Artur Teżyk

HPLC-MS/MS method for the simultaneous determination of clopidogrel, its carboxylic acid metabolite and derivatized isomers of thiol metabolite in clinical samples.

A fast and reproducible HPLC-MS/MS method was developed for the simultaneous determination of clopidogrel (CLP), its carboxylic acid derivative (CLPM), derivatized thiol metabolite isomers MP-H3 and the active MP-H4 in incurred human plasma. CLP, CLPM, MP-H3 and MP-H4 isomers together with the internal standard piroxicam were extracted from plasma samples using a simple protein precipitation with acetonitrile. The analytes were separated on HPLC Zorbax Plus C18 column via gradient elution with water and acetonitrile, both containing 0.1% (v/v) formic acid. Detection of the analytes were performed on a triple-quadrupole MS with multiple-reaction-monitoring via electrospray ionization. Calibration curves of the analytes prepared in 250μL plasma were found to be linear in ranges: 0.25-5.00ng/mL for CLP, 0.25-50.00ng/mL for MP-H3 and MP-H4 isomers and 50-10,000ng/mL for CLPM. The lower limit of quantitation was 0.25ng/mL for CLP, MP-H3, MP-H4 and 50.00ng/mL for CLPM. Intra- and inter-assay precision, expressed as relative standard deviation, was ≤18.1% for CLP, ≤15.2% for CLPM, ≤10.1% for MP-H3 and ≤19.9% for MP-H4. Intra- and inter-day accuracy of the method, expressed as relative error, was ≤16%. The analytes were stable in samples stored for 6h in autosampler, in plasma samples for 24h at room temperature and for 3 months at -25°C. Resolution of CLP, CLPM and MP-H3 and MP-H4 isomers of thiol metabolite during one analytical run was reported in patient plasma. The HPLC-MS/MS method was applied for pharmacokinetic studies of CLP and its metabolites in patients treated with daily dose of 75mg CLP.

Flubromazolam – A new life-threatening designer benzodiazepine

Abstract Context: In addition to designer benzodiazepines such as etizolam, deschloroetizolam, pyrazolam, diclazepam, nifoxipam, or clonazolam, a new psychoactive substance like flubromazolam, triazole of flubromazepam has become available. Flubromazolam is currently not marketed as a medication but rather as a research chemical and recreational drug. It mostly causes sedative effects but also has moderate anti-anxiety and muscle relaxant effects. A case of a severe intoxication of flubromazolam has been reported. Case details: A 27-year-old man, presented with deep coma, bilateral pinpoint unreactive pupils, acute respiratory failure and hypotension, complicated by hypoxic ischemic changes in the central nervous system. A positive result of a urine screening test confirmed the presence of benzodiazepines, which resulted in administration of flumazenil and improved patient consciousness. Quantitative method of liquid chromatography indicated flubromazolam in the patient’s serum at 59 ng/mL and urine at 105 ng/mL about 19 h after ingestion of 3 mg dose. On admission, serum creatine kinase was 15 960 U/L. The patient was treated with mechanical ventilation, intravenous fluids, flumazenil and continuous infusion of norepinephrine at a dose of 0.12 µg/kg/min. The patient survived and on the ninth day of hospitalization he was transferred to the Department of Neurology. Discussion: Flubromazolam is a new designer drug. Recreational use may be a cause of prolonged, severe intoxication associated with coma, hypotension, and rhabdomyolysis.

Rapid and sensitive liquid chromatography-tandem mass spectrometry method for determination of protein-free pro-drug treosulfan and its biologically active monoepoxy-transformer in plasma and brain tissue

For the first time a high performance liquid chromatography method with tandem mass spectrometry detection (HPLC-MS/MS) was developed for simultaneous determination of a pro-drug treosulfan (TREO) and its active monoepoxide (S,S-EBDM) in biological matrices. Small volumes of rat plasma (50 μL) and the brain homogenate supernatant (100 μL), equivalent to 0.02 g of brain tissue, were required for the analysis. Protein-free TREO, S,S-EBDM and acetaminophen, internal standard (IS), were isolated from the samples by ultrafiltration. Complete resolution of the analytes and the IS was accomplished on Zorbax Eclipse column using an isocratic elution with a mobile phase composed of ammonium formate - formic acid buffer pH 4.0 and acetonitrile. Detection was performed on a triple-quadrupole MS via multiple-reaction-monitoring following electrospray ionization. The developed method was fully validated according to the current guidelines of the European Medicines Agency. Calibration curves were linear in ranges: TREO 0.2-5720 μM and S,S-EBDM 0.9-175 μM for plasma, and TREO 0.2-29 μM and S,S-EBDM 0.4-44 μM for the brain homogenate supernatant. The limits of quantitation of TREO and S,S-EBDM in the studied matrices were much lower in comparison to the previously used bioanalytical methods. The HPLC-MS/MS method was adequately precise (coefficient of variation≤12.2%), accurate (relative error≤8.6%), and provided no carry-over, acceptable matrix effect as well as dilution integrity. The analytes were stable in acidified plasma and the brain homogenate supernatant samples for 4 h at room temperature, for 4 months at-80°C as well as within two cycles of freezing and thawing, and demonstrated 18-24h autosampler stability. The validated method enabled determination of low concentrations of TREO and S,S-EBDM in incurred brain samples of the rats treated with TREO, which constitutes a novel bioanalytical application.

