Evaluation of Antipsychotic Drugs' Stability in Oral Fluid Samples.

Antipsychotics have narrow therapeutic windows, and their monitoring in biological fluids is therefore important; consequently, stability in those fluids must be investigated during method development and validation. This work evaluates the stability of chlorpromazine, levomepromazine, cyamemazine, clozapine, haloperidol, and quetiapine in oral fluid (OF) samples, using the dried saliva spots (DSS) sampling approach and gas chromatography coupled to tandem mass spectrometry. Since many parameters can influence the stability of the target analytes, design of experiments was adopted to check the crucial factors that affect that stability in a multivariate fashion. The studied parameters were the presence of preservatives at different concentrations, temperature, light, and time. It was possible to observe that antipsychotic stability improved when OF samples in DSS were stored at 4 °C, with a low ascorbic acid concentration, and in the absence of light. With these conditions, chlorpromazine and quetiapine were stable for 14 days, clozapine and haloperidol were stable for 28 days, levomepromazine remained stable for 44 days, and cyamemazine was stable for the entire monitored period (146 days). This is the first study that evaluates the stability of these antipsychotics in OF samples after application to DSS cards.

Chiral separation of four phenothiazines by nonaqueous capillary electrophoresis and quality by design-based method development for quantification of dextromepromazine as chiral impurity of levomepromazine.

The separation of the enantiomers of mepromazine, promethazine, thioridazine and alimemazine was studied by nonaqueous capillary electrophoresis in the presence of cyclodextrins using 1 M acetic acid and 50 mM ammonium acetate in methanol as background electrolyte. Heptakis(2,3-di-O-acetyl-6-O-sulfo)-ß-cyclodextrin, heptakis(2,3-di-O-methyl-6-O-sulfo)-ß-cyclodextrin (HDMS-ß-CD) and octakis(2,3-di-O-methyl-6-O-sulfo)-γ-cyclodextrin were the most effective chiral selectors for mepromazine, promethazine and alimemazine. Subsequently, a method for the determination of dextromepromazine as chiral impurity of levomepromazine was developed employing quality by design principles. Using HDMS-ß-CD as selector, a fractional factorial resolution V+ design was employed for evaluating the knowledge space, while a central composite face centered design provided further method optimization and the basis for the computation of the design space by Monte Carlo simulations. The final experimental conditions included a 30/40.2 cm fused-silica capillary with 75 µm inner diameter and a background electrolyte composed of 0.75 M acetic acid and 55 mM ammonium acetate in methanol containing 27.5 mg/mL HDMS-ß-CD. The applied voltage was 22 kV and the capillary temperature was 15°C. Following method robustness testing via a Plackett-Burman design, the method was validated for dextromepromazine in the range of 0.01 to 3.0 % relative to a concentration of 0.74 mg/mL levomepromazine and applied to the analysis of reference standards of the European Pharmacopoeia and commercial tablets. The assay also allowed the detection of levomepromazine sulfoxide although the quantitation of the compound was hampered by the poor peak shape of the late migrating diastereomer.

Simultaneous determination of dextromepromazine and related substances 2-methoxyphenothiazine and levomepromazine sulfoxide in levomepromazine on a cellulose tris(4-methylbenzoate) chiral column.

A high-performance liquid chromatography method for the determination of dextromepromazine, levomepromazine sulfoxide and 2-methoxyphenothiazine in levomepromazine samples was developed. The separation of the analytes was achieved within 10 min on a stationary phase containing cellulose tris(4-methylbenzoate) as chiral selector. The mobile phase consisted of 0.1% diethylamine in methanol with a flow rate of 1.0 mL/min. The method was validated according to the International Council for Harmonization guideline Q2(R1). The detection limits based on a signal-to-noise ratio of 3 were in the range of 0.002 to 0.005 µg/mL. The method proved to be precise and accurate in the concentration range of 0.025-1.0 % for levomepromazine sulfoxide and 2-methoxyphenothiazine and 0.025% to 3.0% for dextromepromazine relative to a concentration of 0.1 mg/mL of levomepromazine, with the exception of levomepromazine sulfoxide at the 0.1% level. The method was subsequently applied to the analysis of finished pharmaceutical products as well as of reference substances of the European Pharmacopoeia.

Forensic toxicological analyses of drugs in tissues in formalin solutions and in fixatives.

Forensic toxicological drug analyses of human specimens are usually performed immediately after autopsy or on frozen preserved tissues. Occasionally, cases require analysis of drugs from tissues fixed in formalin solution. To improve the estimation of the level of drug in tissues following formalin fixation, we studied drug concentrations in human tissues, liver and kidney, that were collected from a drug-positive autopsy case. Parts of tissues were preserved in formalin solution for 1, 3, 6 and 13 months. Tissues obtained before and after preservation, along with tissue-exposed fixatives, were assayed using gas chromatography-mass spectrometry; all of the samples were assayed for the presence of drugs and changes in the drug concentrations both before and after preservation in formalin. Concentrations of assayed drugs decreased upon fixation in formalin; levels of these drugs did not necessarily show further decreases during subsequent storage in fixative, up to 13 months. Distinct trends in drug levels were found in liver and kidney. In liver, the levels of chlorpromazine, levomepromazine, and promethazine decreased to 23-39% at 1 month after preservation; all 3 of these drugs were detected at all tested time points of preservation. Bromazepam was not detected at 13 months after preservation. Milnacipran was the most unstable after preservation in formalin solution among all of the assayed drugs. In kidney, all assayed drugs exhibited reduced stability during preservation compared to levels in liver. Methamphetamine and methylenedioxymethamphetamine were not detected in any time points of tissues. The proportions of the drugs that remained within the tissues differed between liver and kidney. Also, S-oxide compounds of chlorpromazine and levomepromazine, which were not observed before preservation, were detected in fixed liver tissues and their fixatives at 3, 6 and 13 months of preservation. These results suggest that analyses in formalin-fixed tissues need to include analysis of various organ-tissues and their fixatives at multiple time points for the duration of preservation. These analyses should include detection of chemical degradation/denaturation products, such as S-oxides of chlorpromazine and levomepromazine.

