219 research outputs found
Oral drug therapy in elderly with dysphagia
No full textDemographic indicators forecast that by 2050, the elderly will account for one-third of the global population. Geriatric patients require a large number of medicines, and in most cases, these products are present on the market as solid oral dosage forms. However, this population tends to suffer difficulties with swallowing, defined as dysphagia. In this contest, caregivers in hospital geriatric units routinely compound solid oral dosage forms by crushing tablets or opening capsules to facilitate their administration. This practice requires a manipulation of original formulation making necessary to consider different issues: decrease of drug efficacy, increase in toxicity, problems of instability, lowering of palatability, cross-contamination and loss of drugs. The present work deals with the possibility to improve dysphagic patient compliance under therapy with a cholesterol-lowering drug, pravastatin sodium salt, a widely prescribed molecule traded on the market just as immediate-release tablets. Chemical-analytical and microbiological stability of an aqueous solution of pravastatin starting from tablets has been investigated with the aim to administer the solution orally by using syringe directly in feeding tube. Then, to optimize the compounding process of commercial tablets of water-soluble molecules in a semisolid preparation, a hydrogel for oral admistration has been formulated. The objective was to obtain a product having a suitable consistency and a release kinetic comparable to that of immediate-release tablet. Therefore, patient might switch pharmacological therapy from original solid form to the gelified formulation assuring compliance to treatment. This work demonstrates the possibility to reformulate pravastatin tablets as liquid pharmaceutical formulation or gel with the aim of improving life quality and safety in drug administration
Dextran and its potential use as tablet excipient
No full textDextrans are a class of carbohydrate polymers extensively applied in pharmaceutical applications, particularly as drug conjugate macromolecular carriers or drug delivery systems. These polysaccharides improve the stability of the therapeutics enabling also the control of their release, via either the parenteral and or oral routes. In the latter case, due to their gel forming ability they may have potential as hydrophilic matrix tablets for sustained drug release.
In this paper, we investigated the behaviour of different molecular weight (1, 40, 500 and 2300 kDa) dextrans as tabletting excipients. Powder particle size and hygroscopic studies have been reported, together with tabletability, tablet stability and tablet swelling. Moreover we use tramadol as model compound to evaluate the ability of dextrans to control drug dissolution. The results suggest that dextrans with lower molecular weights may be a promising excipient to be used as filler for immediate release tablets, due to their good tabletability and fast dissolution rate, while dextrans with higher molecular weights could be an efficient disintegrant due to their swelling ability
Acrylic Polymers as thickening agents for tetraglycol cosolvent
No full textThis article evaluated the thickening properties of two different Eudragits, L and RS, in tetraglycol cosolvent in order to obtain high viscosity systems characterized by controlled release properties. Tetraglycol was chosen for its ability to dissolve a wide range of water insoluble drugs, while Eudragit RS and L for their specific dissolution and permeability properties under physiological conditions. Study of the rheological properties was performed to characterize elastic and viscous properties of Eudragit/tetraglycol samples in function of frequency and temperature. For all systems, the results outlined a liquid like behavior, as observed for dilute polymer solutions. In fact the fitting of the log G′-log G′′ versus frequency curves showed a good agreement with the Rouse or Zimm models. So despite the increase in viscosity, samples still behaved like liquid systems. After the addition of paracetamol the release characteristics were defined pointing out the great release control properties of both Eudragit L and RS, which showed different release kinetics depending on the pH of the environment. Semisolid Eudragits/tetraglycol systems can be considered as a new alterative for the sustained release of insoluble or poorly water-soluble drugs
Characterization and Stability of Emulsion Gels Based on Acrylamide/Sodium Acryloyldimethyl Taurate Copolymer
