Formulation and in vitro characterization of ciprofloxacin floating and bioadhesive extended-release tablets

Recent advancements and perspective of ciprofloxacin-based antimicrobial polymers

In recent years, microbial pathogens, which are major sources of infections, have become a widespread concern across the world. The number of deaths caused by infectious diseases is continually rising, according to World Health Organization records. Antimicrobial resistance, particularly resistance to several drugs, is steadily growing in percentages of organisms. Ciprofloxacin is a second-generation fluoroquinolone with significant antimicrobial activity and pharmacokinetic characteristics. According to studies, many bacteria are resistant to the antibiotic ciprofloxacin. In this article, we look into polymers as ciprofloxacin macromolecular carriers with a wide range of antibacterial activity. We also discuss the latter form of coupling, in which ciprofloxacin and polymers are covalently bonded. This article also discusses the use of antimicrobial polymers in combination with ciprofloxacin in a various sectors. The current review article provides an overview of publications in the last five years on polymer loaded or modified with ciprofloxacin having applications in numerous sectors.

Citric Acid: A Multifunctional Pharmaceutical Excipient

Citric acid, a tricarboxylic acid, has found wide application in the chemical and pharmaceutical industry due to its biocompatibility, versatility, and green, environmentally friendly chemistry. This review emphasizes the pharmaceutical uses of citric acid as a strategic ingredient in drug formulation while focusing on the impact of its physicochemical properties. The functionality of citric acid is due to its three carboxylic groups and one hydroxyl group. These allow it to be used in many ways, including its ability to be used as a crosslinker to form biodegradable polymers and as a co-former in co-amorphous and co-crystal applications. This paper also analyzes the effect of citric acid in physiological processes and how this effect can be used to enhance the attributes of pharmaceutical preparations, as well as providing a critical discussion on the issues that may arise out of the presence of citric acid in formulations.

Tocotrienols-rich naringenin nanoemulgel for the management of diabetic wound: Fabrication, characterization and comparative in vitro evaluations

The present research had been attempted to formulate and characterize tocotrienols-rich naringenin nanoemulgel for topical application in chronic wound conditions associated with diabetes. In due course, different phases of the nanoemulsion were chosen based on the solubility study, where combination of Capryol 90 and tocotrienols, Solutol HS15, and Transcutol P were selected as oil, surfactant, and cosurfactant, respectively. The nanoemulsions were formulated using the spontaneous emulsification method. Subsequently, Carbopols were incorporated to develop corresponding nanoemulgels of the optimized nanoemulsions. Thermodynamically stable optimized nanoemulgels were evaluated for their globule size, polydispersity index (PDI), surface charge, viscosity, mucoadhesive property, spreadability, in vitro release and release mechanism. Further, increasing polymer concentration in the nanoemulgels was reflected with the increased mucoadhesive property with corresponding decrease in the release rate of the drug. The optimized nanoemulgel (NG1) consisted of uniform dispersion (PDI, 0.452 ​± ​0.03) of the nanometric globules (145.58 ​± ​12.5) of the dispersed phase, and negative surface charge (−21.1 ​± ​3.32 ​mV) with viscosity 297,600 ​cP and good spreadability. In vitro release of naringenin in phosphate buffer saline revealed a sustained release profile up to a maximum of 74.62 ​± ​4.54% from the formulated nanoemulgel (NG1) within the time-frame of 24 ​h. Alternatively, the release from the nanoemulsion was much higher (89.17 ​± ​2.87%), which might be due to lack of polymer coating on the dispersed oil droplets. Moreover, the in vitro release kinetics from the nanoemulgel followed the first-order release and Higuchi model with non-Fickian diffusion. Therefore, encouraging results in this research is evident in bringing a promising future in wound management, particularly associated with diabetes complications.

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Thermodynamically stable naringenin-loaded tocotrienol-rich nanoemulgels were fabricated using spontaneous method.

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Developed nanoemulgel possesses nanometric globule size with good spreadability.

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Controlled in vitro release was obtained over a period of 24 ​h.

