Delivery Orifice Research Articles

Modelling the controlled drug release of push-pull osmotic pump tablets using DEM

The push-pull osmotic pump tablet is a promising drug delivery approach, offering advantages over traditional dosage forms in achieving consistent and predictable drug release rates. In the current study, the drug release process of push-pull osmotic pump tablets is modelled for the first time using the discrete element method (DEM) incorporated with a microscopic diffusion-induced swelling model. The effects of dosage and formulation design, such as delivery orifice size, drug-to-polymer ratio, tablet surface curvature, friction between particles and cohesion of polymer particles, on the drug release performance are systematically analysed. Numerical results reveal that an enlarged delivery orifice significantly increases both the total drug release and the drug release rate. Moreover, the larger the swellable particle component in the tablet, the higher the drug release rate. Furthermore, the tablet surface curvature is found to affect the drug release profile, i.e. the final drug release percentage increases with the increasing tablet surface curvature. It is also found that the drug release rate could be controlled by adjusting the inter-particle friction and the cohesion of polymer particles in the formulation. This DEM study offers valuable insights into the mechanisms governing drug release in push-pull osmotic pump tablets.

Current Trends in Osmotic Pump Drug Delivery Systems

Traditional oral drug delivery methods, which typically release medication immediately, often lead to fluctuations in plasma drug concentration, potentially causing suboptimal therapeutic outcomes and side effects. Osmotic pump drug delivery systems address these issues by providing a controlled release mechanism that ensures a steady and predictable release of the drug over an extended period. This controlled release enhances patient compliance by reducing the frequency of dosing and maintaining uniform blood concentration levels, thereby improving therapeutic efficacy. Unlike conventional drug delivery methods, osmotic pumps are less influenced by physiological variables within the gastrointestinal tract, making them a reliable and consistent option for controlled drug delivery. These systems operate on the principles of osmosis, utilizing a semipermeable membrane to regulate the influx of water into the drug-containing core, which then generates osmotic pressure to drive the drug out through a delivery orifice. This review provides an in-depth discussion of the principles behind osmotic drug delivery systems, the various types available, their benefits, and the challenges they present. It also highlights the significance of these systems in modern pharmaceutical applications, demonstrating how they represent a significant advancement over traditional methods by optimizing drug release profiles, improving patient adherence, and ultimately enhancing therapeutic outcomes

An Insight into Osmotic Drug Delivery Systems

Abstract: The dosing pattern of the conventional drug delivery system results in continuously changing and unpredictable plasma concentrations as this system has modest control on the release of the drug along with almost negligible effectual concentration near the site of interest. The problems coupled with conventional drug delivery can be triumphed over by employing osmotic drug delivery systems, which are one of the most budding strategies utilizing osmotic pressure to release active pharmaceutical ingredients in an optimized manner at a controlled rate. Various formulation parameters which influence the release of drugs from these systems include osmotic pressure wielded by the core components, the drug’s solubility, and the size of the delivery orifice in conjunction with the characteristics of the semipermeable membrane. However, it is completely autonomous of the gastrointestinal tract’s anatomical environment and concomitant meal ingestion. The aim of this manuscript is to study the earlier osmotic pumps, their working principles, along with their limitations, and novel approaches having significant benefits over older ones. The current manuscript covers all the aspects of the osmotic drug delivery system, including its principle of osmosis, the historical background, its advantages and disadvantages, basic components, various factors influencing its design, its various types, and evaluation parameters. Novel approaches to osmotic drug delivery systems along with future prospective have also been described.

