Antibiotic-loaded plaster of Paris implants coated with poly lactide-co-glycolide as a controlled release delivery system for the treatment of bone infections

Dual role of tannic acid and pyrogallol incorporated in plaster of Paris: Morphology modification and release for antimicrobial properties

The design of bioactive plasters is of major interest for the amelioration of dental and bone cements. In this article, a one pot and environmentally friendly strategy based on the addition of a cheap polyphenol-tannic acid (TA) or the main phenolic constituent of TA, namely pyrogallol (PY)- able to interact with calcium sulfate is proposed. Tannic acid and pyrogallol not only modify the morphology of the obtained plaster+TA/PY composites but a part of it is released and provides strong-up to twenty fold- antibacterial effect against Staphylococcus aureus. It is shown that the higher antibacterial efficiency of PY is related to a greater release compared to TA even if in solution the antibacterial effect of PY is lower than that of TA when reported on the basis of the molar concentration in PY units.

Porous Polymer Scaffolds based on Cross-Linked Poly-EGDMA and PLA: Manufacture, Antibiotics Encapsulation, and In Vitro Study

Porous polymer materials derived from poly(ethylene glycol dimethacrylate) (poly-EGDMA) and antibiotic containing polylactide (PLA) are obtained for the first time. Porous poly-EGDMA monoliths with a system of open interconnected pores are synthesized by a visible light-induced radical polymerization of EGDMA in the presence of 70 wt% of porogenic agent, e.g., 1-butanol, 1-hexanol, 1-octanol, or cyclohexanol. The porosity of the obtained polymers is 75-78%. A modal pore size depends on the nature of the porogen and varies from 0.5 µm (cyclohexanol) to 12 µm (1-butanol). The polymer matrix made with 1-butanol features the presence of pores ranging from 1 to 100 µm. The pore surface of poly-EGDMA matrices is inlayered with poly-D,L-lactide (M_n  23 × 10³  Da, PDI 1.31). The PLA-modified poly-EGDMA retains a porous structure that is similar to the initial poly-EGDMA but with improved strength characteristics. The presence of antibiotic containing PLA ensures a high and continuous antibacterial activity of the hybrid polymeric material for 7 days. The nontoxicity of all the porous matrices studied makes them promising for clinical tests as osteoplastic materials.

Coatings as the useful drug delivery system for the prevention of implant-related infections

Implant-related infections (IRIs) which led to a large amount of medical expenditure were caused by bacteria and fungi that involve the implants in the operation or in ward. Traditional treatments of IRIs were comprised of repeated radical debridement, replacement of internal fixators, and intravenous antibiotics. It needed a long time and numbers of surgeries to cure, which meant a catastrophe to patients. So how to prevent it was more important than to cure it. As an excellent local release system, coating is a good idea by its local drug infusion and barrier effect on resisting biofilms which were the main cause of IRIs. So in this review, materials used for coatings and evidences of prevention were elaborated.

Procedure for single-stage implant retention for chronic periprosthetic infection using topical degradable calcium-based antibiotics

INTRODUCTION

Surgical treatment using DAIR (debridement, systemic antibiotics, and implant retention) can lead to high rates of treatment success in cases of early periprosthetic joint infection (PJI) but can fail in late-onset cases. Supplementary local antibiotic therapy is not yet generally established and lacks evidence-based proof of efficacy. The aim of this study was to analyze DAIR outcomes in recurrent PJI cases and patients who are not suitable for a two-stage exchange, using additional degradable calcium-based antibiotics.

METHODS

All patients fulfilled the Infectious Diseases Society of America (IDSA) guidelines for chronic late-onset PJI but were not suitable for a multistage procedure because of their individual operation risk. A total of 42 patients (mean age, 73 years) were treated using a single-stage algorithm consisting of DAIR, followed by implantation of degradable antibiotics chosen in accordance with an antibiogram. OSTEOSET® (admixed ceftriaxone/vancomycin/tobramycin) and Herafill-Gentamycin® were used as carrier systems. The follow-up period was 23 months (± SD, 10.3). The study is based on institutional review board (IRB) approval.

RESULTS

The clinical entities were chronic PJI of the hip (45.2%), knee (28.6%), and knee arthrodesis (26.2%). The bacterial spectrum was composed of Staphylococcus epidermidis (29%), Staphylococcus aureus (21%), and Enterococcus faecalis (21%). 21.4% showed a combination of two or more bacteria. In 73.8%, permanent remission was achieved, while 11.9% showed chronic PJI under implant retention. Implant retention could be achieved in 85.7%.

CONCLUSION

DAIR usually shows low levels of success in difficult-to-treat cases. However, we could demonstrate the successful treatment of patients with recurrent PJI (typically considered DAIR-inappropriate) using degradable antibiogram-based topical calcium-based antibiotics. Over 70% of the cases went to remission and over 85% of the implants could be retained.

