A Review of Wastewater-Based Epidemiology Studies for the Assessment of Over-the-Counter Medicines Used as Recreational Drugs: The Example of Dextromethorphan.

The 'recreational use' of selected over-the-counter (OTC) medicines is an unofficial activity. The traditional surveys assessing the use of drugs are affected by the bias of underreporting and are thus unreliable. The development of analytical techniques helps to monitor the substances at trace levels, such as in wastewater, and might be applied to estimate the consumption of an analyte of interest and ensure additional, evidence-based information complementary to population surveys. We reviewed studies focused on evaluating the estimated consumption of drugs as a reliable and unbiased source of evidence-based information (called wastewater-based epidemiology, WBE) to monitor the scale of this phenomenon. We found there is a need to test not only narcotics in the environment but also medicines that may be abused or recreationally used. The reviewed studies show methods that might provide reliable information about consumption of drugs, narcotics, and OTC medications for proposing targeted, preventive actions. Moreover, as all the selected studies were based on mass spectrometry, there is a potential to include the dextromethorphan and/or related compounds as part of the screening for narcotics and OTC drugs that can be socially harmful, overused, or misused. This article reviews the analytical methods for detecting dextromethorphan and/or its transformation products in environmental water samples.

Serum Proteomic Profiles of Patients with High and Low Risk of Endometrial Cancer Recurrence.

Endometrial cancer is the most common gynecological cancer worldwide. Classifying endometrial cancer into low- or high-risk groups based on the following features is recommended: tumor grade, lymphovascular space invasion, myometrial involvement, and non-endometrioid histology. Despite the recent progress in molecular profiling of endometrial cancer, a substantial group of patients are misclassified based on the current criteria. This study aimed to identify proteins that could be used as biomarkers for the stratification of endometrial cancer patients into low- or high-risk groups. The proteomic analysis of serum samples from endometrial cancer patients was performed using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The data were then analyzed using chemometric algorithms to identify potential biomarkers. Nineteen precursor ions were identified as fragments of eighteen proteins which included (1) connective tissue matrix proteins, (2) cytoskeletal proteins, and (3) innate immune system molecules and stress proteins. These biomarkers could be used to stratify the high- and low-risk patients, thus enabling more precise treatment decisions.

Mass spectrometry imaging in gynecological cancers: the best is yet to come.

Mass spectrometry imaging (MSI) enables obtaining multidimensional results simultaneously in a single run, including regiospecificity and m/z values corresponding with specific proteins, peptides, lipids, etc. The knowledge obtained in this way allows for a multifaceted analysis of the studied issue, e.g., the specificity of the neoplastic process and the search for new therapeutic targets. Despite the enormous possibilities, this relatively new technique in many aspects still requires the development or standardization of analytical protocols (from collecting biological material, through sample preparation, analysis, and data collection, to data processing). The introduction of standardized protocols for MSI studies, with its current potential to extend diagnostic and prognostic capabilities, can revolutionize clinical pathology. As far as identifying ovarian cancer subtypes can be challenging, especially in poorly differentiated tumors, developing MSI-based algorithms may enhance determining prognosis and tumor staging without the need for extensive surgery and optimize the choice of subsequent therapy. MSI might bring new solutions in predicting response to treatment in patients with endometrial cancer. Therefore, MSI may help to revolutionize the future of gynecological oncology in terms of diagnostics, treatment, and predicting the response to therapy. This review will encompass several aspects, e.g., contemporary discoveries in gynecological cancer research utilizing MSI, indicates current challenges, and future perspectives on MSI.

Multielemental Analysis of Bee Pollen, Propolis, and Royal Jelly Collected in West-Central Poland.