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First-order release and Higuchi model with non-Fickian diffusion was established in the in vitro release kinetic profile.

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This nanoemulgel could be a promising tool in the management of chronic wound condition.

Application of Nanocellulose Derivatives as Drug Carriers; A Novel Approach in Drug Delivery

BACKGROUND

The production of nanocellulose for drug delivery systems has achieved increased attention in the past decade. High capacity for swelling and absorption of the liquid phase, high flexibility in creating different derivatives, economical cost, and ease of access to the primary source, all of these properties have encouraged researchers to use nanocellulose and its derivatives as a high-performance drug carrier.

OBJECTIVE

The recent progress summary of cellulose-based nanocarriers designing and practical approaches in drug delivery.

METHODS

We conducted a literature review on the development of the nanocellulose and its derivatives as a high-performance drug carrier.

RESULTS

In this review, we have attempted to present the latest advances in cellulose modifications for the design of pharmaceutical nanocarriers. At first, cellulose properties and structural classification of nanocellulose were introduced. Then, focusing on medical applications, some efforts and laboratory trials in cellulose-based nano designing were also discussed. The findings demonstrate the benefits of nanocellulose in drug delivery and its potential for modifying by adding functional groups to enhance drug delivery efficiency. Due to the physical and chemical properties of cellulose and its high flexibility to interact with other compounds, a broad perspective can be imagined in the diverse research and novel forms of nanocarriers.

CONCLUSION

The cellulose nanocarriers can be considered as an attractive platform for researchers to design new structures of pharmaceutical carriers and increase the efficiency of these nanocarriers in drug delivery for the treatment of diseases such as cancer.

Development of Paroxetine Hydrochloride Single Layer Controlled-Release Tablets Based on 3² Factorial Design

Major depressive disorder (MDD) is one of the main contributors to disability and suicide mortality globally. Paroxetine hydrochloride (PHH) is the most potent antidepressant used for MDD treatment. Due to its reduced side effects PAXIL^® CR is a widely-used controlled-release formulation of PHH. However, the complicated double-layer production of PAXIL^® CR faces the risk of layer separation. In this study, PHH enteric coating single layer controlled-release tablets (PHH-EC-SLTs) were designed as a simplified substitution of PAXIL^® CR through a rational formulation screening. The optimized PHH-EC-SLTs showed similar release behaviors in vitro to PAXIL^® CR and the release profiles corresponded to a zero-order release model (R² = 0.9958). Polymer matrix erosion was the main release mechanism, according to the fitting exponents n > 1 in the Korsmeyer-Pappas model. Crucial pharmacokinetic parameters including peak-reaching time (T_max), peak concentration (C_max) and the area under the blood level-time curve (AUC_0-48) of PHH-EC-SLTs and PAXIL^® CR had no significant difference (p > 0.05) and the relative bioavailability (F = 97.97%) of PHH-EC-SLTs demonstrated their similar pharmacokinetic profiles in vivo. In view of avoiding layer separation risk and simplifying the preparation processing, the self-made PHH-EC-SLTs could be considered as a safe and economic alternative to PAXIL^® CR.

Pharmaceutical Applications of Cellulose Ethers and Cellulose Ether Esters

Cellulose ethers have proven to be highly useful natural-based polymers, finding application in areas including food, personal care products, oil field chemicals, construction, paper, adhesives, and textiles. They have particular value in pharmaceutical applications due to characteristics including high glass transition temperatures, high chemical and photochemical stability, solubility, limited crystallinity, hydrogen bonding capability, and low toxicity. With regard to toxicity, cellulose ethers have essentially no ability to permeate through gastrointestinal enterocytes and many are already in formulations approved by the U.S. Food and Drug Administration. We review pharmaceutical applications of these valuable polymers from a structure-property-function perspective, discussing each important commercial cellulose ether class; carboxymethyl cellulose, methyl cellulose, hydroxypropylcellulose, hydroxypropyl methyl cellulose, and ethyl cellulose, and cellulose ether esters including hydroxypropyl methyl cellulose acetate succinate and carboxymethyl cellulose acetate butyrate. We also summarize their syntheses, basic material properties, and key pharmaceutical applications.

