methylcellulose and tartaric-acid

Gelation temperature of MC was reduced from 59°C to 54°C with the addition of 10% PEG. Sodium tartrate (NaT) and sodium citrate (NaC) were added to the MC-PEG solution to further reduce the gelation temperature close to physiological temperature. Different techniques were used to measure the gelation temperature of all formulations. It was observed that NaC was more effective in reducing the gelation temperature of MC-PEG combination than NaT. Environmental scanning electron microscopy (ESEM) images of hydrogels containing NaC and NaT showed that NaC containing hydrogel having an interconnected microporous structure instead of the hollow rod like structure as in the case of NaT containing hydrogel. In vitro drug release studies showed that drug release time increased from 6 to 9h by only changing the type of salt from NaT to NaC in MC-PEG combination.

Topics: Citrates; Drug Carriers; Gels; Hydrogels; Kinetics; Methylcellulose; Ophthalmic Solutions; Polyethylene Glycols; Sodium Citrate; Tartrates; Temperature; Viscosity

Gelation temperature of methylcellulose (MC) can be altered by adding different additives. Pure MC showed sol-gel transition at 60°C. Sodium citrate and sodium tartrate were used alone and in combination to see the effect of individual salt and combination of salts on the gelation temperature of MC. The gelation temperature of all the binary and ternary combinations of MC and salts were measured with different methods such as test tube tilting method (TTM), UV-vis spectroscopy, viscometry, and by rheometer and also the morphology of gels were characterized with the help of environmental scanning electron microscopy (ESEM). It was observed that when 0.1 M sodium citrate (NaC) and 0.1 M sodium tartrate (NaT) were used separately, the gelation temperature of MC was reduced up to 44°C and 47°C respectively but when mixture of NaC and NaT (0.1 (M) NaC and 0.1 (M) (NaT)) were used the gelation temperature was further reduced to 36°C. It was clear from ESEM images that when NaC and NaT were used separately the formation of network was not distinguishable. But, well-connected network structure was observed when a mixture 0.1 M NaC and 0.1 M NaT was used.

Topics: Citrates; Hydrogels; Methylcellulose; Rheology; Sodium Citrate; Tartrates; Transition Temperature; Viscosity

Irbesartan (IBS) is a hydrophobic drug with poor aqueous solubility and dissolution rate. Solid dispersions (SDs) of IBS were prepared with both small molecules (tartaric acid and mannitol) and polymeric additives (polyvinyl-pyrrolidone, PVP, and hydroxypropyl methylcellulose, HPMC). A 9.5 and 7 folds enhancement in solubility over the crystalline form (14.6 microg mL-1) was observed for tartaric acid (138 microg mL-1) and PVP (103 microg mL-1), respectively. Powder X-ray diffraction confirmed that IBS existed in the glassy state in all cases, even with excipients having low glass transition temperature. Thermal methods (differential scanning calorimetry and hot stage microscopy) were used to evaluate the miscibility of the drug and additives. These techniques suggested that tartaric acid led to generation of >>amorphous solutions<< in contrast to >>amorphous suspensions<< in other three cases. The in vitro dissolution of IBS depended on the additive load and increased with increasing concentration in the case of tartaric acid, an acidifying excipient. The results indicate the suitability of even small molecules for providing solubility benefits, which can be attributed to the good glass forming ability and reasonable ability of IBS to remain in the glassy state.

Topics: Angiotensin II Type 1 Receptor Blockers; Biphenyl Compounds; Calorimetry, Differential Scanning; Chemistry, Pharmaceutical; Crystallography, X-Ray; Excipients; Hypromellose Derivatives; Irbesartan; Kinetics; Mannitol; Methylcellulose; Microscopy; Models, Chemical; Povidone; Powder Diffraction; Solubility; Tartrates; Technology, Pharmaceutical; Tetrazoles; Transition Temperature

Floating pellets were prepared using the melt pelletization process in a Mi-Pro high shear mixer (Pro-C-epT, Belgium). Formulations were based on a mixture of Compritol and Precirol as meltable binders and on the use of sodium bicarbonate and tartaric acid as gas-generating agents. Good floating abilities were obtained by using the gas-generating agents in both the inner matrix and the outer coating layer of the pellets. In vitro evaluation of floating capability was performed both by using the resultant weight apparatus and by counting floating pellets at the surface of beakers containing 0.1N HCl solution, in vivo evaluation of floating pellets capabilities was also performed. Riboflavin-containing floating pellets (FRF) were administered orally to nine healthy volunteers versus non-floating pellets (NFRF). Volunteers were divided in two groups, fasted group (n=4) 729 kcal and fed group (n=5) 1634 kcal as the total calorie intake on the testing day. An increase of urinary excretion of riboflavin was observed when the volunteers were dosed with the floating pellets, especially after feeding. As riboflavin has a narrow window of absorption in the upper part of small intestine, this phenomenon could be attributable to the gastric retention of floating pellets.