Evaluation of a novel biodegradable thermosensitive keto-hydrogel for improving postoperative pain in a rat model

This study evaluates the sustained analgesic effect of ketorolac-eluting thermosensitive biodegradable hydrogel in the plantar incisional pain model of the rat hind-paw. A ketorolac-embedded 2, 2'-Bis (2-oxazolin) (BOX) linking methoxy-poly(ethylene glycol) and poly(lactide-co-glycolide) (mPEG-PLGA) diblock copolymer (BOX copolymer) was synthesized as keto-hydrogel based on optimal sol-gel phase transition and in vitro drug release profile. The effect of keto-hydrogel on postoperative pain (POP) was assessed using the established plantar incisional pain model in hind-paw of rats and compared to that of ketorolac solution. Pain and sensory threshold, as well as pain scoring, were evaluated with behavioral tests by means of anesthesiometer and incapacitance apparatus, respectively. Pro-inflammatory cytokine levels (TNF-α, IL-6, VEGF, and IL-1β) around incisional wounds were measured by ELISA. Tissue histology was assessed using hematoxylin and eosin and Masson’s trichrome staining. Ten mg/mL (25 wt%) keto-hydrogel showed a sol-gel transition at 26.4°C with a 10-day sustained drug release profile in vitro. Compared to ketorolac solution group, the concentration of ketorolac in tissue fluid was higher in the keto-hydrogel group during the first 18 h of application. Keto-hydrogel elevated pain and sensory threshold, increased weight-bearing capacity, and significantly reduced the levels of TNF-α, IL-6, and IL-1β while enhanced VEGF in tissue fluid. Histologic analysis reveals greater epithelialization and collagen deposition around wound treated with keto-hydrogel. In conclusion, our study suggests that keto-hydrogel is an ideal compound to treat POP with a secondary gain of improved incisional wound healing.

Sustainable Release of Vancomycin from Silk Fibroin Nanoparticles for Treating Severe Bone Infection in Rat Tibia Osteomyelitis Model

The successful treatment of bone infections is a major challenge in the field of orthopedics. There are some common methods for treating bone infections, including systemic antibiotic administration, local nondegradable drug vehicles, and surgical debridement, and each of these approaches has advantages and disadvantages. In the present study, the antibiotic vancomycin (VANCO) was loaded in silk fibroin nanoparticles (SFNPs) and the complexes were then entrapped in silk scaffolds to form sustained drug delivery systems. The release kinetics of VANCO from SFNPs alone and when the SFNPs were entrapped in silk scaffolds were assessed at two different pH values, 4.5 and 7.4, that affected the release profiles of VANCO. Disk diffusion tests performed with pathogens causing osteomyelitis methicillin-resistant Staphylococcus aureus (MRSA) showed antibacterial activity of the released drug at two different pH values. Additionally, injection of 8 × 10⁶ CFU MRSA in rat's tibia induced severe osteomyelitis disease. Radiographic and histopathological analyses were performed to evaluate the effectiveness of treatment after 6 weeks. The VANCO-loaded silk fibroin nanoparticles entrapped in scaffolds reduced bone infections at the defected site with better outcomes than the other treatment groups. In conclusion, the delivery system with good biocompatibility and sustained release properties would be appropriate for further study in the context of osteomyelitis disease.

Antimicrobial Formulations of Absorbable Bone Substitute Materials as Drug Carriers Based on Calcium Sulfate

Substitution of bones is a well-established, necessary procedure to treat bone defects in trauma and orthopedic surgeries. For prevention or treatment of perioperative infection, the implantation of resorbable bone substitute materials carrying antibiotics is a necessary treatment. In this study, we investigated the newly formulated calcium-based resorbable bone substitute materials containing either gentamicin (CaSO4-G [Herafill-G]), vancomycin (CaSO4-V), or tobramycin (Osteoset). We characterized the released antibiotic concentration per unit. Bone substitute materials were implanted in bones of rabbits via a standardized surgical procedure. Clinical parameters and levels of the antibiotic-releasing materials in serum were determined. Local concentrations of antibiotics were measured using antimicrobial tests of bone tissue. Aminoglycoside release kinetics in vitro per square millimeter of bead surface showed the most prolonged release for gentamicin, followed by vancomycin and, with the fastest release, tobramycin. In vivo level in serum detected over 28 days was highest for gentamicin at 0.42 μg/ml, followed by vancomycin at 0.11 μg/ml and tobramycin at 0.04 μg/ml. The clinical parameters indicated high biocompatibility for materials used. None of the rabbits subjected to the procedure showed any adverse reaction. The highest availability of antibiotics at 14.8 μg/g on day 1 in the cortical tibia ex vivo was demonstrated for gentamicin, decreasing within 14 days. In the medulla, vancomycin showed a high level at 444 μg/g on day 1, decreasing continuously over 14 days, whereas gentamicin decreased faster within the initial 3 days. The compared antibiotic formulations varied significantly in release kinetics in serum as well as locally in medulla and cortex.

Elution of Clindamycin and Enrofloxacin From Calcium Sulfate Hemihydrate Beads In Vitro

OBJECTIVE

To compare the in vitro elution characteristics of clindamycin and enrofloxacin from calcium sulfate hemihydrate beads containing a single antibiotic, both antibiotics, and each antibiotic incubated in the same eluent well.

STUDY DESIGN

Experimental in vitro study.

METHODS

Calcium sulfate hemihydrate beads were formed by mixing with clindamycin and/or enrofloxacin to create 4 study groups: (1) 160 mg clindamycin/10 beads; (2) 160 mg enrofloxacin/10 beads; (3) 160 mg clindamycin + 160 mg enrofloxacin/10 beads; and (4) 160 mg clindamycin/5 beads and 160 mg enrofloxacin/5 beads. Chains of beads were formed in triplicate and placed in 5 mL phosphate buffered saline (PBS; pH 7.4 and room temperature) with constant agitation. Antibiotic-conditioned PBS was sampled at 14 time points from 1 hour to 30 days. Clindamycin and enrofloxacin concentrations in PBS were determined using high-performance liquid chromatography.

RESULTS

Eluent concentrations from clindamycin-impregnated beads failed to remain sufficiently above minimum inhibitory concentration (MIC) for common infecting bacteria over the study period. Enrofloxacin eluent concentrations remained sufficiently above MIC for common wound pathogens of dogs and cats and demonstrated an atypical biphasic release pattern. No significant differences in elution occurred as a result of copolymerization of the antibiotics into a single bead or from individual beads co-eluting in the same eluent well.

