Development of hollow/porous calcium pectinate beads for floating-pulsatile drug delivery

Combining antioxidants and processing techniques to improve oxidative stability of a Schizochytrium algal oil ingredient with application in yogurt

Oxidative instability limits incorporation of ω-3 fatty acids (FAs) into some products. This research combined processing techniques with antioxidant addition to overcome these barriers. Oleogels, microencapsulates, and microencapsulated gel ingredients were prepared using Schizochytrium spp. algal oil (AO) in combination with α, β, γ, and δ tocopherols or 1-o-galloylglycerol (GG) as antioxidants. Ingredients were tested for physicochemical stability and optimal ingredients were selected to prepare yogurts as a model food with ideal matrix. Yogurts were analyzed for physicochemical properties. After 24-days storage at 4 °C, yogurt containing microencapsulated oleogel with GG as antioxidant exhibited average peroxide and p-Anisidine values of 7.17 mmol O2/kg of oil and 118.85 abs/g, respectively. These values were similar to store-bought yogurt using saturated fat source, with values of 6.83 mmol O2/kg of oil and 117.95 absorbance/g, respectively. These results could lead to incorporation of ω-3 FAs into foods, cosmetics, and pharmaceuticals in the future.

Advancement in Therapeutic Intervention of Prebiotic-Based Nanoparticles for Colonic Diseases

Intestinal flora has become a therapeutic target for the intervention of colonic diseases (CDs) with better understanding of the interplay between microbiota and CDs. Depending on unique properties and prominent ability of regulating the intestinal flora, prebiotics can not only achieve a colon-specific drug delivery but also maintain the intestinal homeostasis, thus playing a positive role in the intervention of CDs. Currently, different studies on prebiotic-based nanoparticles have been contrived for colonic drug delivery and have shown great potential in curing various CDs, such as colitis and colorectal cancer. Nevertheless, there is a lack of systematic survey on the use of prebiotic nanoparticles for the treatment of CDs. This review aims to generalize the state-of-the-art of prebiotic nanomedicines specific for CDs. The species and function of intestinal flora and various kinds of prebiotics available as well as their regulating effects on intestinal flora were expounded. A variety of prebiotic nanoparticles pertinent to colon-targeted drug delivery systems were illustrated with particular emphasis on their curative activities on CDs. The efficacy and safety of prebiotic-based colonic drug delivery systems (p-CDDs) were also analyzed. In conclusion, the synergy between prebiotic nanoparticles and their cargos may hold promise for the treatment and intervention of CDs.

Optimized copolymeric microstructured platforms for smart controlled delivery of an anticoagulant drug: Preparation, in vitro assessment and crossover study in healthy adult human volunteers

In the present study, novel micro-structured copolymeric carriers were developed based on the grafting technology where acrylamide was chemically crosslinked with different types of Eudragits® (NE30D, L100, RL30D, or RS30D) based on a 4¹*2¹ factorial design. The designed systems efficiently engulfed the anticoagulant drug dipyridamole (DIP), within their formed entangled mesh of crosslinked polymeric network. An optimized formulation, ECOP4 with a desirability-value of 0.706, (in which DIP is engulfed within a copolymeric network of acrylamide and Eudragit® RS30D) showed high engulfment capacity (97.13 ± 1.34%) and controlled DIP release over 8 h. FTIR studies revealed absence of interactions between DIP and the formed copolymer. ECOP4 was further inserted within an easily-administered safe raft forming system composed of a mixture of LM-pectin and gellan gum. A pharmacokinetic study was performed using human volunteers to determine DIP concentration in their plasma after administering the designed formulation using the high-performance liquid chromatography (HPLC) method. A crossover design was adopted comparing the designed formulation with Persantin® 25 mg tablets as a reference standard. Superior results were obtained for the optimized formulation regarding the measured pharmacokinetic parameters (AUC_0-24h, C_max, and T_max) with a 2.31 fold increase in relative bioavailability, which reveals the usefulness of the designed grafted dipyridamole formulation in site-specific delivery system.

