• Journal of Pharmaceutical Investigation
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• v.6 no.3
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• pp.58-69
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• 1976

It is well established that dissolution is freruently the rate limiting step in the gastrointestinal absorpton of a drug from a solid dosage from. The relationship between the dissolution rate and absorption is particularly distinct when considering drugs of low solubility. Consequently, numerous attempts have been made to modify the dissolution characteristics of poorly water soluble drugs. Since dissolution rate is directly proportional to surface area, one may increase the rate by decreasing the particle size of the drug. Levy has considered a number of methods by which a drug may be presented to the GI fludids in finely divided from. The direct method is the utilization of microcrystalline or micronized particles. A second method involves the administration of solutions from which, upon dilution with gastric fluids, the dissolved drug will precipitate in the form of very fine particles. A more unique way of obtaining microcrystalline dispersions of a drug has been ercently suggested by Sekiguchi et al. They have first proposed the formation of a eutectic mixture of a poorly water soruble drug with a physiologically inert, easily soluble carrier. When such systems are exposed to water or GI fluids, the soluble carrier will dissolve rapidly and the finely dispersed drug particles will then be released. It has been suggested by Shefter and Higuchi that the formation of crystalline solvate could be a powerful tool in affecting rapid disslution of highly insoluble substances. Goldberg et al. have noted that the formation of solid solution could reduce the particle size to a minimum and increase the dissolution rate as well as the solubility of the durgs. It has also been shown that the rates of solution of drugs were appreciably increased by coprectipitating the drug with soluble polymers. The increase was found to be sensitive to the method of preparation, the molecular weight of polymer and the particular ratio of drugs to polymer. Although several investigations have demontrated that the solubility and/or dissolution rates of drugs can be increased in this manner, little information is available in the literature related to the in vivo absorption pattern of drugs orally administered as PVP coprecipitates. Recently, however, it was demonstrated that both the rate and extent of absorption of the insoluble drug could be markedly enhanced when orally administered to rats in the form of a coprecipitate with PVP. The purpose of the present investigation was to ascertain the general appility of soluble polymer coprectation technique as a method for enhancing the in vitro dissolution rate of hydrophobic indomethacin. To accomplish this aim, the dissolution characteristics of pure indomethacin, indomethcin-polymer physical mixtures and indomethacin-polymer coprecipitates were quantitatively studied by comparing their relative dissolution rates. The solubility and dissolution behavior of these systems were also examined.

• Korean Journal of Materials Research
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• v.14 no.1
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• pp.35-40
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• 2004

In this study, dissolution characteristics of four types of commercial calcium phosphate ceramics were investigated in distilled water with respect to chemical composition and microstructure. For all samples, no significant damage was observed after 3 days of immersion. Following the 7 days of immersion, surface dissolution of the ceramics containing a crystalline phase susceptible to water such as TCP, even pure hydroxyapatite, was initiated at grain boundaries and the dissolution was extended interior to the material along the grain boundaries. In the considerably dissolved area, there was grain separation followed by the formation of 20 $\mu\textrm{m}$ of cavities. In at least one case, the residual pores on the surface appeared to initiate dissolution. In a dissolved area, a crack during the fracture propagates along the grain boundaries resulting in intergranular fracture, while transgranular fracture occurs in a dense area without significant dissolution.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.232.1-232.1
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• 2003

Purpose. To develop a hard gelatine capsule containing meloxicam (Yuhan Meloxam capsule$\^$TM/), in vitro dissolution characteristics and bioavailability in beagle dog were compared with commercial product (Mobic capsule$\^$TM/). Methods. Meloxicam capsule$\^$TM/ was prepared by powder filling method using meloxicam, lactose, magnesium stearate, and others. The release of Meloxicam capsule$\^$TM/ and Mobic capsule$\^$Tm/ were monitored by USP dissolution method under various dissolution donditions - dissolution medium (pH 1.2, 4.0, 6.8 and water). (omitted)

• YAKHAK HOEJI
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• v.31 no.3
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• pp.189-196
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• 1987

This study was carried out to investigate the effect of surfactant on the dissolution of relatively hydrophilic drugs, such as sulfanilamide (SF) and sulfacetamide (SFA) granules prepared by wet granulation. The additive incorporated in the granules is starch or microcrystalline cellulose(MCC) as an excipient, PVP as a binder, and polysorbate 80 (P-80) as a surfactant. The dissolution characteristics of SF and SFA granules in distilled water were as follows: The values of T$_{75%}$ were 4.60 and 2.50min, respectively for SF and SFA granules. Incorporation of 0.1% P-80 in SF granule ratarded the dissolution of SF as compared with control, but addition of 0.1% P-80 to SFA granule improved the dissolution of SFA in comparison with control. In SF and SFA granules formulated with either starch or PVP, the release of the drug was increased as compared with control. In SF granule, the dissolution of the drug was further reduced by the inclusion of P-80 in the granule containing starch or PVP. Incorporation of P-80 in SFA granule with starch or PVP affected little on the dissolution of the drug. Addition of a nonswelling excipient, MCC decreased the dissolution rate of SF and SFA granules. as compared with each control. The presence of P-80 in these granules made the dissolution rate slower in comparison with the granules containing only MCC.

