Studies of drug interactions with alpha1-acid glycoprotein by using on-line immunoextraction and high-performance affinity chromatography.

A method that combined on-line immunoextraction with high-performance affinity chromatography was developed to examine the binding of drugs with α1-acid glycoprotein (AGP). Affinity microcolumns containing immobilized polyclonal anti-AGP antibodies were developed that had a capture efficiency of up to 98.4% for AGP and a binding capacity of 0.72nmol AGP when using a 20mm×2.1mm i.d. microcolumn. These microcolumns were employed in various formats to examine the binding of drugs to normal AGP and AGP that had been adsorbed from serum samples for patients with systemic lupus erythematosus (SLE). Drugs that were screened in zonal elution experiments for their overall binding to these types of AGP included chlorpromazine, disopyramide, imipramine, propranolol, and warfarin. Most of these drugs showed an increase in their binding to the AGP from SLE serum when compared to normal AGP (i.e., an increase of 13-76%); however, disopyramide gave a 21-25% decrease in retention when the same AGP samples were compared. Frontal analysis was used to further evaluate the binding of disopyramide and imipramine to these forms of AGP. Both drugs gave a good fit to a model that involved a combination of saturable and non-saturable interactions with AGP. Changes in the non-saturable interactions accounted for most of variations seen in the binding of disopyramide and imipramine with the AGP samples. The methods used in this study could be adapted for use in personalized medicine and the study of other proteins or drugs using aqueous mixtures or clinical samples.

Rapid determination of some psychotropic drugs in complex matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography.

Simple and rapid determinations of some psychotropic drugs in some pharmaceutical wastewater and human plasma samples were successfully accomplished via the tandem dispersive liquid-liquid microextraction combined with high performance liquid chromatography-ultraviolet detection (TDLLME-HPLC-UV). TDLLME of the three psychotropic drugs clozapine, chlorpromazine, and thioridazine was easily performed through two consecutive dispersive liquid-liquid microextractions. By performing this convenient method, proper sample preconcentrations and clean-ups were achieved in just about 7min. In order to achieve the best extraction efficiency, the effective parameters involved were optimized. The optimal experimental conditions consisted of 100µL of CCl4 (as the extraction organic solvent), and the pH values of 13 and 2 for the donor and acceptor phases, respectively. Under these optimum experimental conditions, the proposed TDLLME-HPLC-UV technique provided a good linearity in the range of 5-3000ngmL-1 for the three psychotropic drugs with the correlation of determinations (R2s) higher than 0.996. The limits of quantification (LOQs) and limits of detection (LODs) obtained were 5.0ngmL-1 and 1.0-1.5ngmL-1, respectively. Also the proper enrichment factors (EFs) of 96, 99, and 88 for clozapine, chlorpromazine, and thioridazine, respectively, and good extraction repeatabilities (relative standard deviations below 9.3%, n=5) were obtained.

Extraction and determination of trace amounts of chlorpromazine in biological fluids using hollow fiber liquid phase microextraction followed by high-performance liquid chromatography.

In the present work, hollow fiber liquid phase microextraction (HF-LPME) in conjunction with reversed-phase HPLC/UV was developed for extraction and determination of trace amounts of chlorpromazine in biological fluids. The drug was extracted from an 11 ml aqueous sample (source phase; SP) into an organic phase impregnated in the pores of the hollow fiber (membrane phase; MP) followed by the back-extraction into a second aqueous solution (receiving phase; RP) located in the lumen of the hollow fiber. The effects of several factors such as the nature of organic solvent, compositions of SP and RP solutions, extraction time, ionic strength and stirring rate on the extraction efficiency of the drug were examined and optimized. Under the optimal conditions, enrichment factor of 250, dynamic linear range of 1-500 microgl(-1), and limit of detection of 0.5 microgl(-1) were obtained for the drug. The percent relative intra-day and inter-day standard deviation (R.S.D.%) based on three replicate determinations were 6.7 and 10.3%, respectively. The method was applied to drug level monitoring in the biological fluids and satisfactory results were obtained.

High-performance liquid chromatography of some basic drugs on a n-octadecylphosphonic acid modified magnesia-zirconia stationary phase.