Experimental study on drilling micro-hole through micro-EDM and optimization of multiple performance characteristics

Drilling of micro-hole with fine edges and smooth internal surfaces finds numerous applications in manufacturing industries; holes drilled in injection nozzles, drug delivery orifices and spinneret holes are some of examples. This work carries out an experimental investigation and parametric optimization on micro-hole drilling using micro-electrical discharge machining (µ-EDM) process. The machining experiments are conducted employing Taguchi L16 orthogonal array for evaluating machining time (t) average overcut (AOV), taper angle (TA), entry overcut (EnOV), exit overcut (ExOV) and material removal rate (MRR) as process performances, while voltage (V), capacitance (pF) and feed rate (µm/s) are considered as process parameters. The influence of process parameters on the responses is studied at different cutting conditions. The drilled micro-holes profile is studied in terms of burrs, craters, spots on the edges and internal surfaces using micrographs obtained with optical and scanning electron microscopes. The ANOVA result reveals that capacitance is the most significant parameter for t, AOV, TA, MRR, EnOV and ExOV. For simultaneous optimization of three performance measures (i.e., t, AOV and TA), an overall evaluation criterion has been evaluated and optimum cutting conditions such as voltage: 80 V, capacitance: 100 pF and feed rate: 15 µm/s are obtained. The expected outcome obtained at the optimum condition is improved by 10.57% (36.934 to 40.839) over the grand average of performance. The confirmation experimental result at optimum cutting condition (i.e., 39.378) is comparable with the expected result (i.e., 40.839).

Influence of Electrode Tool Length on the Micro EDM Drilling Performance

Micro electrodischarge (micro EDM) machining, due to its wide application range, is one of the most commonly used technologies for machining in micro scale. Common application of precise micro EDM drilling among others concerns machining of holes in fuel injectors or drug delivery orifices. The paper presents results of research of the micro EDM drilling at Institute. There are derived characteristics of micro drilling in the stainless steel samples depending on the electrode tool length (distance between machined surface and tool electrode clamp). The main comparison coefficients are tool wear ratio, material removal rate / machining efficiency and machining accuracy / quality. Presented results concern micro EDM drilling experiments which were performed for tool electrode diameter of 0,1mm and workpieces of 1mm thick. There are also derived conclusions on process optimization and process planning for cost and time effective machining, taking into account the machining time, electrode tool re-clamping time depending on the number of micro-holes to be drilled in the single workpiece. Presented results and their discussion cover problems which we came across during investigations and commercial micro EDM drilling services.

FORMULATION DEVELOPMENT AND EVALUATION OF ELEMENTARY OSMOTIC TABLET OF LISINOPRIL DIHYDRATE

Objective: Lisinopril Dihydrate is one of the antihypertensive drug used to control the high blood pressure. Osmotically Controlled release tablet of Lisinopril Dihydrate was performed for reducing dosing frequency and patient compliance.Methods: Elementary osmotic tablets of Lisinopril Dihydrate were developed using Sodium chloride as a key ingredient which gives osmogent property which provides driving force inside the core tablet and which leads to release of the drug. Microcrystalline cellulose used as a release retardant material in the present work. Different formulations were prepared by varying the concentrations using 32 factorial designs. It was applied to see the effect of variables Sodium chloride (X1) and MCC (X2) on the response percentage drug release as a dependent variable. These formulations were evaluated for, Hardness, Flow property, Thickness, Friability, Drug content and In vitro drug release. Tablets were coated with a semipermeable membrane using 5% w/v cellulose acetate(CA) in acetone and PEG 400(1%) used as Plasticizer. Coated Elementary osmotic tablets were drilled for delivery orifice using a standard micro drill of diameter size 0.8 mm.Results: Drug release rate was increased as the increase in the concentration of sodium chloride and release rate decreased on increasing the concentration of MCC. Drug release rate was directly proportional to delivery orifice size. SEM Study carried out for detection of diameter size of the delivery orifice. The FTIR studies demonstrate that there was no interaction between polymer and drug.Conclusion: The optimized formulation was stable for 3 mo of accelerated stability study

СУЧАСНИЙ СТАН СТВОРЕННЯ, ВИРОБНИЦТВА ТА ДОСЛІДЖЕННЯ ТАБЛЕТОВАНИХ ЛІКАРСЬКИХ ПРЕПАРАТІВ Повідомлення 25. Осмотичні системи вивільнення та доставки лікарських речовин: характеристика імплантаційних мініосмотичних, оральних та спеціальних типів осмотичних систем, їх застосування

Проведено огляд літературних джерел щодо характеристик та можливостей застосування імплантаційних мініосмотичних, оральних та спеціальних типів осмотичних систем вивільнення та доставки лікарських речовин, наведено приклади осмотичних систем, які зареєстровані на світовому ринку.

