Sustained Release Drug Delivery System with the Role of Natural Polymers: A review

An appropriately designed sustained release dosage form is opted to be a major goal in solving the problems which arises regarding the targeting of a drug to a specific organ or tissue and for controlling its rate of delivery to the target site. The development of oral sustained release system has proven to be a major challenge to formulation scientist due to their inability to restrain as well as localize the system at targeted areas of the gastrointestinal tract. Therefore the development of matrix type drug delivery system is promising option regarding the development of an oral sustained release system. There is availability of wide variety of polymers which helps the formulation scientist to develop sustained/controlled release products. The attractiveness of these dosage forms is increasing because of their awareness towards toxicity and ineffectiveness when administered by oral route in the form of tablets and capsules. Numerous advantages are provided by sustained release products over conventional dosage forms through optimizing various bio-pharmaceutics, pharmacokinetic and pharmacodynamics properties of drugs and finally leads to reduction in dosing frequency to such an extent that only once daily dose is required for therapeutic management with maximum utility of drug with reduction in both local as well as systemic side effects. They can cure or control diseased condition in shortest possible time with smallest quantity of drug to assure greater patient compliance. Polymer swelling, drug dissolution and its diffusion are the known mechanisms for drug release through polymer network. Keywords: Oral drug delivery system, sustained release dosage form, matrix system, polymer swelling, drug diffusion

A Review on Microsponge Delivery System

Microsponge is recent novel technique for control release and target specific drug delivery system. Microsponge technology has been introduced in pharmaceutical industry to provide the controlled release of active drug ingredient for the application into the skin in order to decrease systemic exposure and reduce local cutaneous reactions to active drugs. Microsponges comprises of microporous beads, typically 10-25 microns in diameter, loaded with active agent. The microsponge releases its active ingredient on a time mode, when applied to the skin,  and also in response to other stimuli that are used mostly for topical and recently for oral administration. Microsponge technology has many favourable characteristics which make It all around suitable as drug delivery vehicle. Microsponge systems can suspend or entrap a wide variety of substances, and then be incorporated into a formulated product such as a gel, cream, liquid or powder. The outer surface is mostly porous, allowing the sustained flow of substances out of the sphere. Microsponge drug delivery system causes increased efficacy for the topically active agents with enhanced safety and product stability for a longer period of time with reduction in side effects. In addition their non-allergenic, non-irritating, non-mutagenic and nontoxic behaviour makes them the suitable dosage form. The present review emphasis Microsponge drug delivery system along with its release mechanism. Keywords: Novel drug delivery system, Microsponges, Microsponge drug delivery system, Quasi-emulsion solvent diffusion method

Preparation and Characterization of Itraconazole Microsponges using Eudragit RSPO and Study the Effect of Stirring on the Formation of Microsponges

The purpose of the present study was to prepare and evaluate Itraconazole loaded microsponges using Eudragit for the controlled release of the drug and study the effect of stirring rate on the formation of microsponges. Microsponges containing Itraconazole were prepared by using quasi-emulsion solvent diffusion method at different stirring rate i.e. 500, 800, 1000, 1200 and 1500rpm.  Particle size of prepared microsponge was observed in the range of 78.43 to 23.18 µm. Scanning electron microscopy revealed the porous, spherical nature of the microsponges. The production yield, entrapment efficiency, and drug content were found to be 80.88%, 84.53% and 82.89%. The formulation with higher drug to polymer ratio 1:10 (i.e. F5) was chosen to investigate the effect of stirring rate on the morphology of microsponges. As the speed was increased, the particle size of microsponges was reduced and uniform spherical microsponges were formed. As drug polymer ratio increased, Production yield, drug content and entrapment efficiency was found to be increased while drug: polymer ratio has reverse effect on particle size, as drug: polymer ratio increase, particle size decreases. The cumulative percentage drug release upto 8hrs for F5 was 89.54% and the mechanism of drug release from the formulations during the dissolution was determined using the zero order, first order, higuchi equation and Peppas equation. All formulations were best fitted to Zero order and peppas plot. The best formulation F5 follows Zero order release. Keywords: Microsponges, Itraconazole, stirring rate, Quasi-emulsion solvent diffusion metho

Formulation and Evaluation of Fluconazole Microsponge using Eudragit L 100 by Quasi Emulsion Solvent Diffusion Method

The aim of the present study is to formulate and evaluate the fluconazole microsponge by using Eudragit L 100. Microsponge was made because they provide controlled as well as target specific release of the drug. Thus study the effect of stirring rate on the formation of microsponge. Microsponge containing Fluconazole were prepared by quasi-emulsion solvent diffusion method at different stirring rate i.e 500, 800, 1000, 1200 and 1500 rpm. Particle size of prepared microsponge was observed in the range of 76.2 to 32.5μm. Scanning electron microscopy revealed the porous, spherical nature of the microsponges. The production yield, entrapment efficiency and drug content were found to be 78.24%, 82.76%, 81.36%. The impact of Drug: Polymer ratio and process variables i.e stirring speed and stirring time on the physical features of microsponges like production yield, mean particle size, entrapment efficiency were examined. It was shown that production yield, drug content and entrapment efficiency was found to be increase with increase in drug polymer ratio while drug: polymer ratio has reverse effect on particle size, as drug: polymer ratio increase, particle size decrease. As the polymer concentration increased, more amount of polymer surrounding the drug, thus increasing the thickness of the wall of the polymer matrix which lead to extended diffusion path and ultimately to lesser drug release or more sustained release. The effect of stirring rate on the morphology of microsponge. The formulation with higher drug to polymer ratio 1:8 (i.e F4) was chosen to investigate the effect of stirring rate on the morphology of microsponges. The dispersion of the drug and polymer within the aqueous phase was found to be dependent on the agitation speed. As the speed was increased the size of microsponges was reduced and the microsponges were found to be spherical and uniform. Keywords: Novel drug delivery system, Microsponges, Eudragit L 100, Fluconazole, Quasi-emulsion solvent diffusion method