The high-performance liquid chromatographic behavior of some basic drugs was studied on a n-octadecylphosphonic acid modified magnesia-zirconia (C18PZM) stationary phase. The effect of mobile phase variables such as methanol content, ionic strength, and pH on their chromatographic behavior was investigated. The retention mechanism of basic drugs on the stationary phase was elucidated. The results indicate that both hydrophobic and cation-exchange interactions contribute to solute retention under most chromatographic conditions. The inherent Brönsted-acid sites and also the adsorbed Lewis base anionic buffer constituents on accessible ZM surface Lewis acid sites play a role in the retention of ionized solutes by cation-exchange interaction. However, especially at high mobile phase pH, the retention of basic drugs depends mainly on hydrophobic interactions between solutes and support. Separations of the basic drugs on the C18PZM phase by a predominantly reversed-phase retention mode were very promising. The mixed-mode retention feature on this phase, as a result of the adsorbed Lewis base anionic buffer constituents acting as sites for cation-exchange, could also be very useful, e.g. for enhancing the chromatographic selectivity of such analytes. The C18PZM seems to be an excellent alternative to silica-based reversed-phase stationary phase for the separation of strongly basic solutes.

[Determination of epinephrine, chlorpromazine and promethazine by capillary electrophoresis with scanning voltammetric detector].

With a self-constructed electrochemical detection system, the determination of epinephrine, chlorpromazine and promethazine has been studied by using capillary electrophoresis with scanning voltammetric detector. Scanning potential generation and data acquisition were carried out with D/A and A/D converter board that mounted on a 486DX66 computer. A complex software, which was written by authors in BORLAND C++, was serve to data acquisition, abstraction of three-dimension data, display and print of the electrophorograms. Using a 25 microns x 70 cm fused-silica capillary, the optimum conditions for separation and detection of titled drugs are 10 mmol/L K2HPO4 + H3PO4 (pH 3.0) running electrolyte, 20 kV separation voltage, hydrodynamic injection 10 s at 20 cm height, scanning potential from +0.4 to +1.0 V vs. SCE. With the optimizing condition, the separation of titled drugs is satisfactory, and good reproducibility and low limit are obtained. In this study, all experiments are carried out under air-conditioning (18 degrees C) and constant humidity (relative humidity 50%). In comparison to amperometric detection, scanning voltammetric detection has the advantages of minimizing fouling of the working electrode surface, and direct identification of unknown chemicals by voltammetric curves.

Development of a melanin-based high-performance liquid chromatography stationary phase and its use in the study of drug-melanin binding interactions.

Drug-melanin interactions were studied using a melanin-based HPLC column. Two approaches were chosen for the preparation of the stationary phases: covalent coupling of synthetic L-dopa melanin and in situ polymerization of L-dopa. Retention of a series of phenothiazines on melanin-based stationary phases was attributed to binding to melanin. Frontal affinity chromatography experiments on one melanin-based column allowed us to calculate the affinity and binding capacity of chlorpromazine and promethazine. A competition was observed between chlorpromazine and haloperidol which was qualitatively consistent with previously described results. Data indicated that the interaction was not a simple competition at one site.

Immunoassay reagents for psychoactive drugs. Part 3. Removal of phenothiazine interferences in the quantification of tricyclic antidepressants.

Phenothiazines and their metabolites are known to interfere in the quantification of tricyclic antidepressants (TCAs). A method for selective chemical modification of phenothiazines by chloramine-T in the presence of TCAs is described. This method allows for accurate quantification of the TCA analyte in a serum sample without interference from the modified phenothiazine.

[The comparative characteristics of the extractive capacity of solvents in removing aminazine from liver tissue]. / Sravnitel'naia kharakteristika ékstragiruiushchei sposobnosti nekotorykh rastvoritelei pri izvlechenii aminazina iz tkani pecheni.

Comparative assessment of extractive ability of some solvents with different physical and chemical properties is presented. Use of amphiphilic solvent acetone to isolate aminazine gave higher results. Experimental works (on dogs) showed that use of aqueous acid solutions for aminazine extraction in chemical toxicological investigation is unsuitable.

Reversed-phase liquid chromatography for the separation of chloropromazine, imipramine and some of their metabolites.

Reversed-phase liquid chromatography on a C18 bonded silica with water-alcohol mixtures containing decylamine as the mobile phase was investigated for its applicability to the separation of chlorpromazine, imipramine and their metabolites. The addition of decylamine to the mobile phase was found to be necessary in order to obtain symmetrical peaks. The influence of the decylamine and ethanol concentrations and of the pH of the mobile phase was investigated and these parameters were found to be useful for the adjustment of the retention. The phase system developed was found to be suitable for the required separation. The phase system was applied to the analysis of imipramine and its metabolites, desmethylimipramine and didesmethylimipramine, and desmethylchlorpromazine in human plasma.