Federica Vitali

Physical Carboxymethylscleroglucan/Calcium Ion Hydrogels as Modified Drug Delivery Systems in Topical Formulations

A carboxymethyl derivative of scleroglucan (Scl-CM) with a 65±5% carboxylic group degree of derivatization (DD) was recently synthesized and characterized. Aqueous solutions of the polymer underwent to a sharp transition toward a gel like behaviour in the presence of divalent ions such as Ca+2. Physical hydrogels with different Scl-CM/Ca+2 ratios were prepared and characterized for their rheological behaviour. Their potential as drug delivery systems was also evaluated. To this end three non steroidal anti-inflammatory drugs (NSAIDs) were loaded into the hydrogels obtained with 2% w/v solution of Scl-CM and 0.05 and 0.1 M CaCl2. The release rate of the drugs was critically related to the salt concentration. By an appropriate combination of the hydrogels prepared using different amounts of salt, it was possible to obtain a system able to release diclofenac with zero-order kinetics. Primary skin irritation tests showed a good biocompatibility of the new polymer, as well as of its hydrogels. These results suggest a potential of the new hydrogels for the development of modified delivery systems in topical formulations.

pH-sensitive hydrogels of dextran: synthesis, characterization and in vivo studies.

pH-Sensitive hydrogels of dextran were synthesized by photochemical cross-linking reaction of methacrylate dextran (DEX-MA) at different derivatization degree, functionalized with acidic residues through reaction with phthalic anhydride. The hydrogels were characterized by FT-IR spectra, swelling measurements, experiments of chemical and enzymatic hydrolyses. The swelling data agreed with the formation of networks having pH-sensitive behaviour. This property was confirmed by the morphological examination performed by scanning electron microscopy on samples maintained in media at different pH. (S)-4-Isobutyl-2-phenylpropionic acid (ibuprofen) was loaded into the polymeric matrices. The analysis of the release profiles of the drug from the three networks showed that all the matrices were able to retain ibuprofen during the transit through the stomach, releasing it in a sustained way in the intestinal tract at a rate strictly dependent on the derivatization degree in methacrylic groups. In vivo studies verified the biocompatibility of the materials. Moreover, when the matrix loaded with ibuprofen was administered to rats, it was able to protect them from the ulcerogenic effects of the drug.

Antiproliferative and cytotoxic activity of extracts from Cistus incanus L. and Cistus monspeliensis L. on human prostate cell lines

Benign prostatic hypertrophy (BPH) is a common condition in elderly men that impairs quality of life and leads to a number of medical complications. The use of phytotherapeutic compounds in patients with relatively moderate BPH symptoms has been growing steadily. In the present study, acute toxicity of lyophilised aqueous extracts of Cistus incanus L. and Cistus monspeliensis L., collected in Sicily, was evaluated on the shrimp (Artemia salina L.) lethality assay, an alternative test to determine the toxicity of natural products. The cytotoxic and growth inhibitory effects were studied on normal human prostate cells (PZ-HPV-7 and PNT1A) and on a lung fibroblast cell line (V79-4). Cell proliferation was evaluated by MTT and SRB assays. Cytotoxicity was measured using the Trypan blue exclusion assay. Cistus extract treatment on prostate cell lines resulted in an almost identical growth inhibitory response and in a significant decrease in an cell viability. These findings indicate the biologically relevant effect of polyphenolic compounds present in Cistus extracts, and suggest that these substances may prove beneficial in BPH treatment.

Novel pH-Sensitive Physical Hydrogels of Carboxymethyl Scleroglucan

A carboxymethyl derivative of scleroglucan (Scl-CM) with derivatization degree 300 ± 10 was synthesized and characterized by Fourier transform infrared spectroscopy, potentiometer titration, mucus adhesion studies, and rheological measurements. Rheological measurements showed the ability of the polymer to undergo sol-gel transitions even in the absence of salts. Swelling experiments, performed on freeze-dried samples in different media, showed good affinity of these hydrogels toward the aqueous media and a pH-sensitive behavior. Four nonsteroidal anti-inflammatory drugs (NSAIDs) were loaded into the physical hydrogels obtained from 2.0% (w/v) solutions of the polymer. The results of the release studies carried out in conditions simulating the gastrointestinal tract showed that the new hydrogels could be suggested for the modified oral delivery of NSAIDs, particularly damaging for the gastric mucosa. In vivo studies proved the biocompatibility of the matrix and the absence of any gastric damage for administration of ulcerogenic doses of diclofenac loaded into the hydrogel (DIC/Scl-CM-300). Moreover, DIC/Scl-CM-300 was found to be effective in peripheral analgesia.

Antiulcer Potential of a Standardized Extract of Red Orange Juice in the Rat

A standardized red orange extract (Red Orange Complex, ROC) has been evaluated for its potential protective effect on ethanol- and indomethacin-induced gastric lesions in rats. Oral administration of the ROC significantly prevented the development of gastric lesions in these experimental models. In addition, the effect of the ROC on the spontaneous healing of acetylsalicylic acid (ASA) ulcers in rats was examined. The spontaneous healing of gastric ulcer was significantly accelerated by repeated administration of the ROC. The histological condition of the mucosa, examined by scanning electronic microscopy (SEM), confirmed the in vivo data. The results, on the whole, indicate that the ROC possesses favourable antiulcer and cytoprotective properties in rat. This study was performed according to the international principles for laboratory animal use and care (EEC Directive of 1986; 86/609/EEC).

Dextran-based hydrogel microspheres obtained in w/o emulsion: preparation, characterisation and in vivo studies.

Abstract The cross-linking reaction in w/o emulsions of dextran (DEX) functionalised with methacrylic groups, having or not acid residues in side chain, can be used to easily prepare polysaccharide hydrogel microspheres with properties suitable for drug delivery applications. The formation of a chemical network within the obtained particles was evaluated with FT-IR spectroscopy, whereas morphology and dimensions of the microspheres were investigated with optical and scanning electron microscopy. At the same time, swelling measurements were carried out on freeze-dried particles in different aqueous media simulating biological fluids. Preliminary release experiments performed with ibuprofen, betamethasone and vitamin B12 chosen as model drugs, showed that these microspheres could be suitable as modified drug delivery systems in oral formulations. Finally, in vivo writhing experiments were carried out in mice in order to verify the antinociceptive activity of betamethasone loaded into the new polysaccharide hydrogel microspheres.