Apparent First-order Degradation Research Articles

Deep mineralization of bisphenol A via Cu–Mn spinel oxide nanospheres anchored N-doped carbon activated peroxymonosulfate

Fenton-like technology can efficiently remove recalcitrant pollutants, but developing catalytic oxidation system for deep mineralization of pollutants remains a challenge. Therefore, Cu–Mn spinel oxide nanospheres anchored N-doped carbon (CMO/NC) was prepared by a one-step calcination method and used to activate peroxymonosulfate (PMS) for efficient mineralization of bisphenol A (BPA). With the use of 0.5 g/L CMO/NC and 0.2 g/L PMS, the added BPA (50 mg/L) was completely degraded and deeply mineralized (nearly 95.2 %) in 9 min. The apparent first-order degradation rate constant k was 0.557 min−1, which was 61.9, 6.2 and 2.5 times than those in the systems of N-C/PMS (0.009 min−1), CuO/NC/PMS (0.09 min−1) and Mn3O4/NC/PMS (0.22 min−1). A comparison between the catalytic performances of CMO/NC catalysts prepared by changing the dosage of urea confirmed the catalysis synergism between Cu–Mn spinel oxides and N-C. A further comparison between the catalytic performances of CMO/NC catalysts prepared by varying the Cu/Mn molar ratio of the precursors showed that the synergy between Cu and Mn sites promoted the catalytic activity, with a synergistic effect factor of 1.8. XPS and H2-TPR characterizations proved that strong Cu-Mn interaction caused Mn species easier to donate electrons to PMS and Cu species easier to accept electrons from PMS. The degradation pathway and intermediate toxicity suggested that the system did not produce secondary pollution. Based on the results of EPR and capture experiments confirming that 1O2 was the major active species, a mechanism on PMS activation was proposed. Through investigations of continuous flow BPA wastewater removal, the influence of coexisting anions and catalyst cycling stability, it was clearly demonstrated that the present system had broad application prospects.

Reevaluation of the Reactivity of Superoxide Radicals with a Sulfonamide Antibiotic, Sulfacetamide: An Experimental and Theoretical Study

Superoxide radical (O2•–) is a ubiquitous reactive oxygen species in sunlit natural waters. Here, we selected sulfacetamide (SCT) as a representative sulfonamide antibiotic to investigate its reactivity with O2•–, as this reaction was reported to be fast with the rate constant k of 7.0 × 107 M–1 s–1. The degradation kinetics of SCT were first studied in the classic McDowell systems (i.e., ultraviolet, acetone, and alcohols) for optimal O2•– productivity. Comparison of the apparent first-order degradation rates (kapp) revealed that 70 mM acetone and 1 M isopropanol were optimal for kapp, but it was only ∼10% faster than the control. The small degree of enhancement of kapp led us to suspect its high reported reactivity with O2•–. Therefore, we reevaluated this reaction in organic and aqueous solutions by a suite of spectroscopic techniques, and all evidence indicated that the measured k values were 6 orders of magnitude smaller than the reported one. The low reactivity was also confirmed by theoretical calculations at the M06-2X level of theory. Our results are of practical and scientific importance for the holistic assessment of the role of O2•– in remediation and attenuation of organic contaminants in natural and engineered waters.

Spatially-distinct redox conditions and degradation rates following field-scale bioaugmentation for RDX-contaminated groundwater remediation

In situ bioaugmentation for cleanup of an hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)-contaminated groundwater plume was recently demonstrated. Results of a forced-gradient, field-scale cell transport test with Gordonia sp. KTR9 and Pseudomonas fluorescens strain I-C cells (henceforth “KTR9” and “Strain I-C”) showed these strains were transported 13 m downgradient over 1 month. Abundances of xplA and xenB genes, respective indicators of KTR9 and Strain I-C, approached injection well cell densities at 6 m downgradient, whereas gene abundances (and conservative tracer) had begun to increase at 13 m downgradient at test conclusion. In situ push-pull tests were subsequently completed to measure RDX degradation rates in the bioaugmented wells under ambient gradient conditions. Time-series monitoring of RDX, RDX end-products, conservative tracer, xplA and xenB gene copy numbers and XplA and XenB protein abundance were used to assess the efficacy of bioaugmentation and to estimate the apparent first-order RDX degradation rates during each test. A collective evaluation of redox conditions, RDX end-products, varied RDX degradation kinetics, and biomarkers indicated that Strain I-C and KTR9 rapidly degraded RDX. Results showed bioaugmentation is a viable technology for accelerating RDX cleanup in the demonstration site aquifer and may be applicable to other sites. Full-scale implementation considerations are discussed.

