Formulation, Optimization, in vitro and in-vivo evaluation of levofloxacin hemihydrate Floating Tablets

Abstract The objective of the present investigation was to design, optimize and characterize the gastro retentive floating levofloxacin tablets and perform in-vivo evaluation using radiographic imaging. The floating tablets were prepared by using polymers i.e hydroxy propyl methyl cellulose (HPMC-K4M) and carbopol-940 individually and in combination by nonaquous granulation method. All the Formulations were evaluated for swelling index (S.I), floating behavior and in-vitro drug release kinetics. The compatibility study of levofloxacin with other polymers was investigated by FTIR, DSC, TGA and XRD. Results from FTIR and DSC revealed no chemical interaction amongst the formulation components. The optimized formulation (F11) showed floating lag time (FLT), total floating time (TFT) swelling index (S.I) of 60 sec, >16h and approximately 75 %, respectively. Moreover, F11 showed zero order levofloxacin release in simulated gastric fluid over the period of 6 h. X-ray studies showed that total buoyancy time was able to delay the gastric emptying of levofloxacin floating tablets in rabbits for more than 4 hours. In conclusion the optimized formulation (F11) can be used for the sustained delivery of levofloxacin for the treatment of peptic ulcer.

The Design And Development Of Carvedilol Gastroretentive Floating Drug Delivery Systems Using Hydrophilic Polymers And In Vitro Characterization

Objective: The primary aim of the present examination was to create carvedilol phosphate floating tablets using factorial designs and for retention in the upper portion of the gastrointestinal (GI) tract to sustain the dissolution where the solubility of carvedilol phosphate is more in an acidic medium. Methods: The floating tablets of carvedilol phosphate were ready to employ different concentrations and a combination of these polymers of Na-alginate, Carbopol 934P, and sodium carboxymethyl cellulose (NaCMC) with lubricants magnesium stearate by direct compression technique. In the present experiment, involved sodium bicarbonate and citric acid as a gas-producing agent. Fifteen formulations structured and judged for pre-compression components like the angle of repose, bulk and tapped density, Hausner’s ratio, compressibility index, and post-compression factors are weight uniformity, hardness, drug content, friability, in vitro buoyancy, dissolution studies, and Fourier transforms infrared spectroscopy (FTIR). Results: The drug released 90.02% in 12 h by combining NaCMC (7.5 mg) and Na-alginate (7.5 mg) in the formulation F14 towards the achievement of sustained release. Batch F14 selected as optimized, as provided desired zero-order release profile as well as floating lag time 20 s and total floating time>12 h, and the mechanism of drug release observed (n = 1.098, super case-II transport). Conclusion: From the results fulfilled that all the preparation found to be within the pharmacopeia limits and was the best dosage form to treat moderate heart failure and hypertension. The in vitro dissolution profiles of all formulations placed into various kinetic models, the statistical parameters like slope, regression coefficient and intercept determined. The gastro-retentive dosage form to maintain the sustain drug delivery, which would improve the maximum therapeutic efficacy and patient compliance.

Lipid-based floating multiparticulate delivery system for bioavailability enhancement of berberine hydrochloride

The objective of the present investigation was to design and optimize lipid-based floating multiparticulate of Berberinehydrochloride (BERH), so as to increase its solubility and to reduce P-Glycoprotein mediated efflux in the intestine,hence to improve oral bioavailability. Solid dispersions were prepared using hydrophilic carriers gelucire 44/14and gelucire 50/13 in different ratio. The prepared solid dispersion of BERH was further formulated into sustainrelease gastroretentive floating pellets using hydrophobic lipid carrier gelucire 43/01 as release retardant, sodiumbicarbonate (NaHCO3) and hydroxylpropyl methyl cellulose K4M (HPMC K4M) as gas former and matrix polymer,respectively. The effect of amount of gelucire 43/01 and NaHCO3: HPMC K4M were studied and optimized using a3-level, 2-factor, factorial design. Solid dispersion of BERH compared to pure drug showed 4-fold enhancement inaqueous solubility. The optimum system could float for more than 8 hours and showed 88.46% drug release in 8 hours.The pharmacokinetic study conducted in male Wistar rats indicated 2.32-fold increase in relative bioavailability ofoptimized formulation compare to the marketed tablet. The lipid-based floating pellets of BERH were obtained andcould be an applicable choice to deliver BERH with improved bioavailability in effective use for various clinicalapplications.

