Plasma Concentrations Of Midazolam Research Articles

Treatment of agitation in terminally ill patients with intranasal midazolam versus subcutaneous midazolam: study protocol for a randomised controlled open-label monocentric trial (MinTU Study)

BackgroundIntranasal (i.n.) drug application is a widely known and low-invasive route of administration that may be able to achieve rapid symptom control in terminally ill patients. According to the German S3 guideline “Palliative care for patients with incurable cancer”, benzodiazepines, such as midazolam, are recommended for the treatment of terminal agitation. To the best of our knowledge there is no evidence for i.n. midazolam in terminally ill patients. We aim to assess the use of i.n. midazolam as an alternative to subcutaneous administration of the drug.MethodsIn this monocentric, randomised, controlled, open-label investigator initiated trial, n = 60 patients treated at the palliative care unit of a University Hospital will be treated with 5 mg midazolam i.n. versus 5 mg subcutaneous (s.c.) midazolam in the control arm when terminal agitation occurs (randomly assigned 1:1). The estimated recruitment period is 18 months. Treatment efficacy is defined as an improvement on the Richmond Agitation Sedation Scale (Palliative Version) (RASS-PAL) and a study specific numeric rating scale (NRS) before and after drug administration. Furthermore, plasma concentration determinations of midazolam will be conducted at t1 = 0 min, t2 = 5 min, and t3 = 20 min using liquid chromatography/mass spectrometry (LC-MS). The primary objective is to demonstrate non-inferiority of midazolam i.n. in comparison to midazolam s.c. for the treatment of agitation in terminally ill patients.DiscussionMidazolam i.n. is expected to achieve at least equivalent reduction of terminal agitation compared to s.c. administration. In addition, plasma concentrations of midazolam i.n. are not expected to be lower than those of midazolam s.c. and the dynamics of the plasma concentration with an earlier increase could be beneficial.Trial registrationGerman Clinical Trials Registry DRKS00026775, registered 07.07.2022, Eudra CT No.: 2021-004789-36.

NANONIZED CURCUMIN IMPROVED ORAL BIOAVAILABILITY OF BROMOCRIPTINE THROUGH CYP3A ENZYME INHIBITION IN RATS

Curcumin (CUR) a water insoluble dietary flavonoid and is reported to inhibit CYP3A4 enzyme. The objective of present study was to assess the effect of CUR and nanonized curcumin (NC) on bromocriptine (BRO) metabolism in rats. NC was prepared by antisolvent precipitation method and was evaluated for particle size and solubility. CYP3A inhibitory activity of CUR was assessed in vitro using erythromycin-N-demethylase (EMD) assay. CYP3A inhibitory effect of CUR and NC confirmed in vivo using pharmacokinetic study of midazolam. These findings were further confirmed by an in vivo pharmacokinetic study in which BRO was administered (10 mg/kg, p.o) to CUR and NC (60 mg/kg, p.o.) pretreated (10 days) rats and its plasma concentrations were determined by HPLC analysis. CUR significantly (p less than 0.05) inhibited CYP 3A activity in EMD assay. CUR and NC significantly (p less than 0.05) increased plasma concentrations of midazolam in dexamethasone pretreated rats. In addition, in vivo studies revealed that CUR and NC pretreatments significantly (p less than 0.05) increased Cmax and AUC and decreased CL/F of BRO compared with BRO group.NC pretreatment may increase the bioavailability of BRO which could be mediated through the inhibition of CYP 3A enzymes.

