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Biomedical subjects

B B Sheth

Publications and source records attributed to B B Sheth.

15 recordsLinked to original sources
PubMed1999

Influence of an optimized non-ionic emulsifier blend on properties of oil-in-water emulsions.

Properties of oil-in-water emulsions containing non-ionic emulsifiers were evaluated in relation to nature of the dispersed phase, emulsifier composition and processing parameters. Particle size of mineral oil (hydrocarbons)-in-water emulsions was independent of the HLB of an optimized emulsifier blend, whereas, the particle size of olive oil (triglycerides)-in-water emulsions was the smallest at the optimum HLB of the emulsifier blend. The non-ionic emulsifiers reduced the particle size of mineral oil emulsions more efficiently than that of olive oil emulsions. Contrary to previously published reports, the nature of the dispersed phase, HLB of the emulsifier blend or the initial particle size of emulsions showed no influence on the final particle stability of the emulsions. This difference was attributed to the optimization of the emulsifier blend and processing parameters in the preparation of emulsions.

Emulsions↗
PubMed1980

Reduced dialysis of nitrofurantoin and hydrocortisone acetate from methylcellulose solutions.

Factors affecting reduction in the permeation rate of nitrofurantoin and hydrocortisone acetate from methylcellulose solutions through a cellulose membrane were investigated. The factors evaluated were the effect of polymer agglomeration and whether the drugs formed a complex with the polymer. The influence of polymer agglomeration was evaluated by dynamic dialysis studies of nitrofurantoin dissolved in solutions of methylcellulose 400 cps, which agglomerates, and in methylcellulose 50 cps, which does not exhibit this behavior. Dialysis rates of this drug were measured as a function of polymer concentration, ionic strength, heating time prior to measurement, and temperature. The effect of polymer agglomeration on the permeation rates of hydrocortisone acetate was studied by varying the ionic strength of the drug-polymer solution. Complex formation studies were conducted for both drugs by the equilibrium dialysis method. Polymer agglomeration caused a substantial reduction in the dialysis rate of both drugs in methylcellulose 400 cps solutions. There was less reduction in the dialysis rate of nitrofurantoin with increased polymer concentration of methylcellulose 50 cps solutions, which was attributed to the increase in the bulk viscosity of the solution. There was no evidence of complex formation of the drugs with the polymers.

Chemical Phenomena↗
PubMed1979

Evaluation of adsorption from dispersion charge profile.

The evaluation of adsorption behavior from the charge profile of an adsorbent dispersion determined as a function of the adsorbate concentration was investigated by the streaming current measurement, using methylene blue and erythrosine as adsorbates and activated charcoal, microcrystalline cellulose, and polyvinylpolypyrrolidone as adsorbents. Adsorption capacity was evaluated using streaming current versus solute concentration plots of dye solutions and of corresponding dye solutions equilibrated with the adsorbent. It was also determined by adsorption isotherm measurement and application of the Langmuir equation. Good agreement was obtained between the adsorption capacity values from streaming current data and adsorption isotherm measurements for microcrystalline cellulose, suggesting that adsorption here was a surface phenomenon without water-soluble extractives affecting particle charge. Similar agreement was not obtained for charcoal adsorption, and this result was attributed to the unusual adsorption behavior of charcoal. Since polyvinylpolypyrrolidone gave a dispersion with high particle charge, the streaming current method could not be used with this system. The charge profile could be useful in characterizing powders for unusual adsorption behavior and possible water-soluble extractives as well as for surface area estimation in the absence of these factors.

Adsorption↗
PubMed1976

Effect of polymers on dissolution from drug suspensions.

The effect of three viscosity grades of methylcellulose on the dissolution-dialysis rate of nitrofurantoin suspensions was investigated using a cell designed to provide a large surface area for dialysis. Apparent dialytic rate constants of drug dispersions and solutions were measured in 0.1 N HC1 and in pH 7.4 buffer. Samples containing methylcellulose had lower rates of dialysis, with the lowest rate being observed for samples in which the polymer was used as the suspending agent. The reduced rate of dialysis of the drug suspension containing methylcellulose is thought to be due to complexation of the drug in solution with the polymer as well as formation of microscopic regions of high viscosity surrounding the undissolved drug particles leading to a reduction in the dissolution rate of the drug. An empirical relationship was obtained to enable the estimation of the effective drug concentration in the dissolution chamber for drug dispersions. The method is based on utilizing dialysis rate data of drug solutions. This relationship could be used for comparing suspension formulations in terms of the amount of drug available for dialysis.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Improving emulsification efficacy of lecithin by formulation design. I: Effect of adding a secondary surfactant.

