In vitro evaluation and intra-articular administration of biodegradable microspheres containing naproxen sodium

Applications and prospects of intra-articular drug delivery system in arthritis therapeutics

Arthritis is a kind of chronic disease that affects joints and muscles with the symptoms of joint pain, inflammation and limited movement of joints. Among various clinical therapies, drug therapy has been extensively applied because of its accessibility, safety and effectiveness. In recent years, the intra-articular injection has dramatic therapeutic effects in treating arthritis with high patient compliance and low side effects. In this review, we will introduce pathology of arthritis, along with the accessible treatment and diagnosis methods, then we will summarize major advances of current hopeful intra-articular delivery systems such as microspheres, hydrogels, nanoparticles and liposomes. At last, some safety assessments in the preclinical work and the main challenges for the further development of intra-articular treatment were also discussed.

Chitosan-Coated Hydroxypropylmethyl Cellulose Microparticles of Levodopa (and Carbidopa): In Vitro and Rat Model Kinetic Characteristics

Background

Parkinson's disease is a neurodegenerative disorder, and a major cause of disability. Levodopa, a prodrug of dopamine, remains the gold standard in the pharmacological management of Parkinson's disease. Despite several attempts to improve the clinical efficacy of levodopa, new oral levodopa formulations are needed to overcome irregular absorption and variable plasma concentrations.

Objective

The aim of this study was to evaluate the in vitro and in vivo kinetic properties of chitosan-coated hydroxypropylmethyl cellulose microparticles of levodopa (and carbidopa).

Methods

Microparticles were formulated by encapsulating levodopa powder in chitosan-coated hydroxypropylmethyl cellulose using the spray-drying method. Levodopa microparticles were evaluated for size, zeta potential, drug loading capacity, encapsulation efficiency and in vitro release. In evaluating in vivo pharmacokinetics, Sprague Dawley rats were administered either levodopa/carbidopa powder, levodopa/carbidopa microparticles, or Sinemet CR (a controlled release formulation of levodopa/carbidopa). The dose of respective formulations administered was 20/5 mg/kg; 20 mg levodopa combined with 5 mg carbidopa per kilogram body weight of animals. Treatments were administered via the oral route every 12 hours. Blood samples were collected after predetermined times following the third dose. Plasma was obtained from blood collected, and levodopa levels determined by HPLC. Pharmacokinetic parameters, including C_max, T_max, AUC, and t_½ of the various formulations, were estimated.

Results

The mean (SD) size of levodopa microparticles was 0.5 (0.05) µm with polydispersity index of 0.41 and a zeta potential of 10.8 mV. Of the expected 20% drug loading, the actual drug loading capacity of levodopa microparticles was found to be 19.1%, giving an encapsulation efficiency of 95.7%. The in vitro release kinetics of levodopa microparticles showed a controlled and sustained release, with about 80% release occurring after 12 hours. In vivo pharmacokinetic studies showed that rats administered levodopa/carbidopa microparticles had greater AUC (612.7 [17.42] ng.h/mL) and higher C_max (262.4 [38.86] ng/mL) compared with Sinemet CR: AUC 354.7 (98.09) ng.h/mL and C_max 95.5 (20.87) ng/mL. However, Sinemet CR had a much longer half-life (6.1 [2.58] hours) compared with levodopa/carbidopa microparticles (2.0 [0.31] hours).

Conclusions

Findings from this study suggest that chitosan-coated hydroxypropylmethyl cellulose microparticles of levodopa/carbidopa may give relatively high levels of levodopa in circulation. (Curr Ther Res Clin Exp. 2020; 81:XXX–XXX)

© 2020 Elsevier HS Journals, Inc.

An Efficient, Lung-Targeted, Drug-Delivery System To Treat Asthma Via Microparticles

BACKGROUND

Chronic diseases such as diabetes, asthma, and heart disease are the leading causes of death in developing countries. Public health plays an important role in preventing such diseases to improve individuals' quality of life. Conventional dosage schemes used in public health to cure various diseases generally lead to undesirable side effects and renders the overall treatment ineffective. For example, a required concentration of drug cannot reach the lungs using conventional methods to cure asthma. Microspheres have emerged as a confirmed drug-delivery system to cure asthma.

METHOD

In this paper, a salbutamol-loaded poly lactic acid-co-glycolic acid-polyethylene glycol (PLGA-PEG) microsphere (SPP)-based formulation was prepared using a Buchi B-90 nanospray drier. Face-centered central composite design (CCD) was applied to optimize the spray-drying process.

