Population Pharmacokinetic-Pharmacodynamic Modeling of Ropivacaine in Spinal Anesthesia

Ropivacaine pharmacokinetics in the arterial and venous pools after ultrasound-guided continuous thoracic paravertebral nerve block

Background and Aims

Although thoracic paravertebral blockade (TPVB) is employed in thoracic surgery to ensure satisfactory postoperative analgesia, large doses of anesthetics are required and manifestations of local anesthetic systemic toxicity (LAST) may appear. Currently, there are limited data on the pharmacokinetics of ropivacaine after continuous TPVB. The aim of this prospective study was to investigate ropivacaine kinetics, in the arterial and venous pools, after continuous TPVB and assess the risk of LAST.

Material and Methods

Immediately after induction of general anesthesia, an ultrasound-guided continuous TPVB at T5 or T6 or T7 thoracic level was performed in 18 adult patients subjected to open thoracotomy. A 25-ml single bolus injection of ropivacaine 0.5% was administered through thoracic paravertebral catheter, followed by a 14 ml/h continuous infusion of ropivacaine 0.2% starting at the end of surgery. Quantification of total ropivacaine concentrations was performed using a validated high-performance liquid chromatography method. Population pharmacokinetic models were developed separately for arterial and venous ropivacaine data.

Results

The best model was one-compartment disposition with an additional pre-absorption compartment corresponding to thoracic paravertebral space. Gender had a significant effect on clearance, with females displaying lower elimination than males. Some patients had ropivacaine concentrations above the toxic threshold, but none displayed evidence of LAST. Continuous thoracic paravertebral nerve blocks provided adequate postoperative analgesia.

Conclusion

Ropivacaine doses at the upper end of clinical use (800 mg/d) did not inflict the manifestations of LAST and provided adequate postoperative pain control. Pharmacokinetic models were developed, and the effect of gender was identified.

A new pharmacokinetic model of urinary methotrexate to assess adherence in rheumatoid arthritis

BACKGROUND AND OBJECTIVES

Methotrexate (MTX) is the first-line therapy for rheumatoid arthritis (RA). While therapeutic adherence is essential to successful management, no objective MTX assay is currently available. Using population pharmacokinetic modelling (PopPK), our objective was to describe the urinary MTX (MTXu) kinetics in treated patients and to evaluate its abilities to assess the MTX-adherence.

METHODS

The association between urinary methotrexate level and methotrexate administration was assessed using a generalized linear model. Then, a population pharmacokinetic model was developed based on data from 59 patients using with Monolix 2021. R2. Simulations were run to establish a reference kinetic profile and evaluate the proportion of samples predicted as true positives.

RESULTS

Compared to the control group, multivariate analysis showed that MTXu was independently associated with methotrexate administration (p < 0.0001) with a sensitivity and specificity greater than 99%. The final PopPK model selected was a two-compartment model with first-order absorption and elimination. Internal and external validation of the model met all predefined criteria. When using an analytical assay with a LOQ equal to 1 nM, the proportion of samples predicted as true positives is over 90%, as a function of MTX dose (7.5-25 mg/week) and post-administration sampling days (1-7 days).

CONCLUSION

We developed a pharmacokinetic model able to describe expected patterns of urinary methotrexate. This allowed us to propose a new objective test of MTX adherence, which could help in routine practice to differentiate patients who are truly unresponsive to methotrexate from those who are unresponsive because of non-adherence.

Negative Impact of ST-Segment Elevation Myocardial Infarction and Morphine Dose on Ticagrelor Uptake and Pharmacodynamics: A Population PK/PD Analysis of Pooled Individual Participant Data

BACKGROUND

Ticagrelor is widely used in patients with stable and acute coronary artery disease. Understanding the factors that influence its pharmacokinetics (PK) and pharmacodynamics (PD) could improve therapeutic outcomes. We therefore performed a pooled population PK/PD analysis using individual patient data from two studies. We focused on the impact of morphine administration and ST-segment elevation myocardial infarction (STEMI) on the risk of high platelet reactivity (HPR) and dyspnea.

