Current Issue : January-March Volume : 2011 Issue Number : 1 Articles : 14 Articles
Goal of targeting drugs to specific sites in the body, where the pharmacological action is desired and sparing other tissues has been actively pursued all these years. Currently the problems associated with systemic drug administration are: the lack of drug specific affinity toward a pathological site; even biodistribution of pharmaceuticals throughout the body; non-specific toxicity and other adverse side-effects due to high drug doses. The increased concentration of a drug in the site of disease made possible by targeted delivery can be used to increase efficacy, reduce side effects, or achieve some of both. Drug targeting, i.e. predominant drug accumulation in the target zone independently on the method and route of drug administration, may resolve many of these problems. Currently, the principal schemes of drug targeting include direct application of a drug into the affected zone, passive drug targeting (spontaneous drug accumulation in the areas with leaky vasculature, or Enhanced Permeability and Retention-EPR-effect), ‘physical’ targeting (based on abnormal pH value and/or temperature in the pathological zone), magnetic targeting (or targeting of a drug immobilized on paramagnetic materials under the action of an external magnetic field), and targeting using a specific ‘vector’ molecules (ligands having an increased affinity toward the area of interest). The last approach provides the widest opportunities. Various pharmaceutical carriers as soluble polymers, microcapsules, microparticles, cells, cell ghosts, liposomes, and micelles have been successfully used for targeted drug delivery in vivo. In this article we are concerning mainly on active targeting which include manipulation or modification of drug carrier so that it easily approaches the particular biosite....
Earlier medicines were made to release the drugs in an immediate or extended fashion. However, in recent years, pulsatile drug delivery systems (PDDS) are gaining growing interest. A pulsatile drug release, where the drug is released rapidly after a well defined lag-time at the right site of action at right time and in the right amount, could be advantageous for many drugs or therapies over conventional dosage form and results in improved patient therapeutic efficacy and compliance. These systems are designed according to the circadian rhythm of the body. Pulsatile release systems can be classified in multiple-pulse and single-pulse systems. In stimuli induced drug release is controlled by the stimuli, such as the pH or enzymes present in the intestinal tract or enzymes present in the drug delivery system and externally regulated system where release is programmed by external stimuli like magnetism, ultrasound and electrical effect. Diseases wherein PDDS are promising include asthma, peptic ulcer, cardiovascular diseases, arthritis, cancer, Diabetes, Neurological disorders and hypercholesterolemia. A product available as once a daily formulation based on pulsatile release like PulsinCap is mentioned in the review....
Amoxicillin is an extended spectrum aminopenicillin antimicrobial agent, most efficiently used in eradication of Helicobacter pylori. The present investigation is concerned with the development of the Gastro retentive floating tablets, containing amoxicillin, which after oral administration were designed to prolong the gastric residence time and thus to obtain better eradication rate and also to minimize the incident of bacterial resistance as well as side effects. Various formulations were developed by using Guar-gum as natural hydrocolloid; HPMC as a release rate controlling and gel forming polymer; Sodium bi-carbonate as gas generating agent. The air-pockets formed by effervescent of Sodium bi-carbonate within the floating system and natural hydrocolloid provided low density which lead to excellent in-vitro floating behavior of the tablets. All the formulations had floating lag time below 2 minutes and constantly floated on dissolution medium for more than 12 hours. From among all the developed formulations, as F3 prolonged the drug release for longer period of time, they were nominated as best formulations. Thus, best formulations satisfied physico-chemical parameters, floating time and in vitro drug release profile requirements for a floating drug delivery system....
The present research has been undertaken with the aim to develop a topical gel formulation for valacyclovir by using various gelling agents (viz., carbopol 934, sodium carboxy methylcellulose, guar gum and hydroxypropyl methylcellulose) in to various types of gel formulations (hydrogels, isopropyl alcoholic gels, proniosomal gels). The prepared gels were evaluated for pH, rheological behavior (viscosity, spreadability, and extrudability), drug content, in vitro drug diffusion and also characterized by IR studies. There is no interaction between drug and carrier. Drug content was found to be high (>98%) and uniform in gels. Effect of gelling agent and type of gel formulation on the release of drug from the gels was studied. The order of release of drug from various gel formulations was as follows: Hydrogel > isopropyl alcohol gel > proniosomal gel. The release of Valacyclovir was slow and extends for longer period following first order kinetics. The order of release of the drug from various gelling agents was as follows HPMC > Corbopol 934 > NaCMC > Guargum....
Formulation and Evaluation of Floating Microspheres of Captopril for Prolonged Gastric Residence Time...