A Phase 3 open-label study of the efficacy, safety and pharmacokinetics of buccally administered midazolam hydrochloride for the treatment of status epilepticus in pediatric Japanese subjects

BackgroundIn Japan, intravenous (IV) administration of antiepileptic drugs in a healthcare setting is the preferred treatment option that is both licensed and recommended for initial treatment of status epilepticus (SE). However, prompt conveyance to a healthcare institution and IV access may be difficult in patients experiencing a seizure and so delay treatment. Thus, there is an unmet need for an alternative effective antiepileptic drug with an easier and more rapid mode of administration. In this study we evaluated a midazolam hydrochloride oromucosal solution (MHOS) that can be simply and rapidly administered to patients in SE. MethodsA Phase 3, interventional, multicenter, nonrandomized study was conducted in 28 clinical centers in Japan. Pediatric subjects in convulsive SE received treatment with buccal MHOS with dosage based on their age. The primary efficacy outcome was the percentage of subjects with seizure termination within 10 min and a 30-min absence of visible seizure activity from time of administration. Safety evaluations included respiratory depression and the frequency of treatment-emergent adverse events (TEAEs). Pharmacokinetic (PK) profile was also assessed. ResultsThe study population comprised 25 subjects with a median age of 2.8 years and median bodyweight of 13.4 kg. The primary efficacy outcome was achieved in 80 % of subjects; 84 % of subjects had seizure resolution within 10 min. Nine subjects experienced a total of 13 TEAEs, and protocol-defined respiratory depression occurred in one subject. Mean maximum plasma midazolam concentration was 78.0 ng/mL, and mean time to peak concentration was 20.5 min, demonstrating that achieving maximum plasma midazolam concentration is not required for seizure cessation. ConclusionsThe efficacy, safety and pharmacokinetic profile of MHOS in pediatric Japanese subjects was consistent with that observed in non-Japanese populations. Compared to IV treatments, MHOS offers easier administration which may reduce the time to treatment and thereby minimize the sequelae of prolonged seizures.

Midazolam and hydroxymidazolam plasma concentrations can be monitored with selected biochemical and physiological parameters of palliative care patients

Rationale & objectiveMidazolam is one of top three drugs used in palliative care. Its use increases in the last days of hospice patients’ lives while safe dosage can be challenging. Equations currently used to estimate glomerular filtration rate, e.g: the Cockroft-Gault (eGFRCR) and the Modification of Diet in Renal Disease (eGFRMDRD) ones, do not generate precise calculations, especially in palliative patients exhibiting variations in body parameters. Our aim was to seek new relationships between mean midazolam (Mavg) and alfahydroxymidazolam (OH-Mavg) concentrations in plasma, and selected biochemical and physiological parameters of palliative patients, to enable optimal midazolam pharmacotherapy. Study design, participants and interventionsThe pilot study included 11 Caucasians, aged 42–95, with advanced cancer disease, receiving midazolam in a hospice in-patient unit. We tested correlations among Mavg, BMI, eGFRMDRD, midazolam clearance (CL), OH-Mavg, bilirubin (Bil) and blood creatinine concentration (Cr). F test and leave-one out (LOO) validation was applied to verify the correlations’ significance and predictive ability. ResultsWe found ten statistically significant (p < 0.05) correlations related to midazolam pharmacokinetics and physiological factors. We formulated two equations with high degree of predictive ability, based on the eGFRMDRD→CL and the (Bil + BMI × Ln(Cr))→Mavg-(OH-Mavg) correlations.The limitations of the study mainly revolve around its pilot nature and the need to continue testing the results on a bigger population.No funding to disclose. ConclusionsThe significance of correlations corresponding to the arithmetic expressions confirms that Bil, BMI, Ln(Cr) analyzed simultaneously report a series of processes on which midazolam metabolism depends. Two of ten correlations proposed came close to meet all LOO validation criteria. Current findings can help optimize midazolam treatment in palliative therapy.

Sedation With Midazolam After Cardiac Surgery in Children With and Without Down Syndrome: A Pharmacokinetic-Pharmacodynamic Study.