Assessing circadian rhythms during prolonged midazolam infusion in the pediatric intensive care unit (PICU) children

BACKGROUND This study evaluates possible circadian rhythms during prolonged midazolam infusion in 27 pediatric intensive care unit (PICU) children under mechanical ventilation. METHODS Blood samples for midazolam and 1-OH-midazolam assay were collected throughout the infusion at different times of the day. The blood pressure, heart rate and body temperature were recorded every hour for the rhythms analysis. Population nonlinear mixed-effect modeling with NONMEM was used for data analysis. RESULTS A two-compartment model for midazolam pharmacokinetics and a one-compartment model for midazolam metabolite adequately described the data. The 24 h profiles of all monitored physiological parameters were greatly disturbed/abolished in comparison with the well-known 24 h rhythmic patterns in healthy subjects. There was no significant circadian rhythm detected with respect to midazolam pharmacokinetics, its active metabolite pharmacokinetics and all monitored parameters. CONCLUSIONS We concluded that the light-dark cycle did not influence midazolam pharmacokinetics in intensive care units children. Also, endogenous rhythms in critically ill and sedated children are severely disturbed and desynchronized. Our results confirmed that it is necessary to adjust the dose of midazolam to the patients body weight. The low value of midazolam clearances observed in our study was probably caused by mechanical ventilation, which was shown to decrease the cardiac output.

Direct high-performance liquid chromatography method with refractometric detection designed for stability studies of treosulfan and its biologically active epoxy-transformers

Treosulfan (TREO) is an alkylating agent registered for treatment of advanced platin-resistant ovarian carcinoma. Nowadays, TREO is increasingly applied iv in high doses as a promising myeloablative agent with low organ toxicity in children. Under physiological conditions it undergoes pH-dependent transformation into epoxy-transformers (S,S-EBDM and S,S-DEB). The mechanism of this reaction is generally known, but not its kinetic details. In order to investigate kinetics of TREO transformation, HPLC method with refractometric detection for simultaneous determination of the three analytes in one analytical run has been developed for the first time. The samples containing TREO, S,S-EBDM, S,S-DEB and acetaminophen (internal standard) were directly injected onto the reversed phase column. To assure stability of the analytes and obtain their complete resolution, mobile phase composed of acetate buffer pH 4.5 and acetonitrile was applied. The linear range of the calibration curves of TREO, S,S-EBDM and S,S-DEB spanned concentrations of 20-6000, 34-8600 and 50-6000 μM, respectively. Intra- and interday precision and accuracy of the developed method fulfilled analytical criteria. The stability of the analytes in experimental samples was also established. The validated HPLC method was successfully applied to the investigation of the kinetics of TREO activation to S,S-EBDM and S,S-DEB. At pH 7.4 and 37 °C the transformation of TREO followed first-order kinetics with a half-life 1.5h.

Determination of prodrug treosulfan and its biologically active monoepoxide in rat plasma, liver, lungs, kidneys, muscle, and brain by HPLC–ESI–MS/MS method

&NA; A prodrug treosulfan (TREO) is currently investigated in clinical trials for conditioning prior to hematopoietic stem cell transplantation. Bioanalysis of TREO and its active derivatives, monoepoxide (S,S‐EBDM) and diepoxide, in plasma and urine underlay the pharmacokinetic studies of these compounds but cannot explain an organ pharmacological action or toxicity. Recently, distribution of TREO and S,S‐EBDM into brain, cerebrospinal fluid, and aqueous humor of the eye has been investigated in animal models and the obtained results presented clinical relevance. In this paper, a selective and rapid HPLC–ESI–MS/MS method was elaborated and validated for the studies of disposition of TREO and S,S‐EBDM in rat plasma, liver, lungs, kidneys, muscle, and brain. The two analytes and codeine, internal standard (IS), were isolated from 50 &mgr;L of plasma and 100 &mgr;L of supernatants of the tissues homogenates using ultrafiltration Amicon vials. Chromatographic resolution was accomplished on C18 column with isocratic elution. The limits of quantitation of TREO and S,S‐EBDM in the studied matrices ranged from 0.11 to 0.93 &mgr;M. The HPLC–MS/MS method was adequately precise and accurate within and between runs. The IS‐normalized matrix effect differed among the tissues and was the most pronounced in a liver homogenate supernatant (approximately 0.55 for TREO and 0.35 for S,S‐EBDM). Stability of the analytes in experimental samples was also established. The validated method for the first time enabled determination of TREO and S,S‐EBDM in the six life‐important tissues in rats following administration of the prodrug. HighlightsRapid and simple HPLC–MS/MS method to quantify treosulfan and its active monepoxide.Enables to study the distribution of the analytes from rat plasma into five tissues.The analytes levels in liver, lung, kidney, and muscle reported for the first time.