CONCLUSION

Clindamycin-impregnated beads cannot be recommended for treatment of infection at the studied doses; however, use of enrofloxacin-impregnated beads may be justified when susceptible bacteria are cultured.

Antimicrobial food packaging: potential and pitfalls

Nowadays food preservation, quality maintenance, and safety are major growing concerns of the food industry. It is evident that over time consumers’ demand for natural and safe food products with stringent regulations to prevent food-borne infectious diseases. Antimicrobial packaging which is thought to be a subset of active packaging and controlled release packaging is one such promising technology which effectively impregnates the antimicrobial into the food packaging film material and subsequently delivers it over the stipulated period of time to kill the pathogenic microorganisms affecting food products thereby increasing the shelf life to severe folds. This paper presents a picture of the recent research on antimicrobial agents that are aimed at enhancing and improving food quality and safety by reduction of pathogen growth and extension of shelf life, in a form of a comprehensive review. Examination of the available antimicrobial packaging technologies is also presented along with their significant impact on food safety. This article entails various antimicrobial agents for commercial applications, as well as the difference between the use of antimicrobials under laboratory scale and real time applications. Development of resistance amongst microorganisms is considered as a future implication of antimicrobials with an aim to come up with actual efficacies in extension of shelf life as well as reduction in bacterial growth through the upcoming and promising use of antimicrobials in food packaging for the forthcoming research down the line.

The use of bone cement for the localized, controlled release of the antibiotics vancomycin, linezolid, or fusidic acid: effect of additives on drug release rates and mechanical strength

Bone cement containing antibiotics is commonly used to treat orthopedic related infections. However, effective treatment (especially of resistant bacteria, methacillin-resistant Staphylococcus aureus (MRSA)) is compromised by very low levels of drug release so that typically less than 10% of loaded drug is released over a 6-week period. The objective of this study was to investigate the effect of incorporation of water soluble excipients (polyethylene glycol, sodium chloride, or dextran) into antibiotic-loaded cement on mechanical strength and drug release properties. Poly(methyl methylacrylate) cement implants containing various amounts of drug (vancomycin, linezolid or fusidic acid (all MRSA active)) and excipients were cast in the form of beads or films and characterized using differential scanning calorimetry. Mechanical strength as assessed by Young's modulus was determined by thermo-mechanical analysis. Drug release was measured by incubation in phosphate buffered saline with analysis by HPLC methods. The inclusion of sodium chloride up to 20% w/w caused only minor reductions in Young's modulus. Vancomycin and linezolid released very slowly from unmodified bone cement beads (less than 3% released by 4 weeks) whereas fusidic acid released more quickly (approximately 8% released by 4 weeks). The inclusion of sodium chloride or dextran in bone cement resulted in major increases in the release rate of vancomycin, linezolid and fusidic acid. These studies support the inclusion of sodium chloride and dextran in bone cement to increase the release rate of vancomycin, linezolid, or fusidic acid without compromising the mechanical strength of the composite material.

Antimicrobial food packaging: potential and pitfalls

Nowadays food preservation, quality maintenance, and safety are major growing concerns of the food industry. It is evident that over time consumers' demand for natural and safe food products with stringent regulations to prevent food-borne infectious diseases. Antimicrobial packaging which is thought to be a subset of active packaging and controlled release packaging is one such promising technology which effectively impregnates the antimicrobial into the food packaging film material and subsequently delivers it over the stipulated period of time to kill the pathogenic microorganisms affecting food products thereby increasing the shelf life to severe folds. This paper presents a picture of the recent research on antimicrobial agents that are aimed at enhancing and improving food quality and safety by reduction of pathogen growth and extension of shelf life, in a form of a comprehensive review. Examination of the available antimicrobial packaging technologies is also presented along with their significant impact on food safety. This article entails various antimicrobial agents for commercial applications, as well as the difference between the use of antimicrobials under laboratory scale and real time applications. Development of resistance amongst microorganisms is considered as a future implication of antimicrobials with an aim to come up with actual efficacies in extension of shelf life as well as reduction in bacterial growth through the upcoming and promising use of antimicrobials in food packaging for the forthcoming research down the line.

Highly efficient release of simvastatin from simvastatin-loaded calcium sulphate scaffolds enhances segmental bone regeneration in rabbits

A number of clinical and experimental studies have investigated the effect of simvastatin on bone regeneration. In the present study, the release of simvastatin from simvastatin-loaded calcium sulphate (CS) scaffolds and the effect of these scaffolds on osteogenic differentiation of bone marrow-derived mesenchymal stem cells (MSCs) in vitro and the effect of simvastatin locally applied from CS scaffolds on bone regeneration were investigated. A total of 26 complete 1.2-cm bone defects were created in the ulna of rabbits, which were treated with CS, simvastatin-loaded CS or recombinant human bone morphogenetic protein 2 (rhBMP)-2-loaded CS. Simvastatin was highly efficiently released from simvastatin-loaded CS at the onset and stable release was maintained. Alkaline phosphatase was highly expressed in the MSCs co-cultured with simvastatin/CS scaffolds for 7 and 14 days. The defects treated with rhBMP-2-loaded CS and simvastatin-loaded CS showed significantly higher X-ray analysis scores and a larger amount of bone formation as determined by histology compared with the CS group (P<0.05). No significant differences in the X-ray score and bone formation were observed between groups with rhBMP-2-loaded CS and simvastatin-loaded CS (P>0.05). Simvastatin is capable of promoting osteogenic differentiation of MSCs in vitro and stimulating bone regeneration when locally released from CS scaffolds into bone defects. The beneficial effect of simvastatin was similar to that of rhBMP-2. In conclusion, the present study suggested that the simvastatin-loaded CS scaffolds may have great potential in bone tissue engineering.