To compare the pharmacokinetics and pharmacodynamics of IV midazolam after cardiac surgery between children with and without Down syndrome. Prospective, single-center observational trial. PICU in a university-affiliated pediatric teaching hospital. Twenty-one children with Down syndrome and 17 without, 3-36 months, scheduled for cardiac surgery with cardiopulmonary bypass. Postoperatively, nurses regularly assessed the children's pain and discomfort with the validated COMFORT-Behavioral scale and Numeric Rating Scale for pain. A loading dose of morphine (100 µg/kg) was administered after coming off bypass; thereafter, morphine infusion was commenced at 40 µg/kg/hr. Midazolam was started if COMFORT-Behavioral scale score of greater than 16 and Numeric Rating Scale score of less than 4 (suggestive of undersedation). Plasma midazolam and metabolite concentrations were measured for population pharmacokinetic- and pharmacodynamic analysis using nonlinear mixed effects modeling (NONMEM) (Version VI; GloboMax LLC, Hanover, MD) software. Twenty-six children (72%) required midazolam postoperatively (15 with Down syndrome and 11 without; p = 1.00). Neither the cumulative midazolam dose (p = 0.61) nor the time elapsed before additional sedation was initiated (p = 0.71), statistically significantly differed between children with and without Down syndrome. Population pharmacokinetic and pharmacodynamics analysis revealed no statistically significant differences between the children with and without Down syndrome. Bodyweight was a significant covariate for the clearance of 1-OH-midazolam to 1-OH-glucuronide (p = 0.003). Pharmacodynamic analysis revealed a marginal effect of the midazolam concentration on the COMFORT-Behavioral score. The majority of children with and without Down syndrome required additional sedation after cardiac surgery. This pharmacokinetic and pharmacodynamic analysis does not provide evidence for different dosing of midazolam in children with Down syndrome after cardiac surgery.

Effect of Chronic Kidney Disease on Hepatic Clearance of Drugs in Rats.

The pharmacokinetics of some hepatically cleared drugs have been reported to fluctuate in patients with renal impairment, but the definitive factors have not been clarified. We compared the pharmacokinetics of some drugs with different hepatic elimination processes in a chronic kidney disease (CKD) rat model, to optimize their administration during kidney injury. We chose indocyanine green (ICG), midazolam (MDZ), and acetaminophen (APAP) as reference drugs to determine changes in hepatic clearance pathways in presence of CKD. Drugs were intravenously administered via the jugular vein to the CKD model rats, previously established by adenine administration, and then, blood, bile, and urine samples were collected. The plasma concentration of ICG, which is eliminated into the bile without biotransformation, increased; and its total body clearance (CLtot) significantly decreased in the CKD group compared to the control group. Moreover, the plasma concentrations of MDZ and APAP, metabolized in the liver by CYP3A and Ugt1a6 enzymes, respectively, were higher in the CKD group than in the control group. The biliary clearances of APAP and its derivative APAP-glucuronide increased in the CKD group, whereas their renal clearances were markedly decreased with respect to those in the control group. Altogether, plasma concentrations of some hepatically eliminated drugs increased in the CKD rat model, but depending on their pharmacokinetic characteristics. This study provides useful information for optimizing the administration of some hepatically cleared drugs in CKD patients.

Sensitive determination of midazolam and propofol in human plasma by GC–MS/MS

A sensitive method was developed for the simultaneous determination of midazolam and propofol in human plasma samples via modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction for their analysis by gas chromatography–tandem mass spectrometry (GC–MS/MS). Detailed optimization and validation experiments were conducted; plasma quality control samples spiked with two drugs and two internal standards (ISs) were extracted using the QuEChERS technique and determined by GC–MS/MS. The present method was applied to the measurements in an actual clinical case. The regression equations for midazolam and propofol in plasma displayed good linearity (r > 0.9978) from 10 to 1000 ng/mL with a limit of quantification of 10 ng/mL. The intra- and interday precisions for both drugs were not greater than 8.6%. The accuracies of quantitation ranged from 98 to 110%. The extraction efficiencies of midazolam and propofol for plasma were 93 to 117%. The method was successfully applied to the analyses of plasma midazolam and propofol concentrations in a brain-injured patient subjected to hypothermia, which validated the present methodology. In this study, the authors have successfully established the detailed procedure for GC–MS/MS analysis of midazolam and propofol in human plasma. The sensitivity and specificity of the present method for the drugs were almost comparable to those by the standard liquid chromatography–tandem mass spectrometry. To their knowledge, this is the first report for analysis of midazolam/propofol by GC–MS/MS.