RESULTS

The drug content and product yield were found to be 72%±0.8% and 86%±0.4%, respectively; drug release (91.1%) peaked for up to 12 hrs in vitro. Microspheres obtained from the spray dryer were found to be shriveled. The experiments were carried out and verified using various groups of rabbits. In our study, the particle size (8.24 µm) was observed to be an essential parameter for drug delivery. The in vivo results indicated that the targeting efficacy and drug concentration in the lung was higher with the salbutamol-loaded PLGA-PEG SPP formulation (1,410.1±10.11 µg/g, 15 mins), as compared to the conventional formulation (92±0.56 µg/g, 10 min). The final product was stable under 5°C±2°C, 25°C±2°C, and 40°C±2°C/75%±5% relative humidity. In addition, these co-polymers have a good safety profile, as determined by testing on human alveolar basal epithelium A549 cell lines.

CONCLUSION

Our results prove that microspheres are an alternative drug-delivery system for lung-targeted asthma treatments used in public health.

Advances in nanomedicine for the treatment of ankylosing spondylitis

Ankylosing spondylitis (AS) is a complex disease characterized by inflammation and ankylosis primarily at the cartilage–bone interface. The disease is more common in young males and risk factors include both genetic and environmental. While the pathogenesis of AS is not completely understood, it is thought to be an immune-mediated disease involving inflammatory cellular infiltrates, and human leukocyte antigen-B27. Currently, there is no specific diagnostic technique available for this disease; therefore conventional diagnostic approaches such as clinical symptoms, laboratory tests and imaging techniques are used. There are various review papers that have been published on conventional treatment approaches, and in this review work, we focus on the more promising nanomedicine-based treatment modalities to move this field forward.

Liposome-encapsulated fish oil protein-tagged gold nanoparticles for intra-articular therapy in osteoarthritis

AIM

To provide multilayered combination therapies encompassing nanoparticles and organic peptides and to assess their efficacy in the treatment of arthritis.

MATERIALS & METHODS

Fish oil protein (FP) was isolated from fish oil glands and tagged with spherical gold nanoparticles (GNPs). Tagged GNPs were encapsulated in DPPC liposomes (FP-GNP-DPPC) and characterized.

RESULTS & CONCLUSION

FP increased the hydrophilicity of GNP, while encapsulation of FP-GNP within liposomes increased the hydrophobicity. In vitro release studies of FP-GNP-DPPC exhibited sustained release of FP in simulated synovial fluid. FP-GNP-DPPC injected into intra-articular joints of rats displayed anti-osteoarthritic effects in osteoarthritic rat model. This is the first study to report the anti-osteoarthritic activity of FP and DPPC encapsulated FP-GNP liposomes.

Celecoxib-loaded PEA microspheres as an auto regulatory drug-delivery system after intra-articular injection

In this study, we investigated the potential of celecoxib-loaded polyester amide (PEA) microspheres as an auto-regulating drug delivery system for the treatment of pain associated with knee osteoarthritis (OA). Celecoxib release from PEA microspheres and inflammation responsive release of a small molecule from PEA was investigated in vitro. Inflammation responsive release of a small molecule from PEA was observed when PEA was exposed to cell lysates obtained from a neutrophil-like Hl-60 cell line. Following a short initial burst release of ~15% of the total drug load in the first days, celecoxib was slowly released throughout a period of >80days. To investigate biocompatibility and degradation behavior in vivo, celecoxib-loaded PEA microspheres were injected in OA-induced (ACLT+pMMx) or contralateral healthy knee joints of male Lewis rats. Bioactivity of celecoxib from loaded PEA microspheres was confirmed by PGE₂ measurements in total rat knee homogenates. Intra-articular biocompatibility was demonstrated histologically, where no cartilage damage or synovial thickening and necrosis were observed after intra-articular injections with PEA microspheres. Degradation of PEA microspheres was significantly higher in OA induced knees compared to contralateral healthy knee joints, while loading the PEA microspheres with celecoxib significantly inhibited degradation, indicating a drug delivery system with auto regulatory behavior. In conclusion, this study suggests the potential of celecoxib-loaded PEA microspheres to be used as a safe drug delivery system with auto regulatory behavior for treatment of pain associated with OA of the knee.

Tartrate/tripolyphosphate as co-crosslinker for water soluble chitosan used in protein antigens encapsulation

In drug delivery research, several toxic chemical crosslinkers and non-toxic ionic crosslinkers have been exploited for the synthesis of microparticles from acetic acid soluble chitosan. This paper hypothesized the implementation of sodium potassium tartrate (SPT) as an alternative crosslinker for sodium tripolyphosphate (TPP) and SPT/TPP co-crosslinkers for synthesis of the microparticles using water soluble chitosan (WSC) for encapsulation of Bovine serum albumin (BSA) as a model protein, and Tetanus toxoid (TT) as a model vaccine. The crosslinking was confirmed by FT-IR, SEM with EDS. The XRD entailed molecular dispersion of proteins and thermal analysis confirmed the higher stability of STP/TPP co-crosslinked formulations. The resultant microparticles were exhibiting crosslinking degree (52-67%), entrapment efficiency (72-80%), particle size (0.3-1.7μm), zeta potential (+24 to 46mV) and mucoadhesion (41-68%). The superiority of SPT over TPP was confirmed by higher crosslinking degree and entrapment efficiency. However, co-crosslinking were advantageous in higher regression values for Langmuir adsorption isotherm, slower swelling tendency and extended 30days controlled in-vitro release study. TT release obeyed the Quasi-Fickian diffusion mechanism for single and cocrosslinked formulations. Overall, in crosslinking of chitosan as biological macromolecules, STP/TPP may be alternative for single ionic crosslinked formulations for protein antigen delivery.

