Development and validation of a sensitive assay for analysis of midazolam, free and conjugated 1-hydroxymidazolam and 4-hydroxymidazolam in pediatric plasma: Application to Pediatric Pharmacokinetic Study

Perfluoropolyether-Based Gut-Liver-on-a-Chip for the Evaluation of First-Pass Metabolism and Oral Bioavailability of Drugs

In the evolving field of drug discovery and development, multiorgans-on-a-chip and microphysiological systems are gaining popularity owing to their ability to emulate in vivo biological environments. Among the various gut-liver-on-a-chip systems for studying oral drug absorption, the chip developed in this study stands out with two distinct features: incorporation of perfluoropolyether (PFPE) to effectively mitigate drug sorption and a unique enterohepatic single-passage system, which simplifies the analysis of first-pass metabolism and oral bioavailability. By introducing a bolus drug injection into the liver compartment, hepatic extraction alone could be evaluated, further enhancing our estimation of intestinal availability. In a study on midazolam (MDZ), PFPE-based chips showed more than 20-times the appearance of intact MDZ in the liver compartment effluent compared to PDMS-based counterparts. Notably, saturation of hepatic metabolism at higher concentrations was confirmed by observations when the dose was reduced from 200 μM to 10 μM. This result was further emphasized when the metabolism was significantly inhibited by the coadministration of ketoconazole. Our chip, which is designed to minimize the dead volume between the gut and liver compartments, is adept at sensitively observing the saturation of metabolism and the effect of inhibitors. Using genome-edited CYP3A4/UGT1A1-expressing Caco-2 cells, the estimates for intestinal and hepatic availabilities were 0.96 and 0.82, respectively; these values are higher than the known human in vivo values. Although the metabolic activity in each compartment can be further improved, this gut-liver-on-a-chip can not only be used to evaluate oral bioavailability but also to carry out individual assessment of both intestinal and hepatic availability.

Simultaneous detection of a panel of nine sedatives and metabolites in plasma from critically ill pediatric patients via UPLC-MS/MS

Sedative use can result in adverse drug reactions. Intensive care unit patients are especially at risk and pharmacokinetic modeling of drug concentrations is an approach to develop precision dosing strategies. However, limited blood sampling availability in critically ill children and need for multiple assays to quantify a variety of commonly used sedatives creates logistical challenges. The goal of this project was to develop a sensitive and selective assay for the simultaneous quantification of a panel of sedatives comprised of midazolam (MDZ), alpha hydroxymidazolam (1- OH MDZ), dexmedetomidine (DEX), morphine (MOR), morphine-3-glucuronide (M3G), morphine-6-glucuronide (M6G), fentanyl (FEN), norfentanyl (NF), and hydromorphone (HM) in small volume pediatric plasma samples. A sensitive and efficient ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS/MS) method was developed following FDA guidance for bioanalytical validation. Minimal sample preparation consisting of simple protein precipitation extraction using acetonitrile with internal standards was utilized. Analyte separation was achieved using a gradient mixture of (A: 0.15% formic acid in water and B: Acetonitrile) and a Waters Acquity C18, 1.7 µm (2.1 × 100 mm) column. Assays were linear over the clinical concentration ranges: MDZ, MOR, HM: 0.5-125 ng/mL; 1-OH MDZ, M3G, M6G: 5-500 ng/mL; and DEX, FEN, NF: 0.05-7.5 ng/mL (R2 > 0.99 for all). Assay run time was 10 min and required only 100 μL of plasma. Initial testing of samples from pediatric patients demonstrates adequacy of assay to measure sedatives and metabolites at clinical concentrations confidently in low volumes of plasma. This novel highly-sensitive and specific method to measure a total of nine different analytes (five sedatives, four metabolites) simultaneously enables comprehensive analysis of a panel of sedatives in small volumes such as in pediatric ICU patients.