The present research is to develop an optimized gastro retentive drug delivery system containing Metformin Hydrochloride using Gum Kondagogu and to investigate the effect of formulation and processing parameters on the release rate of the drug. The effervescent granules were prepared by wet granulation technique using Gum Kondagogu which is a natural polymer used to control the release. Sodium bicarbonate was used in formulation whose function is gas generation. The granules were lubricated with magnesium stearate and talc and compressed. Tablets were characterized for physical properties, floating characteristics (floating lag-time, floating time), swelling index, wetting time, drug content and evaluated for in vitro release characteristics for 10 hrs in 0.1N HCl at 370C. The similarity factor, T50 and T90 were used as parameters for selection of the best formulation in comparision with commercial product. The tablet erosion, drug diffusion, polymer swelling and the resulting release patterns varied significantly with the type of matrix forming Natural polymer used. Hence Gum Kondagogu can be ascertained as a low dense compound which has gas evolving as well as binding properties and thus, excellent in vitro floating behavior of the tablet was found out. Comparable release profiles between the commercial product and the designed system (F4) were obtained. Altering the concentration of Natural polymer, binding agent and gas-evolving agent are found to have a significant influence on the release rate with accurate control and prolongation of the drug release patterns. The order of drug release from all the formulations followed zero order kinetics and mechanism of the drug release followed Korsmeyer-Peppas mechanism....
Nocturnal asthma is a condition prevalent in two-third of asthmatics, in which there is variable night time exacerbations of asthmatic conditions associated with worsening of lung function. Asthmatic attacks occur especially around 4 am. Theophylline (dimethylxanthine), is a methylxanthine drug used in therapy for respiratory diseases such as COPD and asthma. This study attempts to design and evaluate a chronomodulated drug delivery system of theophylline with a lag time of 6 hours. The present work is aimed to design a pulsatile tablet with a core which contains a disintegrant with swelling property, coated with a pH dependent polymer. The coating ruptures when the fluid enters the core as the disintegrant swells. The percentage weight gain in coating is varied from 1 to 8%. The coated tablets showed a proportionate increase in lag time with increase in the coating level (147 to 438 mins. for coating of 1 to 8% respectively). Further, this proportionality was utilized to optimize the formulation, 32 factorial design was applied considering superdisintegrant concentration and coating level as the factors for three levels. The results revealed that the lag time increases with increase in coating level and decreases with increase in concentration of superdisintegrant. The batch with 4 % of superdisintegrant and 6 % weight gain showed desired lag time Ã?Å? 6 hrs. with desirable In-vitro drug release profile. The optimized formulation complied with the ICH stability testing guidelines. The developed pulsatile tablet formulation thus produced promising results for oral delivery....
Sustained release technology is relatively new field and as a consequence, research in the field has been extremely fertile and has produced many discoveries. The matrix system is most often used for a drug-controlled release from a pharmaceutical dosage form. Isoniazid is an antitubercular, with half life of 1.5-4 hours and requires multiple daily doses to maintain adequate plasma concentration. By considering the facts about drug, the present study was aim to formulate and evaluate the sustained release oral matrix tablet by using Isoniazid as a model drug and see the effects of different polymers to prolong the release of drug for extended period of time. Various formulations of sustained release tablets of Isoniazid were developed using various polymers Guargum, Carbopol, Tragacanth Gum and PEG-6000, in different proportion and combinations by direct compression technique, Bulk density, tapped density, compressibility index, and Hausner ratio before being punched as tablets. Observations of all formulations for physical characterization had shown that, all of them comply with the specifications of official pharmacopoeias and or standard references. Results of in vitro release profile indicated that formulation (F2) was the most promising formulation as the extent of drug release from this formulation was high as compared to other formulations. It was observed that tablets of batch F2 followed the Zero order release profiles. From the above results and discussion it is concluded that formulation of sustained release tablet of Isoniazid containing Guar gum (1.5%), Batch F2 can be taken as an ideal or optimized formulation of sustained release tablets for 12 hour release as it fulfills all the requirements for sustained release....
Exhaustive efforts have been made toward the administration of drugs via alternative routes that are poorly absorbed after the oral administration. The vagina has been studied as a suitable site for local and systemic delivery of drugs. There are a large number of vaginal medications on the market. Most of them, however, require frequent applications due to their short vaginal residence time. A prolonged vaginal residence time of formulations is therefore a key parameter for improved therapeutic efficacy. Promising approaches for prolonging the residence time base on mucoadhesion, were in- situ sol-to-gel transition and mechanical fixation. Mucoadhesive drug delivery systems can be tailored to adhere to the vaginal tissue. In-situ gelling systems offer the advantage of increased viscosity in vaginal cavity and consequently reduce outflow from the vagina. Mechanical fixation needs specially shaped drug delivery systems and reduce the frequency of administration significantly. Numerous models of contraceptive vaginal rings (CVRs) have been studied, but only two have reached the market: NuvaRing, a combined ring that releases etonogestrel (ENG) and ethinylestradiol (EE), and Progering, a progesterone-releasing ring for use in lactating women....