High azithromycin concentration in lungs by way of bovine serum albumin microspheres as targeted drug delivery: lung targeting efficiency in albino mice

Background

Following administration, the antibiotic travels freely through the body and also accumulates in other parts apart from the infection site. High dosage and repeated ingestion of antibiotics in the treatment of pneumonia leads to undesirable effects and inappropriate disposition of the drug. By way of targeted lung delivery, this study was intended to eliminate inappropriate azithromycin disposition and to achieve higher azithromycin concentration to treat deeper airway infections.

Methods

The Azithromycin Albumin Microspheres (AAM) was prepared by emulsion polymerization technique. The optimized AAM was subjected to in vitro release study, release kinetics, XRD and stability studies. Further, in vivo pharmacokinetics and tissue distribution of azithromycin released from AAM and azithromycin solution in albino mice was investigated to prove suitability of moving forward the next steps in the clinic.

Results

The mean particle size of the optimized AAM was 10.02 μm, an optimal size to get deposited in the lungs by mechanical entrapment. The maximum encapsulation efficiency of 82.3 % was observed in this study. The release kinetic was significant and best fitted for Korsmeyer-Peppas model (R² = 0.9962, n = 0.41). The XRD and stability study showed favorable results. Azithromycin concentration in mice lungs (40.62 μg g⁻¹, 30 min) of AAM was appreciably higher than other tissues and plasma. In comparison with control, azithromycin concentration in lungs was 30.15 μg g⁻¹ after 30 min. The azithromycin AUC (929.94 μg h mL⁻¹) and intake rate (r_e) (8.88) for lung were higher and statistically significant in AAM group. Compared with spleen and liver, the targeting efficacy (t_e) in mice lung increased by a factor of 40.15 and ~14.10 respectively. Subsequently by a factor of 8.94, the ratio of peak concentration (C_e) in lung was higher in AAM treated mice. The AAM lung tissue histopathology did not show any degenerative changes.

Conclusions

High azithromycin concentration in albino mice lung was adequately achieved by targeted drug delivery.

Particle-based technologies for osteoarthritis detection and therapy

Osteoarthritis (OA) is a disease characterized by degradation of joints with the development of painful osteophytes in the surrounding tissues. Currently, there are a limited number of treatments for this disease, and many of these only provide temporary, palliative relief. In this review, we discuss particle-based drug delivery systems that can provide targeted and sustained delivery of imaging and therapeutic agents to OA-affected sites. We focus on technologies such as polymeric micelles and nano-/microparticles, liposomes, and dendrimers for their potential treatment and/or diagnosis of OA. Several promising studies are highlighted, motivating the continued development of delivery technologies to improve treatments for OA.

Particles for Local Delivery of Proteins Using Intra-Articular Route

Designing a vehicle for local delivery of proteins using intra-articular route is an attractive option to minimize the adverse effects associated with systemic exposure and to maximize the efficacy. Slowly dissolving silylated microparticles are designed with specific size and shape that are capable of extending the retention time of a model protein (bovine serum albumin) in the murine knee joint. No cytotoxicity is observed for the reconstituted formulation when tested against synovial fibroblasts and RAW 264.7 macrophages.

Intra-articular Administration of Chitosan Thermosensitive In Situ Hydrogels Combined With Diclofenac Sodium-Loaded Alginate Microspheres

The aims of this study were to prepare fine intra-articular-administrated chitosan thermosensitive hydrogels combined with alginate microspheres and to investigate the possibility of those hydrogels as a drug delivery system for promoting the anti-inflammation effect. Diclofenac sodium containing alginate microspheres was prepared by a modified emulsification and/or gelation method and then dispersed into injectable thermosensitive hydrogels, consisting of chitosan and β-glycerophosphate. The final combined hydrogels were evaluated in terms of their morphology properties, rheological properties, in vitro drug release, and in vivo biocompatibility and pharmacodynamics behaviors. The optimized formulation exhibited sol-gel transition at 31.72 ± 0.42°C and quickly turned into gel within 5 min, with sustained drug release characteristics followed Ritger-Peppas equation, which could prolong the in vitro drug release to 5 days. In addition, the anti-inflammation efficacy of the combined hydrogels in rabbits with experimental rheumatoid arthritis was higher than that of drug solution and pure chitosan hydrogels. Those results demonstrated that these combined hydrogels could become a potential drug delivery system for improving the therapeutic effect of diclofenac sodium and suggested an important technology platform for intra-articular administration.

