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Eye is the most sensitive organ of the body. Designing of ocular drug delivery system is the  most challenging field for pharmaceutical scientists as less than 5% of administered drug enters the eye due to the complicated anatomical structure of the eye, small absorptive surface and low transparency of the cornea, lipophilicity of corneal epithelium, pre corneal loss (due to nasolacrimal drainage), bonding of the drug with proteins contained in tear fluid, blinking, low capacity of conjunctival sac, that restricts the entry of drug molecule at the site of action and ultimately leads to poor ocular therapy. To improve ophthalmic drug bioavailability, there are considerable efforts directed towards newer drug delivery systems for ophthalmic administration. These novel drug delivery systems offer manifold advantages over conventional systems as they increase the efficiency of drug delivery by improving the release profile and also reduce drug toxicity. A lot of research going on in this area proves the fact that in situ gelling systems can be beneficial in the ocular drug delivery. In situ gel forming systems are drug delivery systems that are in solution form before administration in the body but once administered, undergo  in situ gelation, to form a gel triggered by external stimulus such as temperature, pH etc.  This review is to Specify a brief summary about in situ gels, various approaches for in situ gelling systems, different types of polymers used in in situ gels, their mechanisms of gel formation and evaluation of polymeric in situ gel. Keywords: in situ gel, polymers, Temperature induced in situ gel system, pH induced in situ gel system, Ion activated systems.

The aim of the present study was to develop a tablet formulation for sustained release of venlafaxine HCl. Control or sustained release formulations have great applications in improving the physicochemical properties and the pharmacokinetic profile of the drugs. Carbopol tablets containing venlafaxine HCl were developed successfully by wet granulation technique. The tablets were evaluated for matrix integrity and drug release in 0.1 N HCl using USP II dissolution apparatus maintained at optimum conditions. The developed tablets were robust and possessed excellent physicochemical properties. The tablets showed great matrix integrity and withstood the hydrodynamic environment of the dissolution medium for > 12 hours. The hydration and swelling behaviour of the tablets was excellent. It was found that the swelling characteristics of the tablets depended on the amount of the polymer used in the tablets as well as the polymer/drug ratio. The tablets provided more than 90% drug release over a period of 12 hours. The drug release data was subjected to kinetic dissolution modelling. It was found that the drug release from the tablets followed Korsmeyer-Peppas model of drug release. This suggests that the mechanism of the drug release from the formulations may be both diffusion as well as polymer erosion. Keywords: Sustained release, Carbopol, Venlafaxine HCl

Sustained release formulations have been extensively studied for their benefits in improving various physicochemical and pharmacokinetic properties of large number of drugs. The aim of this study was to develop and evaluate sustained release capsules of losartan potassium in order to provide drug release over a long period of time. This allows the drug much time for absorption in gastrointestinal tract (GIT) and hence may increase the bioavailability of the drug. Carbopol 971 P was used as rate controlling polymer for the preparation of capsules. The capsules were evaluated for matrix integrity and drug release using USP type II dissolution apparatus. The sustained release capsules showed excellent matrix integrity and released more than 90% of the drug over a period of 12 hours. The kinetic studies showed that the drug release from the carbopol matrices followed Korsmeyer Peppas release kinetics and hence the mechanism of drug release was a combination of more than one processes i.e. diffusion and erossion. Hydration volume as well as matrix integrity were affected by the change in the amount of the polymer in the capsules. The study suggests that carbopol 971P capsules can be efficiently used to control and extend the release of losartan potassium over a long period. Thus improved absorption and bioavailability can be achieved which requires further studies in animals in future. Keywords: Sustained release, Carbopol, Hydration volume, Capsules