In vitro elution characteristics of gentamicin and vancomycin from synthetic bone graft substitutes

Objects:

Beta tricalciumphosphate pellets loaded with individualized antibiotics may represent novel options in the treatment of osteomyelitis and infectious bone disease. Here, the in vitro antibiotic elution of vancomycin and gentamicin from the synthetic bone graft substitutes Cerasorb^® and Cerasorb M^® was tested.

Methods:

Antibiotic elution and concentration of gentamcin and vancomycin were measured using photometrically-based measurement and homogeneous particle-enhanced turbidimetric inhibition immunoassays (PETINIA).

Results:

Initially both materials showed a high release of the loaded antibiotics, with Cerasorb M^® showing lower release levels for gentamicin and vancomycin than Cerasorb^®. Gentamicin concentrations of Cerasorb M granules and Cerasorb were below the minimum detectiontreshold until day four and six of the experiment respectively. The vancomycin release-level followed a similar pattern, although the vancomycin concentration eluted by Cerasorb M^® granules stayed above the detection threshold during the experimental time.

Conclusions:

Cerasorb^® and Cersorb M^® may represent a new treatment option in osteomyelitis and infectious bone disease.

Mesenchymal stem cell sheet transplantation combined with locally released simvastatin enhances bone formation in a rat tibia osteotomy model

Nonunion of fractured bones is a common clinical problem for orthopedic surgeons. This study aimed to investigate the effects of simvastatin locally applied from calcium sulfate (CS) combined with a mesenchymal stem cell (MSC) sheet on fracture healing. In vitro, the proliferation and differentiation of rat bone marrow-derived MSCs stimulated by simvastatin were investigated. In vivo, an osteotomy model was made in rat tibia, and fractured tibias were treated with CS, CS/simvastatin, CS/MSC sheet or simvastatin-loaded CS with MSC or untreated (control). Tibias were harvested at 2 or 8 weeks and underwent real-time quantitative polymerase chain reaction, x-ray, micro-CT and histological analysis. The expression levels of bone morphogenetic protein 2, alkaline phosphatase, osteocalcin, osteoprotegerin and vascular endothelial growth factor of simvastatin-induced MSCs increased with the concentrations of the simvastatin, significantly higher than those in the MSCs group. At 2 weeks, the CS/simvastatin/MSC sheet group showed significantly higher expressions of bone morphogenetic protein 2, alkaline phosphatase, osteocalcin, osteoprotegerin and vascular endothelial growth factor, with more callus formation around the fracture site compared with the other four groups. At 8 weeks, complete bone union was obtained in the CS/simvastatin/MSC sheet group. By contrast, newly regenerated bone tissue partially bridged the gap in the CS/simvastatin group and the CS/MSC sheet group; the control and CS group showed nonunion of the tibia. These results show that both simvastatin and the MSC sheet contributed to the formation of new bone and that the tibia fracture was completely healed by transplantation of the MSC sheet with locally applied simvastatin. Such MSC sheet with locally applied simvastatin might contribute to the treatment of fractures, bone delayed unions or nonunions in clinical practice.

IN VITRO ELUTION OF GENTAMICIN FROM LOCALLY IMPLANTABLE BEADS

Locally implantable antibiotic beads have been approved for their efficacy in treating chronic osteomyelitis. This study aimed to compare the in vitro elution characteristics of commercial antibiotic cement (Septopal®) with those of custom-made gentamicin cement and gentamicin-loaded plaster of Paris. Septopal® had a better inhibitive effect than custom-made gentamicin cement and gentamicin-loaded plaster of Paris for both S. aureus and P. aeruginosa at one month. The elution of gentamicin from Septopal® declined gradually over one month in contrast to those of custom-made gentamicin cement and gentamicin-loaded plaster of Paris, which had a burst effect of elution and showed a small amount of gentamicin after one week. There was a significantly higher total amount of gentamicin eluted from Septopal® than from other types of noncommercially prepared beads. The variability of the inhibitive effect of custom-made gentamicin cement was more pronounced than those of Septopal® and gentamicin-loaded plaster of Paris groups. In conclusion, Septopal® has a better elution characteristic than custom-made gentamicin cement and gentamicin-loaded plaster of Paris in the in vitro study.

Infection, inflammation, and bone regeneration: a paradoxical relationship

Various strategies have been developed to promote bone regeneration in the craniofacial region. Most of these interventions utilize implantable materials or devices. Infections resulting from colonization of these implants may result in local tissue destruction in a manner analogous to periodontitis. This destruction is mediated via the expression of various inflammatory mediators and tissue-destructive enzymes. Given the well-documented association among microbial biofilms, inflammatory mediators, and tissue destruction, it seems reasonable to assume that inflammation may interfere with bone healing and regeneration. Paradoxically, recent evidence also suggests that the presence of certain pro-inflammatory mediators is actually required for bone healing. Bone injury (e.g., subsequent to a fracture or surgical intervention) is followed by a choreographed cascade of events, some of which are dependent upon the presence of pro-inflammatory mediators. If inflammation resolves promptly, then proper bone healing may occur. However, if inflammation persists (which might occur in the presence of an infected implant or graft material), then the continued inflammatory response may result in suboptimal bone formation. Thus, the effect of a given mediator is dependent upon the temporal context in which it is expressed. Better understanding of this temporal sequence may be used to optimize regenerative outcomes.