Effect of particle size on the biodistribution of nano- and microparticles following intra-articular injection in mice

Intra-articular (IA) injection of extended drug release forms based on biodegradable microparticles holds promise for the treatment of joint diseases. However, the fate of microparticles following intra-articular injection is controversial and has not been thoroughly investigated. The aim of this work was therefore to evaluate the biodistribution of fluorescent poly(lactic acid) particles of different sizes after IA injection in arthritic or healthy mice. Regardless of the inflammatory status of the joint, 300 nm-nanoparticles leaked from the joint. Due to inflammation and related increase of vascular permeability, 3 μm-microparticles that were retained in the non-inflamed synovial membrane leaked from the inflamed joint. Complete retention of 10 μm-microparticles was observed independently of the joint inflammatory status. Embedding particles in a hyaluronic acid gel prolonged the retention of the formulations only in inflamed joints. Depending on particle's size, formulations were preferentially eliminated by blood vessels or lymphatic pathways. Poly(lactic acid) particles of 3 μm were biocompatible and retained in knee joints at least for 6 weeks. This work highlights the need to deliver hyaluronic acid-embedded particles of at least 3 μm to guarantee their retention in inflamed joints. These results will contribute to the rational design of long-lasting formulations to treat acute and chronic joint diseases.

Drug delivery systems for intra-articular treatment of osteoarthritis

INTRODUCTION

Intra-articular (IA) drug delivery is very useful in the treatment of osteoarthritis (OA), the most common chronic joint affliction. However, the therapeutic effect of IA administration depends mostly on the efficacy of drug delivery.

AREAS COVERED

The present article reviews the current status of IA therapy for OA treatment as well as its rationale. Outlines of drug delivery parameters such as release profile, retention time, distribution, size and transport that influence the drug's biological performance in the joints are summarized. New delivery systems, currently under investigation, including liposome, nanoparticle, microparticle and hydrogel formulations are introduced. Functionalized drug delivery systems by targeting and thermoresponsiveness that are being investigated for OA treatment via IA therapy are also addressed.

EXPERT OPINION

Several delivery systems, including liposome, microparticles, nanoparticles and hydrogels, have been investigated for the sustained drug delivery to the joints. These can be advanced by the use of functionalized drug delivery systems that can lead targeting to specific regions and thermoresponsiveness for prolonged drug release in the joints. Further advances will bring forth new biocompatible and biodegradable materials as a drug carrier or new combination regimens. Future innovations in this field should be directed toward the development of adapted delivery systems that can induce tissue regeneration in OA patients.

In vitro evaluation of S-(+)-ibuprofen as drug candidate for intra-articular drug delivery system

Intra-articular drug delivery systems (DDSs) are envisaged as interesting alternative to locally release non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen to reduce pain in patients with osteoarthritis. The present study examines the efficacy of S-(+)-ibuprofen on cartilage degradation as drug candidate for DDS loading. Humeral cartilage and joint capsule explants were collected from healthy sheep shoulder joints and they were cultured in mono- or in co-culture for 13 days with LPS in combination with S-(+)-ibuprofen at 50 µM and 1 mM. S-(+)-ibuprofen (50 µM) blocked prostaglandins production in LPS-activated explants but did not reduce cartilage degradation. By contrast, 1 mM S-(+)-ibuprofen treatment of cartilage explants reduced nitric oxide synthesis by 51% (p = 0.0072), proteoglycans degradation by 35% (p = 0.0114) and expression of serum amyloid protein - the main protein induced upon LPS challenge - by 44% (p < 0.0001). On contrary, in presence of synovial membrane, the protective effects of S-(+)-ibuprofen on cartilage damages were significantly diminished. At 1mM, S-(+)-ibuprofen reduced the cell lysis during culture of cartilage and joint capsule either in mono- or in co-culture. This study performed on sheep explants shows that 1 mM S-(+)-ibuprofen inhibited cartilage degradation via a mechanism independent of cyclooxygenase inhibition. Reduction of prostaglandins synthesis at 50 µM in all treatment groups and reduction of cartilage degradation observed at 1 mM suggest that S-(+)-ibuprofen could be considered as a promising drug candidate for the loading of intra-articular DDS.