To study the comparative dissolution profiles of sustained release tablets of metformin hydrochloride by using various hydrophilic polymers

In this research study an attempt was made to formulate sustained release matrix tablets of Metformin Hydrochloride as it possesses relatively shorter plasma half-life, low bioavailability. The sustained release formulations of the drug were capable of maintaining the plasma level for 8-12 hours. The overall objective of this research was to formulate the tablet by using various hydrophilic polymers i.e. Xanthan gum, Guar gum, Aloe barbadensis and Methocel K4M. Tablets were prepared by wet granulation method. In Vitro studies were performed by USP XX apparatus I, basket and the data was analyzed using zero order, first order, and Korsmeyer and Higuchi models. Nine formulations were made, out of which F-9 formulation which was composed of Aloe Barbadensis in the ratio of 1:2, with combination of other polymers (xanthan gum, guar gum and methocel K4 M) showed maximum drug release within 12 hours with sustained release profile because Aloe barbadensis showed maximum swelling followed by entanglement of polymers chains, thus gave maximum gel strength which provides main retarding factor for the drug release. The use of three polymers (xanthan gum, guar gum and methocel K4M) alone in the different formulations i.e. from F-1 to F-6 was not able to sustain the drug release because of their rapid solubilization in acidic pH leads to pores in the matrix, finally causes surface erosion and initial disaggregation of the matrix tablet prior to gel layer formation around tablet core causes rapid release of the drug within 1 hour as compared to F-9 formulation. Keywords: Sustained drug delivery system, Aloe Vera, Methocel K4M, Xanthan gum, Guar gum and Metformin HCl

Formulation and Evalution of Levamisole Niosomes by using Sonication method

Niosomes or non- ionic surfactants vesicles are one of the many different carriers for transporting a drug molecule to its site of action. Niosomes are vesicular system similar to liposomes that can be used for amphiphilic and lipophilic drugs. Niosomes are biocompatible, biodegradable, non- immunogenic and exhibit flexibility. Niosomes has been widely used for controlled release drug delivery system. Niosomes can entrap both hydrophobic and hydrophilic drugs.  Niosomes are chemically stable drug delivery systems. Niosomes are biocompatible, biodegradable, non- immunogenic and exhibit flexibility in structure. Niosomes have been widely used for controlled drug delivery system. They have been prepared with different ratios of surfactants and cholesterol and their properties have been determined by scanning electron microscopy. There are five batches of Levamisole niosomal preparations were prepared by changing the surfactant concentration but keeping the cholesterol concentration constant. The surfactant used Span40 and the five batches of niosomal preparations in the ratios of 1:1:1, 1:2:1, 1:3:1, 1:4:1 and 1:5:1 (Surfactant: cholesterol: drug). Furthermore, the release profiles, entrapment efficiency, size distribution and stability of these niosomes under various temperatures were studied. Niosomes were prepared using Span40 by using sonication method. The test changes in the characteristics of the liposomes. Keywords- Niosomes, Compositions, Preparation methods, Factors affecting, characterizations, in- vitro methods, Applications

Novel Strategy: Microsponges for Topical Drug Delivery

Microsponge delivery system is a unique and effective technology for the controlled release of topical agents. It is highly cross- linked porous, polymeric microspheres that can entrap wide range of active agents and in response to trigger or stimuli and release them onto the skin over a time. It consists of micro-porous beads, typically 5-300µm in diameter that acquire the flexibility to entrap a wide variety of active ingredients such as fragrances, sunscreens, emollients, anti-fungal, anti-infective, and anti-inflammatory agents etc., that are mostly used to prolong the topical administration of the drug . Recently it was investigated that microsponges also used for oral drug delivery system. The topical agent formulation with microsponge delivery system can be prepared in many different forms, such as cream, gel, or lotion. When the formulation is applied to the skin, the MDS releases its active ingredients on a time and in response to other stimuli (rubbing, temperature, pH etc.). They reduce side effects, enhance stability and modify drug release. Because of the size of the microsponges they cannot pass through the stratum corneum, so they remain on the skin surface and slowly releasing the active ingredients over a period. Slow rate of release from MDS reduce the irritancy associated with the topical agents. Slow and gradual release pattern of MDS prevents excessive build-up of the active agents in the epidermis and dermis. Therefore, these particles, remains on the surface of the skin and its fine lines delivering the active over prolonged time.                                                                      Keywords: Microsponge Delivery System, Quasi- emulsion solvent diffusion

Adaptive Tetrahedral Meshing for Personalized Cardiac Simulations

International audiencePersonalized simulation for therapy planning in the clinical routine requires fast and accurate computations. Finite-element (FE) simulations belong to the most commonly used approaches. Based on medical images the geometry of the patient's anatomy must be faithfully represented and discretized in a way to find a reasonable compromise between accuracy and speed. This can be achieved by adapting the mesh resolution, and by providing well-shaped elements to improve the convergence of iterative solvers. We present a pipeline for generating high-quality, adaptive meshes, and show how the framework can be applied to specific cardiac simulations. Our aim is to analyze the meshing requirements for applications in electrophysiological modeling of ventricular tachycardia and electromechanical modeling of Tetralogy of Fallot