Rapid simultaneous determination of ketamine and midazolam in biological samples using ion mobility spectrometry combined by headspace solid-phase microextraction

Ketamine (Ket) and midazolam (Mdz) are among well-known anesthetic agents which frequently coadministered in surgical procedures and emergency department. Only a few reports have been published for the simultaneous analysis of these compounds. In the present study, we reported a simple, sensitive, and rapid method for simultaneous determination of Ket and Mdz based on headspace solid-phase microextraction coupled with ion mobility spectrometry (HS-SPME-IMS). Ion mobility spectrometer operated under positive mode of a corona discharge ionization source using ammonia as a dopant. The effective parameters on the extraction process consisting of pH of the sample, extraction temperature, extraction time, salt concentration were optimized. The calibration plots exhibited good linearity over the concentration ranges of 10-800 and 100-1500 µg L^-1 and detection limit of 8.9 and 52 µg L^-1 for Ket and Mdz respectively with correlation coefficients greater than 0.99. The relative standard deviation (RSD) for five replicate measurements was determined to be less than 8%. Finally, the applicability of the proposed method was tested in human plasma and serum samples. These tests showed that the matrix in serum samples interfere with midazolam determination but quantitative recoveries from 85 to 95 % were obtained for both drugs in the human plasma samples. The method herein provides simple and suitable approach while minimizing sample preparation and the overall complexity of the analysis in comparison to existing methodologies.

Physicochemical stability of compounded midazolam capsules over a one-year storage period

Objectives

In patients suffering from chronic liver disease, the hepatic metabolism of drugs is perturbed and the metabolic capacity is difficult to assess. Midazolam could be used as a phenotypical probe to predict the metabolic capacity of CYP3A to adjust dosages of drug substrates of this cytochrome. In this context, a prospective clinical trial is going to be conducted in our institution and a hospital preparation of midazolam capsules suitable for the clinical trial was developed. The objective of the present work was to assess the physicochemical stability of the formulation over 12 months to set shelf life.

Methods

Three batches of 1 mg capsules were prepared using midazolam hydrochloride and microcrystalline cellulose as a diluent. The capsules were stored at ambient temperature and protected from light. To measure the evolution of the capsules content, a stability-indicating high-performance liquid chromatography (HPLC) method was developed with ultraviolet (UV) detection at 254 nm. Data were confirmed using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method.

Results

After one year, midazolam hydrochloride content remained higher than 95% of the initial concentration in capsules.

Conclusions

The results show that 1 mg midazolam capsules are stable for 12 months at room temperature and under dark conditions.

A fast and simple method for the simultaneous analysis of midazolam, 1-hydroxymidazolam, 4-hydroxymidazolam and 1-hydroxymidazolam glucuronide in human serum, plasma and urine

For the quantification of the sedative and anesthetic drug midazolam and its main (active) metabolites 1-hydroxymidazolam, 4-hydroxymidazolam and 1-hydroxymidazolam glucuronide in human serum, human EDTA plasma, human heparin plasma and human urine a single accurate method by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed. Protein precipitation as sample preparation, without the need of a time-consuming deglucuronidation step for the quantification of 1-hydroxymidazolam glucuronide, resulted in a simple and rapid assay suitable for clinical practice with a total runtime of only 1.1  min. The four components and the isotope-labeled internal standards were separated on a C₁₈ column and detection was performed with a triple-stage quadrupole mass spectrometer operating in positive ionization mode. The method was validated based on the "Guidance for Industry Bioanalytical Method Validation" (Food and Drug Administration, FDA) and the "Guideline on bioanalytical method validation" of the European Medicines Agency (EMA). Linearity was proven over the ranges of 5-1500 μg/L for midazolam, 1-hydroxymidazolam and 4-hydroxymidazolam and 25-5000 μg/L for 1-hydroxymidazolam glucuronide, using a sample volume of 100 μL. Matrix comparison indicated that the assay is also applicable to other human matrices like EDTA and heparin plasma and urine. Stability experiments showed good results for the stability of midazolam, 1-hydroxymidazolam and 1-hydroxymidazolam glucuronide in serum, EDTA and heparin plasma and urine stored for 7 days under different conditions. At room temperature, 4-hydroxymidazo-lam is stable for 7 days in EDTA plasma, but stable for only 3 days in serum and heparin plasma and less than 24 h in urine. All four compounds were found to be stable in serum, EDTA plasma, heparin plasma and urine for 7 days after sample preparation and for 3 freeze-thaw cycles. The assay has been applied in therapeutic drug monitoring of midazolam for (pediatric) intensive care patients.