No full textSepineo P 600, a concentrated dispersion of acrylamide/sodium acryloyldimethyl taurate copolymer in isohexadecane, has self-gelling and thickening properties and the ability to emulsify oily phases, which make it easy to use in the formulation of gels and o/w emulsion gels. In this paper, gels were prepared using a Sepineo P 600 concentration between the 0.5% and 5% (w/w), and then emulsion gel was also prepared from the 3% Sepineo gel by adding a specific amount of almond oil. All the prepared systems were analyzed and characterized by oscillation rheology and acoustic spectroscopy. The particle size of the oil droplets and the microrheological extensional moduli (G′ and G′′) of the systems were determined from acoustic parameters and used together with the classical oscillatory rheological tests to assess the stability of the systems. Classical oscillatory analysis revealed that the dynamic moduli were very dependent on polymer concentration; as this parameter increased, there was progressive improvement in the sample elasticity. In fact, the mechanical spectra of the 0.5% and 1% (w/ w) Sepineo samples were characterized by strong frequency dependence and multiple crossover points, typical of dilute polymer solution with no organized structure. On the other hand, the 3-5% (w/w) concentration systems showed typical gel-like spectra, marked by the absence of crossover points between the dynamic moduli and by weak dependence on frequency. Nevertheless, the elastic properties of the gel-like structure even at elevated polymer concentrations were not strongly long-lasting, as demonstrated by the increase of the viscous contribution in the low frequency range during acoustic spectroscopy analysis. This fact could indicate that the gel structure is characterized by weak polymer-polymer interactions, an advantageous characteristic for topical administration, as the sample is thus easier to rub into the skin. Finally, both rheology and acoustic spectroscopy indicated that addition of the oily phase caused minimal changes to the elastic character of the gel. Thus, Sepineo P 600 gel and emulsion gel are very effective systems for use in topical and other types of applications
Caratterizzazione del processo di compressione di materiali farmaceutici: approcci empirici e reologici.
No full textTablets, the most widely used pharmaceutical dosage form, are prepared by the compression process through which two punches exert pressure on mixtures of powders or granules, loaded within a confined space. Despite the apparent simplicity of the process, it is not free from problems that in some cases make it difficult to apply. In particular, the feasibility of this process is mainly related to the characteristics of the material to be compressed, such as flowability, adhesiveness and tabletability. While in the first two cases it is possible to effectively operate by the addition of suitable excipients or by introducing a further production step such as granulation, in the case of poor tabletability these solutions may not be effective in the presence of high levels of active ingredient. Low tabletability is essentially related to the rheological features of the material to be compressed and, more specifically, to a high elasticity of the material itself, which cause the production of fragile or damaged tablets (capping and lamination). Since the rheological behaviour of the materials is strictly time-dependent, these problems are more relevant by the increase of production speed and consequently they are more frequent during the production phase than in the small scale development. The analysis of compression behaviour has been a topic of interest over the years and it has been attempted to develop models that can mathematically describe this process and predict its outcome in the various materials. The first models have been developed since the 1960's. That proposed by Heckel (Trans Metal Soc Aime, 1961) is the more frequently applied. Although it has been formulated as a scientific theory, the starting point is based on an assumption that has never been verified and can therefore be considered as an empirical model. Another semi-empirical approach is that based on the calculation of compression / decompression work by force-displacement traces. In this case, the main limitation is due to the fact that some essential contributions to the definition of the various energies involved are ignored (friction and heat). In the early 1980s, the compression process began to be studied through a rheological approach. Rippie and Danielson (J Pharm Sci, 1981) were the first to attempt to define the viscoelasticity of pharmaceuticals by deriving rheological parameters directly from the compression process, while Radebaugh et al (Int J Pharm, 1989) addressed the problem by analyzing tablets through oscillatory tests. Since the mid-2000s, however, it has been attempted to develop a predictive method by linking the rheological properties of individual discrete units to be compressed with the compaction performance (Bashaiwoldu et al, Int J Pharm, 2004 and Adv Powder Technol 2011; Cespi et al, Eur J Pharm Biopharm, 2007).This last approach is the most promising though limited by the ability to perform rheological tests only when the materials consist of particles of a certain size and regular shape
Acoustic spectroscopy for the characterization of doxorubicin-loaded liposomes
No full textAcoustic spectroscopy is a powerful technique for materials
characterization, yet underestimated in pharmaceutical
field. In particular, it measures the variation of ultrasound
parameters as sound speed and attenuation when an
ultrasound wave passes through a materials. Measurements
of sound speed or attenuation at a single low-ultrasound
frequency in function of temperature are able to detect
thermal transitions. Instead, the dependence of attenuation
over a broad-range of frequency (generally 1-100 MHz) is
employed to obtain information about particle size and
volume fraction of samples (Povey M.J.W.,2006).