Pharmacokinetics of midazolam in sevoflurane-anesthetized cats

ObjectiveTo estimate the pharmacokinetics of midazolam and 1-hydroxymidazolam after midazolam administration as an intravenous bolus in sevoflurane-anesthetized cats. Study designProspective pharmacokinetic study. AnimalsA group of six healthy adult, female domestic cats. MethodsAnesthesia was induced and maintained with sevoflurane. After 30 minutes of anesthetic equilibration, cats were administered midazolam (0.3 mg kg–1) over 15 seconds. Venous blood was collected at 0, 1, 2, 4, 8, 15, 30, 45, 90, 180 and 360 minutes after administration. Plasma concentrations for midazolam and 1-hydroxymidazolam were measured using high-pressure liquid chromatography. The heart rate (HR), respiratory rate (fR), rectal temperature, noninvasive mean arterial pressure (MAP) and end-tidal carbon dioxide (Pe′CO2) were recorded at 5 minute intervals. Population compartment models were fitted to the time–plasma midazolam and 1-hydroxymidazolam concentrations using nonlinear mixed effect modeling. ResultsThe pharmacokinetic model was fitted to the data from five cats, as 1-hydroxymidazolam was not detected in one cat. A five-compartment model best fitted the data. Typical values (% interindividual variability where estimated) for the volumes of distribution for midazolam (three compartments) and hydroxymidazolam (two compartments) were 117 (14), 286 (10), 705 (14), 53 (36) and 334 mL kg–1, respectively. Midazolam clearance to 1-hydroxymidazolam, midazolam fast and slow intercompartmental clearances, 1-hydroxymidazolam clearance and 1-hydroxymidazolam intercompartment clearance were 18.3, 63.5 (15), 22.1 (8), 1.7 (67) and 3.8 mL minute–1 kg–1, respectively. No significant changes in HR, MAP, fR or Pe′CO2 were observed following midazolam administration. Conclusion and clinical relevanceIn sevoflurane-anesthetized cats, a five-compartment model best fitted the midazolam pharamacokinetic profile. There was a high interindividual variability in the plasma 1-hydroxymidazolam concentrations, and this metabolite had a low clearance and persisted in the plasma for longer than the parent drug. Midazolam administration did not result in clinically significant changes in physiologic variables.

Effect of Multiple-Dose Aprocitentan Administration on the Pharmacokinetics of Midazolam in Healthy Male Subjects

Aprocitentan is an orally active dual endothelin receptor antagonist that targets a novel pathway in the treatment of difficult-to-control (resistant) hypertension. The drug-drug interaction potential of aprocitentan on cytochrome P450 (CYP) 3A enzymes was investigated in this open-label, two-treatment single-sequence study. The primary and main secondary objectives were to study the pharmacokinetics of midazolam in the absence and presence of aprocitentan and the safety and tolerability of combined administration, respectively. Nineteen healthy male subjects received a single dose of 8mg midazolam. Thereafter, they started aprocitentan treatment (loading dose of 150mg followed by 50mg once daily) and received another single dose of midazolam with aprocitentan at steady state. Pharmacokinetics and tolerability of midazolam and its metabolite 1-hydroxy midazolam were assessed over 24h after each midazolam administration. At steady state, aprocitentan did not affect the area under the plasma concentration-timecurve and maximum plasma concentration (Cmax) of midazolam and 1-hydroxy midazolam, with a geometric means ratio (GMR) of midazolam + aprocitentan/midazolam alone close to 1 and 90% confidence intervals (CI) between 0.88 and 1.23. For the Cmax of 1-hydroxy midazolam the GMR (90% CI) was 0.86 (0.70-1.05). Somnolence, a known side-effect of midazolam, was reported as the most frequent adverse event. There were no relevant differences in tolerability parameters between treatments. Aprocitentan does not alter the pharmacokinetics of midazolam to a clinically relevant extent and was well tolerated when administered concomitantly. Therefore, aprocitentan can be administered together with drugs that are substrates of CYP3A without dose adjustments.