Assessment of midazolam pharmacokinetics in the treatment of status epilepticus

OBJECTIVES

Refractory status epilepticus (RSE) is often treated with midazolam boluses and continuous infusions, but there is considerable variability in dosing and efficacy. We aimed to evaluate the performance of a clinical midazolam dose escalation pathway for the treatment of pediatric RSE that was designed based on a novel midazolam pharmacokinetic model.

DESIGN

Prospective pharmacokinetic study of midazolam bolus and escalation of continuous midazolam infusion.

SETTING

Pediatric Intensive Care Unit in quaternary-care academic hospital.

SUBJECTS

Children between two months to seventeen years of age who received clinically-indicated midazolam infusion for treatment of RSE.

INTERVENTION

Blood sampled at regular intervals during treatment. Main study outcome measure was the accuracy of a pharmacokinetic model to predict serum midazolam concentrations.

MEASUREMENTS AND MAIN RESULTS

We analysed data from six subjects. Three subjects had serum midazolam concentrations close to those predicted by our initial model (accuracy 88.9-170.2 %) which incorporates body weight, hepatic function, and renal function. For the other three subjects, all of whom were receiving pre-existing chronic benzodiazepine therapy prior to the RSE episode, the model grossly overestimated serum concentrations (predictive error 420.3-722.5 %). Once the model was corrected for the impact of pre-existing chronic benzodiazepine use on clearance, predicted concentrations more closely reflected those measured in subjects.

CONCLUSION

We evaluated a clinical midazolam RSE treatment pathway but discovered that the model on which the pathway was based was not accurate for all patients. We therefore developed a novel pharmacokinetic midazolam model in children with RSE treated with continuous midazolam infusion. This model incorporates body weight, hepatic and renal function, and importantly, a correction factor for pre-existing chronic benzodiazepine use. Once validated, this model may guide dosing and drive the development of more effective treatment pathways for continuous midazolam in RSE.

LC-MS based stability-indicating method for studying the degradation of lonidamine under physical and chemical stress conditions

Background and purpose:

Lonidamine is a hexokinase II inhibitor, works as an anticancer molecule, and is extensively explored in clinical trials. Limited information prevails about the stability-indicating methods which could determine the forced degradation of lonidamine under stressed conditions. Hence, we report the use of a rapid, sensitive, reproducible, and highly accurate liquid chromatography and mass spectrometry method to analyze lonidamine degradation.

Experimental approach:

The Xbridge BEH shield reverse phase C18 column (2.5 μm, 4.6 × 75 mm) using isocratic 50:50 water: acetonitrile with 0.1% formic acid can detect lonidamine with help of mass spectrometer in tandem with an ultraviolet (UV) detector at 260 nm wavelength.

Findings/ Results:

A linear curve with r² > 0.99 was obtained for tandem liquid chromatography-mass spectrometry (LC-MS)-UV based detections. This study demonstrated (in the present set up of isocratic elution) that LC-MS based detection has a relatively high sensitivity (S/N (10 ng/mL): 220 and S/N (20 ng/mL): 945) and accuracy at lower detection and quantitation levels, respectively. In addition to developing the LC-MS method, we also report that the current method is stability-indicating and shows that lonidamine gets degraded over time under all three stress conditions; acidic, basic, and oxidative.

Conclusion and implications:

LC-MS based quantitation of lonidamine proved to be a better method compared to high-performance liquid chromatography (HPLC)-UV detections for mapping lonidamine degradation. This is the first report on the stability-indicating method for studying the forced degradation of lonidamine using LC-MS method.