Beehive products possess nutritional value and health-promoting properties and are recommended as so-called "superfoods". However, because of their natural origin, they may contain relevant elemental contaminants. Therefore, to assess the quality of bee products, we examined concentrations of a broad range of 24 selected elements in propolis, bee pollen, and royal jelly. The quantitative analyses were performed with inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) techniques. The results of our research indicate that bee products contain essential macronutrients (i.e., K, P, and S) and micronutrients (i.e., Zn and Fe) in concentrations depending on the products' type. However, the presence of toxic heavy metals makes it necessary to test the quality of bee products before using them as dietary supplements. Bearing in mind that bee products are highly heterogenous and, depending on the environmental factors, differ in their elemental content, it is necessary to develop standards regulating the acceptable levels of inorganic pollutants. Furthermore, since bees and their products are considered to be an effective biomonitoring tool, our results may reflect the environment's condition in west-central Poland, affecting the health and well-being of both humans and bees.

Development of an LC-MS Targeted Metabolomics Methodology to Study Proline Metabolism in Mammalian Cell Cultures.

A growing interest in metabolomics studies of cultured cells requires development not only untargeted methods capable of fingerprinting the complete metabolite profile but also targeted methods enabling the precise and accurate determination of a selected group of metabolites. Proline metabolism affects many crucial processes at the cellular level, including collagen biosynthesis, redox balance, energetic processes as well as intracellular signaling. The study aimed to develop a robust and easy-to-use targeted metabolomics method for the determination of the intracellular level of proline and the other two amino acids closely related to proline metabolism: glutamic acid and arginine. The method employs hydrophilic interaction liquid chromatography followed by high-resolution, accurate-mass mass spectrometry for reliable detection and quantification of the target metabolites in cell lysates. The sample preparation consisted of quenching by the addition of ice-cold methanol and subsequent cell scraping into a quenching solution. The method validation showed acceptable linearity (r > 0.995), precision (%RSD < 15%), and accuracy (88.5-108.5%). Pilot research using HaCaT spontaneously immortalized human keratinocytes in a model for wound healing was performed, indicating the usefulness of the method in studies of disturbances in proline metabolism. The developed method addresses the need to determine the intracellular concentration of three key amino acids and can be used routinely in targeted mammalian cell culture metabolomics research.

Serum free amino acid levels in rheumatoid arthritis according to therapy and physical disability.

BACKGROUND: In presented study the amino acid analysis was performed in serum derived from rheumatoid arthritis patients (RA) according to undertaken therapy and classification of physical disability. The results were compared with previously published data. METHODS: The levels of 31 free amino acids were determined in 50 serum samples derived from RA subjects and 51 controls. The RA patients were divided into two groups according to the therapy (methotrexate/leflunomide, infliximab/adalimumab/etanercept/tocilizumab, prednisolone/NSAID) and classification of physical disability of the patients. Levels of amino acids were measured by LC-MS/MS. The obtained results were subjected to multivariate statistical tests. RESULTS: According to the therapy that was being used, threonine differentiated RA patients treated with methotrexate/leflunomide - infliximab/adalimumab/etanercept/tocilizumab (p = 0.00954) and infliximab/adalimumab/etanercept/tocilizumab - prednisolone/NSAID (p = 0.03109), while tryptophan differentiated RA patients treated with methotrexate/leflunomide - infliximab/adalimumab/etanercept/tocilizumab (p = 0.01723). In the functional classification, arginine differentiated RA samples between class III and IV (p = 0.02332), while glycine differentiated them between class I+II and III of the Steinbrocker functional classification (p = 0.03366). CONCLUSIONS: An analysis of the metabolome profile requires the use of validated bioanalytical methods that are strictly dedicated for this purpose. The obtained results are not accidental (p value less than 0.05), and all of the selected amino acids play an important role in inflammation and immune response. It is suggested that studied amino acids can be considered as a markers for diagnosis of RA and monitoring pharmacotherapy of the disease.

The concomitant use of lapatinib and paracetamol - the risk of interaction.