Removal of Pesticides with Endocrine Disruptor Activity in Wastewater Effluent by Solar Heterogeneous Photocatalysis Using ZnO/Na2S2O8

The solar photocatalysis has received increasing attention in the last years due to its great potential as eco-friendly technology to detoxify wastewater polluted with estrogenic and/or androgenic chemicals. In this context, this study aims to demonstrate the photocatalyzed degradation of two fungicides (vinclozoline and fenarimol) and four insecticides (malathion, fenotrothion, quinalphos, and dimethoate) all of them with endocrine-disrupting activity, in a wastewater effluent under natural sunlight and pilot plant scale. For this, we have combined hydroxyl radical (HO•)- and sulfate radical (SO4●−)-based advanced oxidation processes (AOPs) by using of ZnO as photocatalyst and Na2S2O8 as oxidant, respectively. Previously, catalyst loading, effect of electron acceptor, and pH conditions were optimized using a lab photoreactor under artificial light. As a result, 200 mg L−1 of ZnO and 250 mg L−1 of Na2S2O8 were used in the further experiment at pilot plant scale at pH around 7. The results show that the use of the tandem ZnO/Na2S2O8 strongly enhances the reaction rate of the studied pesticides as compared with the photolytic test. All pesticides followed an apparent first-order degradation curve. The necessary time for 90% degradation (DT90) under sunlight irradiation ranged from 26 to 1000 min (2–75 min as normalized illumination time, t30W) for malathion and fenarimol, respectively. At the end of the lighting, the remaining percentage of dissolved organic carbon (DOC) was up to 92% lower than its initial content and toxicity (Vibrio fischeri) decreased from 65% of inhibition to an acceptable value of 12% at the end of the treatment. A weak increase in the electrical conductivity (EC) was observed due to the mineralization process. The findings confirm the efficacy of the treatment to remove pesticides from wastewater using natural sunlight as renewable energy source, mainly in sunny areas as Mediterranean basin.

Solid-State and Solution Characterization of Myricetin.

Myricetin (MYR) is a natural compound that has been investigated as a chemopreventative agent. MYR has been shown to suppresses ultraviolet B (UVB)-induced cyclooxygenase-2 (COX-2) protein expression and reduce the incidence of UVB-induced skin tumors in mice. Despite MYR's promise as a therapeutic agent, minimal information is available to guide the progression of formulations designed for future drug development. Here, data is presented describing the solid-state and solution characterization of MYR. Investigation into the solid-state properties of MYR identified four different crystal forms, two hydrates (MYR I and MYR II) and two metastable forms (MYR IA and MYR IIA). From solubility studies, it was evident that all forms are very insoluble (<5 μg/ml) in pure water. MYR I was found to be the most stable form at 23, 35, and 56°C. Stability determination indicated that MYR undergoes rapid apparent first-order degradation under basic pH conditions, and that degradation was influenced by buffer species. Apparent first-order degradation was also seen when MYR was introduced to an oxidizing solution. Improved stability was achieved after introducing 0.1% antioxidants to the solution. MYR was found to have good stability following exposure to ultraviolet radiation (UVR), which is a consideration for topical applications. Finally, a partitioning study indicated that MYR possess a log P of 2.94 which, along with its solid-state properties, contributes to its poor aqueous solubility. Both the solid-state properties and solution stability of MYR are important to consider when developing future formulations.

Perchlorate natural attenuation in a riparian zone

Multiple lines of evidence were used to document the natural attenuation of perchlorate in a shallow alluvial aquifer. In the upgradient, aerobic portion of the aquifer, perchlorate did not biodegrade. However, natural flushing by groundwater flow is reducing perchlorate concentrations in the aquifer over time. Perchlorate concentrations in the source area are expected to meet cleanup criteria in 11 to 27 years without active remedial measures. At the distal end of the plume, perchlorate is rapidly degraded as it migrates upward through organic rich littoral zone sediments. Apparent first-order degradation rates in groundwater were about 0.20 d−1 and are consistent with laboratory macrocosm rates (0.12 d−1). qPCR results show a distinct region of the littoral zone where perchlorate degraders are elevated. The Eh within this zone varies from +0.1 to +0.3 V indicating perchlorate degraders can thrive in moderately oxidizing conditions. The study has shown that (i) there was no apparent perchlorate biodegradation in aerobic aquifer; (ii) perchlorate declines over time in aerobic aquifer due to flushing; (iii) there was a rapid perchlorate attenuation in organic rich littoral zone; and, (iv) qPCR results show large increases in perchlorate degraders in the littoral zone.