Development and validation of a liquid chromatography coupled to tandem mass spectrometry method for the simultaneous quantification of five analgesics and sedatives, and six of their active metabolites in human plasma: Application to a clinical study on the determination of neurological death in the intensive care unit

A sensitive and selective high-performance liquid chromatographic method coupled to tandem mass spectrometry was developed and validated for the quantification of morphine, hydromorphone, fentanyl, midazolam and propofol and their metabolites morphine-3-β-d-glucuronide, morphine-6-β-d-glucuronide, hydromorphone-3-β-d-glucuronide, 1'-hydroxymidazolam-β-d-glucuronide, α-hydroxymidazolam and 4-hydroxymidazolam in human plasma using potassium oxalate/sodium fluoride mixture as anticoagulant. Human plasma samples (0.4 mL) to which were added a mixture of eleven deuterated internal standards were subjected to solid phase extraction using a mixed-mode polymeric Oasis PRiME MCX in 96-well format. Propofol was selectively eluted and further derivatized using 2-Fluoro-1-methylpyridinium p-toluenesulfonate, whereas the remaining 10 analytes were eluted separately and further concentrated. The derivatized propofol was analyzed separately in a second injection. The analytes were chromatographically separated on a Kinetex phenyl-hexyl analytical column in gradient elution mode, using a mobile phase consisting of aqueous ammonium formate/formic acid buffer and methanol. The overall run time was 8 min. Detection was performed using an AB/SCIEX 4000 QTRAP instrument with positive electrospray ionization employing scheduled multiple reaction monitoring mode. The lower limits of quantification ranged from 0.02 to 5 ng/mL depending on the analyte. Calibration curves covered a concentration range of 1000× in all cases but 1'-hydroxymidazolam-β-d-glucuronide where it covered a range of 500 × . The validated method was accurate and precise, the intra-day accuracy and precision of quality control samples (4 concentration levels, n = 6 each) being within 91.5-112 % and 1.3-13.2 % (coefficient of variation), respectively, and inter-day (n = 24; 4 days) accuracy and precision of quality control samples (3 concentration levels) being within 94.8-103.5 % and 3.2-11.2 % (coefficient of variation). Mean absolute extraction recoveries were above 60 % for all compounds, except for hydromorphone-3-β-d-glucuronide (44 %) and for 1'-hydroxymidazolam-β-d-glucuronide (33 %). Internal standard corrected matrix effect ranged from -4.8 to 3.8 % in normal plasma and in plasma containing 1 % hemolyzed blood. Analytes were stable (above 90 %) in plasma and blood for 19 h at 22 °C, in blood for 90 h at 5 °C, in plasma for 60 days at -20 °C, for 4 months at -70 °C and after three freeze-thaw cycles, and in the injection solvent for at least 3 days in the autosampler. The present method is successfully being applied in a multicenter clinical study for the analysis of plasma samples from patients in intensive care units from a number of Canadian hospitals.

Morphine Dose Optimization in Critically Ill Pediatric Patients With Acute Respiratory Failure: A Population Pharmacokinetic-Pharmacogenomic Study

OBJECTIVE

To develop a pharmacokinetic-pharmacogenomic population model of morphine in critically ill children with acute respiratory failure.

DESIGN

Prospective pharmacokinetic-pharmacogenomic observational study.

SETTING

Thirteen PICUs across the United States.

PATIENTS

Pediatric subjects (n = 66) mechanically ventilated for acute respiratory failure, weight greater than or equal to 7 kg, receiving morphine and/or midazolam continuous infusions.

INTERVENTIONS

Serial blood sampling for drug quantification and a single blood collection for genomic evaluation.

MEASUREMENTS AND MAIN RESULTS

Concentrations of morphine, the two main metabolites, morphine-3-glucuronide and morphine-6-glucuronide, were quantified by high-performance liquid chromatography tandem mass spectrometry/mass spectroscopy. Subjects were genotyped using the Illumina HumanOmniExpress genome-wide single nucleotide polymorphism chip. Nonlinear mixed-effects modeling was performed to develop the pharmacokinetic-pharmacogenomic model. A two-compartment model with linear elimination and two individual compartments for metabolites best describe morphine disposition in this population. Our analysis demonstrates that body weight and postmenstrual age are relevant predictors of pharmacokinetic parameters of morphine and its metabolites. Furthermore, our research shows that a duration of mechanical ventilation greater than or equal to 10 days reduces metabolite formation and elimination upwards of 30%. However, due to the small sample size and relative heterogeneity of the population, no heritable factors associated with uridine diphosphate glucuronyl transferase 2B7 metabolism of morphine were identified.