METHODS

A parent-metabolite population PK/PD model was developed based on data from 63 STEMI, 50 non-STEMI, and 25 chronic coronary syndrome (CCS) patients. Simulations were then run to evaluate the risk of non-response and adverse events associated with the identified variability factors.

RESULTS

The final PK model consisted of first-order absorption with transit compartments, distribution with two compartments for ticagrelor and one compartment for AR-C124910XX (active metabolite of ticagrelor), and linear elimination for both drugs. The final PK/PD model was an indirect turnover model with production inhibition. Morphine dose and STEMI, independently, had a significant negative effect on the absorption rate (reduction of log([Formula: see text]) by 0.21×morphine dose (mg) and by 2.37 in STEMI patients, both p < 0.001), and the presence of STEMI significantly impacted both efficacy and potency (both p < 0.001). The simulations run with the validated model showed a high rate of non-response in patients with those covariates (RR 1.19 for morphine, 4.11 for STEMI and 5.73 for morphine and STEMI, all three p < 0.001). By increasing ticagrelor dosage, the negative morphine effect was reversible in patients without STEMI and just limited in patients with STEMI.

CONCLUSION

The developed population PK/PD model confirmed the negative impact of morphine administration and presence of STEMI on ticagrelor PK and antiplatelet effect. Increasing ticagrelor doses seems effective in morphine users without STEMI, whereas the STEMI effect is not entirely reversible.

Effect of single spinal anesthesia with two doses ropivacaine on urinary retention after hemorrhoidectomy in male patients

Background

Anorectal diseases are common in the population and include internal, external, and mixed hemorrhoids. Although hemorrhoid surgery is a brief operation, anesthesia, anesthetic drugs, drug concentrations, and anesthesia level control are closely related to postoperative uroschesis. For hemorrhoid surgery, a single spinal block with ropivacaine is commonly used that blocks the S2-S4 parasympathetic nervous system, which in turn governs the voiding reflex, causing postoperative urinary retention; this affects the recovery of patients. This study was performed to investigate the effects of two doses ropivacaine that provided satisfactory analgesia and muscle relaxation and inhibited adverse reflexes on urinary retention after hemorrhoidectomy.

Methods

The study included 200 male patients who underwent anorectal surgery with American Society of Anesthesiologists (ASA) grade I-II single elective spinal anesthesia between March 2021 and March 2022. Patients were randomly assigned to 2 groups using a random number table: Group A (n = 100) received 10 mg 0.5% ropivacaine (1.5 ml 1% ropivacaine + 1.5 ml 10% glucose = 3 ml), and Group B (n = 100) received 15 mg 0.5% ropivacaine (1.5 ml 1% ropivacaine + 1.5 ml 10% glucose = 3 ml).

Results

The anal sphincter exhibited good relaxation, and no obvious traction pain or significant difference in the time of muscle strength recovery was observed between the 10 mg and 15 mg 0.5% ropivacaine groups (P > 0.05). The 10 mg 0.5% ropivacaine group had shorter time of micturition exceeding 100 ml and lower voiding International Prostate Symptom Score than the 15 mg 0.5% ropivacaine group (P < 0.01).

Conclusions

Single spinal anesthesia with 10 mg 0.5% ropivacaine not only provides satisfactory anesthetic effect for hemorrhoidectomy but also has less influence on postoperative uroschesis and is worthy of clinical application.

Trial registration

The study was registered in the Chinese Clinical Trial Registry (http://www.chictr.org.cn; identifier: ChiCTR2,100,043,686) on February 27, 2021.

Development and Validation of a Non-Targeted Screening Method for Most Psychoactive, Analgesic, Anaesthetic, Anti-Diabetic, Anti-Coagulant and Anti-Hypertensive Drugs in Human Whole Blood and Plasma Using High-Resolution Mass Spectrometry

