Hydrophilic Base Research Articles

Improvement of the in vitro release of omeprazole from suppository bases using Kollicoat IR

Solid dispersion of a slightly water soluble drug, omeprazole (OME), was prepared using different concentrations of Kollicoat IR by a spray drying technique. The physicochemical properties of the drug alone and its microparticles were investigated using differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD). The analyses showed that omeprazole transformed from the crystalline state to the amorphous state as confirmed by the disappearance of its melting peak and the characteristic of the crystalline peaks. Solid dispersion of the drug with this hydrophilic polymer was used in suppository formulations to investigate their role in enhancement drug release. The bases used in this study include hydrophilic base, polyethylene glycol (PEG), and lipophilic bases such as Suppocire AM and Witepsol H15. The release of omeprazole from a hydrophilic base was higher than that of a lipohilic base. Also, the release of drug from Supocire AM was superior to Witepsol H15. Incorporation of solid dispersion of drug using Kollicoat IR prepared by spray drying technique increases the release of OME from its suppository bases. The Kinetic study of the release of drug and its solid dispersion was carried out and the results indicated that the release of drug from different suppository bases is diffusion model.

Investigation of DOM and THMFP in two reservoir waters of Changchun (China)

The two reservoir water samples from Xinlicheng (SW1) and Shitoukoumen (SW2) were collected to investigate the characterization of dissolved organic matter (DOM) and trihalomethanes formation potential (THMFP). The six organic fractions were, hydrophilic acid fraction (HPIA), hydrophilic base fraction (HPIB), hydrophilic neutral fraction (HPIN), hydrophobic acid fraction (HPOA), hydrophobic base fraction (HPOB), and hydrophobic neutral fraction (HPON), separated with the XAD-16, AG-MP-50, and WA-10 resins. The DOM chemical composition sequences and specific THMFP of the six organic fractions in two raw waters are different. The experimental results show that HPOB in SW1 and HPOA in SW2 are the main precursor of THMFP among the six organic fractions. However, HPIB exhibits the highest chlorination activity in forming THMs. It is also found that the value of FI/DOC and the THMFP have better positive correlation. Compared with former results, a part of these findings are different from some reports. It is implied that certain sourcewater has a unique nature of DOM and DBPs. © 2009 American Institute of Chemical Engineers Environ Prog, 2010

Improving rheological characteristics of hydrophilic ointment base by treatment with a high-pressure wet-type jet mill

Background: A high-pressure wet-type jet mill is a powerful equipment used for the dispersion and emulsification of substances. In this study, we investigated its usefulness in the preparation of skin cream formulations. Method: We prepared a hydrophilic ointment base as a typical skin cream base, and then treated it with the wet-type jet mill under different conditions. Controllable factors of the wet-type jet mill included processing pressure, treatment cycle, and temperature of the treatment. Result: Treatment with the wet-type jet mill had a great impact on the rheological characteristics of the hydrophilic ointment base. The hysteresis areas and yield values of the treated ointments were significantly increased by increasing the processing pressure and temperature during the treatment. From scanning electron microscopic observations, the oil droplet size of the hydrophilic ointments decreased after treatment with the wet-type jet mill, suggesting that a decrease in oil droplet size mediates changes in the rheological characteristics. Conclusion: Because we can expect the wet-type jet mill to control the rheological characteristics of the ointment, it is a promising tool for the preparation of skin cream formulations.

Phosphatidyl choline-based colloidal systems for dermal and transdermal drug delivery

In this study we have prepared various phosphatidyl choline based colloidal systems, namely liposomes, transfersomes, microemulsions and micelles, using similar excipients and compared their ability to deliver drugs into and through the skin under occlusive and non-occlusive conditions. Hydrophilic propranolol hydrochloride (PHCl) and lipophilic propranolol base (PB) were used as model drugs. All tested parameters, that is formulation composition, drug characteristics and testing conditions, influenced skin permeability and skin retention. A trend was observed showing that the skin permeation as well as skin retention decreases with the amount of phosphatidyl choline in the formulations for both tested model drugs (micelles > transfersomes > liposomes > microemulsion). The lipophilic model drug had higher skin permeability especially when incorporated into the systems containing mainly hydrophilic excipients. Skin retention, however, was not affected by the drug hydrophilicity to the same extent as skin permeability. Occlusion increased both skin retention and skin permeation for both model drugs.