Development of Porous Epoxy Micro-Beads Using Ammonium Bicarbonate through a Single Epoxy Droplet in Corn Oil

This paper explored the effects of ammonium bicarbonate and different ratios of epoxy to polyamide on the formation of porous epoxy micro-beads through a single epoxy droplet. A single drop of a mixture, consisting of epoxy, polyamide, and ammonium bicarbonate, was dropped into heated corn oil at a temperature of 100 °C. An epoxy droplet was formed due to the immiscibility of the epoxy mixture and corn oil. The ammonium bicarbonate within this droplet underwent a decomposition reaction, while the epoxy and polyamide underwent a curing reaction, to form porous epoxy micro-beads. The result showed that the higher ammonium bicarbonate content in the porous, epoxy micro-beads increased the decomposition rate up to 11.52 × 10⁻³ cm³/s. In addition, a higher total volume of gas was generated when a higher ammonium bicarbonate content was decomposed. This led to the formation of porous epoxy micro-beads with a smaller particle size, lower specific gravity, and better thermal stability. At an epoxy to polyamide ratio of 10:6, many smaller micro-beads, with particle sizes ranging from 201 to 400 μm, were obtained at an ammonium bicarbonate content of 10 phr. Moreover, the porous epoxy micro-beads with open pores were shown to have a low specific gravity of about 0.93 and high thermal stability at a high ammonium bicarbonate content. Based on the findings, it was concluded that porous epoxy micro-beads were successfully produced using a single epoxy droplet in heated corn oil, where their shape and particle size depended on the content of ammonium bicarbonate and the ratio of epoxy to polyamide used.

Investigation of Pectin-Hydroxypropyl Methylcellulose-Coated Floating Beads for Pulsatile Release of Piroxicam

OBJECTIVES

The aim of the present study was to prepare pectin-hydroxypropyl methylcellulose-coated floating beads for pulsatile release of piroxicam in the treatment of early morning inflammation.

MATERIALS AND METHODS

Piroxicam-loaded beads were prepared from sodium alginate and hydroxypropyl methylcellulose (HPMC) in different concentrations of calcium carbonate using the ionotropic gelation method. In order to avoid drug release in the upper part of the gastrointestinal tract, the beads were coated with a pectin-HPMC layer using the dip coating method. Size analysis and encapsulation efficiency, drug loading, in vitro release, swelling behavior, and surface morphology studies of the beads were carried out.

RESULTS

The in vitro release study revealed that the pectin-HPMC coating of the beads prevented the release of the drug in an acidic medium and provided pulsed release of the drug after a lag time. Formulation CF4 (containing calcium carbonate in the ratio 3:4 with respect to sodium alginate) exhibited pulsed release of 95.55% at the end of 7 h in phosphate buffer, which was after the desired lag time of 6 h.

CONCLUSION

The study revealed that optimized floating pulsatile beads coated with pectin-HPMC can efficiently retain piroxicam in an acidic medium and that there is pulsed release in an alkaline medium after a lag time. It also showed that the beads prepared can potentially be used for chronotherapeutic treatment of the disease associated with early morning inflammation.

In-Depth Study into Polymeric Materials in Low-Density Gastroretentive Formulations

The extensive use of oral dosage forms for the treatment of diseases may be linked to deficient pharmacokinetic properties. In some cases the drug is barely soluble; in others, the rapid transit of the formulation through the gastrointestinal tract (GIT) makes it difficult to achieve therapeutic levels in the organism; moreover, some drugs must act locally due to a gastric pathology, but the time they remain in the stomach is short. The use of formulations capable of improving all these parameters, as well as increasing the resident time in the stomach, has been the target of numerous research works, with low-density systems being the most promising and widely explored, however, there is further scope to improve these systems. There are a vast variety of polymeric materials used in low-density gastroretentive systems and a number of methods to improve the bioavailability of the drugs. This works aims to expedite the development of breakthrough approaches by providing an in-depth understanding of the polymeric materials currently used, both natural and synthetic, their properties, advantages, and drawbacks.

Pectin and Zinc Alginate: The Right Inner/Outer Polymer Combination for Core-Shell Drug Delivery Systems

Core-shell beads loaded with betamethasone were developed using co-axial prilling as production technique and pectin plus alginate as polymeric carriers. During this study, many operative conditions were intensively investigated to find the best ones necessary to produce uniform core-shell particle systems in a reproducible way. Particularly, feed solutions' composition, polymers mass ratios and the effect of the main process parameters on particles production, micromeritics, inner structure, drug loading and drug-release/swelling profiles in simulated biological fluids were studied. The optimized core-shell formulation F5 produced with a pectin core concentration of 4.0% w/v and an alginate shell concentration of 2.0% w/v (2:1 core:shell ratio) acted as a sustained drug delivery system. It was able to reduce the early release of the drug in the upper part of the gastro-intestinal tract for the presence of the zinc-alginate gastro-resistant outer layer and to specifically deliver it in the colon, thanks to the selectivity of amidated low methoxy pectin core for this district. Therefore, these particles may be proposed as colon targeted drug delivery systems useful for inflammatory bowel disease (IBD) therapy.