Discovery and preclinical development of IIIM-160, a Bergenia ciliata-based anti-inflammatory and anti-arthritic botanical drug candidate / 中西医结合学报

OBJECTIVE@#Bergenia ciliata (Haw.) Sternb. is used in the Indian traditional system of medicine to treat various ailments including rheumatism and to heal wounds. The objective of the present study was to perform a preclinical characterization of the B. ciliata-based botanical extract IIIM-160.@*METHODS@#IIIM-160 was chemically standardized and analyzed for heavy metal content, aflatoxins, pesticides and microbial load. The in vitro and in vivo efficacies were determined in suitable models of inflammation, arthritis and nociception. An acute oral toxicity study was performed in Swiss albino mice. A suitable oral formulation was developed and characterized.@*RESULTS@#Bergenin was found to be the major component (9.1% w/w) of IIIM-160. The botanical lead displayed inhibition of lipopolysaccharide-induced production of proinflammatory cytokines in THP-1 cells, with selectivity toward interleukin-6 (IL-6) and had an excellent safety-window. It showed anti-inflammatory, anti-arthritic and antinociceptive activity in animal models and was not toxic at oral doses up to 2 g/kg in Swiss-albino mice. The gastroretentive, sustained-release capsule formulation showed sustained-release of the bergenin over the period of 24 h, resulting in improved plasma-exposure of bergenin in Sprague-Dawley rats.@*CONCLUSION@#The dual-activity of IL-6 inhibition and antinociception marks the suitability of IIIM-160 for treating rheumatoid arthritis. This study will serve as the benchmark for further research on this botanical formulation.

Updates on Approaches to Increase the Residence Time of Drug in the Stomach for Site Specific Delivery: Brief Review

In the field of oral drug delivery system, a gastroretentive system is gaining popularity day by day. Numerous of research work and extensive literature are published in past few years on gastroretentive drug delivery system. It is the one of the best and appropriate approaches for increasing the residence time of drug in the stomach and diffuses drug slowly in the sustained manner which helps in the site-specific delivery of the drug as well also increases the bioavailability at site-specific of delivery. This helps in many challenges associated with conventional oral drug delivery system. Different ways are used for approaching gastroretention viz. swelling and expandable system, high-density system, magnetic system, bioadhesive system and buoyant system with or without gas generating agents. During data mining well in vitro characterization and in vivo characterization including gamma scintigraphic and MRI techniques are well established and reported. But, still, today in vivo characterization technique is major challenging for the researcher due to its limitation. The documented literature explains the use of animal models like beagle dogs, rabbits and human subjects for in vivo evaluation parameter but it leads to increase in variation that抯 why this delivery system is limited in the market. This paper contains the latest literature compilation and various techniques used for gastroretention with its pros and cons. This review paper helps the researcher to take an overview of basics of gastroretentive drug delivery system and helps in understanding the basics of the system.

Aplicação de resina poliuretânica derivada do óleo de mamona em formas farmacêuticas gastrorretentivas de liberação controlada / Application of polyurethane resin from castor oil in controlled release gastroretentive dosage forms