Osmotically Controlled Drug Delivery System-A Novel Approach

Osmotically controlled drug delivery systems (OCDDS) are most promising systems for controlled drug delivery. Osmotically controlled drug delivery systems utilize osmotic pressure for controlled delivery of active agents. Various patents are available for osmotic drug delivery system like Rose and Nelson pump, Higuchi Leeper pump, Higuchi Theeuwes pump, Elementary osmotic pump etc. Various techniques available for preparation of OCDDS include push pull osmotic pump, Osmotic bursting osmotic pump, Liquid OROS, Telescopic capsule for delayed release, OROS-CT (colon targeting), and Sandwiched osmotic tablet system.These systems can be used for systemic as well as targeted delivery of drugs. Drug delivery from these systems, to a large extent, is independent of physiological factors of GI tract. Release of drug from formulation is depends on various formulation factors such as solubility of drug, osmotic pressure generated in the system, size of the drug delivery orifice, nature & thickness of rate controlling membrane. The present review article mainly focus on the basic components of osmotically controlled drug delivery system, various factors governing drug release from these systems and types of osmotically controlled drug delivery systems. Pharmaceutical Sciences

СУЧАСНИЙ СТАН СТВОРЕННЯ, ВИРОБНИЦТВА ТА ДОСЛІДЖЕННЯ ТАБЛЕТОВАНИХ ЛІКАРСЬКИХ ПРЕПАРАТІВ. Повідомлення 24. Осмотичні системи вивільнення та доставки лікарських речовин: розробка, характеристика та їх класифікація

Проведено огляд літературних джерел щодо розробки та дослідження осмотичних систем вивільнення та доставки лікарських речовин

A novel asymmetric membrane osmotic pump capsule with in situ formed delivery orifices for controlled release of gliclazide solid dispersion system

In this study, a novel asymmetric membrane osmotic pump capsule of gliclazide (GLC) solid dispersion was developed to achieve a controlled drug release. The capsule shells were obtained by wet phase inversion process using cellulose acetate as semi-permeable membrane, glycerol and kolliphor P188 as pore formers, then filled with the mixture of GLC solid dispersion and pH modifiers. Differentiate from the conventional formulations, sodium carbonate was chosen as the osmotic agent and effervescent agent simultaneously to control the drug release, instead of the polymer materials. The ternary solid dispersion of GLC, with polyethylene glycol 6000 and kolliphor P188 as carriers, was prepared by solvent-evaporation method, realizing a 2.09-fold increment in solubility and dissolution rate in comparison with unprocessed GLC. Influence of the composition of the coating solution and pH modifiers on the drug release from the asymmetric membrane capsule (AMC) was investigated. The ultimate cumulative release of the optimal formulation reached 91.32% in an approximately zero-order manner. The osmotic pressure test and dye test were conducted to validate the drug release mechanism from the AMC. The in vivo pharmacokinetic study of the AMC indicated a 102.66±10.95% relative bioavailability compared with the commercial tablet, suggesting the bioequivalence between the two formulations. Consequently, the novel controlled delivery system with combination of solid dispersion and AMC system is capable of providing a satisfactory alternative to release the water-insoluble drugs in a controlled manner.

Development, evaluation, and influence of formulation and process variables on in vitro performance of oral elementary osmotic device of atenolol.