Sorption of the pharmaceuticals carbamazepine and naproxen to dissolved organic matter: Role of structural fractions

Pharmaceutical compounds and dissolved organic matter (DOM) are co-introduced into the environment by irrigation with reclaimed wastewater and/or application of biosolids. In this study, we evaluate the role and mechanism of interaction of the pharmaceuticals naproxen and carbamazepine with structural fractions of biosolids-derived DOM. Sorption interactions were estimated from dialysis-bag experiments at different pHs. Sorption of naproxen and carbamazepine by the hydrophobic acid fraction exhibited strong pH-dependence. With both pharmaceuticals, the highest sorption coefficients ( K DOC) were at pH 4. With the hydrophobic neutral fraction, pH affected only naproxen sorption (decreasing with increasing pH). Among the hydrophilic DOM fractions, the hydrophilic acid fraction exhibited the highest K DOC value for carbamazepine, probably due to their bipolar character. In the hydrophilic acid fraction-naproxen system, significant anionic repulsion was observed with increasing pH. The hydrophilic base fraction contains positively charged functional groups. Therefore with increasing ionization of naproxen (with increasing pH), K DOC to this fraction increased. The hydrophilic neutral fraction exhibited the lowest K DOC with both studied pharmaceuticals. The K DOC value of carbamazepine with the bulk DOM sample was higher than the calculated K DOC value based on sorption by the individual isolated fractions. The opposite trend was observed with naproxen at pH 8: the calculated K DOC value was higher than the value obtained for the bulk DOM. These results demonstrate that DOM fractions interact with each other and do not act as separate sorption domains.

WR279,396, a Third Generation Aminoglycoside Ointment for the Treatment of Leishmania major Cutaneous Leishmaniasis: A Phase 2, Randomized, Double Blind, Placebo Controlled Study

BackgroundCutaneous leishmaniasis (CL) is a disfiguring disease that confronts clinicians with a quandary: leave patients untreated or engage in a complex or toxic treatment. Topical treatment of CL offers a practical and safe option. Accordingly, the treatment of CL with WR279,396, a formulation of paromomycin and gentamicin in a hydrophilic base, was investigated in a phase 2 clinical study in Tunisia and France.MethodsA phase 2, randomized, double blind, vehicle-controlled study was conducted to assess the safety and efficacy of topical WR279,396 when applied twice a day for 20 days as treatment for parasitologically confirmed CL. The study protocol established the primary efficacy end point as complete clinical response (CCR) defined as 50% or greater reduction in the ulceration size of an index lesion by day 50 (D50) followed by complete re-epithelialization by D100, and no relapse through D180.ResultsNinety-two subjects were randomized. Leishmania major was identified in 66 of 68 isolates typed (97%). In the intent-to-treat population, 47 of 50 WR279,396 treated participants (94%) met the definition of CCR, compared with 30 of 42 vehicle-placebo participants (71%) [p = 0.0045]. Erythema occurred in 30% and 24% of participants receiving WR279,396 and placebo, respectively [p = 0.64]. There was no clinical or laboratory evidence of systemic toxicity.ConclusionApplication of WR279,396 for 20 days was found to be safe and effective in treating L. major CL, and offers great potential as a new, simple, easily applicable, and inexpensive topical therapy for this neglected disease.Trial RegistrationClinicalTrials.gov NCT00703924

Natural attenuation and characterization of contaminants composition in landfill leachate under different disposing ages

