PubMed Health⌕ Search

Biomedical subjects

L Maggi

Publications and source records attributed to L Maggi.

At least 19 recordsLinked to original sources
PubMed2006

Matrices containing NaCMC and HPMC 1. Dissolution performance characterization.

In this study hydroxypropylmethylcellulose (HPMC) and sodium carboxymethylcellulose (NaCMC) were used as polymeric carriers to improve controlled release performances of matrix tablets containing a soluble drug. The drug release behaviour of the systems containing these two polymers mixture and each material separately was investigated. To evaluate the effect of the dissolution medium pH, on the drug release performance, release tests were conducted at pH 1, 4.5 and 6.8. In vitro release studies demonstrated that the mixture of the two cellulose derivatives enables a better control of the drug release profiles at pH 4.5 and at 6.8 both in term of rate and mechanism. Texture analysis on the swollen tablets helps to understand drug release kinetic and mechanism. In fact, the results obtained confirm that a gel, which is characterized by high strength and consistence is less susceptible to erosion and chains disentanglement and the drug release mechanism is mainly governed by diffusion. On the contrary, gels, which show a low strength and texture, have low resistance to the fluid erosion action and the release of the active molecule is manly due to polymer relaxation and chains disentanglement moving the drug delivery kinetic towards an erosion/relaxation mechanism.

Carboxymethylcellulose Sodium↗
PubMed2006

Assessment and correlation between clinical patterns, disability and health-related quality of life in patients with low back pain.

AIM: Low back pain (LBP) is the main symptom of most lumbar spine diseases. This symptom, due to physical, psychological and social factors, is correlated to a real disability which can affect the quality of life (QoL.) The aim of this study is to evaluate the QoL and the disability in patients with LBP and to correlate them to clinical patterns. METHODS: In this prospective multidimensional study, 108 patients underwent the following protocol: 1. collection of patient-oriented and disability data with the use of SF-36 and North American Spine Society (NASS); 2. collection of clinical, anamnestic and instrumental data (MRI, CT) with the use of DOVAC files; 3. assessment of disability with the use of Barthel index (BI) and deambulation index (DI). RESULTS: A significant correlation was found between the BI and the physical composite score (PCS), but no significant correlation was noticed between BI and the mental composite score (MCS). DI was not correlated to the SF-36. A positive Lasegue and the absence of the osteo-tendinous reflexes are significantly correlated to the disability and QoL. CONCLUSIONS: This study shows that there is no simple, linear correlation between QoL and disability.

Acute Disease↗
PubMed2006

Multivesicular release at developing Schaffer collateral-CA1 synapses: an analytic approach to describe experimental data.

We developed and analytically solved a simple and general stochastic model to distinguish the univesicular from the multivesicular mode of glutamate release. The model solution gives analytical mathematical expressions for average values of quantities that can be measured experimentally. Comparison of these quantities with the experimental measures allows one to discriminate the release mode and to determine the most probable values of model parameters. The model has been validated at glutamatergic CA3-CA1 synapses in the hippocampus from newborn (P1-P5 old) rats. Our results strongly support a multivesicular type of release process requiring a variable pool of immediately releasable vesicles. Moreover, computing quantities that are functions of the model parameters, the mean amplitude of the synaptic response to the release of a single vesicle (q) was estimated to be 5-10 pA, in very good agreement with experimental findings. In addition a multivesicular type of release was supported by the following experimental evidences: 1) a high variability of the amplitude of successes, with a coefficient of variation ranging from 0.12 to 0.73; 2) an average potency ratio a2/a1 between the second and first response to a pair of stimuli >1; and 3) changes in the potency of the synaptic response to the first stimulus when the release probability was modified by increasing or decreasing the extracellular calcium concentration. Our results indicate that at Schaffer collateral-CA1 synapses of the neonatal rat hippocampus a single action potential may induce the release of more than one vesicle from the same release site.

Action Potentials↗
PubMed2006

Sublingual immunotherapy with Dermatophagoides monomeric allergoid down-regulates allergen-specific immunoglobulin E and increases both interferon-gamma- and interleukin-10-production.

