Marcello Di Sabatino

Polymer–lipid based mucoadhesive microspheres prepared by spray-congealing for the vaginal delivery of econazole nitrate

This research aimed to evaluate a new approach for the preparation of mucoadhesive microparticles and to design an innovative vaginal delivery systems for econazole nitrate (ECN) able to enhance the drug antifungal activity. Seven different formulations were prepared by spray-congealing: a lipid-hydrophilic matrix (Gelucire 53/10) was used as carrier and several mucoadhesive polymers such as chitosan, sodium carboxymethylcellulose and poloxamers (Lutrol F68 and F127) were added. All microparticles were characterized and compared for morphology, particle size, drug loading and solubility in simulated vaginal fluid, bioadhesion to mucosal tissue, dissolution behaviour and for their physicochemical properties. The antifungal activity of the microparticles against a strain of Candida albicans ATCC 10231 was also investigated. Non-aggregated microspheres with high yields (>90%, w/w) and with prevalent size in the range 100-355mum were obtained. Both poloxamers significantly (p<0.01) improved the solubility and in vitro bioavailability of the low solubility drug and the mucoadhesive strength. Poloxamers/Gelucire-based microparticles exhibited an inhibition effect on the C. albicans growth, suggesting their use as an effective treatment for vaginal candidiasis, with potential for reduced administration frequency. In conclusion the results demonstrated that spray-congealing technology can be considered a novel and solvent-free approach for the production of mucoadhesive microparticles for the vaginal delivery of ECN.

Development of microparticulate systems for intestinal delivery of Lactobacillus acidophilus and Bifidobacterium lactis.

In the present study intestinal delivery systems resistant to gastric juice, loaded with the probiotic bacteria Lactobacillus acidophilus LA14 and Bifidobacterium lactis BI07, were produced by the polyelectrolyte complexation. First, beads were prepared by the traditional extrusion method and nine formulations were developed using alginate as main carrier and the biopolymer, xanthan gum (XG), as hydrophilic retardant polymer or the cellulose derivative, cellulose acetate phthalate (CAP), as gastro-resistant polymer. The results showed that the incorporation of the 0.5% (w/v) of XG or the 1% (w/v) of CAP within the 3% (w/v) of alginate solution increased the survival of the probiotic bacteria in acid conditions from 63% of the freeze-dried bacteria up to 76%. Subsequently, these formula was used to prepare smaller microcapsules by means of an atomization device. Despite of the high viscosity of the biomass suspension, the spraying system produced spherical and non-aggregated microcapsules able to survive in harsh condition better than beads: the survival of the probiotic bacteria after acid incubation was 91%. The performance of the microcapsules in simulated gastric fluid (SGF) containing pepsin and in gut medium (GM) containing bile salts was excellent (viability>95%). Furthermore, the viability of probiotic bacteria was maintained after an incubation of 24h in GM. Finally, stability tests performed at 5 degrees C highlighted a bacterial viability of about 82% and 70% after 6 and 9 months, respectively.

Evaluation of solid lipid microparticles produced by spray congealing for topical application of econazole nitrate.

OBJECTIVES The aims of this study were to evaluate the suitability of the spray congealing technique to produce solid lipid microparticles (SLMs) for topical administration and to study the skin permeation of a drug from SLMs compared with solid lipid nanoparticles (SLNs). METHODS Econazole nitrate was used as model drug and Precirol ATO 5 as the lipidic carrier. SLMs and SLNs were both prepared at 5:1, 10:1 and 12.5:1 lipid:drug weight ratios and characterised in terms of particle size, morphology, encapsulation efficiency and chemical analysis of the particle surface. SLMs and SLNs were also incorporated into HPMC K 100M hydrogels for ex-vivo drug permeation tests using porcine epidermis. KEY FINDINGS SLMs had particle sizes of 18-45 microm, while SLNs showed a mean diameter of 130-270 nm. The encapsulation efficiency was 80-100%. Permeation profiles of econazole nitrate were influenced by both particle size (significant difference until 9 h) and the amount of lipid. CONCLUSIONS The results confirm the usefulness of SLNs as carriers for topical administration and suggest the potential of SLMs for the delivery of drugs to the skin.