Polímeros naturais têm sido amplamente utilizados como excipientes farmacêuticos, principalmente por serem biocompatíveis e renováveis. O objetivo deste estudo foi investigar a aplicação da resina poliuretânica derivada do óleo de mamona (RPDOM) em formas farmacêuticas gastrorretentivas de liberação controlada. O trabalho aqui apresentado está dividido em quatro capítulos. O capítulo 1 trata-se de uma visão geral sobre a aplicação dos poliuretanos como sistemas de liberação de fármacos, enfatizando os estudos contendo poliuretanos do óleo de mamona. O capítulo 2 trata-se de uma revisão sistemática sobre sistemas gastrorretentivos de liberação de fármacos. O capítulo 3 trata do desenvolvimento e da caracterização da RPDOM contendo fármaco na sua matriz. Domperidona e cloridrato de verapamil foram escolhidos como fármacos modelos devido ao potencial uso desses em formulações gastrorretentivas. Os estudos físico-químicos mostraram que parte da domperidona interagiu quimicamente com a RPDOM. Visto que não é possível a quebra dessa ligação química durante o estudo de dissolução, parte do fármaco ficou indisponível para liberação. Por outro lado, o verapamil foi incorporado com sucesso na RPDOM pelo método de evaporação do solvente. O verapamil interagiu através de forças intermoleculares com o polímero e esse sistema mostrou um promissor perfil de dissolução. O capítulo 4 trata do desenvolvimento de matrizes monolíticas flutuantes, contendo verapamil como fármaco modelo, espuma de polipropileno como excipiente de baixa densidade e um blend da RPDOM e da celulose microcristalina como sistema matricial. A capacidade de flutuação in vitro das matrizes e o controle da liberação do fármaco foram demonstrados. Por fim, a RPDOM mostrou-se um polímero promissor para o uso em sistemas de liberação controlada de fármacos devido a sua hidrofobicidade e para o uso em sistemas gastrorretentivos flutuantes devido à sua baixa densidade

Natural polymers have been extensively used as pharmaceutical excipients mainly due to their biocompatibility and renewability. The aim of this study was to investigate the application of polyurethane resin from castor oil (PU) in controlled release gastroretentive dosage forms. The work presented herein is divided in four chapters. Chapter 1 is an overview of the application of polyurethanes as drug delivery systems, emphasizing studies containing castor oil-based polyurethanes. Chapter 2 is a systematic review of gastroretentive drug delivery systems. Chapter 3 is about the development and characterization of the PU containing drug in its matrix. Domperidone and verapamil hydrochloride were chosen as model drugs due to their potential use in gastroretentive formulations. Physicochemical studies showed that part of domperidone interacted chemically with PU. Since it is not possible a cleavage of the chemical bond between domperidone and the polyurethane during the dissolution study, part of the drug was not available for release. On the other hand, verapamil was successfully incorporated into PU by solvent evaporation method. Verapamil interacted by intermolecular forces with the polymer and this system showed a promising drug dissolution profile. Chapter 4 shows the development of floating monolithic matrices, containing verapamil as model drug, polypropylene foam as low-density excipient and a blend of PU and microcrystalline cellulose as matrix-forming polymers. The in vitro buoyancy capability of the matrices and the ability to control drug release were demonstrated. Finally, PU proved to be a potential polymer to be used in controlled drug delivery systems due to its hydrophobicity and in gastroretentive floating systems due to its low density

Non-Starch Plant Polysaccharides: Physicochemical Modifications and Pharmaceutical Applications.

Polysaccharides of natural, synthetic or semi-synthetic origin have been used from time immemorial in the development of drug delivery systems designed to achieve tailored and site-specific drug release. Starch-based polysaccharides derived from plants have been extensively studied in this regard. Natural polymeric excipients are preferred over their synthetic counterparts owing to their low cost, availability, biocompatibility, biodegradability and non-toxicity. The present review attempts to provide a new direction and a comprehensive insight on the physical properties, rheological behavior, toxicity profile, pharmaceutical applications, swelling behavior and drug diffusion kinetics from dosage forms based on non-starch polysaccharides of plant origin such as, psyllium, pectin, arabinoxylan, xyloglucan, guar gum galactomannan and konjac glucomannan. It has been observed from the current review that non-starch polysaccharides are safe for human consumption and can be successfully employed to deliver drugs specifically to stomach and colon in a sustained fashion. They have thus widened the scope of natural polymeric excipients and demand better industrial utilization on a commercial scale to minimize cost of production and to satisfy therapeutic needs in safe and effective manner.