Current State and Future Perspectives on Gastroretentive Drug Delivery Systems

In recent years, many attempts have been made to enhance the drug bioavailability and therapeutic effectiveness of oral dosage forms. In this context, various gastroretentive drug delivery systems (GRDDS) have been used to improve the therapeutic efficacy of drugs that have a narrow absorption window, are unstable at alkaline pH, are soluble in acidic conditions, and are active locally in the stomach. In this review, we discuss the physiological state of the stomach and various factors that affect GRDDS. Recently applied gastrointestinal technologies such as expandable, superporous hydrogel; bio/mucoadhesive, magnetic, ion-exchange resin; and low- and high-density-systems have also been examined along with their merits and demerits. The significance of in vitro and in vivo evaluation parameters of various GRDDS is summarized along with their applications. Moreover, future perspectives on this technology are discussed to minimize the gastric emptying rate in both the fasted and fed states. Overall, this review may inform and guide formulation scientists in designing the GRDDS.

Development of novel gastroretentive salbutamol sulfate-loaded sodium alginate-pectin bubble beads prepared by co-axial needle air-injection method and in vivo clinical evaluation by ultrasound studies

In the present study, the salbutamol sulfate-loaded sodium alginate-pectin (SS-loaded SA-PEC) bubble beads have been optimized and evaluated for drug loading, in vitro drug release, in vivo floating behavior in the stomach, etc. Nine batches (F1-F9) of bubble beads with different SA and PEC contents were prepared by novel co-axial needle air-injection method and related to their percent drug loading efficiency (%DLE) and percent drug release at 4 h (%R_4h) as response factors. The multivariate analysis has shown the effect of SA/PEC ratio, total polymer content, as well as their interaction on %DLE and %R_4h. In the quantitative modeling, the satisfactory adjustment of the linear models (along with interaction terms) with the experimental data for both %DLE and %R_4h has confirmed the findings of the multivariate analysis. The optimized SS-loaded SA-PEC bubble beads based on 2D (contours), 3D, desirability, and overlay plots has exhibited %DLE of 87.35 ± 2.48% (n = 3 and error = 2.94%) and %R_4h of 85.79 ± 2.98% (n = 3 and error = 0.25%). The in vitro drug release studies have shown almost complete (≥85%) SS release from all the batches within 4-6 h in simulated gastric fluid (SGF) pH 1.2. The in vivo clinical findings by ultrasound studies have shown excellent floatation (>6 h) behavior of bubble beads in the upper gastrointestinal tract (GIT) and efficient stomach-specific gastroretention.

Electrospun Hydrophilic Janus Nanocomposites for the Rapid Onset of Therapeutic Action of Helicid

The oral delivery of active ingredients for the fast onset of therapeutic effects is a well-known method in patients. In this study, a new kind of hydrophilic Janus structural nanocomposite was designed for the rapid dissolution and transmembrane permeation of helicid, an herbal medicine with poor water solubility. A side-by-side electrospinning process characterized by an eccentric spinneret was developed to fabricate the Janus nanocomposites. The morphology, inner structure, incorporated components and their physical states, hydrophilicity, and functional performances of the Janus nanocomposites were investigated. The experimental results demonstrated that an unspinnable fluid (polyvinylpyrrolidone K10-sodium dodecyl sulfate) could be simultaneously treated with an electrospinnable fluid (polyvinylpyrrolidone K90-helicid) to create Janus structural nanocomposites. The prepared Janus nanofibers exhibited linear morphology and notable side-by-side inner structure with all the incorporated components present in an amorphous state. Both the control of monolithic nanocomposites and the Janus composites can provide more than 10-fold the transmembrane rates of crude helicid particles. Compared with monolithic nanocomposites, the Janus nanocomposites exhibited improved hydrophilicity and can further promote the dissolution and transmembrane permeation of helicid for a potentially faster onset of therapeutic actions. The generation mechanisms and functional performance of Janus nanocomposites were suggested. The preparation protocols reported here can provide a useful approach for designing and developing new functional nanocomposites in the form of Janus structures. Meanwhile, the medicated hydrophilic Janus nanocomposites represent a newly developed kind of nano drug delivery system for the fast onset of therapeutic action of orally administered water-insoluble drugs.