Influence of midazolam-related genetic polymorphism on conscious sedation during upper gastrointestinal endoscopy in a Korean population

Genetic polymorphism can result in abnormal pharmacodynamics that subsequently leads to the individual variance in sedative effects and adverse reactions. The aim of this study was to elucidate the association between midazolam-related genetic polymorphism and sedative effects, including adverse reactions, under conscious sedation during upper gastrointestinal endoscopy. We prospectively enrolled 100 eligible patients undergoing upper gastrointestinal endoscopy. The efficacy of the sedation, adverse reactions, plasma concentration of midazolam and 1-hydroxymidazolam were investigated as well as the genetic polymorphism of MDR1 and CYP3A5. The correlation between genetic polymorphism and sedative effects was assessed. Regarding MDR1 gene, the plasma concentration of midazolam was greater in patients with CGC haplotype (P = 0.012), while it was lower in patients with CAC haplotype (P = 0.005) than in those with other haplotypes. However, genetic polymorphism of neither MDR1 nor CYP3A5 correlated with the plasma concentration of 1-hydroxymidazolam. CGT haplotype of MDR1 was significantly correlated with sedation grade after midazolam administration (P = 0.042). In contrast, genetic polymorphism of CYP3A5 was not correlated with sedation grade. There was no association between genetic polymorphism of MDR1 or CYP3A5 and selected adverse reactions related to midazolam. Genetic polymorphism of MDR1 influences the concentration of midazolam and the sedation grade. However, it is not associated with adverse reactions such as paradoxical response and retrograde amnesia.

Maturation of midazolam clearance in critically ill children with severe bronchiolitis: A population pharmacokinetic analysis

PurposeThe aim of the present study was to develop a population pharmacokinetic model of midazolam, and to evaluate the influence of maturation process and other variability factors in critically ill children with severe acute bronchiolitis, who received a long-term intravenous infusion of midazolam. MethodsIn the study were included 49 critically ill children of both genders (from 0 to 130 weeks of age) with severe acute bronchiolitis hospitalised in intensive care units. Nonlinear mixed effects modelling approach was applied for data analyses and simulations. ResultsThe final model is a two-compartment model that includes the effects of body weight using allometric scaling with fixed exponents and maturation of clearance. For a typical subject, scaled to the adult body weight of 70 kg, population pharmacokinetic values were estimated at 8.52 L/h for clearance (when maturation function was 1), 25.5 L/h for intercompartmental clearance, and 5.71 L and 39.8 L for the volume of the central and peripheral compartment, respectively. Based on the final model, maturation reaches 50% of the adult clearance in 45.9 weeks of postmenstrual age. The influence of gender, ABCB1 genotype and biochemical parameters on midazolam clearance was not detected. Results of simulations indicate the need for reduced dosing in certain groups of patients in order to maintain plasma concentrations of midazolam within recommended values. ConclusionsThe developed population pharmacokinetic model can contribute to the dosing optimisation of midazolam, especially in critically ill children as it includes the influence of size and maturation of clearance, which are important parameters for achieving the desired plasma concentrations of midazolam.

Minor contribution of cytochrome P450 3A activity on fentanyl exposure in palliative care cancer patients

Transdermal fentanyl is widely used to control pain in cancer patients. The high pharmacokinetic variability of fentanyl is assumed to be due to cytochrome P450 3A-mediated (CYP3A) N-dealkylation to norfentanyl in humans. However, recently published clinical studies question the importance of the described metabolic pathway. In this small study in palliative cancer patients under real-life clinical conditions, the influence of CYP3A on fentanyl variability was investigated. In addition to the determination of midazolam plasma concentration to reveal CYP3A activity, plasma concentrations of fentanyl and its metabolite, norfentanyl, were measured in identical blood samples of 20 patients who participated in an ongoing trial and had been on transdermal fentanyl. Fentanyl, norfentanyl, midazolam, and 1′-OH-midazolam were quantified by liquid chromatography/tandem mass spectrometry. Plasma concentrations of fentanyl and norfentanyl exhibited a large variability. Mean estimated total clearance of fentanyl and mean metabolic clearance of midazolam (as a marker of CYP3A activity) were 75.5 and 36.3 L/h. Both clearances showed a weak correlation and hence a minimal influence of CYP3A on fentanyl elimination.