Complex Hydrogels Composed of Chitosan with Ring-opened Polyvinyl Pyrrolidone as a Gastroretentive Drug Dosage Form to Enhance the Bioavailability of Bisphosphonates

Complex hydrogels formed with chitosan (CS) and ring-opened polyvinyl pyrrolidone (roPVP) as a swellable mucoadhesive gastroretentive drug dosage form (smGRDDF) were prepared and characterized. CS/roPVP hydrogels were produced by blending CS with roPVP obtained by basic treatment of PVP. Effects of the heating time and NaOH concentration employed for preparing roPVP, and CS molecular weights (Mws), and roPVP/CS ratios on the swelling ability of the resultant hydrogels were characterized. Rheological characteristics were further examined. Results demonstrated that roPVP obtained in a 0.5 M NaOH solution heated to 50 °C for 4 h was suitable for producing complex hydrogels with CS. At a roPVP/CS ratio of 20:1, hydrogels composed of three different Mws of CS possessed optimal swelling and mucoadhesive abilities and rheological properties. In vitro dissolution revealed sustained drug release. A pharmacokinetic study exhibited that the plasma profile of alendronate followed a sustained manner with 3-fold enhancement of the oral bioavailability. In conclusion, the smGRDDF composed of CS/roPVP complex hydrogels was successfully developed and is potentially applicable to improve the clinical efficacy of bisphosphonates.

Modification of drug delivery to improve antibiotic targeting to the stomach

The obstacles to the successful eradication of Helicobacter pylori infections include the presence of antibiotic-resistant bacteria and therapy requiring multiple drugs with complicated dosing schedules. Other obstacles include bacterial residence in an environment where high antibiotic concentrations are difficult to achieve. Biofilm production by the bacteria is an additional challenge to the effective treatment of this infection. Conventional oral formulations used in the treatment of this infection have a short gastric residence time, thus limiting the duration of exposure of drug to the bacteria. This review summarizes the current research in the development of gastroretentive formulations and the prospective future applications of this approach in the targeted delivery of drugs such as antibiotics to the stomach.

Design and evaluation of an innovative floating and bioadhesive multiparticulate drug delivery system based on hollow structure

In this study a gastric-retentive delivery system was prepared by a novel method which is reported here for the first time. An innovative floating and bioadhesive drug delivery system with a hollow structure was designed and prepared. The floating and bioadhesive drug delivery system was composed of a hollow spherical shell, a waterproof layer (Stearic acid), a drug layer (Ofloxacin), a release retarding film (the novel blended coating materials) and a bioadhesive layer (Carbomer 934P) prepared by using a liquid multi-layering process. A novel blended coating material was designed and investigated to solve the problem of the initial burst release of the formulation and the release mechanism of the novel material was analyzed in this study. The optimized formulation provided the sustained release characteristic and was able to float for 24h. The SEM cross-section images showed that the particulates were hollow with a spherical shell. X-ray images and pharmacokinetic studies (Frel = 124.1 ± 28.9%) in vivo showed that the gastric-retentive delivery system can be retained in the stomach for more than 6h. The floating and bioadhesive particulate drug delivery system based on a hollow structure with a dual function presented here is a viable alternative to other for gastroretentive drug delivery system.

Formulation and in vitro, in vivo evaluation of effervescent floating sustained-release imatinib mesylate tablet

Introduction

Imatinib mesylate is an antineoplastic agent which has high absorption in the upper part of the gastrointestinal tract (GIT). Conventional imatinib mesylate (Gleevec) tablets produce rapid and relatively high peak blood levels and requires frequent administration to keep the plasma drug level at an effective range. This might cause side effects, reduced effectiveness and poor therapeutic management. Therefore, floating sustained-release Imatinib tablets were developed to allow the tablets to be released in the upper part of the GIT and overcome the inadequacy of conventional tablets.