Synthesis, Biological Evaluation, and Docking Studies of trans-Stilbene Methylthio Derivatives as Cytochromes P450 Family 1 Inhibitors

Cytochromes P450 family 1 (CYP1) are responsible for the metabolism of procarcinogens, for example polycyclic aromatic hydrocarbons and aromatic and heterocyclic amines. The inhibition of CYP1 activity is examined in terms of chemoprevention and cancer chemotherapy. We designed and synthesized a series of trans‐stilbene derivatives possessing a combination of methoxy and methylthio functional groups attached in different positions to the trans‐stilbene skeleton. We determined the effects of synthesized compounds on the activities of human recombinant CYP1A1, CYP1A2 and CYP1B1 and, to explain the variation of inhibitory potency of methoxystilbene derivatives and their methylthio analogues, we employed computational analysis. The compounds were docked to CYP1A1, CYP1A2 and CYP1B1 binding sites with the use of Accelrys Discovery Studio 4.0 by the CDOCKER procedure. For CYP1A2 and CYP1B1, values of scoring functions correlated well with inhibitory potency of stilbene derivatives. All compounds were relatively poor inhibitors of CYP1A2 that possess the most narrow and flat enzyme cavity among CYP1s. For the most active CYP1A1 inhibitor, 2‐methoxy‐4′‐methylthio‐trans‐stilbene, a high number of molecular interactions was observed, although the interaction energies were not distinctive.

Analgesic efficacy and safety of epidural oxycodone in patients undergoing total hip arthroplasty: a pilot study.

Background and objectives Oxycodone is poorly studied as an adjuvant to central blockades. The aim of this pilot study was to assess the efficacy and safety of oxycodone hydrochloride in epidural blockade among patients undergoing total hip arthroplasty (THA). Patients and methods In 11 patients (American Society of Anesthesiologists physical status classification system II/III, age range: 59–82 years), THA was conducted with an epidural blockade using 15 mL 0.25% bupivacaine (37.5 mg) with 5 mg oxycodone hydrochloride and sedation with propofol infusion at a dose of 3–5 mg/kg/h. After the surgery, patients received ketoprofen at a dose of 100 mg twice daily. In the first 24 hours postoperative period, pain was assessed by numerical rating scale at rest and on movement; adverse effects (AEs) were recorded; and plasma concentrations of oxycodone, noroxycodone, and bupivacaine were measured. Results The administration of epidural oxycodone at a dose of 5 mg in patients undergoing THA provided analgesia for a mean time of 10.3±4.89 h. In one patient, mild pruritus was observed. Oxycodone did not evoke other AEs. Plasma concentrations of oxycodone while preserving analgesia were >2.9 ng/mL. Noroxycodone concentrations in plasma did not guarantee analgesic effect. Conclusion The administration of epidural oxycodone at a dose of 5 mg prolongs the analgesia period to ~10 hours in patients after THA. Oxycodone may evoke pruritus. A 5 mg dose of oxycodone hydrochloride used in an epidural blockade seems to be a safe drug in patients after THA.

Post-Injection Delirium/Sedation Syndrome after Olanzapine Long-Acting Intramuscular Injection – Who is at Risk?

The post‐injection olanzapine delirium/sedation syndrome (PDSS) was observed in a 60‐year‐old Caucasian, schizophrenic, non‐smoker and underweight [body mass index (BMI), 18.2 kg/m2] women after the fourth intramuscular injection of 405 mg olanzapine pamoate. Clinical symptoms of PDSS were similar to those of acute oral olanzapine intoxication. The patient received supportive treatment and recovered fully. High olanzapine concentrations in serum, with maximum level of 698 ng/mL, were confirmed by liquid chromatography with tandem mass spectrometry (LC‐MS/MS). The authors wonder whether a low BMI and advanced age may predispose patients to PDSS occurrence.

New fluphenazine analogue with antimutagenic and anti-multidrug resistance activity—degradation profile and stability-indicating method

Hydrochloride of 10-{2-hydroxy-3-[N,N-bis-(2-hydroxyethyl)amino]propyl}-2-trifluoromethylphenothiazine (Flu-A) is a analogue of neuroleptic fluphenazine. Flu-A exhibits anti-multidrug resistance, antimutagenic, proapoptopic, and cancer-chemopreventive activities in screening studies. To define identity, quality, and purity of new active substance it is necessary to develop a appropriate analytical method and to establish a degradation profile. Thus, a stability-indicating reversed-phase high-performance liquid chromatography method was developed and validated for quantitative determination of Flu-A in the presence of its degradation products generated under stress conditions. The compound was subjected to oxidation, photolysis, and degradation in aqueous solutions (neutral and acidic), and solid state according to the International Council for Harmonisation Guidelines. The method was also found to be suitable for intermediate and accelerated studies and for the evaluation of kinetic mechanism of Flu-A degradation in aqueous solutions (pH 5.1–7.5, 353 K). The structures of main potential degradation products were established using high-performance liquid chromatography-Electrospray Ionization-mass spectrometry method.