Introduction:Incorporation of pH modifier has been the usual strategy employed to enhance the dissolution of weakly basic drug from floating microspheres. Microspheres prepared using a combination of both ethyl cellulose (EC) and hydroxypropyl methylcellulose (HPMC) which shows highest release were utilize to investigate the effect of fumaric acid (FA), citric acid (CA), ascorbic acid (AA) and tartaric acid (TA) (all 5-20% w/w) incorporation on metoprolol succinate (MS) release.Materials and Methods:EC, HPMC alone or in combination were used to prepare microspheres that floated in simulated gastric fluid and evaluated for a percent yield, drug entrapment, percent buoyancy and drug release. The higher drug release in combination (MS:HPMC:EC, 1:1:2) was selected for the evaluation of influence of pH modifiers on MS release. CA (5-20% w/w), AA (5-20% w/w), FA (5-20% w/w) and TA (5-20% w/w) were added and evaluated for drug release. Present investigation is directed to develop floating drug delivery system of MS by solvent evaporation technique.Results:The microspheres of MS:HPMC:EC (1:1:2) exhibited the highest entrapment (74.36 ± 2.18). The best percentage yield was obtained at MS:HPMC (1:1) (83.96 ± 1.50) and combination of MS:HPMC:EC (1:1:2) (79.23 ± 1.63).Conclusion:MS release from the prepared microspheres was influenced by changing MS-polymer, MS-polymer-polymer ratio and pH modifier. Although significant increment in MS release was observed with CA (20% w/w), TA (20% w/w) and AA (20% w/w), addition of 20% w/w FA demonstrated more pronounced and significant increase in drug entrapment as well as release from MS:HPMC:EC (1:1:2) buoyant microspheres.

Objective: Thermo-modulated in-situ hydrogel (TSHG) are formulated routinely utilizing poloxamer for extended drug release. However physical properties of such formulations may have some flaws, which can be rectified using a combination of polymers with better physical properties such as chitosan. The purpose of the present study was to fabricate biodegradable chitosan-poloxamer-based in-situ drug delivery systems and assessment of their physical properties. Methods: The present chitosan-poloxamer gel base was formulated using a two-stage method. Initially, chitosan gel was prepared by dissolving 1% w/w chitosan in glacial acetic acid. The poloxamer gel was prepared using “cold method”. The final chitosan-poloxamer gel base was prepared by mixing equal amounts of both solutions and evaluated for physical and mechanical properties. Result and Discussion: The DSC thermogram demonstrated no obvious interactions among ingredients or micellization temperature. The gelation temperature of the gel was between 27 and 330C. The pH was 7 with slight clarity. The viscosity of the gel ranged from 15.14 to 41.19 pa.s. The gel was syringable between 4-300C and biodegradable under physiological conditions. The mean particle size of the gel under SEM was found in the range of 300-554 nm. Conclusion: After the evaluation of the formulation, it can be concluded that all the ingredients in the gel showed good compatibility with each other, which could form a stable and homogeneous gel with favorable mechanical and physical properties. Keywords: chitosan, drug delivery system, hydrogels, poloxamer

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Introduction:Alginates can be tailored chemically to improve solubility, physicochemical, and biological properties and its complexation with metal ion is useful for controlling the drug release.Materials And Methods:Synthesized N,O-dimethyl, N-methyl, or N-Benzyl hydroxylamine derivatives of sodium alginate were subsequently complexed with zinc to form beads. Hydroxamation of sodium alginate was confirmed by Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC).Results:The synthesized polymeric material exhibited reduced aqueous, HCl and NaOH solubility. The hydroxamated derivatives demonstrated pulsed release where change in pH of the dissolution medium stimulated the atenolol release.Conclusion:Atenolol loaded Zn cross-linked polymeric beads demonstrated the sustained the plasma drug levels with increased half-life. Although the synthesized derivatives greatly altered the aqueous solubility of sodium alginate, no significant differences in in vitro and in vivo atenolol release behavior amongst the N,O-dimethyl, N-methyl, or N-Benzyl hydroxylamine derivatives of sodium alginate were observed.

Objective: The objective of the present work was to improve aqueous solubility and in vivo bioavailability of curcumin and structural analogues of curcumin such as potassium, calcium, magnesium salts and nitro derivative. Methods: Structural analogues of curcumin were prepared by reaction of curcumin with potassium chloride, magnesium chloride hexahydrate and calcium chloride dihydrate in a suitable solvent. The nitro derivative synthesized by treating curcumin with sulphuric acid and nitric acid. The prepared analogues were evaluated for melting behavior, solubility, UV spectrophotometry, partition coefficient, moisture content, cellular uptake, FTIR analysis, antimicrobial activity and in vivo bioavailability in the rat. Results: Chemical modification of curcumin increased the saturation solubility to 11.6, 16.5, 21.5, 28.0 µg/ml in calcium salt, magnesium salt, potassium salt and nitro derivative respectively, against 8.6 µg/ml of curcumin. The analogues were chemically stable as curcumin analyzed by FTIR spectrophotometry. Increased cellular uptake, as well as enhanced antimicrobial activity, was demonstrated by modified curcumin analogues. Moreover, significant improvement in plasma levels was estimated with nitro derivative. Conclusion: The present work recommends that nitration of curcumin improves aqueous solubility which may improve absorption and in vivo bioavailability.