(1) Background: In toxicological laboratories, various screening methods can be used to identify compounds involved in intoxication. High-resolution mass spectrometry has been increasingly used in this context for the last years, because of its sensitivity and reliability. Here, we present the development and validation of a screening method that uses liquid chromatography coupled with a high-resolution mass spectrometer. (2) Methods: This method required only 100 µL of whole blood or plasma sample. Pretreatment consisted of a rapid and simple deproteinisation with methanol/acetonitrile and zinc sulphate. This new assay was validated according to international guidelines. (3) Results: To perform the method validation, 53 compounds were selected. The selection criteria were as follows: various chemical structures and therapeutic families (>15), large m/z distribution, positive or negative ionisation mode, and various elution times. The assays showed high selectivity and specificity, with optimal process efficiency. The identification limits, determined using predefined criteria, were established at sub-therapeutic or therapeutic concentrations. Applicability was evaluated using spiked plasma controls and external quality controls. (4) Conclusions: The new method was then successfully applied to routine clinical and forensic samples.

The feasibility and safety of cocktail treatment of triple anti-inflammatory agents loaded with gelatin sponge promotes early recovery after posterior percutaneous endoscopic cervical discectomy

Purpose

To investigate whether a cocktail therapy of dexamethasone, ropivacaine, dexmedetomidine, and vitamin B12 can achieve satisfactory pain relief and promote early functional recovery after PPECD.

Methods

Eighty single-level patients with CDH who received PPECD were retrospectively divided into two groups: the cocktail and control groups. Clinical data were recorded and evaluated by a dedicated physician who was not involved in the patient’s treatment. The primary clinical outcomes included visual analog scores (VASs) for upper limber pain and neck disability index (NDI) scores. The follow-up time points were preoperatively and postoperative 1 week, 1 month, 3 months, 6 months, and 12 months. The modified MacNab criteria was used to evaluate the surgical effect of the last follow-up.

Results

The follow-up data of 74 cases were complete, except 6 cases lost to follow-up. There was no significant difference between the two groups in demographics, duration of symptoms, operation stage (p > 0.05), and operation time (80.5 ± 5.5 vs. 81.5 ± 3.5 min). The VAS in the upper limbs pain was significantly higher postoperatively than preoperatively in both groups (p < 0.05). The cocktail group had a lower VAS than the control group 1 week postoperatively (p < 0.05); however, VAS not different between groups at the remaining time points. The NDI scores were significantly better postoperatively than preoperatively, and no significant differences were seen when comparing nodes at postoperative follow-up (p > 0.05). In the control group, two cases with foraminal stenosis were found to have unrelieved pain in the early postoperative period, but the pain was relieved at the final follow-up and did not convert to open decompression surgery.

Conclusions

Cocktail treatment, in which a drug sustained-release material made of gelatin sponge was impregnated with dexamethasone, ropivacaine, dexmedetomidine and vitamin B12, facilitates pain relief and early postoperative recovery after PPECD.

The Perception of the Anesthesiologist Among the Medical, Paramedical and Administrative Staff

Introduction

Anesthesia remains a young medical discipline still relatively unknown by the general public and probably by some health professionals. The objective of the study was to evaluate the perception of anesthesiologist by health professionals working with this specialty.

Methods

We distributed a computerized survey to physicians, residents, paramedical, midwives, and administrative staff in different hospitals between April and July 2018 in Normandy, France. The survey included 38 questions on 6 different topics: communicated image, skills and knowledge, communication, place in patient care, workload, and initial anesthesiologist formation. The survey was validated by a semi-directive interview methodology. A Likert scale from ×2 to +2 (“completely disagree” to “completely agree”) was used for each item.

Results

Six hundred and twenty five out of 2,000 surveys sent were analyzed. The anesthesiologist conveys an image of serenity (+0.94 ± 0.79), has a high degree of responsibility (+1.72 ± 0.59) with important decision-making power (+1.39 ± 0.82). He guarantees patient safety and comfort (+1.07 ± 0.88) with his/her dual competence in anesthesia and intensive care (+1.36 ± 0.82). Anesthesiology requires teamwork (+1.68 ± 0.58) and good communication skills (+1.48 ± 0.73). The anesthesiologist is not perceived as a service provider (−0.33 ± 1.15) but is the physician responsible for perioperative care (+1.69 ± 1.00). His/her workload is moderately perceived as high (+0.71 ± 1.17) but is confronted with potentially conflictual relationships with colleagues from other specialties (+1.40 ± 0.68) and stressful situations (+1.44 ± 0.80).

