Simultaneous determination of dorzolomide and timolol in aqueous humor: A novel salting out liquid–liquid microextraction combined with HPLC

Mohamed, Abdel‐Maaboud I.; Abdel-Wadood, Hanaa M.; Mousa, Heba Salah

doi:10.1016/j.talanta.2014.06.074

Cited by 30 publications

(10 citation statements)

References 20 publications

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“…A possible explanation for this elevated adsorption could be a “salting out” effect, a phenomenon which causes the solubility of nonelectrolytes to decrease in the presence of high salt concentrations. The high affinity for water of the salt molecules causes a dehydration of the TOrCs, decreasing their solubility, a process which is often used in the extraction of various organic components. , In this experiment, the high salinity of the dilute compartment forces the membranes into the low salinity compartment, where their solubility is higher. This causes more TOrC-membrane contact, increasing the adsorption of neutral compounds onto the membrane.…”

Section: Resultsmentioning

confidence: 99%

Properties Governing the Transport of Trace Organic Contaminants through Ion-Exchange Membranes

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Bakelants

Gaublomme

et al. 2014

Environ. Sci. Technol.

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Ion exchange membranes could provide a solution to the selective separation of organic and inorganic components in industrial wastewater. The phenomena governing the transport of organics through the IEM however, are not yet fully understood. Therefore, the transport of trace organic contaminants (TOrCs) as a model for a wide variety of organic compounds was studied under different conditions. It was found that in the absence of salt and external potential, the chemical equilibrium is the main driver for TOrC-transport, resulting in the transport of mainly charged TOrCs. When salt is present, the transport of TOrCs is hampered in favor of the NaCl transport, which shows a preferential interaction with the membranes due to its small size, high mobility and concentration. It is hypothesized that electrostatic interactions and electron donor/acceptor interactions are the main drivers for TOrC transport and that transport is mainly diffusion driven. This was confirmed in the experiments with different current densities, where the external potential seemed to have only a minor influence on the transport of TOrCs. It is only when the salt becomes nearly completely depleted that the TOrCs are transported as charge carriers. This shows that it is very difficult to get preferential transport of organic compounds due to the diffusive nature of their transport.

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Section: Resultsmentioning

confidence: 99%

Properties Governing the Transport of Trace Organic Contaminants through Ion-Exchange Membranes

Vanoppen

Bakelants

Gaublomme

et al. 2014

Environ. Sci. Technol.

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“…For example, Wabuyele et al used SALLE to determine securinine in mouse plasma, 27 and Mohamed et al analyzed anti-glaucoma drugs in aqueous humor samples. 28 Recent examples of miniaturized QuEChERS have also been reported. For example, Gonzalo-Lumbreras et al miniaturized the QuEChERS technique to determine triclosan and its metabolite in fish roe and surimi, 23 while Walorczyk and Drozdzynski used miniaturized QuEChERS to determine 140 pesticides in fruits and vegetables.…”

Section: Resultsmentioning

confidence: 99%

QuEChERS-based approach toward the analysis of two insecticides, methomyl and aldicarb, in blood and brain tissue

et al. 2015

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QuEChERS has been widely utilized for the analysis of pesticides in produce, but it has not been as widely used in clinical test specimens, especially for smaller, sub-gram sample sizes. This study describes the application of a miniaturized QuEChERS methodology toward the analysis of two insecticides, methomyl and aldicarb, in guinea pig blood and brain tissue. Matrix effects and absolute recoveries were investigated for both analytes in the two matrices. While the matrix effects of methomyl in both matrices were minimal at most levels (i.e., from −20% to 20%), aldicarb experienced signal suppression under the described conditions (mean of −47%). However, the matrix effects were not cause for concern due to the sensitivity of the method and the use of matrix-matched standards. The precision and accuracy of the method were excellent over a range of concentrations that spanned three orders of magnitude. The limits of detection (LOD) for both carbamates were determined to be 0.1 ng mL−1 in blood and 0.2 ng g−1 in brain. Other validation parameters, such as linearity, accuracy, precision, and recovery, were also satisfactory in the blood and brain tissue. This method was demonstrated to be sensitive and reproducible, and it should be applicable to the analysis of a wide range of compounds of interest in sub-gram- and sub-milliliter-sized clinical and toxicology specimens.

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“…The rabbits’ eyelids were kindly kept closed for few seconds to prevent dose drainage. After anesthetizing the animals using intramuscularly injected ketamine hydrochloride (50 mg/kg) and xylazine (10 mg/kg), samples of the aqueous humor (50 μl) were withdrawn at the following time intervals: 1, 2, 4, 6, 8, 24 h, using insulin syringe equipped with 29 gauge [ 19 ]. Samples were frozen at -20°C till the time of analysis.…”

Section: Methodsmentioning

confidence: 99%

“…Before analysis, the aqueous humor samples containing DH were mixed with the internal standard solution (Mepivacaine hydrochloride, 50 μg/mL) in ratio 5:1 v/v, and then extracted using acetonitrile (HPLC grade) [ 19 ]. The organic phase was separated, dried under vacuum using vacuum concentrator (Eppendorf 5301; Hamburg, Germany) and reconstituted by a mobile phase composed of acetonitrile: potassium dihydrogen phosphate (30 mMol) containing 0.1% triethanolamine, pH 3.5, mixed in ratio 20:80 v/v as shown in Figure A in S1 File .…”

Section: Methodsmentioning

confidence: 99%

Enhancement of pharmacokinetic and pharmacological behavior of ocular dorzolamide after factorial optimization of self-assembled nanostructures

et al. 2018

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Dorzolamide hydrochloride is frequently administered for the control of the intra-ocular pressure associated with glaucoma. The aim of this study is to develop and optimize self-assembled nanostructures of dorzolamide hydrochloride and L-α-Phosphatidylcholine to improve the pharmacokinetic parameters and extend the drug pharmacological action. Self-assembled nanostructures were prepared using a modified thin-film hydration technique. The formulae compositions were designed based on response surface statistical design. The prepared self-assembled nanostructures were characterized by testing their drug content, particle size, polydispersity index, zeta potential, partition coefficient, release half-life and extent. The optimized formulae having the highest drug content, zeta potential, partition coefficient, release half-life and extent with the lowest particle size and polydispersity index were subjected to further investigations including investigation of their physicochemical, morphological characteristics, in vivo pharmacokinetic and pharmacodynamic profiles. The optimized formulae were prepared at pH 8.7 (F5 and F6) and composed of L-α-Phosphatidylcholine and drug mixed in a ratio of 1:1 and 2:1 w/w, respectively. They showed significantly higher Cmax, and at the aqueous humor with extended control over the intra-ocular pressure, when compared to the marketed product; Trusopt®. The study introduced novel and promising self-assembled formulae able to permeate higher drug amount through the cornea and achieve sustained pharmacological effect at the site of action.

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Simultaneous determination of dorzolomide and timolol in aqueous humor: A novel salting out liquid–liquid microextraction combined with HPLC

Cited by 30 publications

References 20 publications

Properties Governing the Transport of Trace Organic Contaminants through Ion-Exchange Membranes

Properties Governing the Transport of Trace Organic Contaminants through Ion-Exchange Membranes

QuEChERS-based approach toward the analysis of two insecticides, methomyl and aldicarb, in blood and brain tissue

Enhancement of pharmacokinetic and pharmacological behavior of ocular dorzolamide after factorial optimization of self-assembled nanostructures

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