Biodegradable polyesters containing ibuprofen and naproxen as pendant groups

Controlled release of nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen could be beneficial for the treatment of inflammatory diseases while reducing the side effects resulting from their continuous use. Novel biodegradable polyesters solely comprised of biocompatible components (e.g., tartaric acid, 1,8-octanediol, and ibuprofen or naproxen as pendant groups) have been synthesized using tin(II) 2-ethylhexanoate as catalyst at 130 °C and subsequently characterized to determine their structures and physicochemical properties. The polymers release the free drug (ibuprofen or naproxen) in vitro in a controlled manner without burst release, unlike the release rates achieved when the drugs are encapsulated in other polymers. These new biomaterials are not cytotoxic toward mouse fibroblasts up to 0.10 mg/mL. The drugs retain their chemical structure following hydrolytic degradation of the polymer, suggesting that bioactivity is preserved.

Nanoparticles for improved local retention after intra-articular injection into the knee joint

Purpose

To evaluate using cationic polymeric nanoparticles that interact with hyaluronate to form ionically cross-linked hydrogels to increase the intra-articular retention time of osteoarthritis drugs in the synovial cavity.

Methods

In vitro tests included nanoparticle release from cross-linked hydrogels using syringe and membrane dissolution tests, viscosity measurement of synovial fluid containing hydrogels, and release-rate measurement for a model active conjugated to a cationically substituted dextran using a hydrolyzable ester linkage in a sink dissolution test. Nanoparticle retention after intra-articular injection into rat knees was measured in vivo using fluorescence molecular tomography.

Results

Diffusional and convective transport of cationic nanoparticles from ionically cross-linked hydrogels formed in synovial fluid was slower in vitro than for uncharged nanoparticles. Hydrogels formed after the nanoparticles were mixed with synovial fluid did not appreciably alter the viscosity of the synovial fluid in vitro. In vitro release of a conjugated peptide from the cationic nanoparticles was approximately 20% per week. After intra-articular injection in rat knees, 70% of the nanoparticles were retained in the joint for 1 week.

Conclusions

This study demonstrates the feasibility of using cationic polymeric nanoparticles to increase the retention of therapeutic agents in articular joints for indications such as osteoarthritis.

2-Hydroxy-N′-[2-(6-methoxynaphthalen-2-yl)propanoyl]benzohydrazide

In the title compound, C₂₁H₂₀N₂O₄, the naphthalene ring system makes a dihedral angle of 84.5 (3)° with the benzene ring, and the –C(=O)–N(H)–N(H)–C(=O)– torsion angle is 70.7 (7)°, so that the mol­ecule is twisted. An S(6) ring motif is formed via an intra­molecular O—H⋯O hydrogen bond. In the crystal, mol­ecules are linked by N—H⋯O and C–H⋯O hydrogen bonds into supra­molecular layers in the ab plane.

Encapsulation of naproxen in lipid-based matrix microspheres: characterization and release kinetics

The objective of this study was to microencapsulate the anti-inflammatory drug (naproxen) to provide controlled release and minimizing or eliminating local side effect by avoiding the drug release in the upper gastrointestinal track. Naproxen was microencapsulated with lipid-like carnauba wax, hydrogenated castor oil using modified melt dispersion (modified congealable disperse phase encapsulation) technique. Effect of various formulation and process variables such as drug-lipid ratio, concentration of modifier, concentration of dispersant, stirring speed, stirring time, temperature of external phase, on evaluatory parameters such as size, entrapment efficiency, and in vitro release of naproxen were studied. The microspheres were characterized for particle size, scanning electron microscopy (SEM), FT-IR spectroscopy, drug entrapment efficiency, in vitro release studies, for in vitro release kinetics. The shape of microspheres was found to be spherical by SEM. The drug entrapment efficiency of various batches of microspheres was found to be ranging from 60 to 90 %w/w. In vitro drug release studies were carried out up to 24 h in pH 7.4 phosphate buffer showing 50-65% drug release. In vitro drug release from all the batches showed better fitting with the Korsmeyer-Peppas model, indicating the possible mechanism of drug release to be by diffusion and erosion of the lipid matrix.

Formulation, Characterization, and Evaluation of Ketorolac Tromethamine-Loaded Biodegradable Microspheres

Ketorolac tromethamine has to be given every 6 hr intramuscularly in patients for acute pain, so to avoid frequent dosing and patient inconvenience we found it to be a suitable candidate for parenteral controlled delivery by biodegradable microspheres for the present study. Ketorolac tromethamine-loaded microspheres were prepared by o/w emulsion solvent evaporation technique using different polymers: polycaprolactone, poly lactic-co-glycolic acid (PLGA 65/35), and poly lactic-co-glycolic acid (PLGA 85/15). To tailor the release profile of drug for several days, blends of PLGA 65/35 and PLGA 85/15 were prepared with polycaprolactone (PCL) in different ratios. The results revealed that microspheres made with 1:3 (PLGA65/35:PCL) blend released 97% of the drug in 5 days as compared 97% in 30 days in with pure PLGA65/35 microspheres. Microspheres made with 1:1 (PLGA65/35:PCL) and 3:1 (PLGA65/35:PCL released 98% of the drug in 30 days. In microspheres made with 1:3 (PLGA85/15:PCL), almost the entire drug was released in a week whereas in batches made with pure PLGA85/15 and 3:1 (PLGA 85/15:PCL) more than 80% of the drug was released in 60 days as compared with 96% in 60 days in 1:1 (PLGA85/15:PCL). Higher encapsulation efficiency was obtained with microspheres made with pure PLGA 65/35. These formulations were characterized for particle size analysis by Malvern mastersizer that revealed particle size in range of 12-15 micron and 12-22 micron for microspheres made with polymer blends of PLGA 65/35:PCL and PLGA85/15:PCL, respectively. In pure PLGA65/35 and PLGA85/15, particle size was 28 micron and 8 micron, respectively. Surface topography was studied by scanning electron microscopy that revealed a spherical shape of microspheres. From our study it as concluded that with careful selection of different polymers and their combinations, we can tailor the release of ketorolac tromethamine for long periods.