Conclusion

The overall perception of the anesthesiologist in our study appears to be good.

Different Concentrations of Ropivacaine under Ultrasound Guidance on Quadratus Lumbar Muscle Nerve Block in Elderly Patients with Hip Replacement

Objective

To compare the effect of ropivacaine in different concentrations under ultrasound guidance on lumbar muscle nerve blocking in elderly patients undergoing hip replacement surgery.

Methods

60 elderly patients underwent hip replacement in our hospital over a period of April to December of 2019 were equally randomized into control and observation groups, with 30 each. Patients in the control group and observation group received 0.5% and 0.25% ropivacaine to block psoas muscle nerve, respectively. The anesthetic effect of ropivacaine at different concentrations was evaluated by time of sensory block onset and recovery and time of motor block onset and regression, blood pressure, heart rate, visual analogy scale, and postoperative nerve blocking degree.

Results

The onset time of sensory and motor block in the observation group was dramatically higher than that in the control group (P < 0.05), while the recovery time of sensory and motor was significantly shorter than that of the control group (P < 0.05). The heart rate in the observation group was notably lower than that in the control group, while the average blood pressure was remarkably higher (P < 0.05). After surgery, the degree of nerve block in the observation group was much lower compared with the control group (P < 0.05), while no marked difference in the visual analogue scale in the control group before and after surgical intervention was observed (P > 0.05).

Conclusion

The 0.25% ropivacaine method has distinctive advantages over 0.50% ropivacaine psoas nerve anesthesia in hip replacement surgery in elderly patients.

External Evaluation of Population Pharmacokinetic Models and Bayes-Based Dosing of Infliximab

Despite the well-demonstrated efficacy of infliximab in inflammatory diseases, treatment failure remains frequent. Dose adjustment using Bayesian methods has shown in silico its interest in achieving target plasma concentrations. However, most of the published models have not been fully validated in accordance with the recommendations. This study aimed to submit these models to an external evaluation and verify their predictive capabilities. Eight models were selected for external evaluation, carried out on an independent database (409 concentrations from 157 patients). Each model was evaluated based on the following parameters: goodness-of-fit (comparison of predictions to observations), residual error model (population weighted residuals (PWRES), individual weighted residuals (IWRES), and normalized prediction distribution errors (NPDE)), and predictive performances (prediction-corrected visual predictive checks (pcVPC) and Bayesian simulations). The performances observed during this external evaluation varied greatly from one model to another. The eight evaluated models showed a significant bias in population predictions (from -7.19 to 7.38 mg/L). Individual predictions showed acceptable bias and precision for six of the eight models (mean error of -0.74 to -0.29 mg/L and mean percent error of -16.6 to -0.4%). Analysis of NPDE and pcVPC confirmed these results and revealed a problem with the inclusion of several covariates (weight, concomitant immunomodulatory treatment, presence of anti-drug antibodies). This external evaluation showed satisfactory results for some models, notably models A and B, and highlighted several prospects for improving the pharmacokinetic models of infliximab for clinical-biological application.

Population pharmacokinetics of ropivacaine used for local infiltration anaesthesia during primary total unilateral and simultaneous bilateral knee arthroplasty

BACKGROUND

Ropivacaine is commonly used in local infiltration anaesthesia (LIA) as pain management after total knee arthroplasty (TKA). Although considered safe, no studies evaluated the pharmacokinetics of high-dose ropivacaine infiltration in simultaneous bilateral TKA.

METHODS

We studied 13 patients undergoing unilateral and 15 undergoing bilateral TKA. Standard LIA technique was used with ropivacaine 0.2%, 200 ml (400 mg) injected peri-articularly in each knee. Free and total plasma concentrations of ropivacaine were measured within 24 h using liquid chromatography-mass spectrometry. A population pharmacokinetic model was built using non-linear mixed-effects models.