Stability of sulforaphane for topical formulation

Context: Sulforaphane (SFN) is a natural compound that has been investigated as a chemopreventive agent. SFN has been shown to inhibit the activator-protein-1 (AP-1) transcription factor and may be effective for inhibition of ultraviolet (UV) induced skin carcinogenesis. This study was designed to investigate the stability of SFN as a function of pH, temperature and in various solvents and formulations.Materials and methods: Stability was analyzed using high-performance liquid chromatography. A potential lead formulation was identified and evaluated in vivo.Results: SFN was determined to undergo apparent first-order degradation kinetics for the conditions explored. It was observed that SFN undergoes base catalyzed degradation. Buffer species and solvent type impacts stability as well. SFN was found to be very sensitive to temperature with degradation rate changing by a factor of nearly 3.1 for every 10 °C change in temperature (at pH 4.0). SFN completely degraded after 30 days in a conventional pharmaceutical cream formulation. Improved stability was observed in organic formulation components. Stability studies were conducted on two nonaqueous topical formulations: a polyethylene glycol (PEG) ointment base and an organic oleaginous base.Conclusion: Topically applied SFN in the PEG base formulation significantly reduced AP-1 activation after UV stimulation in the skin of a transgenic mouse model, indicating that SFN in this formulation retains efficacy in vivo.

Preformulation, formulation, and in vivo efficacy of topically applied Apomine

Apomine is a novel compound that inhibits the mevalonate/isoprenoid pathway of cholesterol synthesis and may prove effective as a skin cancer chemoprevention therapy. This research was focused on the development of a new delivery approach for chemoprevention of melanoma using topically delivered Apomine. This included evaluating the effect of several factors on the stability of Apomine in solution, utilizing these to develop a topical formulation, and conducting efficacy studies with the developed topical formulation in the TPras mouse model. Preformulation included the influence of pH, buffer species, ionic strength, and organic solvents on the stability of Apomine at four different temperatures. Apomine was determined to undergo apparent first-order degradation kinetics for all conditions evaluated. Apomine undergoes base-catalyzed degradation. Less than 15% degradation is observed after >200 days under acidic conditions. Long-term stability studies were performed on two different topical cream formulations and indicate that both formulations are chemically stable for over 1 year at both 4 and 23 °C. The efficacy of topically applied Apomine, from ethanol and developed 1% cream, was evaluated in vivo against the incidence of melanoma. Regardless of delivery vehicle Apomine treatment caused a significant reduction in tumor incidence. Ethyl alcohol application of Apomine resulted in a greater tumor incidence reduction when compared to the development cream formulation; however, this difference was not significant.

Photocatalytic degradation of organophosphate and phosphonoglycine pesticides using TiO 2 immobilized on silica gel

The photocatalytic degradation of the three pesticides acephate, dimethoate, and glyphosate in water has been investigated using UV light and TiO 2 immobilized on silica gel as photocatalyst. Results show that the pesticides can be efficiently degraded by the UV/TiO 2 system used in the study. Complete (100%) decomposition of dimethoate and glyphosate was attained within 60 min of irradiation, while total degradation of acephate occurred after 105 min of photocatalytic treatment. Acephate and dimethoate decomposition followed the Langmuir–Hinshelwood apparent first-order degradation kinetics, suggesting the photocatalytic nature of pesticide disappearance, whereas glyphosate decomposition was governed by both adsorption and photocatalytic reactions. Evolution of heteroatoms at their highest oxidized states such as SO 4 2 - , NO 3 - , and PO 4 3 - ions provides evidence that pesticide degradation occurred primarily through photocatalytic oxidation reactions. Non-detection of toxic intermediates such as methamidophos and omethoate that have been reported in other studies demonstrates rapid destruction of the pesticides into harmless byproducts using the system.