Chemical Oxygen Demand (COD) composition in landfill leachate would vary as the disposal time extended. Leachates with different ages were collected from Laogang Refuse Landfill of Shanghai, the largest landfill in China with a placement scale of 7600 t refuse per day. To characterize COD composition in leachate, samples were size-fractioned into suspended fractions (> 0.45 μm), colloid fraction (0.45 μm < fraction < 1 K Da MW) and dissolved fractions (< 1 KDa MW) based on the molecular weight distribution. The fractions < 0.45 μm (including colloid fraction and dissolved fractions) in leachate were further divided into 6 fractions, i.e. hydrophobic bases (Ho-base), hydrophobic acids (Ho-acid), hydrophobic neutral (Ho-neutral), hydrophilic bases (Hi-base), hydrophilic acids (Hi-acid) and hydrophilic neutral (Hi-neutral). It was found that the ratio of TOC/TC in leachate decreased over time, indicating that the percentage of organic matters in leachate decreased as the disposal time extended. It was also observed that the hydrophobic fraction accounted to about 50% of the total matters presented in the fraction < 0.45 μm of all leachate samples. The main components in < 0.45 μm fraction were the Ho-acid, Hi-acid and Hi-base fractions. The percentage of Ho-acid in leachate decreased from 60.8% (2 a) to 43.2% (12 a). In addition, leachate with different ages was categorized into 3 phases according to the results of Principle component analysis (PCA). TOC/COD ranges of leachate in periods I, II and III were 40–54.6%, 16.9–41.3% and 10–38.9%, respectively, indicating that the COD contribution of non-carbon reduction substances increased over time in leachate. Hence, the corresponding landfill leachate treatment process should be modified according to the leachate characterization. The results obtained in this study might provide the important information for modeling, design, and operation of landfill leachate treatment systems.

Characterization of dissolved organic matter fractions from Lake Hongfeng, Southwestern China Plateau

With XAD-series and ion exchange resins, dissolved organic matter (DOM) from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid (HA), fulvic acid (FA), hydrophobic neutrals (HON), hydrophilic acids (HIA), hydrophilic bases (HIB) and hydrophilic neutrals (HIN). Those fractions were characterized by high performance size exclusion chromatography, fluorescence spectroscopy and UV absorbance. Among the 6 fractions, FA was predominant and accounted for 51% of the total DOM. The weight-average ( M w) and number-averaged ( M n) molecular weight of these fractions ranged from 1688 to 2355 Da and from 1338 to 1928 Da, respectively. A strong correlation was observed between specific UV absorbance at 280 nm, E 2/ E 3 (absorbance at 250 nm to 365 nm), and the molecular weight for DOM fractions. UV-Vis fulvic-like fluorescence peaks were found in all fractions. Protein-like fluorescence peaks existed in HON may indicate that microbial activity was severely in Lake Hongfeng. There was a significant relationship between fluorescence intensities and specific UV absorbance at 254 nm for those DOM fractions, suggesting their similar luminescence characteristics. The values of fluorescence index ( f 450/500) indicated that hydrophobic fractions may derive from terrestrial sources, and the hydrophilic fractions from microbial and terrestrial origins. Those results suggest that there were inter-relationships between molecular weight, fluorescence and absorbance characteristics, and also subtle consistencies between the hydrophilic and hydrophobic properties and the sources for these 6 fractions from Lake Hongfeng.

Characterization of isolated fractions of dissolved organic matter from sewage treatment plant and the related disinfection by-products formation potential

Dissolved organic matter (DOM) in effluent from a conventional sewage treatment plant was isolated using resin adsorbents into six classes: hydrophobic bases (HoB), hydrophobic acids (HoA) and hydrophobic neutrals (HoN); hydrophilic bases (HiB), hydrophilic acids (HiA) and hydrophilic neutrals (HiN). Organic acids were the most abundant fractions of DOM. Hydrophobic organics especially hydrophobic acids were found to have higher overall disinfection by-products formation potential (DBPFP). Moreover, the potential decreased as the sequence of acids, neutrals and bases. Ultraviolet spectrophotometry at 254 nm (UV 254), fluorescence spectroscopy, size exclusion chromatography and Fourier transform infrared spectroscopy (FTIR) were employed to characterize DOM fractions. And the relationship between the characteristics of DOM fractions and the related DBPFP was discussed in detail. It was found that UV 254 to DOC ratio (SUVA) exhibited a positive correlation with haloacetic acids (HAAs) formation potential whereas distinctive linear correlation was not observed between SUVA and trihalomethanes (THMs) formation potential. Of the fluorescence organics contained in DOM, humic acids exhibited higher chlorine reactivity than fulvic acids. Smaller molecules of humic acids produced more DBPs. Furthermore, a combination of aromatic moieties and aliphatic structures with ν(C O) groups contributed largely to the formation of DBPs.