BACKGROUND: The clinical efficacy and safety of sublingual immunotherapy (SLIT) for aeroallergens has been demonstrated in several trials, whereas the immunological changes induced by this treatment, which may account for the clinical improvement, are still unclear. OBJECTIVE: To investigate the effects of a successful SLIT on the in vitro allergen-driven T cell response and cytokine secretion as well as on the serum levels of chemokines and of IgE, IgG1 and IgG4 antibodies (Abs). MATERIALS AND METHODS: Twenty-five Dermatophagoides pteronyssinus (Dp)-sensitive patients with perennial rhinitic and/or rhinitic and asthmatic symptoms were randomized into two groups (13 untreated (UT) and 12 SLIT-treated) for a 1 year and half study. The proliferative response of peripheral blood mononuclear cell (PBMC) to purified Der p1 allergen, their cytokines (IFN-gamma, IL-4, IL-10 and TGF-beta) production and serum levels of chemokines associated with T helper type 1 (Th1) (CXCL10) or T helper type 2 (Th2) (CCL22) responses and of Dp-specific IgE, IgG1 and IgG4 Abs were evaluated before and after 6 months of treatment. RESULTS: SLIT induced a significant reduction of symptom medication scores after 6, 12 and 18 months of treatment in comparison with UT patients. SLIT-treated patients showed a significant decrease in serum levels of DP-specific IgE Abs, whereas total IgE, and specific IgG1 and IgG4 Abs remained unchanged. The proliferative response of allergen-specific T cells to Der p1 in vitro after 6 months of treatment was reduced, while no effect was observed on T cell proliferation to recall antigen (streptokinase). Moreover, Der p1-driven IFN-gamma and IL-10 were significantly increased in culture supernatants of PBMC from 6 month-treated patients in comparison with those detected at the beginning of therapy. CONCLUSIONS: These data suggest that the allergen-driven enhancement of IL-10- and IFN-gamma-producing T cells precedes and associates with SLIT-induced down-regulation of specific IgE, thus providing a rationale to explain the clinical benefit of SLIT in allergic patients.

Administration, Sublingual↗
PubMed2005

Preparation and evaluation of release characteristics of 3TabGum, a novel chewing device.

A new chewing gum device in the form of a three layers tablet (3TabGum) has been developed. The new drug delivery system is obtained, at room temperature, by direct compression using conventional pharmaceutical equipment. Basically, the resulting chewing gum tablets comprise a gum core combined with two protective antiadherent external layers, which prevent gum adhesion to the punches of the tableting machine. Drug release from a dosage form is the critical step in drug absorption and bioavailability, thus an experimental protocol has been designed to evaluate the efficiency of this kind of therapeutic system by verifying its capability to release the drug dose and by assessing the delivery rate. Simple diffusion into the medium causes the release of only a small percentage of the drug contained in the medicated chewing gum, while the delivery of the major part of the dose occurs during mastication. The results obtained in this study suggest that water soluble drugs are freely and easily released by chewing gums, while for actives characterized by reduced water solubility the release rate depends on the chewing time although all the drugs tested are completely released after a reasonable mastication time.

Chewing Gum↗
PubMed2004

Polymers-gamma ray interaction. Effects of gamma irradiation on modified release drug delivery systems for oral administration.

The aim of this work is to verify the efficiency of two kinds of matrix tablets formulations containing PEO or PVA as retarding polymer. Moreover, since in the last years the exposure to ionizing radiation is a more and more used method to reduce bacterial charge in pharmaceutical products, the effects of gamma irradiation on these two kinds of polymers has been evaluated. The study is performed on matrix tablets containing diltiazem HCl, as model drug, and polyethylene oxides (PEO) of two different molecular weights or polyvinylalchool (PVA) of medium degree of hydrolysis, as drug release modulators. Dissolution of the matrices, release of diltiazem and morphological behaviour of the samples, before and after exposure to increasing doses of gamma irradiation, are investigated in order to verify their stability. The results show that the ionizing radiation does not modify significantly the dissolution trend of the PVA samples; on the contrary, the dissolution and the morphological behaviour of the PEO matrices is strongly affected by the radiation dose received. In particular, the dissolution rate of the irradiated PEO tablets dramatically increases as a function of the irradiation dose and the swelling process, which characterised the non-irradiated PEO samples, was replaced by a rapid erosion process responsible for the quickly dissolution of the matrices. The changes of the dissolution and morphological PEO tablets performances could be explained by a breaking of the polymeric chains (shown by EPR studies) as a consequence of the exposure to gamma rays. These chemical-structural modifications of the polymers are responsible for the reduced efficacy of the PEO systems in controlling the drug release rate.

Administration, Oral↗
PubMed2003

Chemical and physical stability of hydroxypropylmethylcellulose matrices containing diltiazem hydrochloride after gamma irradiation.