Design and Optimization of Hydrodynamically Balanced Oral In situ Gel of Glipizide.

Objective: The purpose of the present investigation was to formulate hydrodynamically balanced oral In situ gel of glipizide inorder to increase the gastric residence time and to modulate the release behavior of the drug. Material and method: In situgel formulations were prepared by using different concentrations of sodium alginate, calcium carbonate, trisodium citrate and release retardant polymers. pH triggered ionic gelation is the mechanism involved in the present study. Taguchi L9 OA experimental design was employed for the optimization of formulations. All the formulations were subjected to various evaluation parameters. Results: Formulation F9 containing 3% of sodium alginate, 1.0 % of CaCO3, 0.2% of trisodium citrate and 0.5% of HPMC-K100M was selected as optimized batch based on Q12 58.26%, floating time 47.76 sec and drug content 98.2%. The release pattern of drug was found to follow first order. The value of ‘n’ from Korsemeyer equation was found to be 1.00 indicating the drug release by supercase II. The DSC study revealed that there was no incompatibility. Gastroretentive X-ray imaging study on Albino rabbit demonstrated that it was able to float in the stomach for more than 8hrs. Pharmacodynamic study on Wistar rats demonstrated significant hypoglycaemic activity of the optimized formulation. Conclusion: It was concluded that the hydrodynamically balanced oral In situ gel of glipizide could be an effective dosage form which remains buoyant and sustain the drug release for 24hrs.

Formulation and in Vitro Evaluation of Ketoprofen Gastric Floating Matrix Tablet Based on Gas Formation.

The purpose of this study was to develop a gastroretentive drug delivery system of ketoprofen with suitable swelling and floating properties to reduce its irritant effect on the stomach and prolong its short duration of action up to 12 h. Floating tablets were prepared employing EC (ethylcellulose), NaCMC (sodium carboxy methylcellulose), HPMC K4M (hydroxypropyl methylcellulose) (release retarding polymers), Sodium bicarbonate (gas-generating agent), Lactose and Avicel (fillers) by gas formation technique. Tablets were evaluated for drug content, weight variation, hardness, thickness, floating behavior, swelling ability and invitro drug release in 0.1 N HCl containing tween 20. The optimized formulations of F3, F4 and E2 exhibited prolonged drug release for 12 h, with short lag time (≤3 min) and long floating duration (≥24 h). ANOVA post hoc multiple comparisons was conducted for significance at P<0.05. Based on kinetic studies, formulations best fitted to Higuchi model. The results indicated that type and amount of polymer, type of fillers and amount of gas generating agent have influenced on drug release and floating behavior.

A review: Gastroretentive drug delivery system (grdds)

One novel approach in this area is GRDDSs (Gastro Retentive Drug Delivery System). GRDDSs can improve the controlled delivery of drugs that have an absorption window by continuously releasing the drug for a prolonged period of time before it reaches its absorption site.The purpose of writing this review was to investigate, compile and present the recent as well as past literatures in more concise way with special focus on approaches which are currently utilized in the prolongation of gastric residence time. These includes floating system, swelling and expanding system, bio/mucoadhesive system, high density system and other delayed gastric emptying devices. The present review addresses briefly about the classification, formulation consideration for GRDDS, factors controlling gastric retention, merits, demerits and applications of gastroretentive drug delivery systems.

