Biomedical subjects

Stefano Giovagnoli

Publications and source records attributed to Stefano Giovagnoli.

17 recordsLinked to original sources

PubMed2006

Preparation of large porous biodegradable microspheres by using a simple double-emulsion method for capreomycin sulfate pulmonary delivery.

The aim of this work was to evaluate if a simple double-emulsion method could be used for developing a new formulation of large porous microspheres (MS) potentially useful for capreomycin sulfate (CS) pulmonary delivery. Poly(DL-lactide-co-glycolide) was used for MS preparation. A simple W/O/W double-emulsion/solvent evaporation preparation method was employed and MS were characterized by UV spectrophotometry, particle size, and scanning electron microscopy. A computer-generated response surface method (RSM) was employed to evaluate % drug content, volume mean diameter (VMD), and span upon variation of two numeric and two categorical factors. MS size distribution was found to be strongly affected by the homogenization method and the type of emulsifier employed. Mean diameters ranged from 1 to 20 microm. The MS presented a proper morphology, with a highly porous interior and a rough surface. Peptide content ranged between 1 and 20%. The region of optimality was referred to as a low VMD and span values, and a high drug content. The best results were found when using a 20% loading, 19.8-3.2 dichloromethane/acetone ratio, ultraturrax mixing, and HPMC as emulsifier. The double-emulsion method allowed the preparation of CS loaded large porous MS having suitable characteristics to match respirability requirements. The use of RSM helped to establish the conditions to obtain formulations potentially useful for a possible CS pulmonary delivery, by using a simple preparation method with a consistent time, cost, and material saving.

Acetone↗

PubMed2006

Preparation and in vitro and in vivo characterization of composite microcapsules for cell encapsulation.

Cell encapsulation technology raises great hopes in medicine and biotechnology. Transplantation of encapsulated pancreatic islets represents a promising approach to the final cure of type 1 diabetes mellitus. Unfortunately, long-term graft survival and functional competence remain only partially fulfilled. Failure was often ascribed to the lack of biocompatibility generating inflammatory response, limited immunobarrier competence, hypoxia, and low beta-cell replication. In the present work, ketoprofen loaded biodegradable microspheres, embedded into alginate/poly-L-ornithine/alginate microcapsules, were prepared in order to release ketoprofen at early stages after implantation. Morphology, size, in vitro release behaviour, and in vivo biocompatibility were assessed. The effect of some preparation parameters was also evaluated. Polymeric microspheres were spherical and smooth, two populations of about 5 and 20 microm of mean diameter characterized the particle size distribution. A high burst effect was observed for all preparations during in vitro release studies. Ketoprofen, plasticizing the polymeric matrix, could be responsible of this release behaviour. Alginate/poly-L-ornithine/alginate microcapsules were not modified upon ketoprofen loaded microspheres encapsulation and an optimal dispersion was obtained. Composite system showed good biocompatibility when a high molecular weight polymer was employed. Therefore a potentially suitable composite system for cell encapsulation was obtained. This system may be successfully used to release NSAIDs and other active molecules capable to improve cell system functional performance and life-span.

Biocompatible Materials↗

PubMed2006

Development of liposomal capreomycin sulfate formulations: effects of formulation variables on peptide encapsulation.

PURPOSE: The aim of this work was the investigation of the effects of preparation variables on drug content for the development of capreomycin sulfate (CS) liposomal formulations as potential aerosol antitubercular agents. METHODS: Dipalmitoylphosphatidylcholine (DPPC), hydrogenated phosphatidylcholine (HPC) and distearoylphosphatidylcholine (DSPC) were used for liposome preparation. A freeze-thawing method was chosen for CS encapsulation. Peptide entrapment, size and morphology were evaluated by UV spectrophotometry, photocorrelation spectroscopy (PCS) and transmission electron microscopy (TEM), respectively. A 2(3) full factorial protocol was designed to evaluate the conditions for CS encapsulation improvement. RESULTS: Peptide content ranged between 1 and 8%. Vesicles showed a narrow size distribution, with average diameters around 1 microm and a good morphology. A mathematical model was generated for each liposomal system and check point analyses revealed good agreement between experimental and predicted values. DPPC liposomes were found to provide the highest CS content. CONCLUSIONS: Peptide content was successfully increased by assessing formulation variable effects using a 2(3) factorial design that proved to be a time saving method helpful in developing new CS liposomal formulations for a possible application in aerosol antitubercular therapies.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2006

Evaluation and optimization of the conditions for an improved ferulic acid intercalation into a synthetic lamellar anionic clay.