The Prediction of the Area under the Curve and Clearance of Midazolam from Single-Point Plasma Concentration and Urinary Excretion in Healthy Volunteers.

There are large inter- and intra-individual variations in CYP3A4 activity. Midazolam, which is predominantly metabolized to 1'-hydroxymidazolam and 4-hydroxymidazolam by CYP3A4, is considered an effective probe for CYP3A4. To determine the area under the curve (AUC) of midazolam or midazolam clearance for CYP3A4 activity, multiple plasma samples of midazolam are required. This study aimed to evaluate whether measurement of a single plasma concentration or urinary excretion of midazolam could be used to predict the AUC of midazolam in healthy volunteers. We conducted a retrospective analysis of two pharmacokinetic studies. Nineteen volunteers received intravenous (5, 15, and 30 µg/kg) and oral (15, 50, and 100 µg/kg) administration of midazolam on sequential days. The midazolam concentration in plasma and urine was determined by LC-MS/MS. Plasma midazolam concentrations showed a good correlation with the AUC at all blood sampling points after the administrations. The coefficient of determination was highest at 1-2 and 2-4 h after intravenous (>0.96) and oral administration (>0.94), respectively, among all the sampling times. The errors for bias and accuracy of prediction were the lowest at 1.5 and 4 h after intravenous and oral administration, respectively. In case of urinary excretion, a significant positive correlation between midazolam and the AUC was observed only after oral administration. Thus, the AUC of midazolam can be evaluated by blood sampling at 1.5 h after intravenous administration and at 4 h after oral administration.

Pharmacokinetics of midazolam and its major metabolite 1-hydroxymidazolam in the ball python (Python regius) after intracardiac and intramuscular administrations.

Midazolam is a benzodiazepine with sedative, muscle relaxant, anxiolytic, and anticonvulsant effects. Twelve ball pythons (Python regius) were used in a parallel study evaluating the pharmacokinetics of 1mg/kg midazolam following a single intracardiac (IC) or intramuscular (IM) administration. Blood was collected from a central venous catheter placed 7days prior, or by cardiocentesis, at 15 time points starting just prior to and up to 72hr after drug administration. Plasma concentrations of midazolam and 1-hydroxymidazolam were determined by the use of high-performance liquid chromatography tandem-mass spectrometry and pharmacokinetic parameters were estimated using noncompartmental analysis. The mean±SD terminal half-lives of IC and IM midazolam were 12.04±3.25hr and 16.54±7.10hr, respectively. The area under the concentration-time curve extrapolated to infinity, clearance, and apparent volume of distribution in steady-state of IC midazolam were 19,112.3±3,095.9ng*hr/ml, 0.053±0.008 Lhr-1 kg-1 , and 0.865±0.289L/kg, respectively. The bioavailability of IM midazolam was estimated at 89%. Maximum plasma concentrations following an IM administration were reached 2.33±0.98hr and 24.00±14.12hr postinjection for midazolam and 1-hydroxymidazolam, respectively, and 22.33±20.26hr postinjection for 1-hydroxymidazolam following IC administration.

Phenobarbital, Midazolam Pharmacokinetics, Effectiveness, and Drug-Drug Interaction in Asphyxiated Neonates Undergoing Therapeutic Hypothermia