• YAKHAK HOEJI
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• v.29 no.3
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• pp.124-129
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• 1985

A dissolution characteristics of phenylbutazone deposited on Avicel and dibasic calcium phosphate by solvent deposition method were studied. The solvent deposition was confirmed by scanning electron microscopy. Avicel was superior to dibasic calcium phosphate as excipient in dissolution rate. Total amount of phenylbutazone dissolved from Avicel deposition system at 30minutes were enhanced 1.2-1.6 times compared with physical mixtures of them. The dissolution rate of 10% solvent deposition system was highest and that of 75% solvent deposition system was lowest in Avicel system and dibasic calcium phosphate system. Dissolution profile of commercial products was dependent on manufacturing conditions and dissolution rate of 10% Avicel system was greater than that of commercial products.

• Journal of Mechanical Science and Technology
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• v.14 no.11
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• pp.1276-1285
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• 2000

The solubility, the surface concentration and the dissolution behavior of carbon dioxide in deep sea were numerically investigated. Base on the calculations the relations between the surface concentration of liquid carbon dioxide droplet with the hydrate film and the solubility and those between the ambient carbon dioxide concentration in the plume and the dissolution rate were obtained. The result show that a carbon dioxide droplet is released both at 1000 m in depth with the initial droplet diameter of 0.011 m or less and at 1500 m in depth with a diameter of 0.015 m or less, and the droplet is completely dissolved below 500 m in depth. The hydrate film acts as a resistant layer for the dissolution of liquid carbon dioxide, and the effect of the hydrate film on the dissolution of liquid carbon dioxide depended upon the depth.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.3
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• pp.366-378
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• 2009

The purpose of this study was to understand fashion product consumers' relationship dissolution by considering the characteristics of customer behavior and examining the connection between the main variables. The survey was conducted on 623 women over 20 years old who had experienced relationship dissolution or problems with regular fashion stores in the areas of Seoul and Kyungki in September 2005. The SPSS 12.0 package and Amos program were used to analyze the data. The results of this study were as follows: First, service recovery justice of a fashion store, interactional justice, distributive justice, and procedural justice had effects on encounter satisfaction. Furthermore, encounter satisfaction influenced relationship dissolution behavior, voice, exit, loyalty, neglect via overall satisfaction. Second, there were differences in relationship dissolution behavior according to consumer loyalty and switching costs.

• Journal of Pharmaceutical Investigation
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• v.20 no.3
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• pp.121-127
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• 1990

Mefenamic acid has been widely used clinically as an anti-inflammatory analgesic. It has poor solubility in water $(41\;{\mu}g/ml)$ and there is the difficulty of dissolution in the mefenamic acid capsules. A study was made to investigate the effect of various surfactants on the dissolution of mefenamic acid capsules. The surfactants used were sodium lauryl sulfate (SLS), Pluronic F-68, F-77, and F-127. Mefenamic acid capsule containing surfactant showed significantly improved dissolution characteristics. The dissolution rate was fast in the order of SLS > F-77 > F-68 > F-127 in mefenamic acid capsules containing 0.2 w/w % surfactant. SLS was selected for further study on the bioavailability in rabbits. The area under the plasma concentration-time curve $(AUC_{0-24})$ of mefenamic acid capsule containing SLS was higher than one of mefenamic acid capsule not containing surfactant.

• Journal of Pharmaceutical Investigation
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• v.19 no.2
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• pp.63-69
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• 1989

Dissolution characteristics of indomethacin (IMC) from hydrophobic polymer solid dispersions were investigated. IMC-polyvinyl chloride (PVC) and IMC-ethylcellulose (EC) solid dispersions were prepared. The dissolution patterns of pure IMC, IMC-PVC and IMC-EC solid dispersions prepared at various ratios (1:1, 1:3, 1:5, 1:9 and 1:19 w/w), and those of corresponding physical mixtures were compared. It was found that the dissolution rates of IMC from solid dispersions with PVC or EC decreased in the order of 1:1>1:3>1:5>1:9>1:19 as the drug to polymer ratios decreased. Also the dissolution rates of IMC from EC solid dispersions increased according to flow rate, but PVC solid dispersions were not affected significantly. After all, PVC and EC matrices could be applied in sustained-release preparation of IMC.

• Journal of Pharmaceutical Investigation
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• v.32 no.1
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• pp.27-33
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• 2002

A self-microemulsifying drug delivery system(SMEDDS) composed of Cremophor $EL^{\circledR},\;Labrasol^{circledR}$, and Lauroglycol $FCC^{circledR}$ was prepared for the enhancement of solubility, dissolution rate and bioavailability of ibuprofen(IBP), which is water-insoluble but soluble in oils and surfactants. Phase diagram with various regions including microemulsion area was depicted. The SMEDDS was encapsulated in soft gelatin capsules and their dissolution characteristics in various media were observed in comparison to the generic products commercially available in the market. Soft capsules of SMEDDS formulation showed better dissolution profiles, especially in acidic condition, than the others. For the period of 1 hr dissolution in pH 1.2 medium, it reached over 70% dissolution from soft capsules, compared to less than 40% dissolution from commercial reference tablets. On the other hand, in vivo pharmacokinetic parameters were obtained after oral administrations of different IBP preparations to Sprague Dawley rats. SMEDDS formulation showed higher $C_{max}$ and greater $AUC_{0-5hr}$ than the suspension of reference tablet or IBP powder. Therefore, it is possible to conclude that a newly developed soft capsules employing SMEDDS provides an alternative preparation to improve oral bioavailability of IBP.