Lapatinib is a tyrosine kinase inhibitor used for the treatment of breast cancer. Paracetamol is an analgesic commonly applied to patients with mild or moderate pain and fever. Cancer patients are polymedicated, which involves high risk of drug interactions during therapy. The aim of the study was to assess the interaction between lapatinib and paracetamol in rats. The rats were divided into three groups of eight animals in each. One group received lapatinib + paracetamol (IL + PA), another group received lapatinib (IIL), whereas the last group received paracetamol (IIIPA). A single dose of lapatinib (100 mg/kg b.w.) and paracetamol (100 mg/kg b.w.) was administered orally. Plasma concentrations of lapatinib, paracetamol and its metabolites - glucuronide and sulphate, were measured with the validated HPLC-MS/MS method and HPLC-UV method, respectively. The pharmacokinetic parameters of both drugs were calculated using non-compartmental methods. The co-administration of lapatinib and paracetamol increased the area under the plasma concentration-time curve (AUC) and the maximum concentration (Cmax) of lapatinib by 239.6% (p = 0.0030) and 184% (p = 0.0011), respectively. Lapatinib decreased the paracetamol AUC0-∞ by 48.8% and Cmax by 55.7%. In the IL + PA group the Cmax of paracetamol glucuronide was reduced, whereas the Cmax of paracetamol sulphate was higher than in the IIIPA group. Paracetamol significantly affected the enhanced plasma exposure of lapatinib. Additionally, lapatinib reduced the concentrations of paracetamol. The co-administration of lapatinib decreased the paracetamol glucuronidation but increased the sulphation. The findings of this study may be of clinical relevance to patients requiring analgesic therapy.

Pharmacokinetics of dexmedetomidine during analgosedation in ICU patients.

Dexmedetomidine (DEX) is a fairly new alfa2-agonist which has been increasingly used in recent years for analgosedation, mostly because it offers a unique ability of providing both moderate level of sedation and analgesia without respiratory depression. Despite of many papers published, there are still only a few concerning the PK of the drug given as long-term infusion in ICU patients. The aim of this work was to characterize the population pharmacokinetics of dexmedetomidine and to investigate the potential benefits of individualization of drug dosing based on patient characteristics in the heterogeneous group of medical and surgical patients staying in intensive care unit. This study was performed in the group of 17 males and 10 females patients with a median age of 59.5 years and median body weight of 75 kg. Blood samples for dexmedetomidine assay were collected from arterial catheter, during and after discontinuation of a standard infusion, that ranged from 24 to 102 h. The following covariates were examined to influence dexmedetomidine PK: age, sex, body weight, patients' health status described by Sequential Organ Failure Assessment Score (SOFA), inotropes usage, and infusion duration. The dexmedetomidine PK was best described by a two-compartment model. The typical values of PK parameters were estimated as 27 L for the volume of the central compartment, 87.6 L for the volume of the peripheral compartment, 38.5 L/h (9.2 mL/min/kg for a 70 kg patient) for systemic clearance and 46.4 L/h for the distribution clearance. Those values are consistent with literature findings. We were unable to show any significant relationship between collected covariates and dexmedetomidine PK. This study does not provide sufficient evidence to support the individualization of dexmedetomidine dosing based on age, sex, body weight, SOFA, and infusion duration.

Understanding Ovarian Cancer: iTRAQ-Based Proteomics for Biomarker Discovery.

Despite many years of studies, ovarian cancer remains one of the top ten cancers worldwide. Its high mortality rate is mainly due to lack of sufficient diagnostic methods. For this reason, our research focused on the identification of blood markers whose appearance would precede the clinical manifestation of the disease. ITRAQ-tagging (isobaric Tags for Relative and Absolute Quantification) coupled with mass spectrometry technology was applied. Three groups of samples derived from patients with: ovarian cancer, benign ovarian tumor, and healthy controls, were examined. Mass spectrometry analysis allowed for highlighting the dysregulation of several proteins associated with ovarian cancer. Further validation of the obtained results indicated that five proteins (Serotransferrin, Amyloid A1, Hemopexin, C-reactive protein, Albumin) were differentially expressed in ovarian cancer group. Interestingly, the addition of Albumin, Serotransferrin, and Amyloid A1 to CA125 (cancer antigen 125) and HE4 (human epididymis protein4) improved the diagnostic performance of the model discriminating between benign and malignant tumors. Identified proteins shed light on the molecular signaling pathways that are associated with ovarian cancer development and should be further investigated in future studies. Our findings indicate five proteins with a strong potential to use in a multimarker test for screening and detection of ovarian cancer.

