Stefano Giovagnoli

Preparation and characterization of poly(D,L-lactide-co-glycolide) microspheres for controlled release of human growth hormone

The purpose of this research was to assess the physicochemical properties of a controlled release formulation of recombinant human growth hormone (rHGH) encapsulated in poly(D,L-lactide-co-glycolide) (PLGA) composite microspheres. rHGH was loaded in poly(acryloyl hydroxyethyl) starch (acHES) microparticles, and then the protein-containing microparticles were encapsulated in the PLGA matrix by a solvent extraction/evaporation method. rHGH-loaded PLGA microspheres were also prepared using mannitol without the starch hydrogel microparticle microspheres for comparison. The detection of secondary structure changes in protein was investigated by using a Fourier Transfer Infrared (FTIR) technique. The composite microspheres were spherical in shape (44.6±2.47 μm), and the PLGA-mannitol microspheres were 39.7±2.50 μm. Drug-loading efficiency varied from 93.2% to 104%. The composite microspheres showed higher overall drug release than the PLGA/mannitol microspheres. FTIR analyses indicated good stability and structural integrity of HGH localized in the microspheres. The PLGA-acHES composite microsphere system could be useful for the controlled delivery of protein drugs.

Biodegradable microspheres as carriers for native superoxide dismutase and catalase delivery

The purpose of this research was to encapsulate superoxide dismutase (SOD) and catalase (CAT) in biodegradable microspheres (MS) to obtain suitable sustained protein delivery. A modified water/oil/water double emulsion method was used for poly(D,L-lactide-co-glycolide) (PLGA) and poly(D,L-lactide) PLA MS preparation co-encapsulating mannitol, trehalose, and PEG400 for protein stabilization. Size, morphology, porosity, mass loss, mass balance, in vitro release and in vitro activity were assessed by using BCA protein assay, scanning electron microscopy, BET surface area, and particle-sizing techniques. In vitro activity retention within MS was evaluated by nicotinammide adenine dinucleotide oxidation and H2O2 consumption assays. SOD encapsulation efficiency resulted in 30% to 34% for PLAMS and up to 51% for PLGA MS, whereas CAT encapsulation was 34% and 45% for PLGA and PLAMS, respectively. All MS were spherical with a smooth surface and low porosity. Particle mean diameters ranged from 10 to 17 μm. CAT release was prolonged, but the results were incomplete for both PLA and PLGA MS, whereas SOD was completely released from PLGA MS in a sustained manner after 2 months. CAT results were less stable and showed a stronger interaction than SOD with the polymers. Mass loss and mass balance correlated well with the release profiles. SOD and CAT in vitro activity was preserved in all the preparations, and SOD was better stabilized in PLGA MS. PLGA MS can be useful for SOD delivery in its native form and is promising as a new depot system.

Ketoprofen poly(lactide-co-glycolide) physical interaction

The aim of this work was to provide an understanding of the interaction occurring between ketoprofen and poly(lacticco-glycodic acid) (PLGA) that leads to polymer plasticization. Experimental glass transition temperature (Tg) values were fitted with the theoretical ones predicted by the Fox and Gordon-Taylor/Kelley-Bueche equations. PLGA films containing different amounts of ketoprofen (KET) were prepared by solvent casting and characterized by scanning electron microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy (FTIR). Differential scanning calorimetry evidenced that KET acted as a plasticizer in a similar biphasic way in both end-capped and uncapped PLGA. At KET contents of 20% to 35%, depending on the investigated polymer, the Tg was around 23°C. Higher KET amounts did not lower further the Tg, and the excess of drug was found to crystallize into the polymeric matrix. Experimental Tgs deviated negatively from the predicted ones probably because of hydrogen bonding. The FTIR spectra of the films, loaded with different amounts of KET, showed a shift to higher wavenumbers for the peaks at 1697 and 1655 cm−1 confirming the presence of some interactions, probably hydrogen bonds between the ketoprofen carboxylic group and the PLGA carbonyl groups along the polymer backbone. The hydrogen bonding between KET and PLGA is probably responsible for KET plasticizing effect. KET behaving as a lubricant may disrupt polymer chain-chain interactions, removing additional barriers to bond rotation and chain mobility.

Mucoadhesive bilayered tablets for buccal sustained release of flurbiprofen

The aim of this work was the design of sustained-release mucoadhesive bilayered tablets, using mixtures of mucoadhesive polymers and an inorganic matrix (hydrotalcite), for the topical administration of flurbiprofen in the oral cavity. The first layer, responsible for the tablet retention on the mucosa, was prepared by compression of a cellulose derivative and polyacrylic derivative blend. The second layer, responsible for buccal drug delivery, was obtained by compression of a mixture of the same (first layer) mucoadhesive polymers and hydrotalcite containing flurbiprofen. Nonmedicated tablets were evaluated in terms of swelling, mucosal adhesion, and organoleptic characteristics; in vitro and in vivo release studies of flurbiprofen-loaded tablets were performed as well.The best results were obtained from the tablets containing 20 mg of flurbiprofen, which allowed a good anti-inflammatory sustained release in the buccal cavity for 12 hours, ensuring efficacious salivary concentrations, and led to no irritation. This mucoadhesive formulation offers many advantages over buccal lozenges because it allows for reduction in daily administrations and daily drug dosage and is suitable for the treatment of irritation, pain, and discomfort associated with gingivitis, sore throats, laryngopharyngitis, cold, and periodontal surgery. Moreover, it adheres well to the gum and is simple to apply, which means that patient compliance is improved.