Methodology

Floating sustained-release Imatinib mesylate tablets were prepared using the wet granulation method. Tablets were formulated using Hydroxypropyl Methylcellulose (HPMC K4M), with Sodium alginate (SA) and Carbomer 934P (CP) as release-retarding polymers, sodium bicarbonate (NaHCO₃) as the effervescent agent and lactose as a filler. Floating behavior, in vitro drug release, and swelling index studies were conducted. Initial and total drug release duration was compared with a commercial tablet (Gleevec) in 0.1 N HCl (pH 1.2) at 37 ± 0.5°C for 24 hours. Tablets were then evaluated for various physical parameters, including weight variation, thickness, hardness, friability, and drug content. Consequently, 6 months of physical stability studies and in vitro gastro-retentive studies were conducted.

Results and Discussion

Statistical data analysis revealed that tablets containing a composition of 14.67% w/w HPMC K4M, 10.67%, w/w Na alginate, 1.33%, w/w Carbomer 934P and 9.33%, w/w NaHCO₃ produced the most favorable formulation to develop 24-hour sustained-release tablets with optimum floating behavior and satisfactory physicochemical characteristics. Furthermore, in vitro release study revealed that the formulated SR tablet had significantly lower C_max and higher T_max compared to the conventional tablet (Gleevec). Thus, formulated SR tablets preserved persistent concentration of plasma up to 24 hours.

Conclusion

In conclusion, in order to suggest a better drug delivery system with constant favorable release, resulting in optimized absorption and less side effects, formulated CP-HPMC-SA based imatinib mesylate floating sustained-release tablets can be a promising candidate for cancer chemotherapy.

Formulation development, optimization, and evaluation of sustained release tablet of valacyclovir hydrochloride by combined approach of floating and swelling for better gastric retention

The present study is intended to enhance gastric retention of sustained release tablet of valacyclovir hydrochloride by combined approach of floating and swelling. The tablets are prepared by direct compression method. Polyethylene oxide (Polyox WSR 303) is selected as the swelling matrix agent. Sodium starch glycolate (SSG) is used as swelling enhancer, and sodium bicarbonate is used as an effervescent agent for floating. A 3(2) full factorial design is applied to systematically optimize the formulation. The concentration of Polyox WSR 303 (X 1) and concentration of SSG (X 2) are selected as independent variables. The percentage drug release at 12 h, floating lag time, and maximum percentage swelling are selected as dependent variables. Formulations are evaluated for hardness, friability, floating lag time, total floating time, percentage swelling, in vitro drug release, and in vivo floating study. The results indicated that X 1 and X 2 significantly affected the drug release properties, floating lag times, and maximum percentage swelling. Release rate decreases as the concentration of Polyox increased. Regression analysis and numerical optimization are performed to identify the best formulation. Formulation F5 prepared with Polyox WSR 303 (15 %) and SSG (10 %) is found to be the best formulation. F5 followed zero-order release mechanism. Swelling and floating gastroretentive tablets of valacyclovir HCl are successfully formulated with controlled delivery to stomach with an aim of increasing the mean residence time in the upper part of GIT where the drug has its absorption window.

Swelling/floating capability and drug release characterizations of gastroretentive drug delivery system based on a combination of hydroxyethyl cellulose and sodium carboxymethyl cellulose