Several works report the use of acoustic spectroscopy for
the characterization of the size and thermal transition of
disperse systems as suspension, emulsion or microemulsion
(Bonacucina G. et al, 2013; Duhkin A.S., 2001). Liposomes
are nano-sized double-bilayer particles of large interest in
drug delivery. A correspondence in the temperature of
phase transitions (Tm) obtained from microcalorimetry and
ultrasound spectroscopy for liposomes prepared from
different phospholipids was found (Taylor T.M. et al,
2005).
In this work attenuation data from high-resolution
ultrasonic spectroscopy in function of temperature were
compared with heat flow (microcalorimetry) and counts
(dynamic light scattering, DLS) in order to highlight the
thermal transitions of liposomes made up of a complex
mixture of PEGylated and not-PEGylated phospholipids.
Moreover, ultrasound spectroscopy was also used to
measure the average size of liposomes in comparisonwith
DLS, the most common technique for particle size
determination
THE USE OF SOUND SPEED MEASUREMENTS IN THE EVALUATION OF POLYMERS MUCOADHESIVENESS
No full textNon disponibil
Rheological, mucoadhesive and release properties of carbopol gels in hydrophilic cosolvents
No full textCarbopol is one of the most common thickening agent for water phases. It is used after neutralisation and its rheological
properties in the aqueous medium are well known. The aim of this work was to investigate the gelation properties of Carbopol
971 e 974 polymeric systems in water-miscible cosolvents such as glycerine and PEG 400. Since in these cosolvents, carboxypolymethylene
precipitates after neutralisation with a base, then the attention was pointed out of the gelation properties of the
different systems at increasing temperature, in order to obtain Carbopols gels avoiding neutralisation and, at the same time,
making possible the dissolution in these gels of insoluble or poorly soluble water drugs. Rheological properties of PEG 400
and glycerine samples were compared with similar systems in water by performing oscillatory analyses and measuring the main
rheological parameters, G, G and δ. The results obtained showed that Carbopol 971 and 974 in PEG 400 gave rise after heating
to gels that show a satisfactory rheological behaviour. The elastic modulus is greater than the viscous one showing a remarkable
elastic character of these samples and the performed frequency sweeps show a typical spectrum of a “gel-like” structure. Being
Carbopols well-known mucoadhesive polymers, gels adhesive properties were studied using the ex vivo method. Then, the
possible cutaneous irritation were also tested using the in vivo method (Draize test). No signs of cutaneous irritation and good
mucoadhesive properties were obtained for the PEG 400 and water gels of Carbopol 974 prepared by heating.
After rheological and mucoadhesive properties were set, paracetamol as a model drug was then inserted in the composition of
the gels and the release characteristics were defined. Dissolution tests pointed out the greater release control properties of PEG
400-Carbopol 971 samples. These studies showed PEG 400-Carbopol systems as a first-rate alternative to traditional water gels
Evaluation of dissolution kinetics of hydrophilic polymers by use of acoustic spectroscopy,
No full textThis paper seeks to demonstrate the feasibility of using a novel analytical technique, acoustic spectroscopy, to characterize the dissolution kinetics of hydrophilic polymers, in particular, three different model polysaccharides: lambda carrageenan, gellan gum, and xanthan gum. The influence of particle size and of analysis temperature (25 or 45 °C) was evaluated through the evolution over time of the microrheological acoustic parameters G′ and G′′. This new method was then compared with classical rheological analysis. To better compare acoustic spectroscopy and rheological analysis, the initial dissolution rate from the slope of the first part of the G′ or viscosity versus time curves was calculated. Both analytical techniques gave the same rank order of kinetics for the powder types and fractions examined; differences in absolute values were due to the fact that the two methods measured different parameters and had different stirring efficiencies. The rheological data obtained with both methods of analysis and their modelling confirmed that acoustic spectroscopy is an effective tool for monitoring and quantifying dissolution kinetics and hence affords a powerful technique for following over time a great number of physical changes occurring in a specific system
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