RESULTS

Peak free ropivacaine concentration was 0.030 (0.017-0.071) μg ml^-1 (mean [99% confidence interval]) vs 0.095 (0.047-0.208) μg ml^-1, and peak total ropivacaine concentration was 0.756 (0.065-1.222) μg ml^-1vs 1.695 (0.077-3.005) μg ml^-1 for unilateral and bilateral TKA, respectively. The pharmacokinetics was ascribed a one-compartment model with first-order absorption. The main identified covariates were protein binding, allometrically scaled body weight on clearance and volume, and unilateral or bilateral surgery on volume.

CONCLUSIONS

This is the first study to investigate the pharmacokinetics of free and total ropivacaine after unilateral and bilateral TKA. A population model was successfully built and peak free ropivacaine concentration stayed below previously proposed toxic thresholds in patients undergoing unilateral and bilateral TKA receiving LIA with high-dose ropivacaine.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04702282.

Incremental Value of CSF Biomarkers in Clinically Diagnosed AD and Non-AD Dementia

Background: Cerebrospinal fluid (CSF) biomarkers are used to diagnose Alzheimer disease (AD), especially in atypical clinical presentations. No consensus currently exists regarding cut-off values. This study aimed, firstly, to define optimal cut-off values for CSF biomarkers, and secondly, to investigate the most relevant diagnostic strategy for AD based on CSF biomarker combinations.

Methods: A total of 380 patients were prospectively included: 140 with AD, 240 with various neurological diagnoses (non-AD). CSF biomarkers were measured using ELISA. Univariate and multivariate analyses were performed using random forest and logistic regression approaches.

Results: Univariate receiver operating curve curves analysis of T-Tau, P-Tau₁₈₁, Aβ₄₂, Aβ₄₀ concentrations, and Aβ₄₂/Aβ₄₀ ratio levels showed AD cut-off values of ≥355, ≥57, ≤706, ≥10,854, and ≤0.059 ng/L, respectively. Multivariate analysis using random forest and logistic regression found that the algorithm based on P-Tau₁₈₁, Aβ₄₂ concentrations and Aβ₄₂/Aβ₄₀ ratio yielded the best discrimination between AD and non-AD populations. The cross-validation technique of the final model showed a mean accuracy of 0.85 and a mean AUC of 0.89.

Conclusion: This study confirms that the Aβ₄₂/Aβ₄₀ ratio was more useful than the Aβ₄₀ concentration in discriminating AD from non-AD populations in daily practice. These results indicate that the Aβ₄₂/Aβ₄₀ ratio should be assessed in all cases, independently of Aβ₄₂ concentrations.

Ticagrelor Prevents Endothelial Cell Apoptosis through the Adenosine Signalling Pathway in the Early Stages of Hypoxia

BACKGROUND

Several studies have reported the beneficial effects of anti-platelet drugs in cardioprotection against ischaemia-reperfusion injuries. To date, no studies have focused on the indirect cytoprotective effects of ticagrelor via adenosine receptor on the endothelium.

METHOD

By evaluating cell viability and cleaved caspase 3 expression, we validated a model of endothelial cell apoptosis induced by hypoxia. In hypoxic endothelial cells treated with ticagrelor, we quantified the extracellular concentration of adenosine, and then we studied the involvement of adenosine pathways in the cytoprotective effect of ticagrelor.

RESULTS

Our results showed that 10 µM ticagrelor induced an anti-apoptotic effect in our model associated with an increase of extracellular adenosine concentration. Similar experiments were conducted with cangrelor but did not demonstrate an anti-apoptotic effect. We also found that A2B and A3 adenosine receptors were involved in the anti-apoptotic effect of ticagrelor in endothelial cells exposed to 2 h of hypoxia stress.

CONCLUSION

we described an endothelial cytoprotective mechanism of ticagrelor against hypoxia stress, independent of blood elements. We highlighted a mechanism triggered mainly by the increased extracellular bioavailability of adenosine, which activates A2B and A3 receptors on the endothelium.

Real Life Population Pharmacokinetics Modelling of Eight Factors VIII in Patients with Severe Haemophilia A: Is It Always Relevant to Switch to an Extended Half-Life?