The aim of this study was to characterize the swelling and floating behaviors of gastroretentive drug delivery system (GRDDS) composed of hydroxyethyl cellulose (HEC) and sodium carboxymethyl cellulose (NaCMC) and to optimize HEC/NaCMC GRDDS to incorporate three model drugs with different solubilities (metformin, ciprofloxacin, and esomeprazole). Various ratios of NaCMC to HEC were formulated, and their swelling and floating behaviors were characterized. Influences of media containing various NaCl concentrations on the swelling and floating behaviors and drug solubility were also characterized. Finally, release profiles of the three model drugs from GRDDS formulation (F1-4) and formulation (F1-1) were examined. Results demonstrated when the GRDDS tablets were tested in simulated gastric solution, the degree of swelling at 6 h was decreased for each formulation that contained NaCMC in comparison to those in de-ionized water (DIW). Of note, floating duration was enhanced when in simulated gastric solution compared to DIW. Further, the hydration of tablets was found to be retarded as the NaCl concentration in the medium increased resulting in smaller gel layers and swelling sizes. Dissolution profiles of the three model drugs in media containing various concentrations of NaCl showed that the addition of NaCl to the media affected the solubility of the drugs, and also their gelling behaviors, resulting in different mechanisms for controlling a drug’s release. The release mechanism of the freely water-soluble drug, metformin, was mainly diffusion-controlled, while those of the water-soluble drug, ciprofloxacin, and the slightly water-soluble drug, esomeprazole, were mainly anomalous diffusion. Overall results showed that the developed GRDDS composed of HEC 250HHX and NaCMC of 450 cps possessed proper swelling extents and desired floating periods with sustained-release characteristics.

Formulation and evaluation of sustained release matrix tablet of rabeprazole using wet granulation technique

Introduction:

Rabeprazole, a member of substituted benzimidazoles, inhibits the final step in gastric acid secretions. This drug claims to cause fastest acid separation (due to higher pKa), and more rapidly converts to the active species to aid gastric mucin synthesis. The most significant pharmacological action of Rabeprazole is dose dependent suppression of gastric acid secretion; without anticholinergic or H2-blocking action. It completely abolishes the hydrochloric acid secretion as it is powerful inhibitor of gastric acid. Rabeprazole is acid labile and hence commonly formulated as an enteric coated tablet. The absorption of rabeprazole occurs rapidly as soon as tablet leaves the stomach.

Aim:

In the present study an attempt was made to formulate and evaluate Rabeprazole sustained release matrix tablet using wet granulation technique incorporating various polymers like HPMC-E15, Carbopol934, and sodium carboxymethyl cellulose (CMC).

Materials and Methods:

The Formulated tablets were evaluated for different physicochemical properties like rheological properties, weight variation, thickness, hardness, % friability, in vitro release studies and drug content.

Results:

Studies revealed that all the physicochemical parameters comply with the official standards. The in vitro release studies exhibits the release up to 90%, over a prolonged period of time which confirms the extended release profile of formulation, having better bioavailability as well as decreased dosing frequency with reduced doses.

Conclusion:

The sustained release matrix tablets of rabiprazole shown better bioavailability, efficacy and potency, when compared with official standards.

Decades of research in drug targeting to the upper gastrointestinal tract using gastroretention technologies: where do we stand?

A major constraint in oral controlled release drug delivery is that not all the drug candidates are absorbed uniformly throughout the gastrointestinal tract (GIT). Drugs having "absorption window" are absorbed in a particular portion of GIT only or are absorbed to a different extent in various segments of the GIT. Thus, only the drug released in the region preceding and in close vicinity to the absorption window is available for absorption. The drug must be released from the dosage form in solution form; otherwise, it is generally not absorbed. Hence, much research has been dedicated to the development of gastroretentive drug delivery systems that may optimize the bioavailability and subsequent therapeutic efficacy of such drugs, as these systems have unique properties to bypass the gastric emptying process. These systems show excellent in vitro results but fail to give desirable in vivo performance. During the last 2-3 decades, researchers from the academia and industries are giving considerable importance in this field. Unfortunately, till date, few so-called gastroretentive dosage forms have been brought to the market in spite of numerous academic publications. The manuscript considers strategies that are commonly used in the development of gastroretentive drug delivery systems with a special attention on various parameters, which needs to be monitored during formulation development.