Antibiotic-loaded chitosan film for infection prevention: A preliminary in vitro characterization

The growing infection rate by methicillin-resistant Staphylococcus aureus, especially with bone fracture fixation implants, is a major concern in extremity musculoskeletal wound treatment. This preliminary investigation evaluates the ability of chitosan film to be loaded with daptomycin and vancomycin in the operating room, in situ loading, and applied to musculoskeletal fixation devices to lessen or prevent infection. Films with 61, 71, and 80% degrees of deacetylation (DDA) made using lactic or acetic acid solvents were analyzed for their antibiotic uptake, elution, and activity along with film swelling ratio, ultimate tensile strength, Young's modulus, adhesive strength, and degradation. Chitosan films after 1 min of rehydration were able in a simulated, clinical setting to maintain mechanical integrity and adhesive strength to be applied to bone fracture fixation devices or implant surfaces. The film percent degradation increased with DDA increasing from 61 to 80%, but film degradation rate decreased in the presence of antibiotics. Eighty percent DDA chitosan films were optimal for absorbing and eluting antibiotics. Antibiotics eluted by the films were active against Staphylococcus aureus. These findings indicate that an 80% DDA chitosan film is potentially advantageous as a clinically adjunctive treatment in musculoskeletal injuries to lessen or prevent infections.

Chitosan sponges to locally deliver amikacin and vancomycin: a pilot in vitro evaluation

BACKGROUND

Open orthopaedic wounds are ideal sites for infection. Preventing infection in these wounds is critical for reducing patient morbidity and mortality, controlling antimicrobial resistance and lowering the cost of treatment. Localized drug delivery has the potential to overcome the challenges associated with traditional systemic dosing. A degradable, biocompatible polymer sponge (chitosan) that can be loaded with clinician-selected antibiotics at the point of care would provide the patient and clinician with a desirable, adjunctive preventive modality.

QUESTIONS/PURPOSES

We asked (1) if an adaptable, porous chitosan matrix could absorb and elute antibiotics for 72 hours for potential use as an adjunctive therapy to débridement and lavage; and (2) if the sponges could elute levels of antibiotic that would inhibit growth of Staphylococcus aureus and Pseudomonas aeruginosa?

METHODS

We fabricated a degradable chitosan sponge that can be loaded with antibiotics during a 60-second hydration in drug-containing solution. In vitro evaluation determined amikacin and vancomycin release from chitosan sponges at six time points. Activity tests were used to assess the release of inhibitory levels of amikacin and vancomycin.

RESULTS

Amikacin concentration was 881.5 microg/mL after 1 hour with a gradual decline to 13.9 microg/mL after 72 hours. Vancomycin concentration was 1007.4 microg/mL after 1 hour with a decrease to 48.1 microg/mL after 72 hours. Zone of inhibition tests were used to verify inhibitory levels of drug release from chitosan sponges. A turbidity assay testing activity of released amikacin and vancomycin indicated inhibitory levels of elution from the chitosan sponge.

CLINICAL RELEVANCE

Chitosan sponges may provide a potential local drug delivery device for preventing musculoskeletal infections.

Clinical effect of subgingivally delivered simvastatin in the treatment of patients with chronic periodontitis: a randomized clinical trial

BACKGROUND

Periodontitis is an inflammatory disease that results in bone resorption creating bony defects, which may cause tooth loss. Various drugs have been studied using local delivery to improve the periodontal health and to achieve periodontal regeneration. Simvastatin (SMV) is a specific competitive inhibitor of 3-hydroxy-2-methyl-glutaryl coenzyme A reductase. The present study was designed to investigate the effectiveness of SMV, 1.2 mg, in an indigenously prepared biodegradable controlled-release gel as an adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis.

METHODS

Sixty patients were categorized into two treatment groups: SRP plus placebo (group 1) and SRP plus SMV, 1.2 mg (group 2). Clinical parameters were recorded at baseline before SRP and at 1, 2, 4, and 6 months; they included modified sulcus bleeding index (mSBI), probing depth (PD), and clinical attachment level (CAL). At baseline and after 6 months, radiologic assessment of intrabony defect (IBD) fill was done using computer-aided software. The mean concentration of SMV in gingival crevicular fluid was estimated by reverse-phase high-performance liquid chromatography.

RESULTS

All subjects tolerated the drug, without any postapplication inflammation. Both therapies resulted in significant improvements. The decrease in mSBI score at 6 months was greater in group 2 (2.3267 +/- 0.8017) compared to group 1 (0.5033 +/- 0.6815). The mean decrease in PD from baseline to 6 months was 1.20 +/- 1.24 mm and 4.26 +/- 1.59 mm in groups 1 and 2, respectively. Mean CAL gain from baseline to 6 months was 1.63 +/- 1.99 mm and 4.36 +/- 1.92 mm in groups 1 and 2, respectively. In group 2, there was greater decrease in mean IBD (1.41 +/- 0.74 mm or 32.54%) compared to group 1 (0.09 +/- 0.58 mm or 2.16%).

CONCLUSION

There was a greater decrease in gingival index and PD and more CAL gain with significant IBD fill at sites treated with SRP plus locally delivered SMV in patients with chronic periodontitis.

Delivery of Antifungal Agents Using Bioactive and Nonbioactive Bone Cements

Background:

Management of fungal osteomyelitis is prolonged and frequently unsuccessful. Antifungal-impregnated cement is sometimes used as adjunctive therapy.

Objective:

To examine the release of antifungals from biodegradable and nonbiodegradable cement carriers.

Methods:

In vitro methods were used to assess antifungal drug release and antifungal activity of impregnated cements commonly used as adjunctive treatment of osteomyelitis. Cements included thermoplastic, nonbioactive polymers (polymethylmethacrylate [PMMA]) or bioactive agents (hydroxyapatite [HAP], β-tricalcium phosphate [β-TCP]) and were formed into spheres (beads).