PURPOSE: The aim of the study is to optimize the intercalation conditions of ferulic acid (FERH), an antioxidant compound, into Mg-Al-hydrotalcite for a safe skin photoprotection. METHODS: The intercalation products were prepared incubating hydrotalcite (HTlc) in aqueous solutions of FERH sodium salt at different temperatures over 4 and 8 days. Quantitative determination of intercalated FERH was performed by thermogravimetric analysis and morphology by scanning electron microscopy (SEM). FERH stability study was carried out at different pHs and temperatures. FERH was analyzed by reversed phase-high-performance liquid chromatography. Response surface methods (RSMs) were used to assess optimal intercalation conditions and FERH stability. RESULTS: In all intercalation products, FERH content was found to be about 48% w/w except when the intercalation process was carried out at 52 degrees C for 8 days and at 60 degrees C for both 4 and 8 days, which resulted to be 40.39, 39.99, and 34.99%, respectively. The RSM designs showed that intercalation improvement can be achieved by working at pH 6, at temperatures below 40 degrees C, and over 4 days of incubation. CONCLUSIONS: The optimal conditions for a proper FERH intercalation were assessed. The development of a new optimized protocol may improve HTlc-FER complex performances and safety by augmenting dosage and reducing the presence of harmful reactive species in the final formulation.

Aluminum Hydroxide↗

PubMed2006

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.

Blood-Brain Barrier↗

PubMed2005

Ketoprofen controlled release from composite microcapsules for cell encapsulation: effect on post-transplant acute inflammation.

Cell encapsulation technology raises hopes in medicine and biotechnology. Encapsulated pancreatic islets is a promising approach for the final solution of Type 1 diabetes. Unfortunately, evidence of long-term encapsulated islet graft survival and functional competence lies behind expectancy. Failure was often ascribed to the lack of biocompatibility generating inflammatory response, or limited immunobarrier competence or hypoxia or finally, low beta-cell replication. In order to prevent severe inflammation at early stages after implantation, composite microcapsules were designed. Biodegradable microspheres containing ketoprofen were enveloped into the well established alginate/poly-L-ornithine/alginate capsules. Polyester microspheres were prepared, by solvent evaporation, and characterized for encapsulation efficiency, particle size and in vitro release. Biocompatibility and efficacy to prevent the inflammatory response were studied in vivo. Good encapsulation efficiency and the desired particle size were achieved. In vitro release studies evidenced a high burst effect probably due to a plasticizing effect of both water and ketoprofen. The composite systems showed good biocompatibility and capacity to completely avoid the inflammatory response and the pericapsular cell overgrowth. In conclusion, the inflammatory response in the immediate post-transplant period can be circumvented using multicompartment microcapsules releasing non-steroidal anti inflammatory drugs.

Animals↗

PubMed2005

Long-term delivery of superoxide dismutase and catalase entrapped in poly(lactide-co-glycolide) microspheres: in vitro effects on isolated neonatal porcine pancreatic cell clusters.

To counterbalance the restricted availability of pancreatic islet tissue for transplant in Type 1 Diabetes Mellitus (T1DM), new methods to provide viable and functional islet cells need to be established. We report on our approach to enhance in vitro viability and function of isolated neonatal pancreatic porcine cell clusters (NPCCs) by co-culturing them with PLGA microsphere entrapped, slowly release superoxide dismutase and catalase. These powerful antioxidizing agents were shown to significantly improve morphology, viability and function, as assessed by microscopy, molecular, biochemical and functional studies, of the incubated NPCCs, as compared to control. Preliminarily, in vitro exposure of isolated NPCCs to slow release microsphere-embedded SOD and CAT could permit or contribute to overcome hurdles associated with scarcity in islet tissue procurement for transplant in T1DM.

Animals↗

PubMed2005

Evaluation of indomethacin percutaneous absorption from nanostructured lipid carriers (NLC): in vitro and in vivo studies.