Development of Novel High Density Gastroretentive Multiparticulate Pulsatile Tablet of Clopidogrel Bisulfate Using Quality by Design Approach

Myocardial infarction, i.e., heart attack, is a fatal condition which is on the increase all over the world. It is reported that a large number of heart attack occur in morning hours which are attributable to platelet aggregation. Chronotherapy at this stage can be crucial. Clopidogrel bisulfate (CLB) is an antiplatelet agent and has become a drug of choice for prevention of heart attack. It is soluble in acidic pH and has a narrow absorption window. So, its long residence time in stomach is desirable. Therefore, a novel high density tablet was developed comprising multiparticulate pellets with pulsatile release necessary to maintain chronotherapy of heart attack. The pellets were prepared by extrusion-spheronization and coated in fluidized bed processor with different coating material to achieve pulsatile release. The size, shape of pellets, and drug release were evaluated. High density tablet containing coated pellets was formulated and evaluated for retention in stomach. Quality by design tools was used to design and optimize the processes. Timed release observed by dissolution study showed lag time of 6 h followed by burst release of drug up to 94% in 1 h. Density of tablets was found to be 2.2 g cm^-3 which is more than gastric fluid. In vivo x-ray studies in rabbit revealed 8 h of gastric retention of tablet at the bottom of the stomach. Thus, CLB high density pulsatile system looks to open up a window of opportunity for developing formulations with drugs that are stable in gastric region and needed chronotheraupetic activity.

Pantoprazole Sodium Loaded Microballoons for the Systemic Approach: In Vitro and In Vivo Evaluation

Purpose: Various floating and pulsatile drug delivery systems suffer from variations in the gastric transit time affecting the bioavailability of drugs. The objective of the study was to develop Pantoprazole Sodium (PAN) microballoons that may prolong the gastric residence time and could enhance the drug bioavailability.

Methods: Microballoons were prepared using Eudragit^®L100 by adopting emulsion solvent diffusion method with non-effervescent approach, in vitro studies were performed and the in vivo evaluation was carried out employing ethanol induced ulceration method. Optimization and validation were carried out through Design Expert^® software.

Results: The results demonstrate an increase in percentage yield, buoyancy, encapsulation efficacy and swelling. Particles were in the size range 80-100 µm following zero order release pattern. SEM study revealed their rough surface with spherical shape, internal cavity and porous walls. DSC thermo gram confirms the encapsulation of drug in amorphous form. Significant anti ulcer activity was observed for the prepared microballoons. The calculated ulcer index and protection were 0.20±0.05 and 97.43 % respectively for LRS-O (optimized formulation).

Conclusion: This kind of pH dependent drug delivery may provide an efficient dosage regimen with enhanced patient compliance.

Factorial designed 5-fluorouracil-loaded microsponges and calcium pectinate beads plugged in hydroxypropyl methylcellulose capsules for colorectal cancer

INTRODUCTION

The work was aimed to develop an enteric-coated hydroxypropyl methylcellulose (HPMC) capsules (ECHC) plugged with 5-fluorouracil (5-FU)-loaded microsponges in combination with calcium pectinate beads.

MATERIALS AND METHODS

The modified quasi-emulsion solvent diffusion method was used to prepare microsponges. A 3(2) factorial design was employed to study the formulation and the effects of independent variables (volume of organic solvent and Eudragit-RS100 content) on dependent variables (particle size, %entrapment efficiency, and %cumulative drug release). The optimized microsponge (F4) was characterized by scanning electron microscopy, powder X-ray diffraction, and thermogravimetric analysis. F4 was plugged along with the calcium pectinate beads in HPMC capsules coated with enteric polymer Eudragit-L100 (Ed-L100) and/or Eudragit-S100 (Ed-S100) in different proportions. An in vitro release study of ECHC was performed in simulated gastric fluid for 2 h, followed by simulated intestinal fluid for next 6 h and then in simulated colonic fluid (in the presence and absence of pectinase enzyme for further 16 h). The optimized formulation was subjected to in vivo roentgenographic and pharmacokinetic studies in New Zealand white rabbits to analyze the in vivo behavior of the developed colon-targeted capsules.

RESULTS

Drug release was retarded on coating with Ed-S100 in comparison to a blend of Ed-S100:Ed-L100 coating. The percentage of 5-FU released at the end of 24 h from ECHC3 was 97.83 ± 0.12% in the presence of pectinase whereas in the control study, it was 40.08 ± 0.02%.

CONCLUSION

Thus, enteric-coated HPMC capsules plugged with 5-FU-loaded microsponges and calcium pectinate beads proved to be a promising dosage form for colon targeting.