Results:

Amphotericin B provided consistent supernatant concentrations (release), between 1.75 and 2.0 ug/mL, over 110 days from all bone cements. Flucytosine and fluconazole were observed for 33–42 days before becoming undetectable from a nonbioactive sphere and 18–22 days from a bioactive sphere. Serum concentrations for micafungin, terbinafine, and anidulafungin impregnated into PMMA rapidly became undetectable, regardless of the matrix used. Investigational β-TCP spheres prolonged release for fluconazole and micafungin, but had no effect on amphotericin B. Serum calcium concentrations decreased 60–80% in all HAP-impregnated drug sphere supernatants. Only amphotericin B–impregnated PMMA impacted supernatant calcium, decreasing concentrations by 50–60%. The antifungal-impregnated beads did not appear to be toxic to osteoblasts during 72 hours of exposure in tissue culture medium.

Conclusions:

Elution characteristics of most antifungals from bone cement spheres are probably not optima) for treatment of deep-seated fungal infections if a similar phenomenon of antifungal release manifests in vivo. Ceramic nonabsorbable impregnated devices must be removed after their lifespan expires and may necessitate another surgical procedure that can increase surgical risk and cost. Bioactive osteoconductive materials may provide a surgical alternative to nonabsorbable matrices. However, there have been no controlled trials demonstrating improved therapeutic outcomes with local therapy and assessing whether biodegradable materials act as a new focus for infection.

Clinical and microbiologic effects of subgingivally delivered 0.5% azithromycin in the treatment of chronic periodontitis

BACKGROUND

Recent developments suggest that the local delivery of antimicrobials into periodontal pockets can improve periodontal health. The present study was undertaken to investigate the clinical and microbiologic effectiveness of azithromycin (AZM) at 0.5% concentration in an indigenously prepared bioabsorbable controlled-release gel as an adjunct to non-surgical mechanical therapy in the treatment of chronic periodontitis.

METHODS

Eighty patients were categorized into two treatment groups: scaling and root planing (SRP) only (group 1) and SRP plus 0.5% AZM (group 2). Clinical parameters were recorded at baseline and 1, 2, and 3 months; they included modified gingival index, modified sulcus bleeding index, probing depth (PD), and clinical attachment level (CAL). At baseline and 6 and 12 weeks, microbiologic assessment was done of the percentage of morphologically different microorganisms (coccoid cells, others [straight rods, filaments, and fusiforms], motile rods, and spirochetes) using darkfield microscopy. The mean concentration of 0.5% AZM in gingival crevicular fluid was estimated by reverse phase high performance liquid chromatography.

RESULTS

Both therapies resulted in significant improvements. Mean PD reduction from baseline to 3 months was 2.13 +/- 0.35 mm and 2.53 +/- 0.52 in groups 1 and 2, respectively. Mean CAL gain from baseline to 3 months was 0.60 +/- 0.63 mm and 1.07 +/- 0.70 mm in groups 1 and 2, respectively. All microbiologic categories showed significant improvement in both groups, with greater improvement in the test group. The mean concentration of AZM at all observed periods (baseline to 28 days) provided sufficient antimicrobial activity (>2 microg/ml) and fulfilled the conditions for a controlled-release device.

CONCLUSION

Although both treatment strategies seemed to benefit the patients, the adjunctive use of 0.5% AZM as a controlled drug-delivery system enhanced the clinical and microbiologic results as shown by the intergroup comparison.

Carrier systems and application of growth factors in orthopaedics

With optimal surgical treatment within an appropriate time frame, bony tissue has the potential to regenerate defects without the formation of scar tissue. However, even under optimal mechanical circumstances and appropriate operative treatment, healing can fail and delayed or non-union occur. In Europe delayed bone healing leads to socio-economic costs of up to 14.7 billion euros per year. In addition to the optimal clinical treatment, the success of bone regeneration depends on the following main aspects: (1) adequate mechanical stabilization and biological competence of the organism, (2) osteogenic cells, (3) osteoconductive structures or scaffolds, and (4) growth factors (Diamond Concept)(1). Further, (5) a sufficient vascularisation is essential for the nutritive supply. Within the last years two growth factors, BMP-2 and BMP-7, were approved for clinical use in orthopaedic and trauma surgery for different indications.(2,3) The establishment of carrier systems and application techniques for growths factors is the focus of current research. The combination of a well established stabilization system and local drug delivery system for bioactive factors could be a therapeutical strategy to optimize bone healing and reduce the complication rate, in the future.

Chitosan films: a potential local drug delivery system for antibiotics

Local antibiotic delivery is an emerging area of study designed to provide alternative methods of treatment to clinicians for compromised wound sites where avascular zones can prevent the delivery of antibiotics to the infected tissue. Antibiotic-loaded bone cement is the gold standard for drug-eluting local delivery devices but is not ideal because it requires a removal surgery. Chitosan is a biocompatible, biodegradable polymer that has been used in several different drug delivery applications. We evaluated chitosan as a potential localized drug delivery device. We specifically determined if chitosan could elute antibiotics in an active form that would be efficacious in inhibiting S. aureus growth. Elution of amikacin was 24.67 +/- 2.35 microg/mL (85.68%) after 1 hour with a final cumulative release of 27.31 +/- 2.86 microg/mL (96.23%) after 72 hours. Elution of daptomycin was 10.17 +/- 3.83 microg/mL after 1 hour (31.61% release) and 28.72 +/- 6.80 microg/mL after 72 hours (88.55%). The data from the elution study suggested effective release of amikacin and daptomycin. The activity studies indicated the eluants inhibited the growth of S. aureus. Incorporating antibiotics in chitosan could provide alternative methods of treating musculoskeletal infections.