The aim of this study was the evaluation, in vitro and in vivo, of indomethacin (IND) release through the skin from nanostructured lipid carriers (NLC). NLC were prepared by ultrasonication, and were characterized in order to determine drug content, and particle size; finally the NLC were processed to hydrogels (A and B). The IND release pattern from NLC hydrogels was evaluated in vitro, to determine its percutaneous absorption through excised human skin (stratum corneum and epidermis, SCE), and in vivo. To evaluate the in vivo IND release, two methods were employed: (1) the IND topical anti-inflammatory activity was determined at different time-points after its cutaneous application; in this case, the UVB-induced erythema on healthy human volunteers, chosen as inflammatory model, was monitored by reflectance visible spectrophotometry; (2) the extent of IND absorption into human skin was performed by the tape-stripping technique. The in vitro percutaneous absorption studies showed lower fluxes of IND through SCE membranes from NLC hydrogels (A and B) in comparison to an aqueous dispersion (C) and a hydro-alcoholic gel (D) both containing free IND. The findings from the former in vivo method showed that the anti-inflammatory effect, following IND topical application, was more prolonged with IND-loaded NLC gel formulation (A) if compared to formulation C and D. The results from tape stripping technique confirmed the trend obtained by the former in vivo method and indicated that IND topical bioavailability in the stratum corneum varied substantially depending upon the formulations (A-D).

Administration, Topical↗

PubMed2004

Unilamellar vesicles as potential capreomycin sulfate carriers: preparation and physicochemical characterization.

The aim of this work was to evaluate unilamellar liposomes as new potential capreomycin sulfate (CS) delivery systems for future pulmonary targeting by aerosol administration. Dipalmitoylphosphatidylcholine, hydrogenated phosphatidylcholine, and distearoylphosphatidylcholine were used for liposome preparation. Peptide-membrane interaction was investigated by differential scanning calorimetry (DSC) and attenuated total internal reflection Fourier-transform infrared spectroscopy (ATIR-FTIR). Peptide entrapment, size, and morphology were evaluated by UV spectrophotometry, photocorrelation spectroscopy, and transmission electron microscopy, respectively. Interaction between CS and the outer region of the bilayer was revealed by DSC and ATIR-FTIR. DSPC liposomes showed enhanced interdigitation when the CS molar fraction was increased. Formation of a second phase on the bilayer surface was observed. From kinetic and permeability studies, CS loaded DSPC liposomes resulted more stable if compared to DPPC and HPC over the period of time investigated. The amount of entrapped peptide oscillated between 10% and 13%. Vesicles showed a narrow size distribution, from 138 to 166 nm, and a good morphology. These systems, in particular DSPC liposomes, could represent promising carriers for this peptide.

Anti-Bacterial Agents↗

PubMed2004

UV spectroscopy and reverse-phase HPLC as novel methods to determine Capreomycin of liposomal fomulations.

Capreomycin (CS) is an antitubercular drug active against several Mycobacterium strains, in particular, against M. Avium. In spite of its activity, it is considered a second line drug because it can induce severe renal and hepatic damages when administered as free drug. However, it is possible to employ drug delivery systems, such as liposomes, to reduce the toxicity of the peptide without loss of its biological activity. For this purpose, appropriately validated time and money saving analytical methods are needed for a careful capreomycin dosage. In the present paper, UV spectroscopy and a reverse-phase HPLC (RP-HPLC) were investigated as alternative methods for capreomycin quantitative analysis. These techniques were validated against the USP XXVI microbiological turbidimetric assay and the normal-phase HPLC (NP-HPLC) method reported in the British Pharmacopoeia 2003. The results obtained showed that either UV spectrophotometry or RP-HPLC are techniques having higher accuracy and reproducibility with respect to the microbiological assay. Moreover, the RP-HPLC method provided improved performances if compared to NP-HPLC. In fact, RP-HPLC showed: (i) enhanced sensitivity and (ii) increased resolution. Thus we propose RP-HPLC and UV as valid alternative methods to the conventional procedures for capreomycin quantitative analysis.

Antibiotics, Antitubercular↗

PubMed2004

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 PLA MS and up to 51% for PLGA MS, whereas CAT encapsulation was 34% and 45% for PLGA and PLA MS, respectively. All MS were spherical with a smooth surface and low porosity. Particle mean diameters ranged from 10 to 17 mum. 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.

Animals↗

PubMed2004

Development of mucoadhesive patches for buccal administration of ibuprofen.