Efficacy of chitosan microspheres for controlled intra-articular delivery of celecoxib in inflamed joints

The use of polymeric carriers in formulations of therapeutic drug delivery systems has gained widespread application, due to their advantage of being biodegradable and biocompatible. In this study, we aimed to prepare celecoxib-loaded chitosan microspheres for intra-articular administration and to compare the retention of the celecoxib solution and chitosan microspheres in the joint cavity. The microspheres were characterized for entrapment efficiency, particle size and surface morphology by scanning electron microscopy. In-vitro drug release studies of microspheres revealed that the microspheres are able to control the release of celecoxib over a period of 96 h. Biodistribution studies of celecoxib and chitosan microspheres were performed by radiolabelling with 99mTc and injecting intra-articularly in rats. The study indicated that following intra-articular administration the distribution of the drug to the organs, like liver and spleen, is very rapid compared with that of the microspheres. Compared with the drug solution, a 10-fold increase in the concentration of the drug in the joint was observed 24 h post intra-articular injection (P &lt; 0.005) when drug was encapsulated in microspheres.

Poly(lactide-co-glycolide) nanoparticle assembly for highly efficient delivery of potent therapeutic agents from medical devices

Controlled delivery of therapeutic agents from medical devices can improve their safety and effectiveness in vivo, by ameliorating the surrounding tissue responses and thus maintaining the functional integrity of the devices. Previously, we presented a new method for providing simultaneous controlled delivery from medical devices, by surface assembly of biodegradable polymer nanoparticles (NPs) encapsulating fluorescent dyes. Here, we continue our investigation with NPs loaded with therapeutic agents, dexamethasone (DEX) or plasmid DNA, and evaluated the bioactivity of the released molecules with macrophage cells associated with inflammation. Over a period of one week, NPs encapsulating DEX released 24.9+/-0.8ng from the probe surface and was successful at suppressing macrophage cell growth by 40+/-10%. This percentage of suppression corresponded to approximately 100% drug delivery efficiency, in comparison with the unencapsulated drug. DNA NP coatings, in contrast, released approximately 1ng of plasmid DNA and were effective at transfecting macrophage cells to express the luciferase gene at 300+/-200 relative luminescence/mg total protein. This amount of luciferase activity corresponded to 100% gene delivery efficiency. Thus, NP coatings were capable of providing continuous release of bioactive agents in sufficient quantities to induce relevant biological effects in cell culture studies. These coatings also remained intact, even after 14 days of incubation with phosphate buffered saline. Although the maximum loading for NP coatings is inherently lower than the more established matrix coating, our study suggests that the NP coatings are a more versatile and efficient approach toward drug delivery or gene delivery from a medical device surface and are perhaps best suited for continuous release of highly potent therapeutic agents.

Intra-articular depot formulation principles: role in the management of postoperative pain and arthritic disorders

The joint cavity constitutes a discrete anatomical compartment that allows for local drug action after intra-articular injection. Drug delivery systems providing local prolonged drug action are warranted in the management of postoperative pain and not least arthritic disorders such as osteoarthritis. The present review surveys various themes related to the accomplishment of the correct timing of the events leading to optimal drug action in the joint space over a desired time period. This includes a brief account on (patho)physiological conditions and novel potential drug targets (and their location within the synovial space). Particular emphasis is paid to (i) the potential feasibility of various depot formulation principles for the intra-articular route of administration including their manufacture, drug release characteristics and in vivo fate, and (ii) how release, mass transfer and equilibrium processes may affect the intra-articular residence time and concentration of the active species at the ultimate receptor site.