An optimized β-tricalcium phosphate and agarose scaffold fabrication technique

Biodegradable scaffolds composed of beta-tricalcium phosphate, and a natural hydrogel, agarose, were prepared by a shaping method based on the thermal gelation of the polymeric component. This technique was modified to facilitate the inclusion, during the scaffold preparation stage, of therapeutic agents that could improve the graft performance. Vancomycin was included in materials containing different amounts of agarose and ceramic without affecting the scaffold consolidation process. These materials, easily injectable, behave like a reinforced hydrogel whose swelling behavior and drug release rate depend on their composition.

Improving the drug selection and development process for combination devices

Combination devices are at the interface of both pharmaceutical and medical device research. While there have been several notable successes in bringing combination devices to market there are drug selection criteria that both the pharmaceutical and medical device companies need to consider. A successful combination device creates a product that has efficacy greater than the sum of the parts. However, failure to address some aspects of the drug or biologic properties in enough detail could result in a suboptimal product, creating a challenging legacy for future iterations. This review addresses the many dimensions including opportunities and challenges of combination device development from both the device and pharmaceutical perspectives.

Elution characteristics and mechanical properties of calcium sulfate-loaded bone cement containing teicoplanin

BACKGROUND

Acrylic bone cement is the most widely used drug delivery system clinically. It has already been shown that antibiotic release is significantly increased when calcium sulfate-loaded acrylic bone cement is used. However, there is no information yet about the mechanical responses of these composite materials. Thus, the purpose of this study was to investigate the effect of calcium sulfate on the elution characteristics and mechanical behavior of teicoplanin-loaded acrylic bone cement.

METHODS

Four groups of acrylic bone cements (GI, GII, GIII, GIV) were prepared using the same liquid/powder ratios. After mixing, the bone cement and additive mixtures were packed into different-type molds to prepare the specimens for the elution and mechanical tests. All of the specimens were tested for two conditions (dry and human plasma solution). The mechanical tests included the setting time (hardness) and tensile, bending, and compression strengths. The fracture surfaces of the failed samples were also examined by scanning electron microscopy.

RESULTS

Teicoplanin release in the calcium sulfate powder added groups (GIII and GIV) was higher than that of GII. When the calcium sulfate and teicoplanin were added on acrylic bone cement, the compressive, bending and tensile strength, hardness values, and elastic modulus decreased. Also, further reductions were evident in human plasma solution.

CONCLUSIONS

Although mechanical properties of tested specimens decreased, all of the results obtained were higher than those required by the American Society for Testing and Materials Standards, but further investigations are necessary before making definitive statements for clinical applications.

Bone Formation With the Combination of Simvastatin and Calcium Sulfate in Critical-Sized Rat Calvarial Defect

Simvastatin, a cholesterol synthesis inhibitor, enhances BMP2 expression in osteoblasts. The purpose of the present study was to examine whether simvastatin stimulates bone regeneration when combined with calcium sulfate as a carrier. Critical-sized bone defects in rat calvaria were treated with calcium sulfate or with combination of 1 mg simvastatin and calcium sulfate. In the combination group, although the least amount of bone formation with intense soft tissue inflammation was observed at 2 and 4 weeks, remarkable bone formation was evident at 8 weeks. Conclusively, the combination of simvastatin and calcium sulfate stimulated bone regeneration in spite of the inflammatory response.

Cyanoacrylate adhesive provides efficient local drug delivery

Biodegradable drug delivery systems have advanced treatment of a wide spectrum of musculoskeletal problems. However, their lack of availability and cost can restrict use. To find an easily available and inexpensive biodegradable implant, we tested a widely used tissue adhesive, n-butyl-2-cyanoacrylate, as a drug-trapping material. We tested vancomycin with commercially available absorbable gelatin-sponge pieces as the scaffold. We evaluated the in vitro and in vivo drug release profiles and in vivo inflammatory response. A mouse muscle pouch model was used for in vivo evaluations. The released vancomycin level was measured by fluorescence polarization immunoassay technique, and a leukocyte count-based grading system was used to evaluate inflammatory response. Our findings suggest the proposed implant provides effective drug release for as much as 42 days in vitro and 14 days in vivo. The presence of n-butyl-2-cyanoacrylate led to a local inflammatory response which decreased after 3 weeks in the group with less adhesive. These results showed that n-butyl-2-cyanoacrylate could efficiently trap and slowly release a drug when used in the structure of a biodegradable local drug delivery device.

Vancomycin biodegradable poly(lactide-co-glycolide) microparticles for bone implantation. Influence of the formulation parameters on the size, morphology, drug loading and in vitro release

The present study investigates vancomycin microencapsulation in biodegradable PLAGA microparticles. To optimize encapsulation efficiency by the double emulsion (w/o/w) solvent evaporation/extraction process, two parameters were studied: surfactant (Span 80) rate and external aqueous phase saturation. In vitro dissolution studies, laser granulometry and scanning electron microscopy were performed to characterize the microparticles. The best results were obtained by stabilizing the first emulsion with 0.5% Span 80 and saturating the external phase with sodium chloride. Such parameters allowed a 95% drug encapsulation efficiency. This process yielded round microparticles with a mean diameter of approximately 170 microm and presenting a smooth surface without any pores. Moreover, this formulation induces a sustained drug release at a constant rate over a period of 10 days. Such materials could be associated with biphasic calcium phosphate granules to form an antibiotic-loaded injectable bone substitute offering a long-term activity in situ.