Assessment of diagnostic utility of multivariate diagnostic models in differential diagnosis of ovarian tumors.

INTRODUCTION: Ovarian cancer (OC) diagnosis remains a clinical challenge due to lack of early symptoms and insufficient accuracy of the available diagnostic methods. The purpose of this study was to determine whether osteopontin could be useful in differential diagnosis of ovarian tumors. MATERIAL AND METHODS: Serum samples from 92 patients qualified for surgical treatment due to ovarian mass were divided into 2 groups according to the histopathological result: OC including borderline ovarian tumors (n = 39) and benign ovarian tumors (BOTs) (n = 53). CA125, HE4 and osteopontin concentrations were measured in all patients. Areas under the receiver operating characteristic curves (AUC of ROC) were used to compare the discriminative ability of the univariate and multivariate diagnostic models. RESULTS: The addition of osteopontin to ROMA significantly improved the diagnostic performance of the test in 3 of the 5 analyses: 1) in the OC vs BOT group (from AUC of 0.955 to 0.975), 2) in premenopausal women OC vs BOT (from AUC of 0.828 to 0.892) and 3) in the FIGO I-II stage OC vs BOT (from AUC of 0.865 to 0.895). It did not alter the diagnostic performance of multifactor tests in the group of postmenopausal women nor in OC FIGO III-IV stage group. Osteopontin was also the best single marker to differentiate between early stage OC and BOTs (AUC of 0.863). CONCLUSIONS: Osteopontin improves the diagnostic performance of a multimarker OC diagnostic test and could be useful in differential diagnosis of ovarian tumors, especially in pre-menopausal women and for early stage OC.

MALDI-TOF-MS analysis in discovery and identification of serum proteomic patterns of ovarian cancer.

BACKGROUND: Due to high mortality and lack of efficient screening, new tools for ovarian cancer (OC) diagnosis are urgently needed. To broaden the knowledge on the pathological processes that occur during ovarian cancer tumorigenesis, protein-peptide profiling was proposed. METHODS: Serum proteomic patterns in samples from OC patients were obtained using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF). Eighty nine serum samples (44 ovarian cancer and 45 healthy controls) were pretreated using solid-phase extraction method. Next, a classification model with the most discriminative factors was identified using chemometric algorithms. Finally, the results were verified by external validation on an independent test set of samples. RESULTS: Main outcome of this study was an identification of potential OC biomarkers by applying liquid chromatography coupled with tandem mass spectrometry. Application of this novel strategy enabled the identification of four potential OC serum biomarkers (complement C3, kininogen-1, inter-alpha-trypsin inhibitor heavy chain H4, and transthyretin). The role of these proteins was discussed in relation to OC pathomechanism. CONCLUSIONS: The study results may contribute to the development of clinically useful multi-component diagnostic tools in OC. In addition, identifying a novel panel of discriminative proteins could provide a new insight into complex signaling and functional networks associated with this multifactorial disease.

The feature selection approach for evaluation of potential rheumatoid arthritis markers using MALDI-TOF datasets.

BACKGROUND: The selection of the most representative mass profiles, in rheumatoid arthritis (RA) serum samples was developed. This allows for selection and identification of potential biomarkers in RA serum samples. METHODS: The RA and controls samples were analyzed using MALDI-TOF. Two different protein elution procedures utilizing ZipTips (E1 and E2) were examined. The statistical evaluation of data was performed using different feature selection (FS) methods in combination with different classifiers, while identification of selected masses was performed using MALDI-TOF-TOF. RESULTS: Utilization of proposed statistical strategy allowed for the selection of different masses according to FS method and elution procedure. Obtained masses were further subjected for targeted identification. The panel of proteins were identified as potential markers. The role of these proteins was discussed in relation to pathomechanism of RA. CONCLUSION: Application of advanced biostatistical analysis of obtained MALDI-TOF datasets, resulted with targeted selection of potential RA biomarkers. Five proteins were identified due the E1 procedure, and six proteins were identified due the E2 procedure, respectively. The panel of identified proteins suggest that presented statistical methodology and proteomic strategy was correct and gave valid results. Obtained results may contribute to development of clinically useful multicomponent diagnostic tool.