Isolation of dissolved organic matter in effluents from sewage treatment plant and evaluation of the influences on its DBPs formation

Dissolved organic matter (DOM) in reclaimed water from a conventional sewage treatment plant was isolated using resin adsorption chromatography technique into six classes: hydrophobic bases (HoB), hydrophobic acids (HoA), hydrophobic neutrals (HoN), hydrophilic bases (HiB), hydrophilic acids (HiA) and hydrophilic neutrals (HiN). It was found that organic acids dominated in reclaimed water and the ratios of UV 254 (absorbance at 254 nm) to dissolved organic carbon (DOC) (SUVA 254) ratio exhibited a common relationship: HoA > reclaimed water > HiA. The influences of chemical structures and experimental conditions on the formation of disinfection by-products (DBPs) were investigated, respectively. SUVA 254 was found to exhibit a positive and statistically significant correlation with DBPs formation potential. The specific trihalomethanes (THMs) and haloacetic acids (HAAs) formation potential decreased as the same sequence: acids, neutrals and bases. The formation of DBPs depended more on a combination of aromatic moieties and aliphatic structures such as hydroxy acids. Furthermore, THMs formed more easily at alkaline conditions; however, hydrophobic organics formed HAAs more easily at acidic conditions, whereas hydrophilic organics achieved relatively high HAAs at both acidic and strong alkaline conditions. Moreover, the observed rate constant for HAAs formation was larger than the rate constant for THMs formation. Addition of ammonia nitrogen (NH 4-N) changed chlorine to chloramines with lower oxidation potential, and correspondingly influenced the formation of DBPs especially at the chlorination breakpoint.

Evaluation of disinfection by-products formation during chlorination and chloramination of dissolved natural organic matter fractions isolated from a filtered river water

Dissolved natural organic matter (DOM) in a filtered river water was isolated and fractionated into six different fractions. Trihalomethanes (THMs) and haloacetic acids (HAAs) formed from these isolated DOM fractions during chlorination and chloramination were determined. Results show that the hydrophobic acid, hydrophilic acid, hydrophilic base and hydrophobic neutral are major precursors of THMs and HAAs. There exist good correlations between the values of specific ultraviolet absorbance at 254 nm of the individual DOM fractions and their disinfection by-products formation potential, indicating that aromatic moieties are responsible for disinfection by-products formation for both hydrophobic and hydrophilic DOM fractions. Chloramination of the DOM fractions yields much less THMs and HAAs than chlorination. For the dominant DOM fraction (i.e. hydrophobic acid) in the water, the yields of THMs and HAAs increase more significantly in chlorination than those in chloramination with the increase of disinfectant dosage, contact time and dissolved organic carbon content.

Design and evaluation of matrices of Eudragit with polycarbophil and carbopol for colon-specific delivery

The purpose of the present study was to investigate the effect of incorporating pH-responsive polymers Eudragit (L100 or S100) in matrix bases composed of hydrophilic polymers polycarbophil and carbopol to design oral controlled release formulations with sigmoidal release profile for colon-specific delivery. Matrix tablets were prepared by wet granulation technique using indomethacin as model drug and were characterized for physical parameters, in vitro drug release, release kinetics, and stability on storage. The gastrointestinal (GI) transit of selected formulations was also investigated in human subjects using gamma scintigraphy. In vitro release studies indicated that the presence of pH-sensitive polymers in hydrophilic polymer base retarded the initial release significantly (10–15% release in 6 h) followed with controlled release for the next 8–10 h in simulated GI fluid pH (without enzymes). The presence of Eudragit in hydrophilic matrix base retarded the swelling of the matrix base in acidic to weakly acidic pH, but in alkaline pH, enhancement in drug release rate was observed due to the dissolution of Eudragit from the base resulting in a porous matrix structure, resulting in around 80–90% release in 14 h of study. In vivo gamma scintigraphy studies in healthy human subjects proved that the formulations had acceptable matrix strength to withstand gastric and colonic transit. The mean colonic residence time of selected designed formulations varied between 15 and 19 h. Such a matrix design could have potential application as colon-specific drug delivery systems with pH- and time-dependent drug release profile.