The objective of this study was to seek improvement in the emulsification efficacy of lecithin by formulation design. A Base Emulsion was developed containing lecithin as the primary emulsifier. The lecithin concentration and method of preparation of the Base Emulsion were optimized to obtain minimum particle size and creaming of the emulsion. Selected hydrophilic and hydrophobic synthetic surfactants were evaluated as secondary emulsifiers for their ability to reduce particle size of the Base Emulsion. The selection of type and concentration of the secondary emulsifier was done by application of the HLB method. The hydrophilic emulsifiers selected were Tween 80, Tween 20, Pluronic F68, and Pluronic F127. The hydrophobic surfactants studied included Span 20, Span 80, Pluronic P103, and Pluronic P123. The median droplet size of the Base Emulsion was 2.7 microns. Addition of the hydrophilic emulsifiers caused an increase in particle size and substantial creaming of the emulsions. Addition of three of four hydrophobic surfactants resulted in particle size reduction, but the emulsions showed substantial creaming. Span 20 was found to be the most effective secondary emulsifier. The median particle size of the emulsion was 1.7 microns. These results suggest that supplementing the hydrophilic attributes of lecithin with an appropriate type and amount of hydrophobic surfactant improves the emulsion properties by applying principles of formulation design.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

A novel self emulsifying parenteral drug delivery system.

The application of three polyhydroxy alcohols for improving parenteral emulsion formulations was investigated. A mixture of lecithin, as the primary emulsifier, and Span 20 as the secondary emulsifier, was used as the emulsifier system. The polyhydroxy alcohols selected were glycerol, propylene glycol and sorbitol. Soybean oil-in-water emulsions were prepared with the addition of increasing concentrations of each polyhydroxy alcohol. It was found that anhydrous mixtures of oil, surfactants and 30% or higher concentration of glycerol formed self emulsifying isotropic liquids, suitable for preparing Parenteral Self Emulsifying Drug Delivery Systems (PSEDDS). Spontaneous emulsification to submicron particle size of 0.4 micron occurred when these isotropic liquids were gently mixed with water. A PSEDDS formulation, containing 0.5% lidocaine, as the model drug showed similar spontaneous emulsification with particle size of 0.39 micron. Formulations containing propylene glycol, or sorbitol or lower concentrations of glycerol did not form self emulsifying mixtures. There were substantial differences in the particle size reduction pattern with each polyhydroxy alcohol. Glycerol was most effective, with minimum particle size obtained at 30% concentration. Addition of propylene glycol resulted in minimum particle size at 60% concentration. But there was increase in particle size at higher concentrations. Sorbitol was not very effective in reducing particle size. Alteration of the surfactant phase distribution at the interface was found to be the primary effect of polyhydroxy alcohols.

Drug Delivery Systems↗
PubMedDate not supplied

Effect of lyophilization on parenteral emulsions.

The feasibility of preparing lyophilized anhydrous products, for reconstitution in to emulsion dosage forms was investigated. Stable soybean o/w emulsions were prepared using a mixture of lecithin and Span 20 as the emulsifiers. Two series of emulsions were prepared for this study, each containing a polyhydroxy alcohol as a consurfactant for particle size reduction. Increasing concentrations of glycerol (10-30% w/w) were added to one group of emulsions and propylene glycol (20-60% w/w) was added to the second group of emulsions. All formulations were found to have good particle size stability. The emulsion formulation containing 30% glycerol could be successfully lyophilized into an anhydrous product. Reconstitution of this lyophilized product resulted in an emulsion essentially similar to the original emulsion prior to lyophilization. This is because the mixture of the oil phase and 30% w/w glycerol formed a self-emulsifying system. All other emulsion formulations were not suitable for lyophilization. These formulations cracked during lyophilization, separating into an upper oil layer and a lower layer of the continuous phase. The formation of an upper oil layer prevented complete drying of these emulsions. The particle size of these lyophilized emulsions, when reconstituted with the external phase was greater than the emulsion particle size prior to lyophilization. But the change in particle size was less with increasing concentrations of polyhydroxy alcohols. These results indicate that emulsions can be lyophilized to prepare a product suitable for reconstitution to a parenteral emulsion dosage form provided the formulation is designed to withstand temperature and phase changes during the lyophilization process.

Emulsions↗
PubMedDate not supplied

Particle size reduction of emulsions by formulation design-II: effect of oil and surfactant concentration.