In recent years, the exposure to gamma-radiation is an increasingly used method to sterilize or to reduce bacterial charge in drug-delivery devices. The aim of this study was to investigate whether the ionizing radiation may be responsible for drug inactivation or for the alteration of the functional excipient used to modulate drug release from a controlled-release delivery system. In this work, we investigated the physical and dissolution stability of prolonged release matrix tablets containing diltiazem hydrochloride, as a model drug, and hydroxypropylmethylcellulose (HPMC) of two different viscosity grades, as the retarding polymer, before and after exposure to increasing doses of gamma-rays. The results show that gamma-irradiation induces chemical modifications in the structure of the active agent, and also of the hydrophilic polymer. The electronic paramagnetic resonance analysis of gamma-irradiated diltiazem has afforded evidence of carbon radicals stemming from C-H bond ruptures and sulphur radicals, the latter being formed mainly after admission of air at room temperature. The major radical products in the HPMC polymer radiolysis have been reckoned with chain scission events in agreement with the results of viscosity measurements that show a progressive decrease of the average molecular weight with increasing the radiation dose. The elaboration of the viscosity data has led to linear relationships between the eta(o)/eta ratio and the radiation dose D which were rationalized with the following equation under the assumption of a Mark-Houwink Sakurada coefficient a approximately equal 1: eta(o)/eta = (1 + uy(o) D)(a). In this equation, D is gamma-radiation dose, eta(o) and eta are the reduced viscosities before and after the irradiation respectively, u is the number average degree of polymerization, and y(o) is the chain scission radiolytic yield. From the linear relationships G(chain scissions) = 1.2 x 10(-6) and 1.4 x 10(-6) moles/J have been obtained for the two HPMC polymer samples M100 and M4 of different molecular weight used in the experiments. These changes could be responsible for the alteration of the drug-release mechanism and reduced polymer efficacy in controlling drug release.

Chemistry, Pharmaceutical↗
PubMed2003

Photostability of extended-release matrix formulations.

The photostability of drugs has been widely studied while less attention is devoted to the possible modifications that UV light may induce on the excipients of a dosage form, in particular, on the functional polymers used to modulate drug delivery. In this work we have evaluated the effect of UV light on the release characteristics of extended-release matrix tablets containing hydroxypropylmethylcellulose (HPMC) or polyethylene oxide (PEO) as retarding polymers. Two different model drugs have been used: nifedipine (insoluble and photolabile drug) and diltiazem (soluble and photostable drug). Photodecomposition of nifedipine was evaluated and the formation of the photoproducts was followed during the dissolution process. Regarding the dissolution stability, the matrix tablets containing HPMC exposed to UV light have not shown significant differences in drug release profiles compared to the same non-irradiated formulation, while the matrix tablets containing PEO and exposed to the same conditions of UV light have shown a remarkable increase of drug release rate within the first minutes of the dissolution test (burst effect) which is particularly critical because it can cause the loss of the desired therapeutic control.

Chemistry, Pharmaceutical↗
PubMed2002

Boar semen controlled delivery system: storage and in vitro spermatozoa release.

Swine spermatozoa were encapsulated in barium alginate and protamine-barium alginate membranes to lengthen their preservation time and to provide a means of controlling their release. Precocious acrosome reactions and secondary anomalies were measured as indices of semen quality. These characteristics were observed for two forms of encapsulated spermatozoa when stored at 18 and 38 degrees C for 24 h and for semen diluted in a classical extender at both temperatures. The results indicate that encapsulation enhances semen preservation, providing protection against membrane damage upon dilution. The effect is even more evident at the higher temperature (38 degrees C), where cell metabolism is higher. An in vitro release test of spermatozoa showed a massive cell delivery from barium alginate capsules within 6 h, and a slow release from protamine-barium alginate capsules. The properties of spermatozoa 24 h after release did not differ from the semen stored at the same temperature in capsules, indicating that the release process does not impair semen quality.

Alginates↗
PubMed2002

Boar semen controlled delivery system: analysis of batch seasonal variability.

A new encapsulation technology of swine semen is proposed to improve the quality of stored spermatozoa and to obtain the controlled release of viable cells, reducing the number of instrumental inseminations. This technology has been employed to produce barium alginate gel capsules in different seasons; an analysis of batch reproducibility was performed, and total capsule diameter, gel thickness and weight of capsules were determined as indices of batch properties. A seasonal variability was found but each batch was substantially homogeneous. The variability could be related to the biological variability of the semen employed as raw material as well as to the technological process.

Animals↗
PubMed2002

Barium alginate cell-delivery systems: correlation between technological parameters.

The most recent trends for the development of several in vitro cell cultures have been oriented towards the cell immobilisation in 3-dimensional scaffolds and cell encapsulation. In fact, an important requirement of cell survival is self-assembly in functional communities, in the presence of an artificial extracellular matrix. In our research, a previously described technique for spermatozoa encapsulation was applied to obtain capsules loaded with an opaque agent as a model, and to perform a formulative study. A process variable, barium ion concentration, was correlated to some capsule properties, such as weight, gel thickness, total and core diameter. Ion concentration can be modified to obtain capsules with predictable characteristics.