Amino Acid Profiles of Serum and Urine in Search for Prostate Cancer Biomarkers: a Pilot Study.

There is a great interest in searching for diagnostic biomarkers in prostate cancer patients. The aim of the pilot study was to evaluate free amino acid profiles in their serum and urine. The presented paper shows the first comprehensive analysis of a wide panel of amino acids in two different physiological fluids obtained from the same groups of prostate cancer patients (n = 49) and healthy men (n = 40). The potential of free amino acids, both proteinogenic and non-proteinogenic, as prostate cancer biomarkers and their utility in classification of study participants have been assessed. Several metabolites, which deserve special attention in the further metabolomic investigations on searching for prostate cancer markers, were indicated. Moreover, free amino acid profiles enabled to classify samples to one of the studied groups with high sensitivity and specificity. The presented research provides a strong evidence that ethanolamine, arginine and branched-chain amino acids metabolic pathways can be a valuable source of markers for prostate cancer. The altered concentrations of the above-mentioned metabolites suggest their role in pathogenesis of prostate cancer and they should be further evaluated as clinically useful markers of prostate cancer.

Diagnostic Value of Serum Angiogenesis Markers in Ovarian Cancer Using Multiplex Immunoassay.

As cancer development involves pathological vessel formation, 16 angiogenesis markers were evaluated as potential ovarian cancer (OC) biomarkers. Blood samples collected from 172 patients were divided based on histopathological result: OC (n = 38), borderline ovarian tumours (n = 6), non-malignant ovarian tumours (n = 62), healthy controls (n = 50) and 16 patients were excluded. Sixteen angiogenesis markers were measured using BioPlex Pro Human Cancer Biomarker Panel 1 immunoassay. Additionally, concentrations of cancer antigen 125 (CA125) and human epididymis protein 4 (HE4) were measured in patients with adnexal masses using electrochemiluminescence immunoassay. In the comparison between OC vs. non-OC, osteopontin achieved the highest area under the curve (AUC) of 0.79 (sensitivity 69%, specificity 78%). Multimarker models based on four to six markers (basic fibroblast growth factor-FGF-basic, follistatin, hepatocyte growth factor-HGF, osteopontin, platelet-derived growth factor AB/BB-PDGF-AB/BB, leptin) demonstrated higher discriminatory ability (AUC 0.80-0.81) than a single marker (AUC 0.79). When comparing OC with benign ovarian tumours, six markers had statistically different expression (osteopontin, leptin, follistatin, PDGF-AB/BB, HGF, FGF-basic). Osteopontin was the best single angiogenesis marker (AUC 0.825, sensitivity 72%, specificity 82%). A three-marker panel consisting of osteopontin, CA125 and HE4 better discriminated the groups (AUC 0.958) than HE4 or CA125 alone (AUC 0.941 and 0.932, respectively). Osteopontin should be further investigated as a potential biomarker in OC screening and differential diagnosis of ovarian tumours. Adding osteopontin to a panel of already used biomarkers (CA125 and HE4) significantly improves differential diagnosis between malignant and benign ovarian tumours.

Usefulness of Amino Acid Profiling in Ovarian Cancer Screening with Special Emphasis on Their Role in Cancerogenesis.