Novel composite microparticles for protein stabilization and delivery

The aim of this work was to develop a novel composite alginate/poly(lactic-co-glycolic) acid microparticulate system for protein stabilization and delivery using bovine insulin as model drug. Alginate particles, prepared by ionic gelation, were embedded into PLGA microparticles using the solvent diffusion evaporation technique. Actual loading was determined by micro-BCA protein assay for total insulin and by reversed phase-high performance liquid chromatography for soluble insulin. Insulin loaded composite microparticles showed reproducible encapsulation efficiency with a higher soluble insulin content when compared to conventional microparticles. Bovine insulin in vitro release studies and adsorption behavior were investigated in 10 mM glycine buffer (pH 2.8) at 37 degrees C. The stability of bovine insulin, solubilized in the above mentioned buffer, was studied as well. In this case, bovine insulin showed to be instable at the investigated conditions and 55% of insulin was lost after 7 days. However, composite microparticle release, characterized by a low burst effect, lasted up to 4 months. Moreover, no significant peptide adsorption on blank PLGA or blank composite microparticles was observed while, a strong interaction between alginate particles and bovine insulin was detected.

Delivering drugs to the central nervous system : A medicinal chemistry or a pharmaceutical technology issue?

This review aims to summarize the non-invasive approaches employed in delivering drugs to the central nervous system which is severely hindered by the presence of the blood-brain barrier (BBB) that limits molecular permeation. Particular attention will be placed on the several available strategies for delivering drugs into the brain, through circumvention of the BBB, in order to critically address the medicinal chemistry and the pharmaceutical technology contributions.

Development of a spray-drying method for the formulation of respirable microparticles containing ofloxacin-palladium complex.

The purpose of this study was to produce low-releasing spray-dried polymeric microparticles (MP) useful to target alveolar macrophages in tuberculosis (TB) inhalation therapy. Ofloxacin (Ofx) was encapsulated as ofloxacin-palladium (Ofx-Pd) complex into poly DL-lactide (PLA) MP by spray-drying. Ofx-Pd was prepared according to a method previously reported. A D-optimal design was employed to optimize drug content (DC), aerodynamic diameter (d(ae)) and span. d(ae) was calculated coupling tap-density to particle size analysis. The MP were characterized by SEM, UV spectrophotometry, and DSC. In vitro drug release was performed in comparison to Ofx loaded PLA MP. The Ofx-Pd complex formed spontaneously with a 1:1 stoichiometry. Inlet temperature, drug loading and polymer concentration resulted the most influential. Optimal MP had span of 0.9, a round shape, d(ae) of 2.5 μm, and DC of 30% (w/w). DSC and SEM analyses correlated with particle size. The optimized MP formulation showed a very low release at pH 7.4 compared to spray-dried Ofx loaded MP, the release increased slightly at lower pHs. Potentially inhalable MP were obtained by an optimized spray-drying process. The very low initial drug release at physiologic pH could be useful to target alveolar macrophages and to avoid systemic exposure.

Lipid nanoparticles for brain targeting I. Formulation optimization

The aim of this study was to optimize the formulation of lipid nanoparticles (NPs), intended for brain targeting, with the aid of a computer generated experimental design. The high pressure homogenization technique, selected for this purpose, was suitable to formulate the 3 investigated lipids (i.e., Softisan(®) 142, SOFT; Compritol(®) 888 ATO, COMP; cetyl palmitate, CP) into nanometre-length particles, while the computer generated experimental design helped to individuate the best preparation conditions with a small number of experimental assay. Even though all the 3 optimized formulations were suitable for intravenous infusion, CP NPs showed the smallest particle size and the appropriate thermal behaviour to be used as carriers in brain targeting applications.

Chitosan films containing mesoporous SBA-15 supported silver nanoparticles for wound dressing

Chitosan films containing mesoporous SBA-15 supported silver nanoparticles (AgNPs) were prepared to be applied as a potential wound dressing material. First SBA-15-silver nanoparticle (SBA-15-Ag) composite materials were prepared by a controlled annealing process without the use of organic solvents and reagents. The SBA-15-AgNPs were characterized in detail by X-ray powder diffraction, field emission scanning electron microscopy and transmission electron microscopy which evidenced the presence of uniformly distributed silver nanostructures inside the silicate pores. UV-vis spectra of the sample showed a band at 430 nm characteristic of the surface plasmon resonance of silver nanoparticles with a diameter below 10 nm and X-ray photoemission spectra confirmed the formation of metal-nanoparticles on the silicate template. Then SBA-15-Ag was used to prepare chitosan films which were characterized in detail. In particular, they showed good hydration properties, water vapor transmission rate and mechanical properties. After hydration films exhibited good antimicrobial activity against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus epidermidis and S. aureus) bacteria.

Multifunctional microcapsules for pancreatic islet cell entrapment: design, preparation and in vitro characterization.

Great advances in cell transplantation have been made, including the recent, remarkable success in pancreatic islet transplantation for the treatment of type 1 diabetes mellitus. Unfortunately, the transplanted cells are very susceptible to oxidative stress that cause severe damage to either allo- or xenogeneic islets upon graft in diabetic patients. Consequently, the transplanted islet functional life span is significantly shortened. The aim of this study was to examine the possible effects of antioxidants on in vitro cultured adult rat islets, and to evaluate the effects of a prolonged-release formulation, in form of cellulose acetate (CA) microspheres, on Vitamin D(3) activity. Isolated rat islets, both free and entrapped in microspheres were treated with Vitamin D(3). The effects of the vitamin were studied at 3, 6 and 9 days of in vitro cell culture. According to insulin secretory patterns, treatment with Vitamin D(3) of both free and CA entrapped microspheres, increased the insulin output as compared to untreated controls. Such positive effects were confirmed under islet static incubation with glucose at day 6. These results suggest that pancreatic islets can be advantageously treated with anti-oxidising vitamins before implantation, and speculatively, with the help of special delivery systems, throughout the islet cell life span, in the post-transplant time period.