Alginates↗
PubMed2002

Dissolution behaviour of hydrophilic matrix tablets containing two different polyethylene oxides (PEOs) for the controlled release of a water-soluble drug. Dimensionality study.

Hydrophilic matrix tablets containing polyethylene oxides as the retarding polymer have been successfully employed in the controlled release of drugs. To evaluate the relative influence of drug diffusion and polymer erosion mechanisms in the drug delivery process, we studied the hydration behaviour of matrix tablets containing a water-soluble drug and PEOs of two different molecular weights: Polyox WSRN 1105 (Mw = 0.9 x 10(6)) and Polyox WSRN 301 (Mw = 4 x 10(6)). The hydration rate, the extent of swelling, and the erosion rate of matrices containing the polymer, the drug and tableting excipients were evaluated in comparison to tablets made of pure polymer. The results of these studies on function of the release behaviour were then discussed. The results show that the higher molecular weight PEO swells to a greater extent and tends to form, upon hydration, a stronger gel, which is therefore less liable to erosion, if compared to the lower molecular weight PEO. This difference in the erosion behaviour can explain the different efficiencies of the two polymeric products in modulating the delivery rate of the water-soluble drug. Moreover, the presence of other soluble components (drug and excipients) in the dosage form enhances the erosion trend of the tablets with a consequent reduction of the efficiency of the polymer in drug release control.

Biocompatible Materials↗
PubMed2002

Characterization and selection of vaginal Lactobacillus strains for the preparation of vaginal tablets.

AIMS: To characterize and select Lactobacillus strains for properties that would make them a good alternative to the use of antibiotics to treat human vaginal infections. METHODS AND RESULTS: Ten Lactobacillus strains belonging to four different Lactobacillus species were analysed for properties relating to mucosal colonization or microbial antagonism (adhesion to human epithelial cells, hydrogen peroxide production, antimicrobial activity towards Gardnerella vaginalis and Candida albicans and coaggregation with pathogens). The involvement of electrostatic interactions and the influence of bacterial metabolic state in the binding of lactobacilli to the cell surface were also studied. Adherence to epithelial cells varied greatly among the Lactobacillus species and among different strains belonging to the same Lactobacillus species. The reduction in surface negative electric charge promoted the binding of several Lactobacillus strains to the cell membrane whereas lyophilization reduced the adhesion capacity of many isolates. The antimicrobial activity of lactobacilli culture supernatant fluids was not directly related to the production of H2O2. CONCLUSIONS: Three strains (Lactobacillus brevis CD2, Lact. salivarius FV2 and Lact. gasseri MB335) showed optimal properties and were, therefore, selected for the preparation of vaginal tablets. The selected strains adhered to epithelial cells displacing vaginal pathogens; they produced high levels of H2O2, coaggregated with pathogens and inhibited the growth of G. vaginalis. SIGNIFICANCE AND IMPACT OF THE STUDY: The dosage formulation developed in this study appears to be a good candidate for the probiotic prophylaxis and treatment of human vaginal infections.

Bacterial Adhesion↗
PubMed2001

Regulation of GABA release by nicotinic acetylcholine receptors in the neonatal rat hippocampus.

1. The whole-cell configuration of the patch-clamp technique was used to study the modulation of giant depolarizing potentials (GDPs) by nicotinic acetylcholine receptors (nAChRs) in CA3 hippocampal neurons in slices from postnatal day (P) 2-6 rats. 2. Bath application of nicotine increased GDP frequency in a concentration-dependent manner. For example, nicotine (0.5-1 microM) enhanced GDP frequency from 0.05 +/- 0.04 to 0.17 +/- 0.04 Hz. This effect was prevented by the broad-spectrum nicotinic receptor antagonist dihydro-beta-erythtroidine (DHbetaE, 50 microM) and partially antagonized by methyllycaconitine (MLA, 50 nM) a competitive antagonist of alpha7 nAChRs. GDP frequency was also enhanced by AR-17779 (100 microM), a selective agonist of alpha7 nAChRs. 3. The GABA(A) receptor antagonist bicuculline (10 microM) and the non-NMDA glutamate receptor antagonist DNQX (20 microM) blocked GDPs and prevented the effects of nicotine on GDPs. In the presence of DNQX, nicotine increased GABA-mediated synaptic noise, indicating that this drug may have a direct effect on GABAergic interneurons. 4. Bath application of edrophonium (20 microM), a cholinesterase inhibitor, in the presence of atropine (1 microM), increased GDP frequency, indicating that nAChRs can be activated by ACh released from the septo-hippocampal fibres. This effect was prevented by DHbetaE (50 microM). 5. In the majority of neurons tested, MLA (50 nM) and DHbetaE (50 microM) reduced the frequency of GDPs with different efficacy: a reduction of 98 +/- 11 and 61 +/- 29 % was observed with DHbetaE and MLA, respectively. In a subset of cells (40 % in the case of MLA and 17 % in the case of DHbetaE) these drugs induced a twofold increase in GDP frequency. 6. It is suggested that, during development, nAChRs modulate the release of GABA, assessed as GDPs, through distinct nAChRs. The rise of intracellular calcium via nAChRs would further strengthen GABA-mediated oscillatory activity. This can be crucial for consolidation of synaptic contacts and for the fine-tuning of the developing hippocampus.