Purpose:Osmotic devices are the most promising strategy-based systems for controlled drug delivery. By optimizing formulation and processing parameters, possible to develop osmotic systems to deliver drugs at predetermined rate with high in vitro-in vivo correlation. The aim of the present investigation was to develop an oral elementary osmotic pump (EOP) of atenolol with zero-order or near zero-order drug release profile.Materials and Methods:Differential scanning calorimetry and Fourier transform-infrared spectroscopy studies did not show any evidence of interaction between the drug and excipients. Formulations were prepared by wet granulation method and coated with cellulose acetate (CA)/ethyl cellulose containing varying amounts of dibutyl phthalate (DBP)/poly (ethylene glycol)-400 as a plasticizer. The effect of different formulation variables on drug release: type and concentration of osmogen and plasticizer, size of the delivery orifice, nature of the rate controlling membrane, and membrane weight gain were studied. The release studies also compared with marketed immediate release formulation.Results:Formulations containing NaCl, mannitol, and combination of both as osmogens in the drug:osmogen ratio of 1:3 and 1:4 showed zero-order drug release. Marketed tablet releases more than 95% drug in different media in 90 min. The 4% CA in acetone with DBP as a plasticizer (at a concentration of 15% w/w of polymer), with orifice diameter 565 μm, and 8.05% increase in weight on coating were found to control the drug release independent of pH and agitational intensity. The formulations were stable for 3 months as per the International Council for Harmonisation guidelines.Conclusion:Atenolol containing EOPs and process parameters on release studies were studied and confirmed based on osmotic technology.

Development of Controlled Release Osmotic Pump Tablet of Glipizide Solid Dispersion

To develop controlled release osmotic pump tablets (COPT) of glipizide (GZ) solid dispersion (SD). In elementary osmotic pump (EOP) tablets, an osmotic core with the drug is surrounded by a semi-permeable membrane which is drilled with a delivery orifice. COPT tablets eliminate the need of drilling process as controlled release can be achieved by the presence of osmogen in the coating. Poorly water soluble drug molecule cannot give satisfactory drug release hence GZ solid dispersion was prepared in the present study. The SDs having different ratio of drug to Poloxamer (PXM) 188 were prepared by hot melt method and optimized by solubility study, drug content estimation and in vitro dissolution study. Effect of two independent variables, amount of osmogen (potassium chloride) and hydrophilic polymer (polyethylene oxide WSR 303), were investigated using 3(2) factorial design. Core and coated tablets were evaluated for pharmacotechnical parameters. In-vitro drug release profiles of COPT tablets were compared with marketed with push-pull osmotic pump tablet, Glucotrol XL. Prepared core and coated tablets showed acceptable pharmacotechnical parameters. Drug release was directly proportional to initial level of hydrophilic polymer, but inversely related to the osmogen, confirming osmotic mechanism. Zero order drug release pattern was achieved which was comparable to marketed product. Novel oral controlled release of glipizide was successfully achieved by incorporating glipizide solid dispersion into osmotic system.

Formulation design and characterization of an elementary osmotic pump tablet of flurbiprofen.

The aim of this study was to develop an elementary osmotic pump tablet of Flurbiprofen and to deliver the drug at a zero-order rate. Elementary osmotic pumps are well known for delivering moderately soluble drugs at a zero-order rate. Elementary osmotic pump tablets containing an inclusion complex of Flurbiprofen was prepared by the direct compression method. The amount of osmotic agent and size of delivery orifice were selected as independent variables. Percent cumulative drug release at 9 h was evaluated for all batches, and it was found that amount of osmotic agent and size of delivery orifice had a significant effect on percent cumulative drug release. The drug release from the developed formulation was found to be independent of pH and agitational intensity. It was also observed that the optimized formulation followed zero-order kinetics and was stable for 6 months at accelerated conditions.

A review on recent innovation in osmotically controlled drug delivery system

In recent years, oral controlled release (CR) system is most acceptable dosage form by the patients. Drugs having short biological half-life and poor water solubility are the suitable candidate for development of CR system. They include dosage forms for oral and transdermal administration as well as injectable and implantable systems. For most of drugs, oral route remains as the most acceptable route of administration. Certain molecules may have low oral bioavailability because of solubility or permeability limitations. Development of an extended release dosage form also requires reasonable absorption throughout the gastro-intestinal tract (GIT). Among the available techniques to improve the bioavailability of these drugs fabrication of osmotic drug delivery system is the most appropriate one. The release of drug(s) from osmotic systems follows zero order. It is mainly governed by various formulation factors such as solubility and osmotic pressure of the core component(s), size of the delivery orifice, and nature of the rate-controlling membrane. The present review highlights an overview of OCDDS. And new technologies, fabrication and recent clinical research in osmotic drug delivery. Further, the challenges of these technologies and its future perspective are also discussed at length.