The objective of this study was to investigate the effect of the concentration of surfactant and oil on particle size reduction and stability of oil-in-water emulsion formulations containing polyhydroxy alcohols. Emulsions were prepared using an emulsifier system consisting of Tween 80 and Span 80 with 5%, 10%, 15% and 20% soybean oil and containing 50% w/w of either propylene glycol (PG) or glycerol (GLY) in the external phase. At each oil concentration, four emulsions were formulated with increasing surfactant concentration to provide emulsions with surfactant to oil (S/O) ratios of 0.1, 0.2, 0.3 and 0.4. Three parameters were evaluated, particle size reduction, particle size stability upon dilution, and viscosity. It was found that increase in S/O ratio resulted in substantial decrease in particle size in all cases. But there was a difference in the particle size reduction pattern between PG and GLY. Increase in oil concentration at the same S/O ratio caused particle size reduction for emulsions with PG but not for emulsions with GLY. The reduction in particle size was also greater for emulsions containing PG. Further, particle size of emulsions containing PG was found to be stable over 24 hours after dilution. However, a slight increase in particle size was observed in emulsions containing GLY. It was also found that the viscosity of emulsions increased with an increase S/O ratio as well as the concentration of the oil.

Drug Compounding↗
PubMedDate not supplied

Particle size reduction of emulsions by formulation design. I: Effect of polyhydroxy alcohols.

The objective of this study was to characterize the effect on particle size and stability of oil-in-water emulsion formulations caused by the addition of polyhydroxy alcohols. Stable soybean oil and hexadecane emulsions were prepared containing increasing amounts of propylene glycol (PG) and glycerol (GLY). A nonionic emulsifier system consisting of Tween 80 and Span 80 was used to achieve optimal stability. Particle size was found to decrease as the level of PG or GLY increased. A three-fold particle size reduction was obtained at a PG level of 40% w/w and at a GLY level of 70% w/w. The particle size of soybean oil emulsions decreased from about 4.8 microns to about 1.7 microns. The particle size of hexadecane emulsions decreased from about 2.7 microns to less than 1 micron. The increase in emulsion viscosity was found to be proportional to the amount of polyhydroxy alcohols added to the formulation. The particle size and creaming stability of the emulsions were found to improve with increasing PG or GLY concentration.

Alkanes↗
PubMedDate not supplied

Evaluation of closure integrity after multiple penetrations.

The purpose of this investigation was to simulate in-use testing of closures to determine how many doses could be reasonably withdrawn from a multiple dose vial of a product without compromising the integrity of the closure. Four types of studies were done: 1) a simulated in-use test, 2) a coring test development study, 3) effect of sterilization on coring, and 4) exploratory studies of closure leakage after multiple penetrations. A modified drill press was used for the studies. West 1888 and West 1535 closures were evaluated by the simulated in-use test using a 26G Needle. The results indicated that few particles were generated after 20 penetrations of both closures. There was a marked increase in particles after 30 penetrations. When sterilized closures were tested, it was found that West 1888 generated no particles after 10 insertions with 21G and 18G needles, but there was an increase in the number of particles after 20 insertions. With West 1535, particles were generated after only 10 insertions. Interestingly, autoclaved closures released fewer particles than closures that were not autoclaved. Leakage was observed only from West 850 closures and only under relatively high pressure differential conditions.

Drug Packaging↗
PubMedDate not supplied

Stability of deslorelin injection.

The stability of deslorelin, a nonapeptide drug, in an injectable drug formulation was studied for 60 months. An HPLC analytical method was developed to quantify deslorelin and benzyl alcohol in deslorelin injection. The samples containing 500 micrograms/mL of deslorelin were stored at--10, 6, 25, 40 and 50 degrees C. No deslorelin degradation was observed in samples stored at 6 degrees C, but the loss of deslorelin in samples stored at 25, 40 and 50 degrees C was found to increase with temperature. The T90 of the product at 6 degrees C was estimated to be greater than 20 years from the short-term stability data of four lots stored at 25, 40 and 50 degrees C. The long-term stability results confirmed that there was no degradation of deslorelin stored at 6 degrees C for 5 years. Liquid secondary ionization mass spectrometry analysis of aged samples showed hydrolysis of deslorelin and the production of a hexapeptide (< Ser-Tyr-D-Trp-Leu-Arg-Pro-NH-Et) with a molecular weight of 847. A second product resulted from the oxidation of the tryptophan indoylyl ring. The oxyindoyle decapeptide structure had an ion m/z of 1298. The mass spectrum of pure deslorelin also is reported.

Alcohol Dehydrogenase↗