Preparation and in vitro evaluation of ciprofloxacin hydrochloride gastro-retentive tablets / 中国药学杂志

OBJECTIVE: To investigate the effect of polymers, including hydrophilic polymers and swelling aids, on floatability and dissolution of ciprofloxacin hydrochloride gastro-retentive tablets. METHODS: Hydroxypropyl methyl cellulose (HPMC), hydroxyethylcellulose (HEC) and hydroxypropylcellulose (HPC) were used as hydrophilic swelling excipients, and disintegrants crospovidone (PVPP XL and PVPP XL-10) or croscarmellose sodium (CCS) were used as swelling agents to facilitate the swelling/floating and drug release. Initial floating time and floating duration were tested to evaluate buoyance, and drug dissolution was tested to evaluate the controlled release. RESULTS: Using HPMC K250 and PVPP XL as excipients for ciprofloxacin hydrochloride gastro-retentive tablets could obtain products with rapid onset of floating, long floating durion and desirable drug release. CONCLUSION: Variety and amount of polymers have dramatic effects on buoyance and drug release of gastro-retentive tablets. HPMC K250 and PVPP XL are suitable excipients for ciprofloxacin hydrochloride gastro-retentive tablets.

Formulation of gastroretentive floating drug delivery system using hydrophilic polymers and its in vitro characterization

The aim of the present research is to formulate and evaluate the gastroretentive floating drug delivery system of antihypertensive drug, propranolol HCl. Gastroretentive floating tablets (GRFT) were prepared by using a synthetic hydrophilic polymer polyethylene oxide of different grades such as PEO WSR N-12 K and PEO 18 NF as release retarding polymers and calcium carbonate as gas generating agent. The GRFT were compressed by direct compression strategy and the tablets were evaluated for physico-chemical properties, in vitro buoyancy, swelling studies, in vitro dissolution studies and release mechanism studies. From the dissolution and buoyancy studies, F 9 was selected as an optimized formulation. The optimized formulation followed zero order rate kinetics with non-Fickian diffusion mechanism. The optimized formulation was characterised with FTIR studies and observed no interaction between the drug and the polymers.

O objetivo da presente pesquisa é o de formular e avaliar o sistema de liberação de fármaco gastrorretentivo flutuante, contendo o anti-hipertensivo, cloridrato de propranolol. Comprimidos gastrorretentivo flutuantes (GRFT) foram preparados utilizando um polímero hidrofílico sintético, o óxido de polietileno, de diferentes graus, tais como GE WSR N-12 K e GE 18 NF, como polímeros de retardamento de liberação, e carbonato de cálcio, como agente gerador de gases. Os GRFT foram comprimidos por compressão direta e avaliados para determinação das propriedades físico-químicas, flutuabilidade in vitro, estudos de inchamento, de dissolução in vitro e de mecanismo de liberação. Dos testes de dissolução e de flutuabilidade, selecionou-se F 9 como formulação otimizada. A formulação otimizada seguiu cinética de ordem zero, com mecanismo de difusão não-Fickiano. Essa formulação foi caracterizada por estudos de FTIR, não se observando interação entre o fármaco e os polímeros.

Design and evaluation of a gastroretentive drug delivery system for metformin HCl using synthetic and semi-synthetic polymers / Diseño y evaluación de un sistema gastro-retentivo de administración de metformina HCl, utilizando polímeros sintéticos y semisintéticos

The aim of the present research was to prepare and evaluate a gastroretentive drug delivery system for metformin HCl, using synthetic and semi-synthetic polymers. The floating approach was applied for preparing gastroretentive tablets (GRT) and these tablets were manufactured by the direct compression method. The drug delivery system comprises of synthetic and semi-synthetic polymers such as polyethylene oxide and Carboxymethyl ethyl cellulose (CMEC) as release-retarding polymers. GRT were evaluated for physico-chemical properties like weight variation, hardness, assay friability, in vitro floating behaviour, swelling studies, in vitro dissolution studies and rate order kinetics. Based upon the drug release and floating properties, two formulations (MP04 & MC03) were selected as optimized formulations. The optimized formulations MP04 and MC03 followed zero order rate kinetics, with non-Fickian diffusion and first order rate kinetics with erosion mechanism, respectively. The optimized formulation was characterised with FTIR studies and it was observed that there was no interaction between the drug and polymers.