Implantation of vancomycin microspheres in blend with human/rabbit bone grafts to infected bone defects

In orthopaedic applications, allografts are used for restoration of bone defects. In order to combine the effects of bone repair and to prevent the infection, antibiotic-impregnated bone grafts are under current investigation with promising early results. In this study, to preserve the stability of antibiotics and to provide appropriate release profiles for 4-6 weeks, antibiotic-loaded microspheres were administered in combination with allografts and vancomycin was the antibiotic loaded to microspheres. Particle size, surface characteristics, loading capacity and in vitro release characteristics of the microspheres with and without allografts were determined. In vivo studies were performed on rabbits and antibiotic amount was determined by a fluorescence polarization immunoassay (FPIA) method from synovial fluid sample aspirated. According to the results, although the in vitro study demonstrated effective antibiotic release of vancomycin from antibiotic-impregnated allografts for 5 weeks, in vivo conditions led to an early instability of the antibiotic (in powder form) and contrary to the high initial loading dose an effective release could not be obtained from the allografts after the first week. Following these studies, it was determined that antibiotic release over a minimum inhibitory concentration (MIC) for 6 weeks was realized from vancomycin-loaded microspheres which were implanted in a blend with allografts in bone defects. In conclusion, preservation of the antibiotic in microspheres maintained the bioactivity and provided the controlled antibiotic release, thus implantation of microspheres in a blend with allografts seemed to be a promising carrier system for the orthopaedic applications.

A thermally responsive biopolymer for intra-articular drug delivery

Intra-articular drug delivery is the preferred standard for targeting pharmacologic treatment directly to joints to reduce undesirable side effects associated with systemic drug delivery. In this study, a biologically based drug delivery vehicle was designed for intra-articular drug delivery using elastin-like polypeptides (ELPs), a biopolymer composed of repeating pentapeptides that undergo a phase transition to form aggregates above their transition temperature. The ELP drug delivery vehicle was designed to aggregate upon intra-articular injection at 37 degrees C, and form a drug 'depot' that could slowly disaggregate and be cleared from the joint space over time. We evaluated the in vivo biodistribution and joint half-life of radiolabeled ELPs, with and without the ability to aggregate, at physiological temperatures encountered after intra-articular injection in a rat knee. Biodistribution studies revealed that the aggregating ELP had a 25-fold longer half-life in the injected joint than a similar molecular weight protein that remained soluble and did not aggregate. These results suggest that the intra-articular joint delivery of ELP-based fusion proteins may be a viable strategy for the prolonged release of disease-modifying protein drugs for osteoarthritis and other arthritides.

Microspheres for Drug Delivery

With advances in biotechnology, genomics, and combinatorial chemistry, a wide variety of new, more potent and specific therapeutics are being created. Because of common problems such as low solubility, high potency, and/or poor stability of many of these new drugs, the means of drug delivery can impact efficacy and potential for commercialization as much as the nature of the drug itself. Thus, there is a corresponding need for safer and more effective methods and devices for drug delivery. Indeed, drug delivery systems—designed to provide a therapeutic agent in the needed amount, at the right time, to the proper location in the body, in a manner that optimizes efficacy, increases compliance and minimizes side effects—were responsible for $47 billion in sales in 2002, and the drug delivery market is expected to grow to $67 billion by 2006.

Celecoxib incorporated chitosan microspheres: in vitro and in vivo evaluation

Recently, considerable interest has been focussed on the use of biodegradable polymers for specialized applications such as controlled release of drug formulations; meanwhile, microsphere drug delivery systems using various kinds of biodegradable polymers have been studied extensively during the past two decades. In the present investigation, it was aimed to prepare microsphere formulations of celecoxib using a natural polymer, chitosan as a carrier for intra-articular administration to extend the retention of the drug in the knee joint. Microsphere formulations were evaluated in vitro for particle size, entrapment efficiency, surface morphology and in vitro drug release. For in vivo studies, (99m)Technetium- labeled glutathione was used as a radiopharmaceutical to demonstrate arthritic lesions by gamma scintigraphy. Evaluation of arthritic lesions post therapy in rats showed a significant difference (P < 0.005) in the group treated with celecoxib solution compared to the group treated with celecoxib loaded chitosan microspheres.

Methotrexate loaded poly(L-lactic acid) microspheres for intra-articular delivery of methotrexate to the joint

A controlled release delivery system that localizes methotrexate (MTX) in the synovial joint is needed to treat inflammation in rheumatoid arthritis (RA). The purpose of this work was to develop and characterize MTX loaded poly(l-lactic acid) (PLLA) microspheres and evaluate in vivo tolerability and MTX plasma concentrations following intra-articular injection into healthy rabbits. MTX loaded PLLA (2 kg/mole) microspheres were prepared using the solvent evaporation method and characterized in terms of size, molecular weight, thermal properties, and release rates into phosphate buffered saline (PBS) (pH 7.4) at 37 degrees C. Biocompatibility was evaluated by observing the swelling of the joints of the rabbits and histological analysis following the injection of the microspheres. MTX concentrations in the plasma and urine samples of rabbits were evaluated by high-performance liquid chromatography (HPLC). MTX loaded microspheres showed a rapid burst phase followed by a slow release phase. MTX loaded and control microspheres were biocompatible and plasma concentrations of MTX were tenfold higher in rabbits injected intra-articularly with free MTX than MTX microspheres. MTX microspheres may retain the drug in the joint by reducing clearance from the joint into the blood.