Spray congealed lipid microparticles with high protein loading: Preparation and solid state characterisation

The spray-congealing technique, a solvent-free drug encapsulation process, was successfully employed to obtain lipid-based particulate systems with high (10-20% w/w) protein loading. Bovine serum albumin (BSA) was utilised as model protein and three low melting lipids (glyceryl palmitostearate, trimirystin and tristearin) were employed as carriers. BSA-loaded lipid microparticles were characterised in terms of particle size, morphology and drug loading. The results showed that the microparticles exhibited a spherical shape, mean diameter in the range 150-300 μm and an encapsulation efficiency higher than 90%. Possible changes in the protein structure as a result of the manufacturing process was then investigated for the first time using UV spectrophotometry in fourth derivative mode and FT-Raman spectroscopy. The results suggested that the structural integrity of the protein was maintained within the particles. Thermal analysis indicated that the effect of protein on the thermal properties of the carriers could be detected. Spray-congealing could thus be considered a suitable technique to produce highly BSA-loaded microparticles preserving the structure of the protein.

Novel multifunctional platforms for potential treatment of cutaneous wounds: Development and in vitro characterization

An original formulative/manufacturing approach for the development of a multi-composite wound dressing able to control the release of a water soluble API (lidocaine HCl) for several days was evaluated. The prepared multi-composite wound dressing is a microstructured spongy matrix, which embeds solid lipid microparticles (SLMs). The matrices were obtained by freeze drying of polyelectrolyte complexes made up two biopolymers: three different chitosan to alginate weight ratios (1:1, 3:1 and 1:3) were studied. The drug-loaded matrices were investigated as regards water uptake ability, swelling, drug loading, morphology and release profiles. SLMs were prepared at two different drug loadings (5% and 25%, w/w) by the spray congealing technology and were then incorporated in the spongy matrices. The characterization of the SLMs evidenced their spherical shape, mean dimensions lower than 20 μm, controlled release and the modification of the drug crystalline state. Comparing the release profiles of the SLMs-loaded sponges, the matrices with 1:3 chitosan/alginate ratio displayed a sustained release profile with the lower burst effect. Then hyaluronan and cysteine were embedded into the matrix to enhance the wound healing properties of the dressing. The final multi-composite platform was able to promote the growth of fibroblasts maintaining its prolonged release characteristic.

Formulating SLMs as oral pulsatile system for potential delivery of melatonin to pediatric population

The formulation development of melatonin (MLT) for infants and children with neurodevelopmental difficulties was fully investigated. This population have a higher prevalence of sleep disorders and present special challenges for drug administration and swallowing. To solve these issues, solid lipid microparticles (SLMs) were designed to obtain an oral flexible dosage form constituted by GRAS excipients and a free flow pulsatile delivery system for MLT, able to maintain its release through 8h. Three groups of SLMs were produced by spray congealing and characterized as regards particle size, morphology, flowability, solid state, drug content and release behavior. The SLMs manipulation with milk and yogurt and the MLT stability in these foods were also investigated. Microparticles with different excipient composition were selected to obtain a pulsatile release pattern over 8h. The final delivery platform displayed a prompt release from group I SLMs together with a lag phase of groups II and III SLMs, followed by a repeated MLT release from group II and a prolonged MLT release related to the last group. Finally, MLT was compatible and stable in milk and yogurt suggesting that microparticles sprinkled into food is acceptable for MLT administration to children unable to swallow capsules or tablets.

Encapsulation of Vitamin A palmitate for animal supplementation: Formulation, manufacturing and stability implications

Two manufacturing methods and numerous formulative approaches have been evaluated to obtain a stable oral pharmaceutical form of Vitamin A palmitate (VAP), a substance very sensitive to light, temperature, humidity and metal ions. The best results were obtained by formulating VAP, stabilized with butylated hydroxytoluene (BHT), in double layer microcapsules constituted by a core of chitosan, Tween 20, CaCl2 and EDTA surrounded by a first chitosan-alginate membrane and an outer membrane of calcium-alginate. This formulation design enabled the production of beads with high drug loading (42% w/w) and high encapsulation efficiency (94%). The stability of VAP-loaded microcapsules was assessed according to EMEA guidelines. This formulation design showed the best performance in terms of VAP recovery (t50% > 360 days) after 1 year of storage at room conditions. This is a very important result considering the poor shelf-life (45 days) of pure VAP stabilized with BHT stored at the same conditions.