Osmotic Drug Delivery Systems: Basics and Design Approaches

Osmotic drug delivery system utilizes the principles of osmotic pressure for the controlled delivery of active pharmaceutical ingredient at a predetermined zero order rate. An appropriately designed osmotic drug delivery is not influenced by different physiologic factors but affected by pharmaceutical factors, which play a pivotal role in modulating the release of drug. The present review critically discussed about the factors affecting drug release from the delivery system such as solubility, osmotic pressure, size of delivery orifice and membrane characteristics. The major arena of this review is to highlight about the different types of osmotic drug delivery systems such as implantable, single chamber, multi chamber osmotic pumps and several specialized type of osmotic pumps. Apart from that this system is a versatile technology useful for delivery of drugs with varying solubility. The additional properties of this delivery system can also exhibit pulsatile release, burst release and colon targeting of drug. Because of its versatility, this above system seems to have promising approach which can result in improved safety profile, stable drug concentrations, uniform drug effects and dosing frequency. Current review also briefly discussed about the patents related to delivery of drugs by the principle osmotic pressure.

Microporous bilayer osmotic tablet for colon-specific delivery

Microporous bilayer osmotic tablet bearing dicyclomine hydrochloride and diclofenac potassium was developed using a new oral drug delivery system for colon targeting. The tablets were coated with microporous semipermeable membrane and enteric polymer using conventional pan-coating process. The developed microporous bilayer osmotic pump tablet (OPT) did not require laser drilling to form the drug delivery orifice. The colon-specific biodegradation of pectin could form in situ delivery pores for drug release. The effect of formulation variables like inclusion of osmogen, amount of HPMC and NaCMC in core, amount of pore former in semipermeable membrane was studied. Scanning electron microscopic photographs showed formation of in situ delivery pores after predetermined time of coming in contact with dissolution medium. The number of pores was dependent on the amount of the pore former in the semipermeable membrane. In vitro dissolution results indicated that system showed acid-resistant, timed release and was able to deliver drug at an approximate zero order up to 24 h. The developed tablets could be effectively used for colon-specific drug delivery to treat IBS.