Enteric coated HPMC capsules plugged with 5-FU loaded microsponges: a potential approach for treatment of colon cancer

The work was aimed at developing novel enteric coated HPMC capsules (ECHC) plugged with 5 Florouracil (5-FU) loaded Microsponges in combination with calcium pectinate beads. Modified quasi-emulsion solvent diffusion method was used to formulate microsponges based on 32 factorial design and the effects of independent variables (volume of organic solvent and Eudragit RS100 content) on the dependent variables (Particle size, %EE & % CDR) were determined. The optimized microsponges (F4) were characterized by SEM, PXRD, TGA and were plugged along with calcium pectinate beads in HPMC capsules and the HPMC capsules were further coated with enteric polymer Eudragit L 100 (Ed-L100) and/ or Eudrgit S 100 (Ed-S 100) in different proportions. In vitro release study of ECHC was performed in various release media sequentially SGF for 2 h, followed by SIF for the next 6 h and then in SCF (in the presence and absence of pectinase enzyme for further 16 h). Drug release was retarded on coating with EdS-100 in comparison to blend of EdS-100: EdL-100 coating. The percentage of 5-FU released at the end of 24 h from ECHC 3 was 97.83 ± 0.12% in the presence of pectinase whereas in control study it was 40.08 ± 0.02% drug. The optimized formulation was subjected to in vivo Roentgenographic studies in New Zealand white rabbits to analyze the in vivo behavior of the developed colon targeted capsules. Pharmacokinetic studies in New Zealand white rabbits were conducted to determine the extent of systemic exposure provided by the developed formulation in comparison to 5-FU aqueous solutions. Thus, enteric coated HPMC capsules plugged with 5-FU loaded microsponges and calcium pectinate beads proved to be promising dosage form for colon targeted drug delivery to treat colorectal cancer.

Utilization of ionotropic gelation technique for bioavailability enhancement of cinnarizine: in-vitro optimization and in-vivo performance in human

Gastro retentive drug delivery system techniques were adopted to deliver drugs having narrow absorption window from a particular site in the GIT. Therefore, gastro retentive dosage forms were retained in the stomach, thus improving absorption and bioavailability would be improved consequently. In this study, cinnarizine (CNZ) was employed as the model drug. CNZ is a poorly soluble basic drug, suffering from low and erratic bioavailability. This is attributed to its pH-dependant solubility (highly soluble at pH < 4). CNZ is characterized by short half-life (3-6 h). Accordingly, floating CNZ emulsion gel calcium pectinate beads were developed. A mixture design was employed to study the effect of the percent of LM pectin (A), the percent of GMO (B) and the percent of Labrafac Lipophile (C) simultaneously on the percent of drug released and loaded. The optimized floating CNZ emulsion gel calcium pectinate beads and Stugeron® (the marketed reference product) were compared through a pharmacokinetic study carried on healthy human volunteers. Fortunately, simple floating CNZ emulsion gel calcium pectinate beads were prepared with zero-order release profile for 12 h. A promising in-vivo CNZ controlled release dosage form with higher bioavailability, when compared to once daily administration of Stugeron® tablets was achieved.

Development of floating chitosan-xanthan beads for oral controlled release of glipizide

Introduction:

The aim of the present work was to develop controlled release, floating and mucoadhesive beads of glipizide by using the polyionic complexation technique. Plasma half-life of glipizide being 2–4 h was selected for development of controlled release dosage form.

Methods:

Formulation batches were designed by employing chitosan as cationic and xanthan gum as anionic polymers. In vitro drug release was evaluated for the period of 24 h in phosphate buffer pH 7.4.

Results:

Sustained release of drug was observed in all formulation batches with % drug release ranging from 87.50% to 100.67%, no significant effect on the drug release was observed after varying chitosan to xanthan gum ratio. Encapsulation efficiency was found to be in the range of 79.48 ± 1.10–94.48 ± 1.52. In vitro bioadhesion studies showed that beads had satisfactory bioadhesive strength ranging from 67.11% ± 1.73% to 93.12% ± 1.56%. Buoyancy studies revealed that beads possess comparable floating capacity in the gastric fluids. Swelling kinetics was carried in pH 1.2 and 7.4 buffers. Significant difference (P < 0.05) in swelling kinetics was observed. Drug to polymer interaction was analyzed by Fourier transform infrared spectroscopy and differential scanning calorimetry studies. Scanning electron microscopy studies revealed that formed beads were discrete with rough and wrinkled surfaces.

Conclusions:

In conclusion, beads were successfully formed by employing chitosan and xanthan gum and showed to possess sustained release effect. Beads also showed pH dependent swelling kinetics, this property can also be applied for the drugs which are susceptible to the acidic environment in the stomach, and comparable bioadhesive and floating properties were also observed.

Role of excipients and polymeric advancements in preparation of floating drug delivery systems

Since decade or two, the development of floating drug delivery systems becomes a significant and novel tool as having low density than gastric content. There are various advanced polymers including chitosan, eudragit, etc., and excipients such as; pore forming agent, surfactants, etc. All of them are discussed briefly, and results are concluded from various reputed researches. We have discussed all natural and synthetic systems with their effect on the release and other parameters which are essential for the floating formulation development.