Evaluation of non-isothermal methods in stability studies of human insulin pharmaceutical preparations

The purpose of this research was to study the thermal stability of a human insulin pharmaceutical preparation using non-isothermal conditions and comparison with classical isothermal experiments. The isothermal studies were performed in the temperature range 20–60 °C, whereas non-isothermal stability studies were performed using a linear increasing temperature program, heating rate 0.25 °C per hour and temperature interval 30–70 °C. Under isothermal conditions, an apparent first-order degradation process was observed at all temperatures. The linear Arrhenius plot suggested that the insulin degradation mechanism was the same within the studied temperature range, with quite large uncertainties due to the small number of degrees of freedom based only on the scatter in the plot, giving an estimated shelf-life at 25 °C of 199.1 days. In non-isothermal conditions, the integral approach was used to estimate the activation parameters. It provides results in good agreement with those of the traditional method, but with the advantage that the uncertainty in the final result directly reflects the goodness of fit of the experimental data, since it takes into account the scatter in the original data. The estimated shelf-life in non-isothermal conditions was quite close to the value derived from isothermal data, 191.4 days, although the 95% confidence interval estimated were slightly higher. This is due to the differences in the estimation method and the nature of the experimental errors. The bootstrap technique is also applied to estimating confidence limits for the Arrhenius parameters and shelf-life. This method is very useful when the underlying distribution function of the parameters is unknown. The results obtained indicate that the Arrhenius parameters follow a normal distribution, whereas the shelf-life follows a log-normal distribution. In any case, the results obtained show that there is no difference between the asymptotic and bootstrap confidence intervals.

Data Analysis of Kinetic Modelling Used in Drug Stability Studies: Isothermal Versus Nonisothermal Assays

Kinetic modelling was applied to predict the stability of cholecystokinin fragment CCK-4 in aqueous solution, which was analyzed by isothermal and nonisothermal methods using a validated stability indicating HPLC method. The isothermal studies were performed in the temperature range 40 to 80 degrees C at pH 12 and ionic strength 0.01 M as constants, whereas nonisothermal stability studies were performed using a linear increasing temperature program, heating rate 0.25 degrees C/h and a temperature interval 40-82 degrees C. The isothermal studies require two-step linear regression to estimate the parameters, resulting in a well-defined confidence interval. Nonisothermal kinetic studies require nonlinear or linear regression by previous transformation of data to estimate the parameters. In this case, the two most popular approaches, derivative and integral, were used and compared. Under isothermal conditions, an apparent first-order degradation process was observed at all temperatures. The linear Arrhenius plot suggested that the CCK-4 degradation mechanism was the same within the studied temperature range, with quite large uncertainties due to the small number of degrees of freedom based only on the scatter in the plot, and giving an estimated shelf life at 25 degrees C of 35.2 days. The derivative approach yields high variability in the Arrhenius parameters, since they are dependent on the number of polynomial terms chosen, so several statistical criteria were applied to select the best model. The integral approach allows activation parameters to be calculated directly from experimental data, and provides results in good agreement with those of the traditional method, but have the advantage that the uncertainty in the final result directly reflects the goodness of fit of the experimental data to the chosen kinetic model. The application of the bootstrap technique to estimating confidence limits for the Arrhenius parameters and shelf life is also illustrated, and shows there is no difference between the asymptotic and bootstrap confidence intervals. Nonisothermal studies give us fast and valuable information about drug stability, although their potential for predicting isothermal behaviour is conditioned by the data analysis method applied.

Preformulation Studies on Imexon

Imexon is an aziridine containing iminopyrrolidone that, through aziridine ring opening, is able to induce oxidative stress resulting in apoptosis. The main objective of this research was to conduct extensive preformulation studies on Imexon in order to understand the factors that affect its stability. The results obtained indicate that the stability of Imexon is dependant on pH, ionic strength, temperature, buffer species, and initial concentration. Degradation of Imexon follows apparent first-order degradation kinetics with the primary degradation product resulting from opening of the aziridine ring. In order to maximize stability, ionic strength, temperature, and initial concentration should be minimized, with an optimal range pH between 7.2 and 9.0. Experimentation with other aqueous solutions indicates that Imexon has increased stability in D5W as opposed to normal saline, while it undergoes rapid degradation in 6% H2O2. Imexon is not ionizable between pH 5.0 to 8.5 and has an aqueous solubility of approximately 25 mg/mL over this range. Solid-state characterization has concluded that Imexon is a crystalline solid that begins decomposition at 165°C, prior to melting.

