bioavailability.

The natural product curcumin is a polyphenolic compound extracted from the rhizome of Curcuma longa L. Curcumin is the principle curcuminoid present in turmeric, responsible for its bright yellow color. Curcumin is a nature’s gift to mankind which has broad range of therapeutic, diagnostic and prophylactic potential. In addition to its use as a spice, flavoring and coloring agent in food, turmeric has been used in India for medicinal values for centuries. In Ayurveda, use of curcumin is well documented for the treatment of various ailments. But the applications of curcumin are curtailed by its low solubility, stability, bioavailability, rapid metabolism and short half life. This weapon can be sharpened and re explored as new age one key answer to many ailments and disorders by using it in the form of liposomal, nanoparticulate, microparticulate drug delivery and also by complexing it with metal ions, polymers, cyclodextrine and other carriers. Curcumin has ability to bind with various transition and earth metal ions to form stable complex. Complexation of curcumin with transition metals is one of the useful ways to overcome the problem related to solubility, stability and bioavailability. From several recent studies, it was observed that curcumin metallocomplexes shows greater therapeutic effects than curcumin alone.

In the present study, an attempt has been made to prepare floating microspheres of clarithromycin designed as gastroretentive dosage form for the treatment of Heliobacter pylori. The floating microspheres were  prepared using different polymers like HPMC- ethyl cellulose, HPMC, eudragit S-100, eudragit L-100, by solvent evaporation/diffusion methods which offer advantage of short processing time, lack of exposure of the ingredients to high temperature and gives high encapsulation efficiency. Formulations were characterized for their particle size, practical yield, entrapment efficiency, in vitro buoyancy, scanning electron microscopy (SEM) and in vitro drug release. Scanning electron microscopy shows that spherical microspheres with porous surface were formed. The optical microscopic studies revealed that the practical yield was more than 61.78% with a particle size range of 105.61-292.40 µm.  The percent entrapment efficiency is about 62.68% and more in larger particle as compared to smaller particle. The percent buoyancy was more than 74.10% up to 12 hours. The particle size, percent yield, percent drug entrapment and percent was increased significantly with increase in polymer concentration. The in vitro release was significantly decreased with in polymer concentration.  Hence it can be inferred that the floating microsphere of clarithromycin as a gastroretentive dosage form may prolong drug release thereby improving bioavailability and enhance opportunity of drug absorption in stomach to prevent degradation of drug under alkaline pH.

In the last decade, poorly soluble drugs have been an area of concern for all the researchers in the field of pharmacy. A number of researches have been carried out to enhance the solubility and dissolution properties of such drugs. This study deals with a comprehensive review of liquisolid technique carried out mainly for biopharmaceutical classification system (BCS) class II & IV drugs. These drugs are having problems of poor solubility, dissolution and thus poor bioavailability. Various studies conducted on a number of drugs so far, have been reviewed. A variety of techniques such as micronization, salt formation, complexation, solid solutions, and liquisolid technique etc. have been used to overcome such problems. It has been observed that liquisolid technique is the most promising way for solubility and dissolution enhancement of such drugs. It can be concluded that liquisolid technique results in increased solubility, dissolution and thus bioavailability.

Phytosomes are recently introduced herbal formulations that are better absorbed, and as a result produce better bioavailability and actions than the conventional phytomolecules or botanical extracts. This is an advanced form of herbal formulations which contains the bioactive phytoconstituents of herbal extract bounded in a lipophilic carrier. Phytosome technology has been effectively used to enhance the bioavailability of many popular herbal extracts and phytoconstituents including Ginkgo biloba, milk thistle, grape seed, green tea, hawthorn, ginseng etc and can be developed for various therapeutic uses or dietary supplements.