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.

Development of press-coated, floating-pulsatile drug delivery of lisinopril

Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor, primarily used for the treatment of hypertension, congestive heart failure, and heart attack. It belongs to BCS class III having a half-life of 12 hrs and 25% bioavailability. The purpose of the present work was to develop a press-coated, floating-pulsatile drug delivery system. The core tablet was formulated using the super-disintegrants crosprovidone and croscarmellose sodium. A press-coated tablet (barrier layer) contained the polymer carrageenan, xanthan gum, HPMC K4M, and HPMC K15M. The buoyant layer was optimized with HPMC K100M, sodium bicarbonate, and citric acid. The tablets were evaluated for physical characteristics, floating lag time, swelling index, FTIR, DSC, and in vitro and in vivo behavior. The 5% superdisintgrant showed good results. The FTIR and DSC study predicted no chemical interactions between the drug and excipients. The formulation containing xanthan gum showed drug retaining abilities, but failed to float. The tablet containing HPMC K15M showed a high swelling index. The lag time for the tablet coated with 200 mg carrageenan was 3±0.1 hrs with 99.99±1.5% drug release; with 140 mg HPMC K4M, the lag time was 3±0.1 hrs with 99.71±1.2% drug release; and with 120 mg HPMC K15M, the lag time was 3±0.2 hrs with 99.98±1.7% drug release. The release mechanism of the tablet followed the Korsmeyer-Peppas equation and a first-order release pattern. Floating and lag time behavior have shown good in vitro and in vivo correlations.

Sinking-magnetic microparticles prepared by the electrospray method for enhanced gastric antimicrobial delivery

A targeted oral drug delivery system is useful to improve the treatment of gastrointestinal diseases. A high density sinking dosage form can sink to the bottom of the stomach near the pylori sections to enhance gastric retention. However, it is difficult to achieve a high density sinking system using the traditional technology. In the current study, novel stomach-specific sinking magnetic microparticles (SMMPs) were prepared via the monoaxial electrospray method for enhanced gastric antimicrobial delivery. The size of SMMPs was approximately 5 μm, and the Fe3O4 nanoparticles were observed in the SMMPs by transmission electron microscopy (TEM). The density of SMMPs increased as the concentration of Fe3O4 nanoparticles in the electrospray inlet flow increased, with the maximum true density of approximately 3.52 g/cm(3). The SMMPs displayed strong magnetism in vitro and in vivo. They can settle down in water within 120 s in vitro, and the settling time decreased to 20 s under a magnetic field. Furthermore, an in vivo γ scintigraphy study demonstrated that (131)I labeled SMMPs were retained in the stomach for over 8 h, and an external permanent magnet can increase their gastric retention time even further. Using Helicobacter pylori as a model bacterium, amoxicillin-loaded SMMPs exhibited a significantly greater eradication of H. pylori compared to the free drug, in vivo. Our results suggested that electrospray is an effective technique to prepare the high density gastroretentive dosage forms. We have shown that stomach-specific SMMPs can supply better treatment for H. pylori infections and have the potential to be used in clinical practice.

Crosslinked ionic polysaccharides for stimuli-sensitive drug delivery

Polysaccharides are gaining increasing attention as components of stimuli-responsive drug delivery systems, particularly since they can be obtained in a well characterized and reproducible way from the natural sources. Ionic polysaccharides can be readily crosslinked to render hydrogel networks sensitive to a variety of internal and external variables, and thus suitable for switching drug release on-off through diverse mechanisms. Hybrids, composites and grafted polymers can reinforce the responsiveness and widen the range of stimuli to which polysaccharide-based systems can respond. This review analyzes the state of the art of crosslinked ionic polysaccharides as components of delivery systems that can regulate drug release as a function of changes in pH, ion nature and concentration, electric and magnetic field intensity, light wavelength, temperature, redox potential, and certain molecules (enzymes, illness markers, and so on). Examples of specific applications are provided. The information compiled demonstrates that crosslinked networks of ionic polysaccharides are suitable building blocks for developing advanced externally activated and feed-back modulated drug delivery systems.