Degradation rates of low molecular weight PAH correlate with sediment TOC in marine subtidal sediments

The degradation rate of low molecular weight (LMW) polycyclic aromatic hydrocarbons (PAH) in subtidal marine sediments was found to correlate with sediment total organic carbon (TOC) in stations sampled two or more times after the North Cape No. 2 fuel oil spill. With 2.5–5 months between samplings, stations with lower sediment TOC had lower fractions of LMW PAH remaining at the time of the second sampling. Apparent first-order degradation rate constants calculated for each station varied by nearly an order of magnitude between stations with a range of TOC from 0.4% to 7.3%. The correlation of degradation rate with sediment TOC can be used to provide improved and site-specific predictions of the initial time-course of LMW PAH concentrations in sediments after oil spills.

COMPARISON OF MECHANICAL TESTS FOR EVALUATING TEXTURAL CHANGES IN POTATOES DURING THERMAL SOFTENING

ABSTRACTThe changes in the texture of cylindrical samples of potato tissues immersed in water at 60, 70, 80 and 90C for up to 80 min were monitored at each temperature in terms of tangent modulus of elasticity in axial and radial compression tests, and elasticity and viscosity parameters in creep and stress relaxation tests. The magnitude of all mechanical test parameters decreased with an increase in heating time and temperature. The creep and stress relaxation responses of individual potato samples were adequately represented by respective mechanical models (R2= 0.94 to 0.99). The mechanical test parameters followed apparent first‐order degradation kinetics due to the effect of thermal softening, and the rate constant was used as an index of the sensitivity of a mechanical test. The radial compression test was relatively more sensitive than the axial test. Based on an overall comparison, the parameters from creep and stress relaxation tests were found to be the most sensitive in describing the textural changes during thermal softening of potatoes.

Degradation and detoxification of aqueous nitrophenol solutions by electron beam irradiation

The goal of this research was to study the degradation of nitrophenol solutions by high-energy electron beam irradiation. The results showed that the degradation processes obey an apparent first-order degradation. At the higher irradiation doses the pH of solutions decreased; however, the dissolved organic carbon of the solutions was essentially unchanged. To investigate the toxicity of the radiolytic products the oxygen uptake rate of activated sludge was determined. The toxicity of irradiated nitrophenol solutions decreased from the initial non-irradiated solutions.

Characterization of propargyl bromide transformation in soil.

Propargyl bromide is being investigated for its potential as a soil fumigant. Characterization of the fate of propargyl bromide in soil is important in determining both efficacy and the threat of environmental contamination. These experiments investigated some of the factors affecting the rate of propargyl bromide degradation in soil and quantified some of the products formed as a result of propargyl bromide degradation in four soils of differing composition and at three initial propargyl bromide concentrations. In all soils at all initial propargyl bromide concentrations, equimolar formation of Br- was observed during propargyl bromide degradation, but little propargyl alcohol (product of hydrolysis) was formed. The apparent first-order degradation coefficient (k) increased with decreasing initial propargyl bromide concentration in all soils, but the mass degraded per unit time increased with increasing propargyl bromide concentration. The rate of propargyl bromide degradation increased with increasing soil organic matter content, and the k value was correlated to the organic carbon content of the soil (correlation coefficient > 0.97 for all concentrations). Repeated application of propargyl bromide did not increase the rate of propargyl bromide degradation in soil. Addition of Br- did not affect the rate of propargyl bromide transformation in soil, so accumulation of Br- in the soil is not expected to impede propargyl bromide degradation.

Consumption of tropospheric levels of methyl bromide by C(1) compound-utilizing bacteria and comparison to saturation kinetics.

Pure cultures of methylotrophs and methanotrophs are known to oxidize methyl bromide (MeBr); however, their ability to oxidize tropospheric concentrations (parts per trillion by volume [pptv]) has not been tested. Methylotrophs and methanotrophs were able to consume MeBr provided at levels that mimicked the tropospheric mixing ratio of MeBr (12 pptv) at equilibrium with surface waters ( approximately 2 pM). Kinetic investigations using picomolar concentrations of MeBr in a continuously stirred tank reactor (CSTR) were performed using strain IMB-1 and Leisingeria methylohalidivorans strain MB2(T) - terrestrial and marine methylotrophs capable of halorespiration. First-order uptake of MeBr with no indication of threshold was observed for both strains. Strain MB2(T) displayed saturation kinetics in batch experiments using micromolar MeBr concentrations, with an apparent K(s) of 2.4 microM MeBr and a V(max) of 1.6 nmol h(-1) (10(6) cells)(-1). Apparent first-order degradation rate constants measured with the CSTR were consistent with kinetic parameters determined in batch experiments, which used 35- to 1 x 10(7)-fold-higher MeBr concentrations. Ruegeria algicola (a phylogenetic relative of strain MB2(T)), the common heterotrophs Escherichia coli and Bacillus pumilus, and a toluene oxidizer, Pseudomonas mendocina KR1, were also tested. These bacteria showed no significant consumption of 12 pptv MeBr; thus, the ability to consume ambient mixing ratios of MeBr was limited to C(1) compound-oxidizing bacteria in this study. Aerobic C(1) bacteria may provide model organisms for the biological oxidation of tropospheric MeBr in soils and waters.