3413 Micro-Electrical Discharge Machining of Reaction-Bonded Silicon Carbide(RB-SiC)

Functional micro-structures are gaining more and more importance in the industrial technologies during the last few years. For example, deep micro holes find a wide range of applications in inkjet printer nozzles, spinnerets holes, turbine blades cooling channels, diesel fuel injection nozzles, drug delivery orifices, etc. Another important example is microlens arrays. The ability of microlens arrays to focus incident light into a series of beam spots makes them useful as important optical elements that are widely used in the area of optoelectronic and optical communications. Due to the wide applications of these functional micro-structures in optical, biomedical engineering and microelectromechanical systems (MEMS), micro fabrication techniques have gained growing interest from researchers and engineers. Recently, the use of reaction-bonded silicon carbide (RB-SiC) as a material in manufacturing optical molding dies for aspherical lenses and microlens arrays has become a new research focus, due to its superior material properties, such as high hardness and strength at elevated temperature, high thermal conductivity, chemical stability, wear resistance and low density. However, due to its high hardness (Vickers hardness 25-35 GPa), it is typically difficult to be machined. Although abrasive machining processes, such as lapping, polishing and grinding can produce a fine surface finish, but the machining efficiency is low and the production cost is high. Diamond cutting is able to produce a high material removal rate, but the severe tool wear in diamond cutting of RB-SiC is the main obstacle that limits its wide application in the industry. Compared to the aforementioned methods, micro electrical discharge machining (micro-EDM) has emerged as a possibly effective machining tool to fabricate complex micro-structures on hard and difficult-to-cut materials like RB-SiC. However, the use of conventional micro-EDM alone to obtain micro-structures with good surface finish and high form accuracy in RB-SiC, is still a challenging issue. The high resistivity of the RB-SiC workpiece is the main limiting factor for the discharge current of micro-EDM, which directly affects the machining efficiency of RB-SiC. The main objective of this study is to develop hybrid machining processes based on micro-EDM for improving the machinability and surface finish of RB-SiC. Carbon nanofibers assisted micro-EDM was proposed to replace the conventional micro-EDM. The effects of carbon nanofibers addition in the dielectric fluid were confirmed experimentally. The machining mechanism and the material migration phenomenon with the addition of carbon nanofibers were investigated and clarified. Next, a novel machining process, namely hybrid micro-EDM process by combining ultrasonic cavitation and carbon nanofibers was proposed, in order to improve the machining efficiency of RB-SiC ceramic material and to prevent from tool material deposition on workpiece. The effectiveness of the hybrid process was verified through the fabrication of micro-structures on RB-SiC. This thesis consists of five chapters. Chapter 1 gives an overview of the background of this research. Firstly, an introduction of the RB-SiC ceramic material, including the fabrication process, material properties, applications and previous machining processes of RB-SiC material were given. EDM was chosen as a method to fabricate micro-structures on the RB-SiC, which can overcome the shortcomings of the abrasive machining process. Then, an overview of the principle of micro-EDM/EDM process was discussed. The problem of machining RB-SiC by using conventional EDM was also pointed out. Some recent developments for enhancing the machinability of hard and brittle ceramic materials by micro-EDM/EDM were reviewed. Finally the objectives and organization of this thesis were stated.

Simultaneous delivery of Nifedipine and Metoprolol tartarate using sandwiched osmotic pump tablet system

The sandwiched osmotic tablet system that could deliver Nifedipine and Metoprolol tartarate simultaneously for extended period of time was developed in order to reduce the problems associated with multidrug therapy of hypertension. This system composed of a middle push layer and attached drug layers of Nifedipine and Metoprolol. The advantage of the sandwiched osmotic tablet system over the commercialized push–pull osmotic tablet system is its simplicity of preparation, as the surface identification was avoided. Polyethylene oxide 600,000 and 8,000,000 g/mole were used as thickening agent of drug layer and the expandable hydrogel of push layer, respectively. It has been observed that amount of polyethylene oxide (PEO) and KCL of the drug and push layer had profound influence on Nifedipine and Metoprolol release. Further, the release of drugs was optimized by the size of the delivery orifice, level of plasticizer and membrane thickness. The optimal osmotic pump tablet was found to deliver both drugs at a rate of approximately zero order for up to 16 h independent of pH and agitational intensity, but dependent on the osmotic pressure of the release media. The formulations were found to be stable after 3 months of accelerated stability studies. Prediction of steady-state levels showed the plasma concentrations of Nifedipine and Metoprolol to be within the desired range. Further sandwiched system had a good sustained effect in comparison with the conventional product. Hence the prototype design of the system could be applied to other combinations of drugs used for cardiovascular diseases, diabetes, etc.

Development of Monolithic Osmotic Pump Tablet System for Isosorbide-5-Mononitrate Delivery and Evaluation of it In Vitro and In Vivo

The objective of this study is to develop the monolithic osmotic pump tablet system (MOTS) containing isosorbide-5-mononitrate (5-ISMN), and to evaluate its in vitro and in vivo properties. The influences of tablet formulation variables, size and location of the delivery orifice, membrane variables, and pH value of the dissolution medium on 5-ISMN release from MOTS have been investigated. These results demonstrated that the tablet core played an important role in MOTS, and membrane variables could affect the 5-ISMN release rate. The optimal formulation of 5-ISMN MOTS was determined by uniform design. Furthermore, the dog pharmacokinetics and relative bioavailability of the test formulation (5-ISMN MOTS) have been compared with the reference formulation (Imdur®: 60 mg/tablet, a sustained release, SR, tablet system) following an oral single dose of 60 mg given to each of six Beagle dogs. The mean drug fraction absorbed by the dog was calculated by the Wagner–Nelson technique. The results showed that drug concentration in plasma could be maintained more stable and longer after the administration of 5-ISMN MOTS compared with the matrix tablets of Imdur®, and a level A “in vitro–in vivo correlation” was observed between the percentage released in vitro and percentage absorbed in vivo. It is concluded that 5-ISMN MOTS is more feasible for a long-acting preparation than 5-ISMN SR tablet system as once-a-day treatment, and it is very simple in preparation, and can release 5-ISMN at the rate of approximately zero order for the combination of hydroxypropylmethyl cellulose as retarder and NaCl as osmogent.