Development of microparticles for oral administration of the non-conventional radical scavenger IAC and testing in an inflammatory rat model.

The bis (1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)-decandioate (IAC), is an innovative non- radical scavenger used with success in numerous disease models such as inflammation, neurological disorders, hepatitis and diabetes. The pharmacological treatments have been performed by the intraperitoneal route of administration, representing to date, the main limit for the drug use. The aim of this study was to develop a delivery system that allows the oral administration of IAC while maintaining its therapeutic efficacy. Solid Lipid Microparticles (SLMs) containing a theoretical 18% (w/w) of IAC have been produced by the spray congealing technology; three formulations have been tested (A, B and C) using different low melting point carriers (stearic acid, Compritol(®) HD5ATO and carnauba wax) alone or in combination. All IAC loaded SLMs exhibited a spherical shape, encapsulation efficiency higher than 94% and particle size suitable for the oral route. Administered per os at different dosages in an inflammation rat model, all SLMs demonstrated their efficacy in reducing oedema and alleviating pain, compared to the gold standards Indomethacin and Paracetamol. These results suggested that the SLMs are an efficacious delivery system for the oral administration of IAC, potentially useful for the treatment of others diseases related to an over production of free radicals.

Comparison of spray congealing and melt emulsification methods for the incorporation of the water-soluble salbutamol sulphate in lipid microparticles

Context: Salbutamol sulphate is widely used as bronchodilator for the treatment of asthma. Its use is limited by the relatively short duration of action and hence sustained delivery of salbutamol sulphate offers potential benefits to patients. Objective: This study explores the preparation of lipid microparticles (LMs) as biocompatible carrier for the prolonged release of salbutamol sulphate. Materials and methods: The LMs were produced using different lipidic materials and surfactants, by classical melt emulsification-based methods (oil-in-water and water-in-oil-in-water emulsions) and the spray congealing technique. Results: For the LMs obtained by melt emulsification a lack of release modulation was observed. On the other hand, the sustained release of salbutamol sulphate was achieved with glyceryl behenate microparticles prepared by spray congealing. These LMs were characterized by scanning electron microscopy, X-ray diffractometry and differential scanning calorimetry. The drug loading was 4.72% (w/w). The particle size distribution measured by laser diffraction and electrical zone sensing was represented by a volume median diameter (Dv50) of 51.7–71.4 µm. Increasing the atomization air pressure from 4 to 8 bar produced a decrease of the Dv50 to 12.7–17.5 µm. Conclusions: Incorporation of the hydrophilic salbutamol sulphate into LMs with sustained release characteristics was achieved by spray congealing.

Formulation of spray congealed microparticles with self-emulsifying ability for enhanced glibenclamide dissolution performance

Abstract Purpose: To develop a novel preparation approach of solid Self-Emulsifying Drug Delivery System (s-SEDDS) based on spray congealing as potential drug delivery technology for poorly water-soluble drug Glibenclamide (GBD). Methods: Several systems were formulated using suitable excipients, solid at room temperature, with different hydrophilic–lipophilic balance, such as Myverol, Myvatex, Gelucire®50/13 and Gelucire®44/14. Cremophor®EL and Poloxamer 188 were selected as surfactants and PEG 4000 as co-solvent. Results: The screening of the best carrier for s-SEDDS manufacturing revealed that Gelucire®50/13 had greater performance. Then, surfactant–co-solvent systems were developed. Dissolution studies showed that all the formulations promoted the solubilisation performance of the GBD with respect to pure drug; in particular the formulation containing Gelucire®50/13 and PEG 4000 increased the drug solubilisation of five times. These microparticles showed self-dispersibility within 60 min and micelles dimensions around 360 nm. Conclusions: Spray congealing is a promising novel manufacturing technique of solid self-emulsifying systems.