On-off pulsed oral drug-delivery systems: a possible tool for drug delivery in chronotherapy

Circadian rhythms regulate most body functions and are important factors to consider when administering drugs. The existence of circadian rhythms in nature and their influences on human biological systems have given rise to the concept of chronotherapy, which is the science of delivering drugs in a synchronized manner with the rhythm-dependent circadian variation inherent in the human body. The safety and efficacy of a drug can be improved by matching the peak plasma concentration during a 24 h period of the rhythms. An on-off pulsed (pulsatile or time-controlled) release drug-delivery system offers rapid and transient release; stepwise release; and the sustained release of a certain amount of drug within a short time period after a predetermined off-release period according to the circadian rhythm of disease states. These systems deliver the drug at the right time and at an appropriate dosage and are the best approach for chronotherapy. These systems show promise for the optimal therapy of chronic diseases such as asthma, hypertension, myocardial infarction and arthritis, which show a circadian dependency. Various technologies have been adopted to mimic circadian rhythms in physiological functions and diseases. This review focuses on the basic concept of circadian rhythm, chronotherapy and recent advances in the development of on-off pulsed oral drug-delivery systems for optimal therapy.

Development of a gastroretentive pulsatile drug delivery platform

Objectives

To develop a novel gastroretentive pulsatile drug delivery platform by combining the advantages of floating dosage forms for the stomach and pulsatile drug delivery systems.

Methods

A gastric fluid impermeable capsule body was used as a vessel to contain one or more drug layer(s) as well as one or more lag-time controlling layer(s). A controlled amount of air was sealed in the innermost portion of the capsule body to reduce the overall density of the drug delivery platform, enabling gastric floatation. An optimal mass fill inside the gastric fluid impermeable capsule body enabled buoyancy in a vertical orientation to provide a constant surface area for controlled erosion of the lag-time controlling layer. The lag-time controlling layer consisted of a swellable polymer, which rapidly formed a gel to seal the mouth of capsule body and act as a barrier to gastric fluid ingress.

Key findings

By varying the composition of the lag-time controlling layer, it was possible to selectively program the onset of the pulsatile delivery of a drug.

Conclusions

This new delivery platform offers a new method of delivery for a variety of suitable drugs targeted in chronopharmaceutical therapy. This strategy could ultimately improve drug efficacy and patient compliance, and reduce harmful side effects by scaling back doses of drug administered.

In vitro and in vivo evaluation of multilayered pastilles for chronotherapeutic management of nocturnal asthma

OBJECTIVE

The present work was undertaken with an objective to design a multilayered dosage form of doxofylline, using pastillation technology, for the chronotherapeutic management of nocturnal asthma.

RESEARCH DESIGN & METHODS

Pastilles consisting of the drug, polyethylene glycol and colloidal silicon dioxide, were generated using an in-house laboratory-scale pastillation device. The pastilles were further coated with enteric polymers and a floating layer, using conventional coater. The pastilles were subjected to physicochemical analysis, morphological characterization, in vitro drug release studies and in vivo pharmacokinetic studies in rats.

RESULTS

It was observed that colloidal silicon dioxide was instrumental in improving the contact angle of the pastilles. The uncoated pastilles released the drug immediately, while the enteric-coated (10% w/w) pastilles were found to have sufficient acid resistance when the coat is applied with 5% (v/v) triethyl citrate as plasticizer. The in vivo blood serum profile indicated that the pastilles coated with the enteric coat and the additional floating coat were effective in significantly delaying the in vivo drug release required for the chronotherapeutic treatment of nocturnal asthma.

CONCLUSION

The present work opens a new alternative to the conventional tablet or capsule dosage form for the development of both immediate-release and modified-release drug delivery systems.

Advances in gastro retentive drug-delivery systems

INTRODUCTION

In recent years, various technological improvements have been achieved and new concepts have been developed, in the area of controlled release solid oral dosage forms, especially for products where an extended time of release is associated with an extended gastric retention time. These Gastro Retentive Systems have been quite investigated because they can improve the in-vivo performance of many drugs.

AREAS COVERED

This paper summarizes current approaches in the research and development of gastro retentive dosage forms from recent literature. Apart from the numerous mechanisms of action involved, a short review of different key parameters is proposed, taking into account the stomach physiology. Most of the current technologies published, patented or marketed are presented. Promising drugs to develop in the near future are mentioned, and the importance of such systems in fixed Dose Combinations is also discussed. The importance of food effect is mentioned, and the impact of the multiple unit systems versus monolithic approach is discussed, especially regarding the dose intake.

EXPERT OPINION

In conclusion, numerous mechanisms like floating, sinking, effervescence, swelling, bioadhesion, magnetic, etc. have been proposed over the years. While most of the proposed systems show promising dissolution profiles and in-vitro retention, only few of them have also shown success in-vivo. Currently, the polymeric swelling monolithic systems are the most prominent marketed forms. The possibility to combine different mechanisms in order to ensure true gastric retention even in the fasted state should be further investigated.