Minimizing the surgical approach in patients with spondylitis

Minimizing the surgical approach in treating patients with spinal infections by using local antibiotic treatment and avoiding a ventral approach reduces the anesthesia and surgical risks in patients with comorbidities. In this study we used calcium sulphate pellets (OsteoSet T and the OsteoSet Bone-void Filler kit) as a delivery system for different antibiotics. Of a group of 32 patients with histologically and microbiologically diagnosed spondylitis, a cohort of 16 patients was treated by just a dorsal surgical approach in combination with a local antibiotic delivery system. Of these 16 patients, 14 patients showed a normalization of the infection parameters, no more bone loss in the spondylitic region, and a bony fusion after 6 to 9 months postoperatively. Two patients died from septic circumstances 4 and 6 weeks postoperatively. Two patients had to have one revision surgery because of a seroma; no other complications caused by the calcium sulphate pellets were observed. The use of calcium sulphate pellets as antibiotic delivery system allows a controlled local antibiotic therapy with an osteoconductive material in combination with a minimized surgical approach. Furthermore, calcium sulphate pellets have proven their reliable capability as bone void filler.

Local antibiotic delivery vehicles in the treatment of musculoskeletal infection

The primary benefit achieved with local antibiotic delivery vehicles is the ability to obtain extremely high levels of local antibiotics without increasing systemic toxicity. Antibiotic-loaded bone cement represents the current standard as an antibiotic delivery vehicle in orthopaedic surgery. Biodegradable alternatives to antibiotic-loaded bone cement also are being used clinically and there are many new products in the active stages of development. These alternatives can be categorized as bone graft, bone graft substitutes or extenders, natural polymers (protein-based products), and synthetic polymers. Composite biomaterials that simultaneously provide the functions of variable antibiotic delivery patterns and also contribute to the process of bone regeneration represent the most ideal class of local antibiotic delivery vehicles. High concentrations of certain antibiotics have been shown to affect the process of normal bone regeneration adversely in a dose dependent response. Considerable investigation still is required to determine the proper use of locally administered antibiotics to negotiate the balance between eradicating infection without excessively inhibiting the processes of bone regeneration.

In vitro and in vivo bactericidal activities of vancomycin dispersed in porous biodegradable poly(epsilon-caprolactone) microparticles

Treatment of methicillin-resistant Staphylococcus aureus osteomyelitis requires a prolonged antibiotic therapy with vancomycin. Because of its weak diffusion, the in situ implantation of vancomycin could be interesting. The activity of vancomycin encapsulated in microparticles was evaluated in vitro and in vivo on rabbit osteomyelitis and showed a good activity compared to intravenous administration.

Nanocrystalline hydroxyapatite and calcium sulphate as biodegradable composite carrier material for local delivery of antibiotics in bone infections

The use of polymethylmetacrylate beads for local delivery of antibiotics requires a second surgical procedure for their removal and resorbable calcium sulphate exhibits cytotoxic effects. In this work, a bioresorbable composite of calcium sulphate and nanoparticulate hydroxyapatite (PerOssal was studied regarding its antibiotic release properties and biocompatibility. Material characteristics of plain PerOssal and pure calcium sulphate pellets were studied using scanning and electron microscopy and X-ray methods. Pellets were soaked with gentamicin and vancomycin, respectively. Release properties of both antibiotics from both materials were investigated over 10 days. Quantitative and qualitative cytotoxic assays were performed for biocompatibility testing. Specific surface was 106 m(2)/g for PerOssal and 2.2 m(2)/g for pure calcium sulphate. Almost complete elution of gentamicin was found for both carrier materials (94.7% for PerOssal vs. 95.8% for calcium sulphate) within 10 days, whereas vancomycin release was higher for PerOssal (96.3% vs. 74.8%). PerOssal showed higher initial and lower release after approximately 5 days compared to calcium sulphate. No significant in vitro cytotoxic differences were found between PerOssal and nontoxic cell culture medium. Calcium sulphate showed cytotoxic effects in two out of four tests. PerOssal exhibits excellent properties regarding resorption, biocompatibility, and antibiotic release.

In vivo tissue response to resorbable silica xerogels as controlled-release materials

Biodegradable, controlled-release carrier materials with non-toxic degradation products are valuable for local delivery of biologically active molecules. Previously, it was shown that room-temperature processed silica sol-gels (or xerogels) are porous, resorbable materials that can release molecules of various sizes in a controlled, time dependent manner. Previous in vitro studies also demonstrated benefits of silica xerogels as controlled-release materials for the treatment of bone infections. Herein the tissue and cell response to xerogels is documented using a subacute implantation procedure. The tissue response was correlated to composition, surface properties, resorption rate and incorporation of the antibiotic vancomycin. Ca- and P-free and Ca- and P-containing xerogels, with and without apatite (AP) surface, were used. Xerogels were implanted either as discs in a subcutaneous site, or as granules in the iliac crest of New Zealand white rabbits. The samples with surrounding tissue were retrieved after 2 and 4 weeks of implantation. Silica xerogels implanted either as discs subcutaneously or as granules in the iliac crest showed a favorable tissue response. The granules, either with or without Ca and P content, gradually resorbed over time. The resorption was accompanied by extensive trabecular bone growth and a minimal inflammatory response. Ca- and P-containing granules with an AP-surface layer showed a slower resorption rate and more extensive new bone growth than those without AP layer. Among AP-coated granules, those with incorporated vancomycin showed the most favorable tissue response. The present in vivo data together with prior in vitro data suggest that these xerogels have potential as controlled-release materials for the treatment of bone infections and as carrier materials for a variety of other applications.