Network copolymers of acrylic and methacrylic acids: Hydrophilic ointment bases for wound-healing preparations

Investigations aimed at the development of a combined wound-healing preparation on a hydrophilic ointment base have been carried out. Copolymers of acrylic acid and its derivatives with a new divinyl monomer, β-vinyloxyethylamide of acrylic acid, are proposed as the bases. It is established that these ointment bases exhibit sufficiently high osmotic activity. Polymer-based complexes including the ethereal oil of smooth wormwood and the proteolytic enzyme protosubtilin showed pronounced antibacterial and wound-healing activity.

Structural Analysis of Polyelectrolyte Film Absorbing Metal Ion by SAXS Utilizing with X-ray Anomalous Dispersion Effect

A distribution of Cu ions in polyelectrolyte film (Nafion) is directly observed with a small-angle X-ray scattering (SAXS) method utilizing an X-ray anomalous dispersion effect. A partial structure factor of the Cu ions, GAA(q), can be derived from the SAXS profiles obtained by scanning the incident X-ray energy around the Cu K absorption edge. GAA(q) has two peaks, indicating that the Cu ions hierarchically distribute in Nafion film. In addition, a standard SAXS also shows that Nafion film has a hierarchical structure. These results mean that the Cu ions locate in the domain where the hydrophilic bases aggregate.

Characteristics and Fouling Behaviors of Dissolved Organic Matter in Submerged Membrane Bioreactor Systems

Although the significance of dissolved organic matter (DOM) in membrane bioreactor (MBR) fouling has been increasingly noted in recent studies, little information is available on the characteristics and fouling potential of DOM at the fractional level. This study sought to gain a more fundamental understanding of the complicated DOM fouling phenomenon. DOM in MBR systems was fractionated into more homogeneous components, namely, hydrophobic aquatic humic substances (AHS), hydrophilic acids (HiA), hydrophilic bases (HiB), and hydrophilic neutrals (HiN) on the basis of hydrophobicity and charge. The fractionation results revealed that hydrophobic AHS were the most abundant component of DOM in MBR systems, whereas the amount and nature of hydrophilic components were variable and sample source specific. Fouling experiments were performed in a stirred-cell filtration system with various types of DOM (i.e., original, prefiltered, and fractionated). The fouling potential of DOM was observed to be greatly affected by its characteristics, and there appeared to be a strong link between the high fouling potential of DOM and its high content of AHS. The key importance of AHS as the major foulants of DOM in MBR systems was further confirmed by the fact that AHS exhibited the highest fouling potential among the four fractional DOM components. Also, it was noted that HiN showed much higher fouling potential than HiA and HiB, and induced mainly irreversible fouling.

Studies on the antimicrobial properties of formulated creams and ointments containing &lt;i&gt;Baphia nitida&lt;/i&gt; heartwood extract

Baphia nitida Lodd (camwood) is widely used medicinal plant in Nigeria for treatment of variety of skin infections. The plant is used in unspecified quantities without standardisation. B. nitida extracts were incorporated in some cream and ointment base in order to present the medicinal plant in an elegant and pharmaceutically acceptable dosage form, as one of the major steps in the scientific evaluation and standardisation of the plant product. The formulated products were evaluated for their antimicrobial activities using agar diffusion technique and microbial challenge test. Their performances were compared with those of standard antiseptic creams and ointments. The results of agar diffusion studies on cream and ointment formulations revealed that the topical bases used to disperse the medicaments could significantly affect the antimicrobial effectiveness of the formulation. Formulations prepared with Aqueous cream BP (a more hydrophilic base; 70% aqueous) exhibited greater antimicrobial activity than the formulation with anionic cream base (a less hydrophilic base; 44% aqueous). Antiseptic creams and ointments containing B. nitida extract, which were effective against various test organisms used in this study, were successful formulated in this work. Journal of Pharmacy & Bioresources Vol. 2(2) 2005: 124-130

FTIR evaluation of functional groups involved in the formation of haloacetic acids during the chlorination of raw water