El objetivo del presente trabajo consistió en preparar y evaluar un sistema de administración gastro-retentivo de metformina HCl, utilizando polímeros sintéticos y semisintéticos. Se aplicó el método de flotación para la elaboración de los comprimidos de retención gástrica (CRG) y éstos se prepararon mediante el método de compresión directa. El sistema de suministro del fármaco estaba constituido por polímeros sintéticos y semisintéticos, tales como el óxido de polietileno y la carboximetil etil celulosa, como agentes retardadores de la liberación del fármaco. Se evaluaron las propiedades físico-químicas de los CRG, tales como: variación de peso, dureza, friabilidad, comportamiento flotante in vitro, capacidad de inflación, estudios de disolución in vitro y su tasa de orden cinético. Se seleccionaron dos fórmulas (MP04 y MC03), sobre la base de la liberación del fármaco y las propiedades de flotabilidad, como fórmulas óptimas. Estas fórmulas MP04 y MC03 optimizadas siguieron cinéticas de velocidad de orden cero, con difusión no-Fickian y tasa cinética de primer orden con mecanismo de erosión, respectivamente. Las fórmulas óptimas se caracterizaron con estudios FTIR y se observó que no hubo interacción entre el fármaco y los polímeros.

Thermal sintering: a novel technique in the design of gastroretentive floating tablets of propranolol HCl and its evaluation / Sinterización térmica: Una técnica novedosa en el diseño de tabletas flotantes gastroretentivas de HCl propanolol y su evaluación

The aim of the present investigation was to formulate thermally sintered floating tablets of propranolol HCl, and to study the effect of sintering conditions on drug release, as well as their in vitro buoyancy properties. A hydrophilic polymer, polyethylene oxide, was selected as a sintered polymer to retard the drug release. The formulations were prepared by a direct compression method and were evaluated by in vitro dissolution studies. The results showed that sintering temperature and time of exposure greatly influenced the buoyancy, as well as the dissolution properties. As the sintering temperature and time of exposure increased, floating lag time was found to be decreased, total floating time was increased and drug release was retarded. An optimized sintered formulation (sintering temperature 50°C and time of exposure 4 h) was selected, based on their drug retarding properties. The optimized formulation was characterized with FTIR and DSC studies and no interaction was found between the drug and the polymer used.

El propósito de la presente investigación fue la elaboración de tabletas flotantes de HCL propanolol térmicamente sinterizadas y estudiar los efectos de las condiciones de sinterización sobre la liberación de la droga, así como sobre sus propiedades de flotabilidad in vitro. Se seleccionó un polímero hidrofílico, el óxido de polietileno, como polímero sinterizado, para retardar la liberación de la droga. Las fórmulas se prepararon mediante un método de compresión directa y se evaluaron mediante estudios de disolución in vitro. Los resultados demostraron que la temperatura de sinterización y el tiempo de exposición tuvieron una gran influencia sobre las propiedades de flotabilidad y de disolución. Se encontró que el intervalo de retardo en la flotación disminuyó, el tiempo total de flotación aumentó y se retardó la liberación de la droga, a medida que aumentaron la temperatura de sinterización y el tiempo de exposición. Se seleccionó una fórmula óptima de sinterización (temperatura de sinterización de 50°C y tiempo de exposición de 4 h), basados en las propiedades retardativas sobre la droga. La fórmula sinterizada se caracterizó mediante estudios FITR y DSC y no se encontró ninguna interacción entre la droga y el polímero utilizado.

Floating drug delivery systems: A better approach.

The purpose of writing this review on floating drug delivery systems (FDDS) was to compile the recent literature with special focus on the principal mechanism of floatation to achieve gastric retention. It is known that differences in gastric physiology (such as, gastric pH, motility) exhibit both intra- as well as inter-subject variability demonstrating significant impact on gastric retention time and drug delivery behaviour. The recent developments of FDDS including the physiological and formulation variables affecting gastric retention, approaches to design single-unit and multiple-unit floating systems, and their classification and formulation aspects are covered in detail. This review also summa-rizes the studies to evaluate the performance and application of floating systems, and applications of these systems.

Formulation and Evaluation of Gastroretentive Floating Tablets of Domperidone Maleate.