A new formulation for topical administration of drugs in the oral cavity has been developed using several film-forming and mucoadhesive polymers. The films have been evaluated in terms of swelling, mucoadhesion and organoleptic characteristics. The best film, containing polyvinylpyrrolidone (PVP) as film-forming polymer and carboxymethylcellulose sodium salt (NaCMC) as mucoadhesive polymer, was loaded with ibuprofen as a model compound and in vitro and in vivo release studies were performed. Statistical investigation of in vitro release revealed that the diffusion process was the main drug release mechanism and the Higuchi's model provided the best fit. In vivo studies showed the presence of ibuprofen in saliva (range 70-210 microg/ml) for 5 h and no irritation was observed. These mucoadhesive formulations offer many advantages in comparison to traditional treatments and can be proposed as a new therapeutic tool against dental and buccal diseases and disturbs.

Acrylates↗

PubMed2004

Leucinostatin-A loaded nanospheres: characterization and in vivo toxicity and efficacy evaluation.

Leucinostatin A (Leu-A) is a nonapeptide exerting a remarkable activity especially against Candida albicans and Cryptococcus neoformans; nevertheless, its employment is limited due its toxicity. Therefore, we recently developed liposomal formulations, as suitable delivery systems, in order to increase its therapeutic index. However, liposomes present disadvantages related to their long-term instability. For this reason poly(lactic-co-glycolic) nanospheres (NS) were chosen as alternative colloidal carriers for Leu-A delivery. NS were formulated by spontaneous emulsification solvent diffusion method. This study investigates the effects of different parameters on drug encapsulation efficiency and particle size as well. The best preparation obtained was also characterized for its in vitro release, in vivo acute toxicity (LD50), and effectiveness against C. albicans in mice. In vitro release was performed over 100 h and resulted sufficiently sustained with more than 93% of the peptide released. Acute toxicity showed that the LD50 was increased more than 18-fold and the study on systemic candidiasis models revealed high effectiveness of the NS in reducing either the growth of fungal colonies in infected mice liver or in the mortality index. In conclusion, we can propose that Leu-A loaded NS could represent a new promising therapeutic system against Candida infection.

Animals↗

PubMed2004

Novel mucoadhesive buccal formulation containing metronidazole for the treatment of periodontal disease.

Mucoadhesive tablets using different mixture of cellulose and polyacrylic derivatives were prepared in order to obtain new formulations containing metronidazole for periodontal disease treatment. All tablets were characterized by swelling studies, ex vivo and in vivo mucoadhesive time, ex vivo mucoadhesion force, in vitro and in vivo release. The best mucoadhesive performance and the best in vitro drug release profile were achieved by using hydroxyethyl cellulose (HEC) and carbomer 940 2:2 ratio. The chosen tablet, containing 20 mg of metronidazole, performed 12 h drug sustained release with buccal concentrations always higher than its MIC.

Acrylic Resins↗

PubMed2004

Potential prodrugs of non-steroidal anti-inflammatory agents for targeted drug delivery to the CNS.

Recently non-steroidal anti-inflammatory drugs (NSAIDs) have been proposed to prevent or to cure Alzheimer's disease. In this respect, we synthesized new potential prodrugs of several NSAIDs in order to increase their access to the brain. The carboxylic group of NSAIDs was attached to the 1,4-dihydro-1-methylpyridine-3-carboxylate moiety, which acts as a carrier, via an amino alcohol bridge, according to the chemical delivery approach developed by Bodor. The lipophilicity of potential prodrugs was evaluated both via traditional experimental parameters, such as partition coefficient and chromatographic R(m) value, and by predictive computational methods. From experimental parameters, all prodrugs were more lipophilic when compared to their corresponding parent compounds and consequently a better blood brain barrier (BBB) penetration is hypothesised. Prodrug lipophilicity was correlated with a calculated log P value according to Kowwin's method. The correlation between experimental Rm0 and calculated log P, determined by PLS analysis, was good for all compounds with the exception of compound 7i. In addition the BBB permeation profile of our synthesized compounds was predicted using the BBB VolSurf model and seven of the synthesized prodrugs resulted in good candidates for BBB penetration.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2003

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.

Animals↗

PubMed2003

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 microm), and the PLGA-mannitol microspheres were 39.7 +/- 2.50 microm. 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.

Delayed-Action Preparations↗