Background: Phenobarbital and midazolam are commonly used drugs in (near-)term neonates treated with therapeutic hypothermia for hypoxic-ischaemic encephalopathy, for sedation, and/or as anti-epileptic drug. Phenobarbital is an inducer of cytochrome P450 (CYP) 3A, while midazolam is a CYP3A substrate. Therefore, co-treatment with phenobarbital might impact midazolam clearance. Objectives: To assess pharmacokinetics and clinical anti-epileptic effectiveness of phenobarbital and midazolam in asphyxiated neonates and to develop dosing guidelines. Methods: Data were collected in the prospective multicentre PharmaCool study. In the present study, neonates treated with therapeutic hypothermia and receiving midazolam and/or phenobarbital were included. Plasma concentrations of phenobarbital and midazolam including its metabolites were determined in blood samples drawn on days 2–5 after birth. Pharmacokinetic analyses were performed using non-linear mixed effects modelling; clinical effectiveness was defined as no use of additional anti-epileptic drugs. Results: Data were available from 113 (phenobarbital) and 118 (midazolam) neonates; 68 were treated with both medications. Only clearance of 1-hydroxy midazolam was influenced by hypothermia. Phenobarbital co-administration increased midazolam clearance by a factor 2.3 (95% CI 1.9–2.9, p < 0.05). Anticonvulsant effectiveness was 65.5% for phenobarbital and 37.1% for add-on midazolam. Conclusions: Therapeutic hypothermia does not influence clearance of phenobarbital or midazolam in (near-)term neonates with hypoxic-ischaemic encephalopathy. A phenobarbital dose of 30 mg/kg is advised to reach therapeutic concentrations. Phenobarbital co-administration significantly increased midazolam clearance. Should phenobarbital be substituted by non-CYP3A inducers as first-line anticonvulsant, a 50% lower midazolam maintenance dose might be appropriate to avoid excessive exposure during the first days after birth.

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.

Alteration of drug-metabolizing enzyme activity in palliative care patients: Microdosed assessment of cytochrome P450 3A

Background: Cytochrome P450 3A is the most relevant drug-metabolizing enzyme in humans as it is involved in the elimination of 50% of marketed drugs. Nothing is known about the activity of cytochrome P450 3A in palliative care patients who have complicated symptoms often associated with a terminal illness. Aim: In order to improve drug dosing in end-of-life care and to avoid drug interactions, cytochrome P450 3A activity was determined in patients of a palliative care unit under real-life clinical conditions. Design: As midazolam is an established marker substance for cytochrome P450 3A activity, this single-arm prospective trial was designed to obtain a 4-h pharmacokinetic profile of midazolam after oral administration of a 10-µg dose from each enrolled patient. Plasma concentrations of midazolam and its primary metabolite 1′-hydroxy-midazolam were quantified by mass spectrometry techniques. Cytochrome P450 3A activity was calculated as partial metabolic clearance from a limited sampling area under the curve. All other drugs taken by the participating patients were considered, as well as recent blood test results and patients’ diagnoses. The trial was registered at German Clinical Trials Register (www.drks.de): DRKS00011753. Setting/participants: The trial was carried out at a university palliative care unit under real-life clinical conditions. Every patient admitted to the ward was screened for possible participation, independent of the individual performance status. Results: Partial metabolic clearance of midazolam in palliative care patients was 31.7 ± 32.1 L/h. This was a highly significant 40% reduction (p < 0.0001) in comparison with the cytochrome P450 3A activity of healthy subjects. Conclusion: Dosing of cytochrome P450 3A substrate drugs (e.g. macrolide antibiotics, benzodiazepines, calcium channel blockers) needs to be adjusted in palliative care patients; otherwise, escalation of debilitating symptoms due to drug interactions might occur.

Decreased Cytochrome P450 3A activity in palliative patients with haematological diseases: Potential impact on supportive drug therapies

Cytochrome P450 3A (CYP3A) is the most relevant drug-metabolizing enzyme in human beings involved in the elimination of about 50% of the marketed drugs. Comprehensive in vivo data of CYP3A activity in palliative patients with haematological diseases are missing. Therefore, CYP3A activity was determined under real-life clinical conditions in patients to gain knowledge about dose adjustments for supportive therapies and symptom management in haematology. The single-arm, prospective trial obtained a 4-hours pharmacokinetic profile of midazolam after oral administration of a microdose as marker substance from each enrolled patient. Plasma concentrations of midazolam and its primary metabolite 1'-hydroxy-midazolam were quantified by mass spectrometry techniques. CYP3A activity was calculated as partial metabolic clearance from an established limited sampling area under the curve. All other drugs taken by the participating patients were considered as well as recent laboratory test results and the patients' diagnoses. Partial metabolic clearance of midazolam in patients with haematological diseases was highly variable (36.9±52.7L/h). In comparison with the CYP3A activity of healthy individuals, this was a highly significant 30% reduction of activity (P<0.0001). Dosing of major CYP3A substrate drugs needs to be reduced in palliative patients with haematological diseases, otherwise escalation of debilitating symptoms due to drug interactions might occur.