An application of UV-derivative spectrophotometry and bivariate calibration algorithm for study of photostability of levomepromazine hydrochloride.

Derivative spectrophotometry and bivariate calibration algorithm were used for study of run of photooxidation of levomepromazine hydrochloride (LV). The actual concentrations of LV and its main degradation product levomepromazine sulphoxide (LV-SO) were calculated using data provided by applied methods. The direct reading of absorbance values at 302 nm and 334 nm were employed for quantification of LV and LV-SO, respectively, in the case of bivariate method. The derivative spectrophotometric method is based on transformation of zero-order spectra into first derivative. The values of first derivative at 334 nm were used for quantification of LV while at 278 nm for assay of LV-SO. The obtained quantitative data were applied for investigation of kinetics of photodegradation of LV.

Fatal acute topiramate toxicity.

A 44-year-old Caucasian female was found dead in bed. Qualitative screening detected ethanol, phenobarbital, and methotrimeprazine. However, none were sufficient to attribute as the cause of death. Additionally, high concentrations of topiramate, an antiepilieptic agent, were found. Analysis of available biological fluids and tissues was carried out with the following results: blood (central) 170 mg/L, liver 140 mg/kg, stomach contents greater than 300 mg, and vitreous fluid 65 mg/L. The cause of death was ascribed to topiramate overdose.

Determination of methotrimeprazine in pharmaceutical preparations by visible spectrophotometry.

A spectrophotometric method is described for determination of methotrimeprazine (levomepromazine). The aim of this work was to develop a simple, rapid, precise, and accurate visible spectrophotometric method for determination of methotrimeprazine in tablet, oral solution, and injection. The method is based on methotrimeprazine reaction with bromophenol blue, resulting in a stable, light yellow-green ion-pair complex that, after extraction with chloroform, presented maximum absorption at 409 nm. Beer's law was obeyed in the concentration range from 5.0 to 25.0 micrograms/ml. The proposed standardized method was applied to commercially available and simulated samples. The accuracy of the method was confirmed by recovery tests.

High performance liquid chromatographic determination of levomepromazine in human breast milk and serum using solid phase extraction.

A high performance liquid chromatographic (HPLC) method has been developed for the determination of levomepromazine in human breast milk and serum. The levomepromazine was extracted by a rapid and simple extraction method using a Sep-Pak C18 cartridge. The extracts were separated by HPLC on a C8 bonded reversed phase column and detected by UV absorbance at 254 nm. There was no interference with endogenous substance in human breast milk and serum. A linear relationship was obtained for the levomepromazine over the concentration range of 10-300 ng/mL. The recoveries of levomepromazine added to human breast milk and serum were 92.5-99.1% and 86.9-103.9%, respectively.

High-performance liquid chromatography of levomepromazine (methotrimeprazine) and its main metabolites.

The phenothiazine drug levomepromazine (methotrimeprazine) has five metabolites which previously have been identified in plasma from psychiatric patients. These are formed by sulphoxidation, N-demethylation, O-demethylation and aromatic hydroxylation in two different positions. A high-performance liquid chromatographic system is described for the analysis of levomepromazine and its main metabolites on a Supelcosil C18-DB column, based on ion-pair formation with sodium docecyl sulphate. The effects of variations in pH, buffer concentration, counter-ion concentration, temperature and concentration and composition of the organic solvent were examined. The six components may be analysed in 27.4 min at room temperature using 25 mM sodium dodecyl sulphate in 500 mM ammonium acetate buffer (pH 5.0)-5% v/v tetrahydrofuran in acetonitrile (50:50, v/v) as the mobile phase.

Fly larvae and their relevance in forensic toxicology.

Toxicological analyses on a putrefied cadaver are sometimes difficult to perform because of the absence of blood and urine. In this study, fly larvae, being living material, are proposed as a new medium of investigation in forensic toxicology. Bromazepam and levomepromazine were identified and assayed in the remains of cerebral tissue, in the clavicle of a putrefied cadaver, and in the fly larvae found on and in the corpse.

Identification of nonpolar methotrimeprazine metabolites in plasma and urine by GLC-mass spectrometry.

Two metabolites of methotrimeprazine, the sulfoxide and the demethylated analog, were identified in extracts from patient plasma by combined GLC-mass spectrometry. Methotrimeprazine and its sulfoxide had similar mass spectra but different GLC retention times. In addition to the metabolites found in plasma, two other metabolites, the didesmethyl analog and the monodesmethyl sulfoxide, were identified in a urine extract.

Metabolism of phenothiazines: identification of N-oxygenated products by gas chromatography and mass spectrometry.

The solid inlet mass spectra of the N-oxide and N-oxide sulphoxide metabolites of promazine, chlorpromazine and methotrimeprazine have been determined at different temperatures and compared with the mass spectra of the main thermolytic product of the N-oxides and N-oxide sulphoxides obtained during combined gas chromatography-mass spectrometry. Diagnostic ions were produced by direct insertion of the compounds at ambient temperature into the mass spectrometer. These ions distinguish the N-oxides of arylalkyl tertiary amines from the N-oxygenated derivatives of primary and secondary arylalkylamines.