The low bioavailability (15%) and good solubility of Domperidone Maleate in acidic pH following oral administration favours development of a gastro retentive formulation. Gastroretentive floating matrix tablets of Domperidone Maleate were successfully prepared with hydrophilic polymers like HPMC K4M, HPMC K15M and HPMC K100M. From the Preformulation studies for drug excipients compatibility it was observed that there was no compatability problem with the excipients used in study. The drug release from most of the formulations follows fickian diffusion. From in-vivo X-ray studies, it was clearly observed that the floating tablets showed a gastric residence of nearly 4.5 hrs in fed state.

In vitro and invivo evaluation of hepato protection and anti ulcer activities of piperine gastro retentive micropspheres

Objective: In the recent years of research, the interest on herbal medicine is continuously increasing. Piperine is an alkaloid extracted from ripen fruits of Piper nigram and was proved in literature for its hepato protective and anti ulcer properties majorly through anti oxidant capability. Methods: In the present investigation gastro retentive, both floating and mucoadhessive microspheres are evaluated for the hepato protection in paracetamol induced model and gastric protection in rats and a comparison was done with conventional microspheres and pure form of piperine. Results: The results clearly showed the significant decrease in the serum levels of the marker enzymes in hepato protective study supported by histopathology along with reduced ulcer index in anti ulcer activity. Conclusion: This clearly indicates that there is an increase in both activities of floating microspheres, mucoadhessive microspheres when compared with the PP and conventional microspheres.

Floating drug delivery systems: A better approach.

The purpose of writing this review on floating drug delivery systems (FDDS) was to compile the recent literature with special focus on the principal mechanism of floatation to achieve gastric retention. It is known that differences in gastric physiology (such as, gastric pH, motility) exhibit both intra- as well as inter-subject variability demonstrating significant impact on gastric retention time and drug delivery behaviour. The recent developments of FDDS including the physiological and formulation variables affecting gastric retention, approaches to design single-unit and multiple-unit floating systems, and their classification and formulation aspects are covered in detail. This review also summa-rizes the studies to evaluate the performance and application of floating systems, and applications of these systems.

Formulation and characterization of gastroretentive discs containing famotidine

In this work a different type of formulation, as disc, containing a selected mucoadhesive polymer, fillers, and binders were investigated for their potential as a mucoadhesive gastroretentive delivery system to deliver famotidine in the stomach. Various types of hydrophilic diluents were evaluated for their swelling and mucoadhesive property and one (polyvinylpyrrolidone, PVP) was selected to combine with the selected mucoadhesive polymer (polyethylene oxide, PEO). Discs with different ratios of PEO and PVP were prepared and evaluated for swelling, dissolution, and mucoadhesion. The swelling property of the discs increased as the concentration of PEO was increased and also did the mucoadhesion. These discs retained their integrity and adherence onto gastric mucosa for more than 10 h under in-vitro conditions. The PEO, in combination with PVP, yielded a non-disintegrating type mucoadhesive dosage form which was suitable for gastroretentive applications to achieve the desired release profile of the drug.

Sistemas farmacêuticos gastrorretentivos flutuantes / Pharmaceutical gastro-retentive systems

Freqüentemente recorre-se à produção de sistemas gastrorretentivos para modular a liberação de fármacos a partir de sistemas farmacêuticos com vistas ao aumento do tempo de permanência do fármaco no trato gastrointestinal. Umas das estratégias mais interessantes passa pela produção de sistemas flutuantes. Estes podem ser classificados em dois grupos: sistemas flutuantes efervescentes e sistemas flutuantes não-efervecentes. Neste artigo apresenta-se uma revisão bibliográfica do que tem sido produzido nesta área nos últimos anos.

Gastro-retentive systems are often produced in order to modulate drugs release from pharmaceutical forms and in this way to increase drug residence time in the gastrointestinal tract. One of the most interesting strategies consists in the preparation of floating devices. These can be classified into two groups: effervescent systems and non-effervescent systems. A review of what has been done in the last years is presented in this article.