Water hyacinth: a possible alternative rate retarding natural polymer used in sustained release tablet design

In recent years natural polymers have been widely used because of their effectiveness and availability over synthetic polymers. In this present investigation matrix tablets of Metformin hydrochloride were formulated using Water hyacinth powder and its rate retardant activity was studied. Tablets were prepared using wet granulation method with 8% starch as granulating agent and 5, 10, 15, 20, 25 and 30% of Water hyacinth powder to the drug. In preformulation study, angle of repose, Carr's Index and Hausner ratio were calculated. Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) studies were performed and no interactions were found between drug and excipients. Weight variation, friability, hardness, thickness, diameter, and in vitro release study were performed with the prepared matrix tablets. Dissolution studies were conducted using USP type II apparatus at a speed of 100 rpm at 37°C ± 0.5 temperature for 8 h. Though all the formulations comply with both BP and USP requirements, formulation F-1 (5% of Water hyacinth) was the best fitted formula. The drug release patterns were explained in different kinetic models such as Zero order, First order, Higuchi, Hixson Crowell, and Korsmeyer-Peppas equations. The current investigation implies that Water hyacinth has the potential to be used as a rate-retarding agent in sustained release drug formulations.

Physical characterizations and sustained release profiling of gastroretentive drug delivery systems with improved floating and swelling capabilities

The aim was to develop gastroretentive drug delivery systems (GRDDSs) by combining floating and swelling. GRDDS tablets formulated with hydroxyethylcellulose (HEC), chitosan (CS) and sodium bicarbonate (SB) for evaluating floating capacity (floating lag time and duration) and swelling characteristics. CS was used because it was swellable in acidic media and biocompatible. Losartan was incorporated into the optimized formulations for sustained release profiling. Results demonstrated that for those formulations at HEC:CS ratio of 5:5 containing CS, both the floating lag time and floating duration were optimal and reached the preferred swelling effect and sustain for 24h. Adding SB improved the floating capabilities for all ratios of HEC:CS, but reduced the swelling ability for those formulations containing a higher portion of low viscosity grade CS. Sustained release profiles for losartan in those formulations were achievable, using all viscosity grades of CS at all examined HEC:CS ratios; however, it is more adjustable at different HEC:CS ratios when using a lower viscosity grade of CS. Optimized GRDDS formulations for losartan composed of an equivalent ratio of HEC to CS with 20mg SB resulted in the tablets floating for more than 16 h and an adjustable sustained release profile.

Optimization and characterization of gastroretentive floating drug delivery system using Box-Behnken design

CONTEXT

One among many strategies to prolong gastric residence time and improve local effect of the metronidazole in stomach to eradicate Helicobacter pylori in the treatment of peptic ulcer was floating drug delivery system particularly effervescent gastroretentive tablets.

OBJECTIVE

The objective of this study was to prepare and evaluate, effervescent floating drug delivery system of a model drug, metronidazole.

METHODS

Effervescent floating drug delivery tablets were prepared by wet granulation method. A three-factor, three levels Box-Behnken design was adopted for the optimization. The selected independent variables were amount of hydroxypropyl methylcellulose K 15M (X1), sodium carboxy methylcellulose (X2) and NaHCO3 (X3). The dependent variables were floating lag time (YFLT), cumulative percentage of metronidazole released at 6th h (Y6) and cumulative percentage of metronidazole released at 12th h (Y12). Physical properties, drug content, in vitro floating lag time, total floating time and drug release behavior were assessed.

RESULTS

YFLT range was found to be from 1.02 to 12.07 min. The ranges of other responses, Y6 and Y12 were 25.72 ± 2.85 to 77.14 ± 3.42 % and 65.47 ± 1.25 to 99.65 ± 2.28 %, respectively. Stability studies revealed that no significant change in in vitro floating lag time, total floating time and drug release behavior before and after storage.

CONCLUSION

It can be concluded that a combination of hydroxypropyl methylcellulose K 15M, sodium carboxy methylcellulose and NaHCO3 can be used to increase the gastric residence time of the dosage form to improve local effect of metronidazole.

Formulation development of gastroretentive tablets of lamivudine using the floating-bioadhesive potential of optimized polymer blends

Objectives

The current studies entail successful formulation of optimized gastroretentive tablets of lamivudine using the floating-bioadhesive potential of carbomers and cellulosic polymers, and their subsequent in-vitro and in-vivo evaluation in animals and humans.