Application of pectin in oral drug delivery

INTRODUCTION

Biopolymers have been used extensively in the pharmaceutical field. Pectin, a biopolymer, has several unique properties that enable it to be used as an excipient or carrier for oral drug delivery systems. Accordingly, several investigators have identified the benefits of pectin-based delivery systems for oral drug administration.

AREAS COVERED

This review first describes the chemical structure, source and production, degree of esterification and gel formation properties of pectin. The application of pectin in various oral drug delivery platforms is also discussed, that is, controlled release systems, gastro-retentive systems, colon-specific delivery systems and mucoadhesive delivery systems.

EXPERT OPINION

Pectin from different sources provides different gelling abilities, due to variations in molecular size and chemical composition. Like other natural polymers, a major problem with pectin is inconsistency in reproducibility between samples, which may result in poor reproducibility in delivery characteristics. Scintigraphic studies and in vivo studies, in both animals and human volunteers, demonstrate the successful development of a pectin-based colon-specific drug delivery system. Pectin-based controlled release systems, gastro-retentive systems and mucoadhesive systems present promising approaches for increasing the bioavailability of drugs, but are in their infancy. A lack of direct correlation between in vitro release and in vivo absorption studies is a major concern with these systems.

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.

Preparation and evaluation of a novel delayed-onset sustained-release system of propranolol hydrochloride

The objective of this work was to prepare and evaluate a new delayed-onset sustained-release system, comprising a sustained-release core tablet with hydroxypropyl methylcellulose as polymer matrix and an ethylcellulose/Eudragit L coating capable of delaying the drug release. The sustained core containing propranolol hydrochloride as the model drug was prepared by granulate tableting and the polymer coating was applied in a computer-controlled coating pan. The dissolution tests demonstrated that the in-vitro drug release was pH-dependent with sufficient gastric resistance, and the lag time (t10%) could be controlled by adjusting the coating level. Three dosage forms including commercial tablet, sustained-release tablet and the delayed-onset sustained-release tablet were administrated to six beagle dogs and the plasma levels of propranolol hydrochloride were measured with high-performance liquid chromatography. The delayed-onset sustained-release tablet had a lag time of 3.0 h in-vitro and 3.5 h in-vivo, and a tmax of 7.0 h. The relative bioavailability for delayed-onset sustained-release tablet was 96.98% compared with commercial tablets. The results indicate that the new propranolol delayed-onset sustained-release system could achieve a relatively constant drug release followed by a programmed lag time, and this may provide a promising drug delivery form for chronopharmacotherapy of certain cardiovascular diseases.

Drug delivery technologies for chronotherapeutic applications

It has been proven that the body follows a 24-hour cycle called a circadian rhythm. This cycle is coordinated by the suprachiasmatic nucleus and controls nearly all bodily functions including those related to drug delivery. Knowledge of the body's circadian rhythm leads to an improved understanding of diseases and their treatment, known as chronotherapy, such that synchronizing drug application in accordance with the natural rhythm of the body leads to improved disease management and a greater patient therapeutic outcome. Chronotherapeutic diseases include asthma, cardiovascular diseases, glaucoma, rheumatoid arthritis and cancers. In order to treat these diseases numerous chronotherapeutic drug delivery systems have been developed, such that drug is released in the period when it is most needed. This review paper attempts to concisely explicate the role of circadian rhythms in various disease states and furthermore describes the various oral drug delivery technologies that have been employed for the treatment of chronotherapeutic diseases.

Novel/conceptual floating pulsatile system using high internal phase emulsion based porous material intended for chronotherapy

The aim of the present study was to design a novel/conceptual delivery system using ibuprofen, anticipated for chronotherapy in arthritis with porous material to overcome the formulation limits (multiple steps, polymers, excipients) and to optimize drug loading for a desired release profile suitable for in vitro investigations. The objective of this delivery system lies in the availability of maximum drug amount for absorption in the wee hours as recommended. Drug loading using 3(2) factorial design on porous carrier, synthesized by high internal phase emulsion technique using styrene and divinylbenzene, was done via solvent evaporation using methanol and dichloromethane. The system was evaluated in vitro for drug loading, encapsulation efficiency, and surface characterization by scanning electron, atomic force microscopy, and customized drug release study. This study examined critical parameters such as solvent volume, drug amount, and solvent polarity on investigations related to drug adsorption and release mostly favoring low-polarity solvent dichloromethane. Overall release in all batches ranged 0.98-52% in acidic medium and 71-94% in basic medium. These results exhibit uniqueness in achieving the least drug release of 0.98%, an ideal one, without using any release modifiers, making it distinct from other approaches/technologies for time and controlled release and for chronotherapy.