Stereoselective internal acyl migration of 1beta-O-acyl glucuronides of enantiomeric 2-phenylpropionic acids.

Internal acyl migration reactions of 1beta-O-acyl glucuronides of 2-arylpropionic acids (profens) are of interest because of their possible role in covalent binding to serum proteins and consequent allergic reactions. The stereoselective degradation of 1beta-O-acyl glucuronides of enantiomeric 2-phenylpropionic acids (PAs), the basic structures of profens, in phosphate buffer (pH 7.4) at 37 degrees C, has been investigated using HPLC. Apparent first-order degradation of 1beta-O-acyl glucuronide and the sequential appearance of 2-, 3- and 4-O-acyl isomers were observed for each enantiomer. Acyl migration was observed to predominate over hydrolysis as in the other profen glucuronides. All the positional isomers and anomers were characterized using NMR and HPLC-NMR. The overall degradation half-life of (R)- and (S)-PA glucuronides was 1.8 and 3.3 h, respectively. These results suggest that (R)-PA glucuronide could be more susceptible to covalent binding to proteins via acyl migration than the corresponding antipode. The lability of the (R)-diastereomer over the antipode is consistent with previous reports on other profen glucuronides. Thus, the diastereomeric PA glucuronides are considered to be the best model compounds for the computation of structural physicochemical parameters to control the stereoselective internal acyl migration of profen glucuronides because PA has the simplest chemical structure of all the profens.

Decomposition of phenol and trichloroethylene by the ultrasound/H 2O 2/CuO process

The combination of sonolysis at 520 kHz and oxidation with H 2O 2 using heterogeneous catalysis was investigated in aqueous solution. To select a convenient heterogeneous catalyst, degradation of 100 mM H 2O 2 in the presence of 1 mg ml −1 Al 2O 3, ZnO, Ni 2O 3 and CuO was determined. The highest apparent first-order degradation rate was measured for CuO. The most intensive luminescence was observed as well with CuO, and therefore this metal oxide was used as heterogeneous catalyst. No effect of sonication was measured on the CuO-catalysed degradation of 100 mM H 2O 2, although sonication affects strongly the specific surface of the CuO-particles. The combination of sonolysis and oxidation with H 2O 2/CuO was tested on the degradation of the hydrophilic compound phenol and the hydrophobic volatile compound trichloroethylene (TCE). The degradation of phenol was slower than if additivity of both degradation mechanisms is assumed. Addition of CuO/H 2O 2 on the other hand did not enhance the degradation rate of TCE at all. TCE does not react with the radicals, probably superoxide radicals, formed by the CuO-catalysed H 2O 2 decomposition and the formation of cavitations is apparently not increased by adding CuO-particles.

Solubility and Stability of Lorazepam in Bile Salt/Soya Phosphatidylcholine–Mixed Micelles

In the present study, the solubility and stability of the drug lorazepam, which was solubilized in bile salt/soya phosphatidylcholine–mixed micelles (BS/SPC-MMs), were investigated. The solubility of lorazepam could be enhanced substantially in different bile salts and also in sugar ether, whereas the solubility in Pluronic F68 (Pl.F68) was of lower order. Moreover, the addition of SPC to different BS solutions greatly enhanced their solubilizing capacities toward lorazepam; this could be correlated with the ability of the formed MM to reduce the surface tension. The stability study showed that lorazepam degradation followed apparent first-order degradation kinetics in phosphate buffer, as well as in the BS/SPC-MM, with highly enhanced stability in the latter system. The stabilizing effect of BS/SPC-MM was higher in the case of trihydroxy BS than for dihydroxy BS. From an Arrhenius plot with degradation constants in a temperature range from 30°C to 60°C, a shelf stability of about 10 months could be calculated for BS/SPC-MM at 5°C. The solubility studies in BS/SPC-MM showed a recrystallization and a polymorphic transition from modification II to I.