polymers

Mucoadhesive drug delivery systems interact with the mucus layer covering the mucosal epithelial surface, and mucin molecules increase the residence time of the dosage form at the site of absorption. Bioadhesion may be defined as the state in which two materials, at least one of which is of a biological nature, are held together for extend periods of time by interfacial forces Mucosal layer represents potential sites for the attachment of any bioadhesive systems because mucosal layer lines number of the body including the gastro intestinal tract, the urogenital tract, vaginal tract, the eye, ear, and nose. The mucoadhesive Bilayer tablets consisting of two various types of drug molecules and they show on set of actions at their particular sites. This review describes the structure of mucosal layer, mechanism of action of mucoadhesion, and preparation techniques of Bilayer tablets and evaluation parameters of tablets.

There are various techniques to control the release rate of the drugs, among which controlling dissolution rate is most popular due to its success and low cost. The use of sustained release dosage forms is increasing in treatment of acute and chronic diseases as they maintain the concentration of drug in plasma above minimum effective concentration and below the minimum toxic level for extended period of time. Thus, sustained drug delivery results in optimum drug therapy with reduced frequency of dosing and side effects. The objectives of the present investigation were to prepare granules of aceclofenac with different polymers and polymer blends by solid dispersion technique and investigate the different tablet evaluation parameters. Solid dispersions were prepared by solvent evaporation technique by using different polymers (Hydroxypropyl methyl cellulose - K4M, Ethyl cellulose, and Eudragit RS-100).Solid state and drug polymer interactions were studied by Fourier transform infra red spectroscopy, Differential scanning calorimetry, X-ray powder diffraction. The pharmaceutical performance was studied by in-vitro dissolution experiments.  Studies for the kinetics of the drug release from tablets showed a good fit to zero order kinetics indicating better controlled release of the drug. Significant effect was observed with polymer, concentration of polymer mixture on similarity factor. In stability study there was no significant change in the tablet properties after exposure to 40 ± 2 0C and 75 ± 5% RH for a period of 3 months.

Over the past few decades, there has been an increased  interest for innovative drug delivery systems to improve safety, efficacy and patient compliance, thereby increasing the product patent life cycle. There are novel types of dosage forms that act very quickly after administration. The basic approach used in development tablets is the use of superdisintegrants like Cross linked carboxymelhyl cellulose (Croscarmeliose), Sodium starch glycolate (Primogel, Explotab), Polyvinylpyrrolidone (Polyplasdone) etc. which provide instantaneous disintegration of tablet after administration. Immediate release liquid dosage forms and parenteral dosage form have also been introduced for treating patients. Liquid dosage form can be suspensions with typical dispersion agents like hydroxypropyl methylcellulose, AOT (dioctylsulfosuccinate) etc. The development of immediate release therapy also provides an opportunity for a line extension in the marketplace, A wide range of drugs (e.g., neuroleptics, cardiovascular drugs, analgesics, antihistamines, and drugs can be considered candidates for this dosage form. In this regard, immediate release formulations are similar to many sustained release formulations that are now commonly available. oral film dosage form not only has certain advantages of other fast disintegrating systems but also satisfies the unmet needs of the market. The present review emphasizes on the potential benefits, design and development of robust, stable, and  innovative orally immediate and their future  scenarios on a global market as a pharmaceutical dosage form.

A drug should be present in dissolved or solublized state before producing its therapeutic effect however in current market more than 40% drugs are poorly soluble in water. Such drugs exhibit poor dissolution rate and slow absorption throughout the gastrointestinal tract which leads to irregular bioavailability. Thus various techniques has been adopted for solubility and dissolution enhancement of poor water soluble drugs thereby bioavailability. Solubility plays an important role in achieving the desired plasma drug concentration. In this review article various techniques like solid dispersion, SLNs, SEDDS, dried emulsion were discussed for solubility and dissolution rate improvement of BCS class II anti hyperlipidemic drug Simvastatin. Amongst various method described in this review, solid dispersion was found to be most used technique by researcher as it provide ease in preparation and efficiency in terms of resolving the solubility and dissolution problems associated with Simvastatin.

As an isolated organ, eye is very difficult to study from a drug delivery point of view. Ophthalmic drug delivery is extremely interesting and highly challenging endeavours. In recent scenario, most eye-diseases are treated with topical application of eye-drops. But these conventional eye-drops have two major problems. 1) It needs frequent administration at every 4 hours or 1 hour if the infection is severe and 2) Formation of crystalline deposits on cornea due to its pH-dependent solubility which is very low. In order to provide the solution to above problems many new formulations have been developed, which include nanosuspension, nanoemulsion, inserts, hydrogels, in-situ gel, etc. The poor bioavailability of ophthalmic solution caused by dilution and drainage from the eye can be overcome by using in-situ forming ophthalmic drug delivery system prepared from polymers that exhibit reversible liquid-gel phase transition. The developed formulation provides better drug product effectiveness, reliability, stability, safety, non-irritancy and prolonged release. Thus, it’s a viable alternative to conventional eye-drops by virtue of its ability to enhance bioavailability through its longer pre-corneal residence time & ability to provide prolonged drug release upto 8 hours. The main important factor is the reduced frequency & the ease of installation resulting in better patient acceptance. Keywords: Ophthalmic delivery, in-situ gel, polymers, liquid-gel phase transition, pre-corneal residence time, prolonged drug release.