This work investigated the formation potential of haloacetic acid (HAA) compounds in the raw water for the Bangkhen water treatment plant (Bangkok, Thailand). The resin adsorption technique (with three different types of resins, i.e. DAX-8, AG-MP-50 and WA-10) was employed to characterize the organic content in the raw water into six fractions, i.e. hydrophobic neutral (HPON), hydrophobic acid (HPOA), hydrophobic base (HPOB), hydrophilic neutral (HPIN), hydrophilic acid (HPIA) and hydrophilic base (HPIB). Hydrophilic species appeared to be the predominant organic species in this water source (approximately 60%) with the neutral fraction being the most abundant (approximately 40%). Hydrophobic species, on the other hand, played the most important role in the formation of haloacetic acids as they contributed to as much as approximately 56% of total HAA formation potential. Among the three hydrophobic species, the hydrophobic base exhibited the highest specific HAA formation with 208 μg HAAs/mg of dissolved organic carbon (DOC). Each organic fraction was examined for its associated functional groups by Fourier transform infrared (FTIR). The investigation of the formation of HAAs was achieved by tracking the changes in the FTIR results of the same water sample before and after the chlorination reaction. Based on the results obtained from this study, carboxylic acids, ketone, amide, amino acids and aromatic characteristic organics seemed to be the main precursors to HAA formation.

The fate of dissolved organic carbon (DOC) in the wastewater treatment process and its importance in the removal of wastewater contaminants

Dissolved organic carbon (DOC) constitutes a parameter of organic pollution for waters and wastewaters, which is not so often studied, and it is not yet regulated by directives. The term 'DOC' is used for the fraction of organics that pass through a 0.45 microm pores' size membrane. The type of wastewater plays an important role in the quality of DOC and it has been shown that DOC may contain aquatic humic substances, hydrophobic bases, hydrophobic neutrals, hydrophilic acids, hydrophilic bases and hydrophilic neutrals. The quality of the DOC is expected to affect its fate in a wastewater treatment plant (WWTP), since a considerable fraction of DOC is not biodegradable, and it may be released in the aquatic environment together with the treated effluent. In the present study, the occurrence of DOC during the wastewater treatment process is investigated and its removal rates during primary, secondary and overall treatment are being estimated. Furthermore, a correlation is being attempted between DOC and the concentrations of selected Persistent Organic Pollutants (POPs) and Heavy Metals (HMs) in the dissolved phase of wastewaters, to examine whether there are common sources for these pollution parameters in WWTPs. Also, DOC is being correlated with the partition coefficients of the above-mentioned pollutants in wastewater, in order to examine the effect of 'solubility enhancement' in WWTPs and to evaluate the result of this phenomenon in the efficiency of a WWTP to remove organic pollutants. For the purposes of this study, 24-h composite wastewater samples were collected from the influent (raw wastewater, RW), the effluent of primary sedimentation tank (primary sedimentation effluent, PSE) and the effluent of secondary sedimentation tank (secondary sedimentation effluent, SSE). Samples were analyzed for the presence of 26 POPs (7 PCBs and 19 organochlorine pesticides), 8 HMs and DOC. Mean concentrations of DOC in RW and PSE were at similar levels (approximately 70 mg l(-1)), suggesting that primary treatment has a minor effect on the DOC content of wastewater. DOC concentrations in SSE were significantly lower (approximately 19 mg l(-1)) as a result of the degradation of organic compounds in the biological reactor. Calculated removals of DOC were 0.8% in the primary treatment, 63% in the secondary treatment, and 69% in the overall treatment, exhibiting large differences from other organic pollution parameters, such as BOD and COD. The overall DOC removal was found to be independent from the DOC concentration in raw wastewater. Poor correlation was also observed between the DOC content and the concentrations of wastewater contaminants, such as persistent organic pollutants (POPs) and heavy metals (HMs), probably suggesting that their occurrence in WWTPs is due to different sources. A good negative linear relationship was revealed between DOC concentrations and the logarithms of the distribution coefficients (Kd) of various POPs and HMs between the solid and the liquid phases of wastewater. This relationship suggests that DOC facilitates hydrophobic pollutants to remain in the dissolved phase thus causing lower removal percentages during the treatment process. DOC was measured at three stages of a municipal WWTP that receives mainly domestic wastewater and urban runoff. DOC concentrations in untreated and primarily treated wastewater were almost equal, and only after the secondary sedimentation there was a decrease. Concentrations and removal rates of DOC were in the same levels as in other WWTPs that receive municipal wastewater. The origin of DOC was found to be different to the one of POPs and of HMs, as no correlation was observed between the concentrations of DOC and the concentrations of these pollutants. On the contrary, DOC was found to have significant negative correlation with the Kd of all pollutants examined, suggesting that it plays an important role in the partitioning of those pollutants between the dissolved and the sorbed phase of wastewaters. This effect of DOC on partitioning can affect the ability of WWTPs to remove toxic pollutants, and that way it facilitates the discharge of those chemicals in the aquatic ecosystems together with the treated effluent. RRECOMMENDATION:By the results of this work it is shown that the presence of DOC in wastewaters can significantly affect the partition of hazardous pollutants between the dissolved and the sorbed phase. It is therefore of importance that this parameter is controlled more in wastewaters, since it can cause a decrease in the efficiency of WWTPs to remove quantitatively persistent pollutants.

