Osteoblast-like MC3T3-E1 cells were cultured in various concentrations of RYRP methanol extract (0.001-1 mg/mL) during the osteoblast differentiation period (1, 5, 10, and 15 days). As measured by 3-[4,5-dimethylthiazol-2-y]-2,5-diphenyltetrazolium bromide assay, RYRP extracts stimulated cell proliferation during a 24-hour period, compared to cooked white rice powder extract. The most pronounced effect was observed at the concentration range between 0.075 and 0.1 mg/mL. This RYRP stimulatory effect for cell proliferation was observed during the whole osteogenic period. Cellular (synthesized) ALP activity was increased at a RYRP extract concentration of 0.075 mg/mL during 15 days of culture, but the medium (secreted) ALP activity did not show any significant change. This cellular ALP activity stimulation by RYRP extract was confirmed by the staining of ALP activity on cell matrix layers for matrix calcification. The results imply that RYRP extract may increase osteogenic effect by stimulating cell proliferation and ALP activity in osteoblastic cells.

Statins and the joint: multiple targets for a global protection?

OBJECTIVES

Evidence exists that the pleiotropic properties of the hydroxy-methyl-glutaryl Coenzyme A reductase inhibitors (statins) are not restricted to the cardiovascular system, as they can also favorably affect the joints, with intriguing implications for the treatment of many rheumatic diseases. In the view of the increasing interest on this topic, we here review the current state of the art.

METHODS

The PubMed database was searched for articles published between 1966 and 2010 for key words referring to statins and joint diseases. All relevant English-written articles were reviewed.

RESULTS

Many pivotal studies clearly demonstrated that HMG-CoA reductase inhibitors exert a wide spectrum of beneficial effects on the 3 main compartments of the joint, ie, the synovium, the cartilage, and the subchondral bone. Such (1) anti-inflammatory, (2) immunomodulating, and (3) anabolic effects strongly support a potential role of these drugs in the treatment and/or the prevention of the most important chronic joint diseases. However, although the majority of the in vivo studies with statins on animal models of inflammatory and degenerative joint diseases showed a marked protective activity substantially confirming the in vitro experiments, data arising from clinical trials are less probative and more conflicting.

CONCLUSIONS

Statins display multiple joint-protective effects. Since oral administration of statins could result in a relatively low drug bioavailability to the joints, alternative routes of administration of the drug (transdermal, intra-articular) and/or specific delivery systems should be developed to establish the entire therapeutic potential of statins in this clinical setting.

Local low-dose lovastatin delivery improves the bone-healing defect caused by Nf1 loss of function in osteoblasts

Postfracture tibial nonunion (pseudoarthrosis) leads to lifelong disability in patients with neurofibromatosis type I (NF1), a disorder caused by mutations in the NF1 gene. To determine the contribution of NF1 in bone healing, we assessed bone healing in the Nf1(ob) (-/-) conditional mouse model lacking Nf1 specifically in osteoblasts. A closed distal tibia fracture protocol and a longitudinal study design were used. During the 21- to 28-day postfracture period, callus volume, as expected, decreased in wild-type but not in Nf1(ob) (-/-) mice, suggesting delayed healing. At these two time points, bone volume (BV/TV) and volumetric bone mineral density (vBMD) measured by 3D micro-computed tomography were decreased in Nf1(ob) (-/-) callus-bridging cortices and trabecular compartments compared with wild-type controls. Histomorphometric analyses revealed the presence of cartilaginous remnants, a high amount of osteoid, and increased osteoclast surfaces in Nf1(ob) (-/-) calluses 21 days after fracture, which was accompanied by increased expression of osteopontin, Rankl, and Tgfbeta. Callus strength measured by three-point bending 28 days after fracture was reduced in Nf1(ob) (-/-) versus wild-type calluses. Importantly, from a clinical point of view, this defect of callus maturation and strength could be ameliorated by local delivery of low-dose lovastatin microparticles, which successfully decreased osteoid volume and cartilaginous remnant number and increased callus BV/TV and strength in mutant mice. These results thus indicate that the dysfunctions caused by loss of Nf1 in osteoblasts impair callus maturation and weaken callus mechanical properties and suggest that local delivery of low-dose lovastatin may improve bone healing in NF1 patients.

Osteogenic activity of locally applied small molecule drugs in a rat femur defect model

The long-term success of arthroplastic joints is dependent on the stabilization of the implant within the skeletal site. Movement of the arthroplastic implant within the bone can stimulate osteolysis, and therefore methods which promote rigid fixation or bone growth are expected to enhance implant stability and the long-term success of joint arthroplasty. In the present study, we used a simple bilateral bone defect model to analyze the osteogenic activity of three small-molecule drug implants via microcomputerized tomography (micro-CT) and histomorphometry. In this study, we show that local delivery of alendronate, but not lovastatin or omeprazole, led to significant new bone formation at the defect site. Since alendronate impedes osteoclast-development, it is theorized that alendronate treatment results in a net increase in bone formation by preventing osteoclast mediated remodeling of the newly formed bone and upregulating osteoblasts.

The risk of revision after primary total hip arthroplasty among statin users: a nationwide population-based nested case-control study

BACKGROUND

Statins have been associated with beneficial effects on bone metabolism and inflammation in both experimental and clinical studies. The association between statin use and the risk of revision after primary total hip arthroplasty has not been examined.

METHODS

We identified 2349 patients from the Danish Hip Arthroplasty Registry who underwent revision of a primary total hip replacement in the period from 1996 to 2005 and matched them, using propensity score matching, with 2349 controls with a total hip replacement who had not had a revision. Using conditional logistic regression, we estimated the relative risk of revision due to all causes and due to specific causes according to postoperative statin use.

RESULTS

The ten-year cumulative implant revision rate in the underlying cohort of 57,581 total hip arthroplasties from the registry was 8.9% (95% confidence interval, 8.4% to 9.4%). Postoperative statin use was associated with an adjusted relative risk of revision of 0.34 (95% confidence interval, 0.28 to 0.41) compared with no use of statin. Statin use was associated with a reduced risk of revision due to deep infection, aseptic loosening, dislocation, and periprosthetic fracture. No difference in the risk of revision due to pain or implant failure was found between statin users and nonusers.

CONCLUSIONS

The use of statins was associated with a substantially lower revision risk following primary total hip arthroplasty. Statins, however, should not be prescribed to healthy patients undergoing total hip arthroplasty in order to improve the longevity of the replacement until further studies have confirmed our finding and the mechanisms for this association have been clarified.