Acetylcholine↗
PubMed2001

Determination of 226Ra in biological samples by adsorption on specific adsorbers.

The determination of 226Ra in biological samples, such as milk and grass, was studied. 226Ra analysis of cow's milk was studied starting from de-fatted milk. The proteins were eliminated by coagulation of the colloidal phase with trichloroacetic acid. Phosphorus was then removed by precipitating it as molybdophosphate and finally adsorption was carried out by using two different adsorbers in order to concentrate and purify radium. Lead rhodizonate (LEHRO) adsorbed on charcoal and partially reduced tin dioxide (PRTD) were utilised. A method for the determination of 226Ra in grass ashes was also investigated. The main interference, due to magnesium, hinders the use of LERHO, so the proposed procedure is based on adsorption of radium on PRTD at pH 9.5. The magnesium concentration was depleted by precipitating barium (carrier) and radium with calcium carbonate at pH 8 before the adsorption step. The high phosphorus concentration in grass also interferes in the determination of 226Ra; phosphorus was eliminated as above via molybdophosphate precipitation. The radium was carried by barium and spiked with 133Ba. The yield of the chemical procedure was evaluated on the basis of 133Ba activity. Radium samples were alpha-counted and the activity was evaluated with a suitable calibration curve. Both exchangers in the milk analysis and PRTD in grass analysis were shown to be helpful in order to set up an easily performed procedure, which allows many samples to be processed simultaneously. All the methods adopted were shown to be very sensitive. Under the experimental conditions used, with 1 L of milk or 5 g of grass ashes, the limit was about 3 mBq 226Ra L-1 milk and < 1 mBq 226Ra g-1 grass ashes.

Adsorption↗
PubMed2000

Effect of drying methods on retention of moist sucralfate gel properties.

The aim of this work was to find a drying procedure for moist sucralfate gel capable of producing dried sucralfate gel that retains the original gel properties of bioadhesion, rheology, and micromeritics. Spray-drying and microwave-drying procedures were employed. Mannitol was used as a gel-protective substance during the drying processes. The spray drying of moist sucralfate gel gave rise to a powder whose water suspensions showed significantly reduced viscosity. The bioadhesion of spray-dried sucralfate gel was strongly reduced by drying. When mannitol was used as a gel protector, the spray-dried sucralfate in part maintained the original bioadhesion of moist sucralfate gel. The preparation of a dried sucralfate gel retaining the bioadhesion characteristics, avoiding the use of mannitol, was made possible using the microwave-drying procedure. The microwave-dried product possesses a granular morphology suitable for direct compression because it is a free flowing and strongly coherent granular powder.

Acid-Base Equilibrium↗
PubMed2000

High molecular weight polyethylene oxides (PEOs) as an alternative to HPMC in controlled release dosage forms.

High molecular weight polyethylene oxides (PEOs) have recently been proposed as an alternative to hydroxypropylmethylcellulose (HPMC) in controlled release matrix tablets. In this study, we compared the performance of PEO and HPMC polymers when employed in the Geomatrix technology, a versatile, well-known method to achieve extended release of drugs at a constant rate. Four core formulations were prepared, containing a soluble drug (diltiazem) and, alternatively, PEO or HPMC of two different viscosity grades. These formulations have the same composition except for the polymer employed. Similarly, four barrier formulations were also prepared, which only differ in the kind of polymer employed. Three-layer Geomatrix systems were then prepared using these core and barrier formulations. The release profiles of the different three-layer systems obtained were compared, to verify if PEO could efficiently replace HPMC in this type of dosage form. The results show that slower release rates can be obtained from the plain matrices containing HPMC compared to PEO, moreover HPMC, used in the barrier formulations, is generally more efficient in controlling drug release rate in three-layer Geomatrix systems.

Calcium Channel Blockers↗