The purpose of this study was to prepare solid dispersions (SD) of Glibenclamide (GLB) and evaluate them for in-vitro drug release enhancement. Glibenclamide is a second generation sulfonylurea antidiabetic drug used to control blood glucose in type 2 diabetic patients, but poor-water solubility is responsible for its low oral bioavailability which has severely restricted it in the clinical application for diabetic control. Therefore, to increase the aqueous solubility and thereby,  in-vitro dissolution of glibenclamide, solid dispersions were prepared with poloxamer-188in the ratio of 1:1, 1:2; 1:4 & 1:6 by solvent evaporation method in ethanol after conducting preliminary screening for the selection of best carrier and ratio for the development of solid dispersion of glibenclamide . Among the prepared SD formulations, GLB-SD4 (1:6 Drug: Carrier ratio) showed highest enhancement in solubility and in-vitro dissolution rate in phosphate buffer (pH 6.8). In-vitro drug release profiles revealed that the drug release (%) of glibenclamide from GLB-SD4 was achieved 6-fold higher than pure drug after 180 mins. It is worth noting that GLB-SD4 provided the highest solubility and in-vitro dissolution rate compared to rest of the SD formulations, pure glibenclamide, market formulation and physical mixtures of glibenclamide in the same medium (Phosphate Buffer pH 6.8) as per the following manner: GLB-SD4 > GLB-PM4 > GLB-MF>Pure GLB. This may be due to more reduction in particle size at molecular level, enhanced wetting properties and better solubilization of P-188 and use of ethanol. The hydrogen bonding interactions between the drug and carrier in the final solid dispersion formulation (GLB-SD4) was detected by Fourier Transform Infrared (FTIR) spectroscopy. These results demonstrated that the carrier (P-188) proved effective in improving the solubility of a poorly soluble glibenclamide, thereby endorsing the application of solid dispersion technology for the

Three-Dimensional (3D) printing is a process where objects are made in successive layers under computer control by fusing or depositing materials. The objects can be of nearly any shape or geometry and come in a computer-aided (CAD) design from 3D model. Since 3D printing began in 1984, it has changed enormously and has been used in a wide range of fields, including medicine and architecture. 3D printing moves rapidly and in future will transform and change the way we live and work from laboratory-based organs to pharmaceutical supplies. 3D printing in pharmaceuticals has been used to produce many novel dosage forms like microcapsules, complex drug-release profiles, nanosuspensions, and multilayered drug delivery devices. It also offers important advantages from the industrial point of view such as cost-efficiency, higher productivity, democracy-making and enhanced cooperation. Keeping in view the recent approval given by USFDA to many drug the focus has now shifted to the personalized medicine as it offers an important benefit to patients who need medications that have narrow therapeutic index or a higher predilection to be influenced by genetic polymorphisms. 3D printer is now seen as a valuable, efficient and economical tool to manufacture individualized medications, tailored to specific patients based on their needs and thereby change the future of pharmacy practice in general and pharmaceutical care in particular.

Among the ocular dosage forms, the physiological and anatomical constraints put forth by the eye is a significant challenge to the pharmaceutical scientists and researchers to target drugs to the posterior segment of the eye, prolong their contact time with the ocular surface and sustained release. Hence novel drug delivery strategies and formulations are to be developed and explored which will overcome the ocular constraints and provide better patient compliance. At present, various novel and controlled drug delivery systems are being developed in order to attain better ocular bioavailability, sustained action of ocular drugs as well as good patient compliance. Ocular insert is an example of such delivery system. These are sterile preparations, with a thin, multilayered, drug-impregnated, solid or semisolid consistency devices placed into cul-de-sac or conjunctiva sac of the eye. Ocular inserts are an alternative approach to overcome the problems associated with conventional ocular dosage forms like solutions, suspensions, ointments, etc. The article hereunder gives a detailed idea about the classification, mechanism of action, formulation, pros and cons; evaluation and future trends of ocular inserts.

The drugs having a narrow absorption window in the gastrointestinal tract (GIT) when administered by oral route are often limited by poor bioavailability due to incomplete drug release and short residence time at the site of absorption. Novel drug delivery systems in the form of gastroretentive systems such as floating systems, mucoadhesive, high-density, expandable have been developed as they provide controlled delivery of drugs with prolonged gastric residence time. Liquid orals are more prone to low bioavailability because they are eliminated quickly from the stomach since they are subjected to faster transit from the stomach/ duodenum. The problems of immediate release and short gastrointestinal residence of liquids are eliminated by formulating as oral in situ gels as they provide the best means to overcome these problems The in situ gel dosage form is a liquid before administration and after it comes in contact with gastric contents due to one or more mechanisms gets converted to gel which floats on gastric contents. This achieves increased residence as well as sustained release. This approach is useful for systemic as well as local effect of drugs administered. This review gives a brief idea about floating oral in-situ gel formation and research done by various scientists on a number of drugs and polymers. Keywords: Floating drug delivery, gastric retention time, In-situ gel.