A drug delivery system (DDS) is defined as a formulation or a device that enables the introduction of a therapeutic substance in the body and improves its efficacy and safety by controlling the rate, time and site of release of drugs in the body. Microsponges are porous, polymeric microspheres that are used mostly for topical and recently for oral administration. Many of conventional delivery systems require high concentrations of active agents to be incorporated for effective therapy because of their low efficiency as delivery systems. Thus, the need exists for delivery systems to maximize the period of time that an active ingredient is present, either on the skin surface or within the epidermis while minimizing its transdermal penetration into the body. Microsponge can be prepared by two different methods namely, (i) liquid- liquid Polymerization suspension method and (ii) quasi emulsification method. The microsponge technology delivers a wide range of applications in development of drug product and cosmetic product....
The field of Nanotechnology is emerging worldwide and there has been tremendous investment in this area with an extensive research and development efforts being focused to create new opportunities for advances in drug delivery systems. This review will discuss the various approaches in the design and development of these nanotechnology platforms that bestow such characteristics to the nanoparticles. These nano-sized objects, e.g., “nanoparticles”, take on novel properties and functions that differ markedly from those seen from items made of identical materials. The small size, customized surface, improved solubility, and multi-functionality of nanoparticles will continue to open many doors and create new biomedical applications. This review will also focus on nanoscale based drug delivery systems that are most prominent and widely studied: hydrogels, polymersomes, nanotubes, dendrimers, quantum dots, nanoshells, and nanomicelles. These drug delivery systems can be potentially translated into targeted cellular and tissue-specific clinical applications designed to achieve maximal therapeutic efficacy with minimal side effects....
The purpose of this research is to investigate different levels of hydrophilic natural gums such as xanthan gum, guar gum and their combination to prepare once a day sustained release matrix tablet of nateglinide. Natural gums have some special features like strong gel-forming property, non-toxicity, synergism and cost effectiveness [1]. Natural polymers also exhibit a rheological synergism when two polymers are mixed together. This phenomenon is called viscous synergism. This property of the natural polymers can be used to reduce the total polymer concentration of the tablet. Tablets were prepared using wet granulation technique. Prior to compression, the granules were evaluated for flow and compression characteristics. An attempt was made to reduce the total polymer concentration from the formulation by preparing blends (M7 –M11) each containing 10% less polymer concentration than previous one giving once a day formulation with least amount of polymer. Also, the matrix tablets showed good mechanical properties such as hardness and friability. The polymer and diluent content were found to have significant influence on In vitro drug release profile. Xanthan and guar gum blend showed the high release retarding efficiency than their individual formulations and reduced the total polymer concentration from the formulation....
The affect of method of preparation, granulating fluid, binder, concentration of binder and the composition of matrix on in vitro release of Alfuzosin was studied with a view to develop extended release formulations for Alfuzosin Hcl. Alfuzosin is a uroselective alpha -1 adrenergic antagonist indicated for the management of moderate to severe benign prostatic hyperplasia. The drug is freely soluble in water, has low dose and short biological half life, hence it is suitable for oral extended release formulations. Extended release formulations for Alfuzosin are necessary to maintain uniform plasma concentrations of Alfuzosin, to reduce frequency of administration and to eliminate cardiovascular adverse effects attributed by Alfuzosin. The drug-excipient compatibility studies were carried out with IR spectral studies. The selected excipients were found to be compatible with the drug. Alfuzosin tablets were prepared by wet granulation method. The prepared granules of Alfuzosin were evaluated for bulk density, tapped density, % compressibility index and hausner’s ratio. Formulated tablets were evaluated for uniformity of weight, assay and in-vitro drug release studies. The in vitro release rate of drug is dependent upon different formulation variables. The release rate of drug from the extended release tablets can be governed by the type of the Polymer and the molecular weight of the polymer employed in the preparation of the tablets. The tablets containing 65.42%w/w lactose, 30%w/w HPMC K 100 M yielded the drug release up to 24 hrs and hence this formulation was selected for the extended release of Alfuzosin....
The advent of new era of pharmaceutical dosage forms, transdermal drug delivery system (TDDS) established itself as an integral part of novel drug delivery systems. Transdermal patches are polymeric formulations which when applied on skin delivers the drug at a predetermined rate across dermis to achieve systemic effects. However Transdermal dosage forms are costly alternatives to conventional dosage forms. Now days these are becoming popular because of their unique advantages such as Controlled absorption, uniform plasma levels, improved bioavailability, reduced side effects, painless and simple application and flexibility of terminating drug administration by simply removing the patch from the skin....
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