CONCLUSIONS

The results provide a better understanding of the disposition of morphine and its metabolites in critically ill children with acute respiratory failure requiring mechanical ventilation due to nonheritable factors. It also provides the groundwork for developing additional studies to investigate the role of heritable factors.

Simultaneous quantitative LC-MS method of ketamine, midazolam and their metabolites (dehydronorketamine, norketamine and 1hydroxymidazolam) for its application in patients on extracorporeal membrane oxygenation (ECMO) therapy

Ketamine (Ket) and midazolam (MDZ) are commonly administered drugs in the intensive care setting for analgesia and sedation. Ket and MDZ are metabolized to dehydro-norketamine (DHNK), nor-ketamine (NK) and 1-hydroxy midazolam (1HMDZ). Limited studies evaluating their pharmacokinetics exists in patients on extracorporeal membrane oxygenation (ECMO) therapy. Therefore, we developed a quantitative, high-performance liquid chromatography-mass spectrometry (with single ion monitoring) method to simultaneously detect Ket, MDZ and their (DHNK, NK and 1HMDZ) metabolites in human plasma. Considerable sensitivity was obtained for the analytes using a C₁₈ HILIC column operated by a high-performance liquid chromatography system coupled with a Thermo Exactive Orbitrap mass spectrometer. Calibration curves were developed for analyte molecules (n = 5) in the presence of carbamazepine (CBZ) as an internal standard. The lower limits of quantitation (LLOQ) for Ket and MDZ were 20 and 10 ng/mL, respectively with the LLOQ for DHNK, NK and 1HMDZ at 470, 320 and 150 ng/ml. Moreover, the percent coefficient of variance and precision for inter- and intra-day runs were within the standards set forth by the ICH and FDA guidelines. This method is sensitive and has been successfully applied to an ongoing pharmacokinetic study in patients on ECMO therapy.

Midazolam Dose Optimization in Critically Ill Pediatric Patients With Acute Respiratory Failure: A Population Pharmacokinetic-Pharmacogenomic Study

OBJECTIVES

To develop a pharmacokinetic-pharmacogenomic population model of midazolam in critically ill children with primary respiratory failure.

DESIGN

Prospective pharmacokinetic-pharmacogenomic observational study.

SETTING

Thirteen PICUs across the United States.

PATIENTS

Pediatric subjects mechanically ventilated for acute respiratory failure, weight greater than or equal to 7 kg, receiving morphine and/or midazolam continuous infusions.

INTERVENTIONS

Serial blood sampling for drug quantification and a single blood collection for genomic evaluation.

MEASUREMENTS AND MAIN RESULTS

Concentrations of midazolam, the 1' (1`-hydroxymidazolam metabolite) and 4' (4`-hydroxymidazolam metabolite) hydroxyl, and the 1' and 4' glucuronide metabolites were measured. Subjects were genotyped using the Illumina HumanOmniExpress genome-wide single nucleotide polymorphism chip. Nonlinear mixed effects modeling was performed to develop the pharmacokinetic-pharmacogenomic model. Body weight, age, hepatic and renal functions, and the UGT2B7 rs62298861 polymorphism are relevant predictors of midazolam pharmacokinetic variables. The estimated midazolam clearance was 0.61 L/min/70kg. Time to reach 50% complete mature midazolam and 1`-hydroxymidazolam metabolite/4`-hydroxymidazolam metabolite clearances was 1.0 and 0.97 years postmenstrual age. The final model suggested a decrease in midazolam clearance with increase in alanine transaminase and a lower clearance of the glucuronide metabolites with a renal dysfunction. In the pharmacogenomic analysis, rs62298861 and rs28365062 in the UGT2B7 gene were in high linkage disequilibrium. Minor alleles were associated with a higher 1`-hydroxymidazolam metabolite clearance in Caucasians. In the pharmacokinetic-pharmacogenomic model, clearance was expected to increase by 10% in heterozygous and 20% in homozygous for the minor allele with respect to homozygous for the major allele.