Topics: Adult; Algorithms; Biological Availability; Delayed-Action Preparations; Diglycerides; Drug Compounding; Drug Delivery Systems; Fasting; Fatty Acids; Humans; Hydrogen-Ion Concentration; Male; Methylcellulose; Middle Aged; Riboflavin; Sodium Bicarbonate; Tartrates

Pyrolysis mass spectrometry (PyMS) was investigated as a rapid tool to distinguish potential bioterror hoax materials from samples containing pathogenic bacteria. A pyrolysis time-of-flight (TOF) mass spectrometer equipped with an alternative ionization technique, metastable atom bombardment (MAB), was used to produce sample spectra. These spectra were analyzed by principal component and discriminant analysis for pattern recognition. Materials investigated were two strains of Vibrio parahaemolyticus, one of which produced the tdh toxin, two Salmonella enterica serotypes, a biological mosquito control product containing spores of Bacillus thuringiensis, and several white to off-white powders (which could be used as hoax materials), such as flour, corn starch, methyl cellulose, and xanthan gum. PyMS distinguished bacterial samples from hoax materials. Furthermore, pattern analysis differentiated Vibrios from Salmonellae, Salmonella enterica Anatum from S. enterica Heidelberg, and the two V. parahaemolyticus strains from each other. The B. thuringiensis mixture was distinguished from other bacteria and powders, suggesting that PyMS with pattern recognition may differentiate samples containing pathogens, including Bacillus spp., from nonbiological agents and that it can be a rapid method for detection of bacteria. MS data acquisition took only 7 min for each sample.

Topics: Bacillus thuringiensis; Bacterial Typing Techniques; Bioterrorism; Flour; Fraud; Hot Temperature; Methylcellulose; Polysaccharides, Bacterial; Salmonella enterica; Sodium Bicarbonate; Spectrometry, Mass, Fast Atom Bombardment; Spores, Bacterial; Starch; Tartrates; Vibrio parahaemolyticus

The objective of this study was to investigate the effect of multicomponent complexation (MCC) of vinpocetine (VP), a poorly soluble base-type drug, with beta-cyclodextrin (betaCD), sulfobutylether beta-cyclodextrin (SBEbetaCD), tartaric acid (TA), polyvinylpyrrolidone (PVP) and hydroxypropylmethylcellulose (HPMC), on the design of controlled release hydrophilic HPMC tablets and to evaluate their in vitro release profiles by a pH gradient method. Multicomponent complexation led to enhanced dissolution properties of VP both in simulated gastric and intestinal fluids, and became possible the development of HPMC tablet formulations with more independent pH dissolution profiles. Drug release process was investigated experimentally using USP apparatus 3 and by means of model-independent parameters. Responses studied included similarity of dissolution profiles, time for 60% of the drug to dissolve (T(60%)), percent of VP released after 7 h (PD(7 h)) and the dissolution efficiency parameter at 12 h (DE(12 h)). Influence of multicomponent complexation was proved to increase the release of VP from HPMC tablets and superior PD(7 h) and DE(12 h) values were obtained in formulations containing VP-CD-TA complexes. Results supported the use of HPMC matrices to provide a useful tool in retarding the release of VP and that dissolution characteristics of the drug may be modulated by multicomponent complexation in these delivery systems, suggesting an improvement on VP bioavailability.

Topics: beta-Cyclodextrins; Body Fluids; Drug Compounding; Gastric Mucosa; Humans; Hydrogen-Ion Concentration; Hypromellose Derivatives; Intestinal Mucosa; Kinetics; Methylcellulose; Models, Biological; Solubility; Tablets, Enteric-Coated; Tartrates; Vinca Alkaloids