生物学的利用能向上を目指したグリチルリチン直腸投与製剤に関する基礎的検討

We investigated the usefulness of a suppository containing highly concentrated glycyrrhizin monoammonium (GZ-NH4) solution prepared by pretreatment with clove oil in rats. The aims of this study were to clarify membrane permeability, the bioavailability of GZ-NH4 and the extent of tissue damage. Membrane permeability was evaluated using Ussing-type diffusion chambers, bioavailability assessed through an in vivo absorption study, tissue damage evaluated through observation of hematoxylin-eosin stained tissues and an in vitro release study was carried out to select the suppository base. The formulations used were a GZ-NH4 solution prepared using phosphate buffered solution (control), GZ-NH4 containing 50% labrasol, and GZ-NH4 pretreated with 2% clove oil at 50°C and 70°C. The GZ-NH4 concentrations of all formulations were set to 50 mg/mL. With the GZ-NH4 pretreated with 2% clove oil formulations, the apparent permeability coefficients (Papp) were 1.7- and 1.9-fold higher, respectively, than that of the control formulation. When the various formulations were applied to the rat rectum at a dose of 50 mg/kg of GZ-NH4, the bioavailability of GZ-NH4 pretreated with 2% clove oil at 70°C was 25%, the highest among the four formulations. In the in vivo absorption study, no damage to the epithelial cells of the rectum was observed. These results suggest that GZ-NH4 pretreated with 2% clove oil at 70°C is the most useful formulation for rectal administration. In the in vitro release study to select suppository base, polyethyleneglycol 1000 (PEG 1000) was selected as the hydrophilic base and Witepsol H-15 as the lipophilic base. The initial release of GZ-NH4 was highest for the Witepsol H-15 suppository base. Overall, our results suggest that a lipophilic suppository containing GZ-NH4 pretreating with 2% clove oil at 70°C has the highest release and absorption rates for GZ-NH4 in rectal administration.

Characterization of haloacetic acid precursors in source water

Raw water from the Bangkok (Thailand) main municipal water supply canal was examined for its natural organic composition by fractionation with adsorption resins. DAX-8 resin was the first resin employed to fractionate the hydrophobic fractions. Fractionation at neutral pH resulted in the separation of the hydrophobic neutral components; at a high pH level (approx. 10) separation of the hydrophobic base components occurred; and at a low pH level (approx. 2) the hydrophobic acid components were separated. AG-MP-50 cationic resin was then used to separate the hydrophilic base components, and WA-10, a weak anionic resin, was applied finally to fractionate the hydrophilic acid and neutral components. Subsequently, each fraction was tested for its chlorine disinfection by-product (DBP) formation potential. The HAA formation tests demonstrated that the various organic fractions had different reactivity levels for the formation of haloacetic acids (HAAs). For this source water, the hydrophilic neutral fraction dominated over the other five fractions in being the main organic component and the most significant precursor of HAAs formation. On the other hand, in terms of specific HAA formation potential (FP), the hydrophobic and hydrophilic base fractions were the most reactive precursors to the formation of HAAs. In all cases, the quantity of HAAs formed depended linearly upon the amount of organic constituents in the water sample.