CONCLUSIONS

This work leveraged available knowledge on nonheritable and heritable factors affecting midazolam pharmacokinetic in pediatric subjects with primary respiratory failure requiring mechanical ventilation, providing the basis for a future implementation of an individual-based approach to sedation.

Vitamin D3 Is Transformed into 1,25(OH)2D3 by Triggering CYP3A11(CYP3A4) Activity and Hydrolyzing Midazolam

Background

Vitamin D3 (VD3) is a commonly used supplement in clinical practice. Cytochrome P450 3A11 (CYP3A11) is the most important monomeric enzyme involved in metabolism of drugs. This study aimed to investigate effects of vitamin D3 (VD3) on CYP3A11 activity.

Material/Methods

Forty male Sprague-Dawley (SD) rats were randomly divided a Control group (peanut oil 0.1 ml/kg/d), a Low-VD3 group (100 IU/kg/d), a Medium-VD3 group (400 IU/kg/d), and a High-VD3 (1600 IU/kg/d) group. Blood samples were collected from the jugular vein after midazolam (MDZ) administration. CYP3A11 expressions in liver and colon were detected by Western blotting and immunohistochemistry (IHC) assay. The concentration of serum 25(OH)D₃ and serum 1,25(OH)₂D₃ were evaluated using ELISA. Effects of different dosages of vitamin D3 on metabolism of MDZ were evaluated using high-performance liquid chromatography (HPLC).

Results

Vitamin D3 significantly enhanced serum 25(OH)D₃ and 1,25(OH)₂D₃ levels in rats compared to Control rats (p<0.05). Expressions of hepatic CYP3A11 were more than 10-fold higher in rats treated with vitamin D3 compared to Control rats (p<0.05). Expressions of colon CYP3A11 were 5-fold higher than in Control rats (p<0.05). CYP3A11 expressions in vitamin D3-treated groups were significantly higher compared to the Control group (p<0.05). MDZ levels were significantly higher in vitamin D3-treated rats compared to that in Control rats (p<0.05). Concentrations of serum MDZ at every sampling point were remarkably lower in the vitamin D3-treated rats than in Control rats (p<0.05).

Conclusions

Vitamin D3 was transformed into 1,25(OH)₂D₃ by triggering CYP3A11 and CYP3A11 activity and by hydrolyzing MDZ.

Prolonged Anesthetic Recovery after Continuous Infusion of Midazolam in 2 Domestic Cats (Felis catus)

Two healthy research cats involved in a randomized, blinded prospective pharmacodynamics study evaluating midazolam continuous-rate infusion as a means to decrease sevoflurane concentrations experienced unexpectedly prolonged recoveries. Midazolam loading doses, infusion rates, and the targeted plasma midazolam concentrations at steady-state were determined by pharmacokinetic modeling based on the results of a preliminary pharmacokinetic study using a single dose of midazolam. In the pharmacodynamics study, cats remained oversedated after recovery from anesthesia, and plasma concentrations of midazolam and its primary metabolite (1-hydroxymidazolam) remained elevated. The use of flumazenil was unsuccessful in timely treatment of oversedation. Administration of intravenous lipid emulsion was used in one of the cats to facilitate recovery and appeared to be effective in both reducing the depth of midazolam-induced oversedation and significantly reducing the plasma concentration of 1-hydroxymidazolam. The effects after the administration of both treatment modalities on clinical signs and plasma drug concentrations in cats are discussed. The observations suggest that cats may eliminate 1-hydroxymidazolam more slowly than expected; consequently dose adjustments may be required when continuous infusion of midazolam is intended. In addition, intravenous lipid emulsion may facilitate recovery from midazolam oversedation, particularly in cases unresponsive to traditional treatment modalities. However, further investigations are warranted to delineate the efficacy of this modality in the treatment of midazolam oversedation.