Maurizio Ricci

Lipid nanoparticles for prolonged topical delivery: An in vitro and in vivo investigation

Dermal therapy is still a challenge due to the difficulties in controlling the active pharmaceutical ingredient (API) fate within the skin. Recently, lipid nanoparticles have shown a great potential as vehicle for topical administration of active substances, principally owing to the possible targeting effect and controlled release in different skin strata. Ketoprofen and naproxen loaded lipid nanoparticles were prepared, using hot high pressure homogenization and ultrasonication techniques, and characterized by means of photo correlation spectroscopy and differential scanning calorimetry. Nanoparticle behavior on human skin was assessed, in vitro, to determine drug percutaneous absorption (Franz cell method) and, in vivo, to establish the active localization (tape-stripping technique) and the controlled release abilities (UVB-induced erythema model). Results demonstrated that the particles were able to reduce drug penetration increasing, simultaneously, the permeation and the accumulation in the horny layer. A prolonged anti-inflammatory effect was observed in the case of drug loaded nanoparticles with respect to the drug solution. Direct as well as indirect evidences corroborate the early reports on the usefulness of lipid nanoparticles as carriers for topical administration, stimulating new and deeper investigations in the field.

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.

Evaluation of in vitro percutaneous absorption of lorazepam and clonazepam from hydro-alcoholic gel formulations

Clonazepam and lorazepam are two anxiolytics, antidepressant agents, having suitable features for transdermal delivery. The objectives of this study were to evaluate the in vitro percutaneous absorption of these drugs through excised human skin (stratum corneum and epidermis, SCE) and to determine their in vitro permeation behavior from a series of hydro-alcoholic gel formulations containing various enhancing agents. The best permeation profile was obtained for both drugs applying them together with Azone in combination with propylene glycol (PG): these enhancers were able to increase the clonazepam and lorazepam percutaneous fluxes at steady-state about threefold, compared to the free enhancer formulations (Control). To explain the mechanism of the used promoters, the benzodiazepine diffusion and partitioning coefficients from the gel containing the enhancers were calculated. The results indicated that the Azone in combination with PG could act by increasing the benzodiazepine diffusion coefficients, Transcutol increased only the SC/vehicle partition coefficients, limonene in combination with PG appeared to increase both partition and diffusion coefficients moderately, while PG did not increase both the parameters. Furthermore, to evaluate the potential application of tested benzodiazepine formulations containing Azone in combination with PG using the flux values from the in vitro experiments, the corresponding steady-state plasma concentrations (C(SS)) were calculated. The obtained calculated C(SS) values are within the lorazepam therapeutic range and suggest that transdermal delivery of this drug could be regarded as feasible.

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.

Chitosan and a modified chitosan as agents to improve performances of mucoadhesive vaginal gels.

New mucoadhesive formulations were designed and studied in order to improve local vaginal therapy by increasing formulation retention prolonging thus drug-mucosa contact time. Some gels were prepared using hydroxyethylcellulose (HEC) alone or mixed with chitosan (CS) or its derivative 5-methyl-pyrrolidinone-chitosan (MPCS) and were loaded with the antibacterial metronidazole (MET) (0.75%). All formulations showed pseudoplastic flow and viscosity increase was observed proportionally to chitosan content (CS>MPCS). Prepared gels showed better extrusion properties (yield stress) than market formulation Zidoval. Mucoadhesion force studies permitted to point out that: (i) CS decreases mucoadhesion force; (ii) MPCS addition increases the mucoadhesion force at high percentage; (iii) all gels containing chitosan showed better mucoadhesive performances than Zidoval. Gels containing MPCS showed higher and faster drug release than those containing CS. All the preparations were able to release higher drug amounts if compared to market formulation. In conclusion MPCS improved gel characteristics in terms of mucoadhesion force, rheological behaviour and drug release pointing out that this modified chitosan is very suitable to obtain manageable and more acceptable vaginal formulation.

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.

Use of SBA-15 for furosemide oral delivery enhancement

The objective of this research was to realize a new oral solid dosage form in order to improve the release of furosemide (FURO) in its preferential absorption region. In fact FURO is a drug labeled in class IV of the Biopharmaceutical Classification System (BCS) characterized by low and variable bioavailability due to both low solubility and low permeability and because of its weakly acid nature is preferentially absorbed in the stomach whereas its solubility is hampered. FURO was included in the mesoporous silica material SBA-15 obtaining an inorganic-organic compound fully characterized by: thermogravimetric analysis (TGA), X-ray Powder Diffraction (XRPD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FT-IR) and nitrogen adsorption-desorption analysis and then submitted to in vitro dissolution. The results showed a remarkable dissolution rate improvement in comparison to the crystalline drug and to the marketed product Lasix®. The inclusion product was also submitted to physical stability studies that revealed the matrix ability to prevent re-organization in crystal nucleus of the drug molecules.

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.