Floating Osmotic Drug Delivery System of Ranitidine Hydrochloride: Development and Evaluation—A Technical Note

Under certain circumstances prolonging the gastric retention of a delivery system is desirable for achieving greater therapeutic benefit of the drugs. For example, drugs that are absorbed in the proximal part of the gastrointestinal tract (1), and drugs that are less soluble in or are degraded by the alkaline pH may benefit from prolonged gastric retention (2). In addition, for local and sustained drug delivery to the stomach and proximal small intestine to treat certain conditions, prolonged gastric retention of the therapeutic moiety may offer numerous advantages including improved bioavailability and therapeutic efficacy, and also the possible reduction of dose size (3). Gastroretentive drug delivery systems (GRDDS) can remain in the gastric region for several hours and hence significantly prolong the gastric residence time of drugs. Various GRDDS reported in literatures provide controlled delivery of drugs in matrix and/or reservoir type systems. The release of drugs from reservoir/matrix type systems is affected by hydrodynamic conditions of the absorption site and also results in bioavailability fluctuation due to gastric pH variation. Osmotic drug delivery system (ODDS) utilizes the principles of osmotic pressure for controlled delivery of drugs (4). Drug release from these systems is independent of pH and other physiological parameters to a large extent and exhibit significant in vitro–in vivo correlation (5). Drug delivery from ODDS follows zero-order kinetics hence provides better control over in-vivo performance. Ranitidine hydrochloride (RH) is a histamine H2-receptor antagonist. It is widely prescribed in active duodenal ulcers, gastric ulcers, Zollinger–Ellison syndrome, gastroesophageal reflux disease, and erosive esophagitis (6). The recommended adult oral dosage of ranitidine is 150 mg twice daily or 300 mg once daily. The effective treatment of erosive esophagitis requires administration of 150 mg of ranitidine four times a day (6). A frequent dosage schedule for patients often leads to poor patient compliance; thus a sustained release dosage form of RH is desirable. The short biological half-life of drug (2.5–3 h) also favours for development of a sustained release formulation. A traditional oral sustained release formulation of RH releases most of the drug at the colon; due to less solubility of RH in small intestine, thus the drug have absorption window in the colon or in stomach. Ranitidine is absorbed only in the initial part of the small intestine and has 50% absolute bioavailability (6). Moreover, colonic metabolism of ranitidine is partly responsible for the poor bioavailability of ranitidine from the colon (7). These properties of RH do not favour the traditional approach to sustained release delivery. Hence, clinically acceptable sustained release dosage forms of RH prepared with conventional technology may not be successful. With all these considerations in mind, we designed floating osmotic drug delivery system (FODDS) of RH. FODDS consists of an osmotic core (containing drug, osmotic agent and excipients), an inner semipermeable membrane (SPM), and an outer compression coating of gelling agent containing gas generating agent and an orifice drilled through both membranes for delivery of drug. When system comes in contact with gastric environment, gas generating agent, generate CO2 by reacting with the surrounding fluid, the gas generated is trapped and protected within the gel (formed by hydration of gelling agent), thus decreasing the density of tablet. As the density of tablet falls below 1 (density of water), the tablet becomes buoyant. At the same time, the osmotic core also draws surrounding fluid across semipermeable membrane because of osmotic pressure gradient and form saturated solution of the drug. This pressure is relieved by the flow of saturated solution of drug through the delivery orifice.