Kinetics of the radicals induced in gamma-irradiated naproxen sodium and apranax. Applicability of ESR technique to monitor radiosterilization of naproxen sodium-containing drugs

In the present work the spectroscopic and kinetic features of the radicals induced in gamma-irradiated naproxen sodium (NS) and apranax (AP) tablet are investigated at room and different temperatures in the dose range of 2.5-25 kGy by electron spin resonance technique (ESR). Radiation produces two different radicals (I, II) in NS quite stable at room temperature but relatively unstable above room temperature, giving rise to a broad singlet centered at g = 2.0057. Dose-response and decay curves associated with the broad singlet were found to follow bi-exponentials. Information concerning the saturation decay rates and activation energies were obtained through the characteristics of these exponentials. Similar calculations were also performed for AP, which contains 550 mg NS as active ingredient, and the applicability of ESR technique for monitoring radiosterilization of AP was discussed.

Preparation, characterization and in vivo distribution of terbutaline sulfate loaded albumin microspheres

Terbutaline sulfate is widely used as a bronchodilator for the treatment of bronchial asthma, chronic bronchitis and emphysema. As it has a short biological half-life, a long acting terbutaline sulfate formulation is desirable to improve patient compliance. Bovine serum albumin microspheres were prepared by an emulsion polymerization method using glutaraldehyde as the crosslinking agent. All microspheres were spherical and smooth with the mean particle size in the range of 22-30 microm. Drug release from the BSA microspheres displayed a biphasic pattern characterized by an initial fast release, followed by a slower release. The released amount was decreased with an increase in the glutaraldehyde concentration. In the absence of trypsin, the time required for complete degradation of microspheres was increased from 144 to 264 h when the glutaraldehyde concentration increased from 0.1 to 0.7 ml. In the presence of trypsin, a linear relationship was obtained between the degradation rates and trypsin concentrations, indicating that saturation was not reached under the experimental conditions. Biodistribution studies indicated that the degree of uptake by the lungs was higher than that of the other organs. All these results demonstrated that terbutaline sulfate loaded microspheres can be used for passive lung targeting.

Precise control of PLG microsphere size provides enhanced control of drug release rate

An important limitation in the development of biodegradable polymer microspheres for controlled-release drug delivery applications has been the difficulty of specifically designing systems exhibiting precisely controlled release rates. Because microparticle size is a primary determinant of drug release, we developed a methodology for controlling release kinetics employing monodisperse poly(D,L-lactide-co-glycolide) (PLG) microspheres. We fabricated 20-, 40- and 65-microm diameter rhodamine-containing microspheres and 10-, 50- and 100-microm diameter piroxicam-containing microspheres at various loadings from 1 to 20%. In vitro release kinetics were determined for each preparation. Drug release depended strongly on microsphere diameter with 10- and 20-microm particles exhibiting concave-downward release profiles while larger particles resulted in sigmoidal release profiles. Overall, the rate of release decreased and the duration increased with increasing microsphere size. Release kinetics from mixtures of uniform microspheres corresponded to mass-weighted averages of the individual microsphere release kinetics. Appropriate mixtures of uniform microspheres were identified that provided constant (zero-order) release of rhodamine and piroxicam for 8 and 14 days, respectively. Mixing of uniform microspheres, as well as control of microsphere size distribution, may provide an improved methodology to tailor small-molecule drug-release kinetics from simple, biodegradable-polymer microparticles.

Influence of irradiation sterilization on poly(lactide-co-glycolide) microspheres containing anti-inflammatory drugs

Gamma-irradiation is finding increasing use in the sterilization of pharmaceutical products. However, irradiation might also affect the performance of drug delivery systems. In this study, the influence of gamma-irradiation on the physicochemical properties of two commonly used non-steroidal anti-inflammatory drugs (NSAIDs) [naproxen sodium (NS) and diclofenac sodium (DS)] was investigated. The drugs were incorporated in poly(lactide-co-glycolide) (PLGA, 50:50; molecular weight 34000 or 88000 Da) microspheres. The biodegradable microspheres were irradiated at doses of 5, 15, 25 kGy using a 60Co source. Drug loading of irradiated and non-irradiated microspheres with both 34000 and 88000 Da polymers were essentially the same. A significant difference was noticed in the particle sizes of the irradiated as compared to the non-irradiated formulations. Notably, in release studies, the amount of active substance released from PLGA microspheres showed an increase with increasing irradiation dose. In DSC, the glass transition temperatures (Tg) of microspheres exhibited a slow increase with irradiation dose.