The aim of this study was to quantitate 42 serum-free amino acids, propose the biochemical explanation of their role in tumor development, and identify new ovarian cancer (OC) biomarkers for potential use in OC screening. The additional value of this work is the schematic presentation of the interrelationship between metabolites which were identified as significant for OC development and progression. The liquid chromatography-tandem mass spectrometry technique using highly-selective multiple reaction monitoring mode and labeled internal standards for each analyzed compound was applied. Performed statistical analyses showed that amino acids are potentially useful as OC biomarkers, especially as variables in multi-marker models. For the distinguishing metabolites the following metabolic pathways involved in cancer growth and development were proposed: histidine metabolism; tryptophan metabolism; arginine biosynthesis; arginine and proline metabolism; and alanine, aspartate and glutamine metabolism. The presented research identifies histidine and citrulline as potential new OC biomarkers. Furthermore, it provides evidence that amino acids are involved in metabolic pathways related to tumor growth and play an important role in cancerogenesis.

PRELIMINARY HIGH PERFORMANCE CAPILLARY ELECTROPHORESIS (HPCE) STUDIES OF ENZYMATIC DEGRADATION OF HYALURONIC ACID BY HYALURONIDASE IN THE PRESENCE OF POLYVALENT METAL IONS.

The aim of this study was, at first, to examine the influence of metal ions on digestion process of hyaluronic acid by hyaluronidase (HAse) using high performance capillary electrophoresis (HPCE) method. The influence of copper(H), zinc(Il), manganese(II) ions on enzymatic degradation of HA by hyaluronidase enzyme (HA-se) were investigated. Secondly, the kinetic parameters, V(max), K(m), k(cat), and k (cat),/K(m) were determined to estimate the impact of these metal ions (Me) on digestion process of hyaluronic acid (HA). The two different HA-Me mole ratios were analyzed. The examined data were always compared to the digestion process of pure HA solution by hyaluronidase, to exhibit the differences in the digestion process of pure hyaluronan as well as the hyaluronan in the presence of metal ions. It was observed that all of the investigated metal ions have influenced the hyaluronic acid degradation process. The most important conclusion was a decrease of the kinetic parameters both K,, and V,. In the result, it can be assumed that in all of the studied samples with metal ions addition, the uncompetitive mechanism of enzyme inhibition occurred. The results of this study may give new insight into foregoing knowledge about hyaluronic acid behavior. Due to the fact that our study was carried out only for three different metal ions in two concentrations, it is necessary to continue further research comprising wider range of metal ions and their concentrations.

STUDY OF OFLOXACIN ENANTIOMERS DISSOLUTION FROM SELECTED SOLID DOSAGE FORMS USING HIGH PERFORMANCE CAPILLARY ELECTROPHORESIS METHOD.

The commercially available coated tablets containing either racemic form of ofloxacin (Tarivid 200 mg, OfloHexal 200 mg and Ofloxacin-Ratiopharm 200 mg) or only levofloxacin S-(-)-isomer (Tavanic 250 mg) were examined. The aim of our study was to establish the kinetics of dissolution rate process of ofloxacin optical isomers (S-(-) and R-(+)-ofloxacin) from solid oral dosage forms using flow-through cell method (USP 4 method). The concentrations of analytes (racemic ofloxacin and its enantiomers) in the samples of tablet extracts as well as in dissolution media (0.1 M/L HCl and phosphate buffer pH 6.8) were determined by validated high performance capillary electrophoresis method. The fraction of the average dose of the individual optical isomers of ofloxacin released from the examined tablets was calculated. In the case of the OfloHexal, Ofloxacin-Ratiopharm and Tavanic it was found to be around 100% for both S-(-) and R-(+)-ofloxacin in 0.1 M/L HCI after 30 min of dissolution test. The fraction of the average dose for the Tarivid tablets was approximately 50% at the same time. A similar results were observed for the Ofloxacin-Ratiopharm and Tavanic tablets examined in phosphate buffer (average fraction about 100% after 30 min), while in the case of Tarivid and OfloHexal the averige fraction of the dose determined in a buffer pH 6.8 was 14% and 44%, respectively. There were not found any differences in the kinetics of dissolution of the S-(-)-ofloxacin and R-(+)-ofloxacin isomers within the same formulation. However, statistically significant differences were found in the dissolution of ofloxacin enantiomers between different preparations.