Methods

Effervescent floating-bioadhesive hydrophilic matrices were prepared and evaluated for in-vitro drug release, floatation and ex-vivo bioadhesive strength. The optimal composition of polymer blends was systematically chosen using central composite design and overlay plots. Pharmacokinetic studies were carried out in rabbits, and various levels of in-vitro/in-vivo correlation (IVIVC) were established. In-vivo gamma scintigraphic studies were performed in human volunteers using 99mTc to evaluate formulation retention in the gastric milieu.

Key findings

The optimized formulation exhibited excellent bioadhesive and floatational characteristics besides possessing adequate drug-release control and pharmacokinetic extension of plasma levels. The successful establishment of various levels of IVIVC substantiated the judicious choice of in-vitro dissolution media for simulating the in-vivo conditions. In-vivo gamma scintigraphic studies ratified the gastroretentive characteristics of the optimized formulation with a retention time of 5 h or more.

Conclusions

Besides unravelling the polymer synergism, the study helped in developing an optimal once-a-day gastroretentive drug delivery system with improved bioavailability potential exhibiting excellent swelling, floating and bioadhesive characteristics.

Effect of formulation parameters on the drug release and floating properties of gastric floating two-layer tablets with acetylsalicylic acid

Floating dosage forms of acetylsalicylic acid, used for its antithrombotic effect, were developed to prolong gastric residence time and increase bioavailability. In the two-layer tablet formulation, hydroxypropyl methylcellulose (HPMC) of high viscosity and an effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The release layer contained the drug, direct tableting agent and different types of matrix-forming polymers such as HPMC of low viscosity, sodium carboxymethylcellulose and chitosan. Tablets were prepared using a direct compression technique. The effect of formulation variables on physicochemical and floating properties and the drug release from tablets were investigated. Floating ability was dependent on the amount of effervescent agent and gel-forming polymer of the floating layer. Drug release was prolonged to 8 hours by changing the type and viscosity of the matrix-forming polymer in the drug-loading layer and all formulations showed a diffusion release mechanisms.

Gastroretentive dosage forms: a review with special emphasis on floating drug delivery systems

In the present era, gastroretentive dosage forms (GRDF) receive great attention because they can improve the performance of controlled release systems. An optimum GRDF system can be defined as a system which retains in the stomach for a sufficient time interval against all the physiological barriers, releases active moiety in a controlled manner, and finally is easily metabolized in the body. Physiological barriers like gastric motility and gastric retention time (GRT) act as obstacles in developing an efficient GRDF. Gastroretention can be achieved by developing different systems like high density systems, floating drug delivery systems (FDDS), mucoadhesive systems, expandable systems, superporous systems, and magnetic systems. All these systems have their own merits and demerits. This review focused on the various aspects useful in development of GRDF including the current trends and advancements.

Floating matrix dosage form for propranolol hydrochloride based on gas formation technique: development and in vitro evaluation

Gastroretentive tablets of propranolol hydrochloride were developed by direct compression method using citric acid and sodium bicarbonate as the effervescent base. Hydroxypropyl methylcellulose; HPMC K15M was used to prepare the floating tablets to retard the drug release for 12h in stomach. Na-carboxymethyl cellulose (NaCMC) or carbopol 934P was added to alter the drug release profile or the dimensional stability of the formulation. Dicalcium phosphate (DCP) was used as filler. Formulations were evaluated for floating lag time, duration of floating, dimensional stability, drug content and in vitro drug release profile. The formulations were found to have floating lag time less than 1min. It was found that the dimensional stability of the formulations increase with increasing concentration of the swelling agent. The release mechanism of propranolol hydrochloride from floating tablets was evaluated on the basis of Peppas and Higuchi model. The ânâ value of the formulations ranged from 0.5201 to 0.7367 (0.5<n<1.0) which indicated anomalous (non-Fickian) transport mechanism. Formulation containing 27.5% HPMC K15M, 29% DCP, 3.75% citric acid and 18.75% sodium bicarbonate seemed most desirable. FTIR, DSC and XRPD studies indicated the absence of any significant chemical interaction within dug and excipients. Stability study of optimized formulation revealed no significant change and found to be stable.