No Relevant Pharmacokinetic (PK) Interaction between Rezafungin and Nine Probe Drugs: Results from a Drug-Drug Interaction (DDI) Study

Introduction Rezafungin (RZF) is a new echinocandin being developed to treat patients with systemic fungal infections and to prevent invasive fungal infections in allogeneic hematopoietic stem cell transplant (HSCT) recipients and other patients at high risk of infection. RZF is differentiated by stable and efficacy-driving pharmacokinetics (PK) that allow for once-weekly dosing. Several in vitro studies have been conducted to assess the potential for rezafungin to alter the PK of other drugs. Based on the results, possible interactions were identified in which the risk of drug-drug interactions (DDIs) could not be ruled out relative to the assumed Ph3 dose of 400 mg once weekly and known PK exposure in healthy subjects. Clinical in vivo evaluations of drug interaction potential were performed proactively. Methods This was an open-label, inpatient study of 26 healthy subjects to assess DDIs between RZF and probe drugs selected for known interactions with CYP enzymes and transporters (and consequently commonly used in evaluations of PK interaction), as well as drugs likely to be coadministered with RZF. A loading dose of RZF 600 mg was administered on the first dosing day, to approximate a steady state plasma concentration of multiple once-weekly 400-mg doses, followed by 400-mg doses on days 10 and 15. Probe drugs were administered as part of a cocktail containing ≥2 drugs, once prior to and once after receiving RZF on a schedule designed to allow for washout between doses and to limit interactions with other drugs (Figure 1). Samples were analyzed to determine RZF, tacrolimus, repaglinide, metformin, rosuvastatin, pitavastatin, caffeine, efavirenz, midazolam and digoxin concentrations in plasma (except for tacrolimus which was in whole blood) to characterize the PK profile of each analyte. PK exposure parameters (area under curve [AUC] and maximum concentration [Cmax]) were calculated from the plasma concentration-time profiles by noncompartmental analysis. Results When rezafungin was dosed concomitantly with metformin, pitavastatin, caffeine, efavirenz, midazolam, digoxin, tacrolimus, repaglinide, and rosuvastatin, no relevant change in systemic concentrations of these probe drugs was observed (Figure 2). PK exposure of all drugs were similar with or without RZF. Maximum changes in mean Cmax or AUC were Conclusion No meaningful PK interactions occurred between RZF and the 9 probe drug substrates tested, providing evidence that no RZF dose adjustment is expected when co-administered with these commonly used drugs.

In Vivo CYP3A Activity in Palliative Care Patients: Study Protocol for a Single Arm Prospective Trial.

Drug interactions are a common cause for escalation of debilitating symptoms in palliative care patients. CYP3A is the most relevant CYP enzyme in humans involved in metabolism of about half of all available pharmaceuticals. To increase knowledge about the CYP3A enzyme and the impact of drug interactions on its activity to improve dosing in palliative care patients. The prospective clinical trial uses a secure method of analyzing CYP3A activity in humans: Administration of a marker substance followed by the determination of its blood concentrations as well as the concentrations of its metabolite at certain points of time and corresponding metabolic clearance calculations. The ongoing trial is carried out at a palliative care unit under real-life clinical conditions. A four-hour pharmacokinetic profile after oral administration of the marker substance (microdose of midazolam) will be obtained from each enrolled patient. Plasma concentrations of midazolam and its primary metabolite will be quantified by mass spectrometry techniques. CYP3A activity will be calculated as partial metabolic clearance from a limited sampling area under the curve. All other drugs taken by the participating patients will be considered as well as recent blood test results and the patients' diagnoses. This is the first prospective study dealing with drug metabolism in patients on a palliative care unit. The trial is based on reliable and established methods aiming to provide improved dosing regimens and thus optimize pharmacological therapies in this specialty.