PROTEOMIC ANALYSIS OF APIS MELLIFERA VENOM DETERMINED BY LIQUID CHROMATOGRAPHY (LC) COUPLED WITH NANO-LC-MALDI-TOF/TOF MS.

The integration of multidimensional liquid chromatography and mass spectrometry analytical plat- form was proposed for proteomic exploration of honeybee venom. The combination of HPLC with nanoLC-MALDI-TOF/TOF MS system was our method of choice for compressing the dynamic range of honeybee venom protein concentration. Honeybee venom samples were separated into 6 fractions using HPLC and further analyzed by nanoLC-MALDI-TOF/TOF. Applied approach allowed to identify in total 394 peptides giving the identification of 50 components including putative toxins and trace elements. Moreover, all 12 known honeybee venom allergens were acknowledged. Additionally, four novel hypothetical proteins have been observed which were not observed in other studies. The newly recognized proteins should be further investigated, in order to characterize their functions in the venom of Apis mellifera.

The pharmacokinetics of propofol in ICU patients undergoing long-term sedation.

The aim of this study was to characterize the pharmacokinetics (PK) of propofol in ICU patients undergoing long-term sedation and to assess the influence of routinely collected covariates on the PK parameters. Propofol concentration-time profiles were collected from 29 patients. Non-linear mixed-effects modelling in NONMEM 7.2 was used to analyse the observed data. The propofol pharmacokinetics was best described with a three-compartment disposition model. Non-parametric bootstrap and a visual predictive check were used to evaluate the adequacy of the developed model to describe the observations. The typical value of the propofol clearance (1.46 l/min) approximated the hepatic blood flow. The volume of distribution at steady state was high and was equal to 955.1 l, which is consistent with other studies involving propofol in ICU patients. There was no statistically significant covariate relationship between PK parameters and opioid type, SOFA score on the day of admission, APACHE II, predicted death rate, reason for ICU admission (sepsis, trauma or surgery), gender, body weight, age, infusion duration and C-reactive protein concentration. The population PK model was developed successfully to describe the time-course of propofol concentration in ICU patients undergoing prolonged sedation. Despite a very heterogeneous group of patients, consistent PK profiles were observed. Copyright © 2016 John Wiley & Sons, Ltd.

Pharmacokinetics and pharmacodynamics of propofol and fentanyl in patients undergoing abdominal aortic surgery - a study of pharmacodynamic drug-drug interactions.

Propofol is routinely combined with opioid analgesics to ensure adequate anesthesia during surgery. The aim of the study was to assess the effect of fentanyl on the hypnotic effect of propofol and the possible clinical implications of this interaction. The pharmacokinetic/pharmacodynamic (PK/PD) data were obtained from 11 patients undergoing abdominal aortic surgery, classified as ASA III. Propofol was administered by a target-controlled infusion system. Fentanyl 2-3 µg/kg was given whenever insufficient analgesia occurred. The bispectral index (BIS) was used to monitor the depth of anesthesia. A population PK/PD analysis with a non-linear mixed-effect model (NONMEM 7.2 software) was conducted. Two-compartment models satisfactorily described the PK of propofol and fentanyl. The delay of the anesthetic effect in relation to PK was described by the effect compartment. The BIS was linked to propofol and fentanyl effect-site concentrations through an additive Emax model. Context-sensitive decrement times (CSDT) determined from the final model were used to assess the influence of fentanyl on the recovery after anesthesia. The population PK/PD model was successfully developed to describe simultaneously the time course and variability of propofol and fentanyl concentrations and BIS. Additive propofol-fentanyl interactions were observed and quantitated. The duration of the fentanyl infusion had minimal effect on CSDT when it was shorter than the duration of the propofol infusion. If the fentanyl infusion was longer than the propofol infusion, an almost two-fold increase in CSDT occurred. Additional doses of fentanyl administered after the cessation of the propofol infusion result in lower BIS values, and can prolong the time of recovery from anesthesia. Copyright © 2016 John Wiley & Sons, Ltd.