Development of swelling/floating gastroretentive drug delivery system based on a combination of hydroxyethyl cellulose and sodium carboxymethyl cellulose for Losartan and its clinical relevance in healthy volunteers with CYP2C9 polymorphism

The aim of this study was to develop an optimal gastroretentive drug delivery system (GRDDS) for administering Losartan. Additionally, the influence of optimized GRDDS on the bioavailability of Losartan and the formation extent of active metabolite E3174 by CYP2C9 polymorphism was investigated. Swellable and floatable GRDDS tablets combining hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (NaCMC), and sodium bicarbonate were prepared at various compression pressures for evaluating swelling characteristics and floating capacity. Then Losartan was incorporated into optimized formulations for in vitro and in vivo characterizations. An appropriate ratio of HEC to NaCMC, addition of sodium bicarbonate, and compression at lower pressures resulted in the tablets floating over SGF for more than 16 h and swelling to 2 cm in diameter within 3h. The release patterns of Losartan from these tablets were pH-dependent. Results of the clinical trials showed that the mean bioavailability from GRD-A (HEC 91.67%, sodium bicarbonate 3.33% and Losartan 8.33%) was approximately 164%, relative to the immediate-release product (Cozaar). MRT and t(max) values were greater and C(max) values were lower for the GRDDS tablets compared with Cozaa. The lower bioavailability of Losartan in the CYP2C9*1/*1 subjects than CYP2C9*1/*3 subjects was found and could be due to the variety of enzymatic activity.

Development and evaluation of gastroretentive norfloxacin floating tablets

Floating matrix tablets of norfloxacin were developed to prolong gastric residence time, leading to an increase in drug bioavailability. Tablets were prepared by the wet granulation technique, using polymers such as hydroxypropyl methylcellulose (HPMC K4M, HPMC K100M) and xanthan gum. Tablets were evaluated for their physical characteristics, viz., hardness, thickness, friability, and mass variation, drug content and floating properties. Further, tablets were studied for in vitro drug release characteristics for 9 hours. The tablets exhibited controlled and prolonged drug release profiles while floating over the dissolution medium. Non-Fickian diffusion was confirmed as the drug release mechanism from these tablets, indicating that water diffusion and polymer rearrangement played an essential role in drug release. The best formulation (F4) was selected based on in vitro characteristics and was used in vivo radiographic studies by incorporating BaSO4. These studies revealed that the tablets remained in the stomach for 180 +/- 30 min in fasting human volunteers and indicated that gastric retention time was increased by the floating principle, which was considered desirable for the absorption window drugs.

Formulation and evaluation of swellable and floating gastroretentive ciprofloxacin hydrochloride tablets

Drugs that have narrow absorption window in the gastrointestinal tract (GIT) will have poor absorption. For these drugs, gastroretentive drug delivery systems offer the advantage in prolonging the gastric emptying time. Swellable, floating, and sustained release tablets are developed by using a combination of hydrophilic polymer (hydroxypropyl methylcellulose), swelling agents (crospovidone, sodium starch glycolate, and croscarmelose sodium) and effervescent substance (sodium bicarbonate). Formulations are evaluated for percentage swelling, in vitro drug release, floating lag time, total duration of floating, and mean residence time (MRT) in the stomach. The drug release of optimized formulation follows the Higuchi kinetic model, and the mechanism is found to be non-Fickian/anomalous according to Krosmeyer-Peppas (n value is 0.68). The similarity factor (f (2)) is found to be 26.17 for the optimized formulation, which the release is not similar to that of marketed produced (CIFRAN OD). In vivo nature of the tablet at different time intervals is observed in the radiographic pictures of the healthy volunteers and MRT in the stomach is found to be 320 +/- 48.99 min (n = 6). A combination of HPMC K100M, crospovidone, and sodium carbonate shows the good swelling, drug release, and floating characters than the CIFRAN OD.