We retrospectively analysed the data files of 171 adults and 87 children/adolescents with severe haemophilia, except for 14 patients (moderate; minor) (1), to develop a global population pharmacokinetic (PK) model for eight factors VIII (FVIII) that could estimate individual PK parameters for targeting the desired level of FVIII activity (FVIII:C); and (2) to compare half-life (HL) in patients switching from a standard half-life (SHL) to an extended half-life (EHL) and evaluate the relevance of the switch. One-stage clotting assay for the measurement of FVIII activity (FVIII:C, IU/mL) was used for population PK modelling. The software, Monolix version 2019R1, was used for non-linear mixed-effects modelling. A linear two-compartment model best described FVIII:C. The estimated PK parameters (between-subject variability) were: 2640 mL (23.2%) for volume of central compartment (V1), 339 mL (46.8%) for volume of peripheral compartment (V2), 135 mL/h for Q (fixed random effect), and 204 mL/h (34.9%) for clearance (Cl). Weight, age, and categorical covariate EHL were found to influence Cl and only weight for V1. This model can be used for all of the FVIII cited in the study. Moreover, we demonstrated, in accordance with previous studies, that Elocta had longer half-life (EHL) than SHL (mean ratio: 1.48) as compared to Advate, Factane, Kogenate, Novoeight, and Refacto.

COMPARING INTRAVITREAL AIR AND GAS FOR THE TREATMENT OF VITREOMACULAR TRACTION

PURPOSE

To compare the effect of intravitreal injections of air with gas on vitreomacular traction (VMT) release and attempt to analyze predictive factors for success.

METHODS

The medical records of patients with symptomatic VMT undergoing intravitreal injections (0.3 mL) of either octafluoropropane (C3F8) or air were retrospectively reviewed. The VMT release (primary end point) and the best-corrected visual acuity (secondary end point) were noted 1 month after injection. At baseline and 1 month after the injection, a macular optical coherence tomography was performed.

RESULTS

Twenty-four eyes of 22 patients were included. Vitreomacular traction was released in 10 cases, 7 among 11 C3F8-injected eyes (63%) and 3 among 13 air-injected eyes (23%) (P = 0.045). In eyes with released VMT, ETDRS improved from 61 ± 35 (0-100) to 65 ± 37 (0-100) 1 month after the injection (P = 0.03). All patients with VMT release had a horizontal vitreomacular adhesion of less than 600 µm. Five eyes (23%) underwent vitrectomy after the injection of gas or air.

CONCLUSION

Posterior vitreous detachment in VMT can be observed with both air and gas injection with a low complication rate. The occurrence of VMT release observed with air seemed to be less frequent than that observed with gas.

Intratumoral distribution of YSNSG cyclopeptide in a mouse melanoma model using microdialysis

The YSNSG peptide is a synthetic cyclopeptide targeting α_vβ₃ integrin with antitumor activity. Previous study has determined main pharmacokinetic parameters in plasma and in tissue in healthy animals using microdialysis. First we aim to assess the impact of a 20 mg/kg dosage instead of 10 mg/kg in tumor growth inhibition. Secondly we aim to investigate the YSNSG peptide distribution in two different tumor regions in animals with melanoma. C57BL/6 mice were exposed at Days 8, 10 and 12 after melanoma cells implantation (B16F1) to different dosage of YSNSG peptide or control, respectively (n = 10 per group). Data analysis was performed at D16, 20 and 24 with a Nonlinear Mixed-Effects (NLME) approach. For pharmacokinetic study n = 8 mice (same disease condition) received YSNSG peptide by intravenous after insertion of two microdialysis probes in central peripheral region of tumor, respectively. Plasma and tissue samples were collected during 2 h. A non-compartmental analysis was performed to determine main pharmacokinetic parameters. There was a significant tumor growth inhibition in mice receiving 20 mg/kg vs Control (p < 0.02). Main plasma parameters were half-life elimination 25.8 ± 8.2 min, volume of distribution 11.9 ± 0.4 mL, clearance 19.8 ± 9.4 mL/h and area under the curve 1,173.6 µg.min/mL. Penetration rate of the YSNSG peptide from plasma to tumor tissue were 3.3 ± 2.1% and 3.4 ± 2.7% in central and peripheral, respectively. Contrary to subcutaneous distribution in healthy animals the distribution of the YSNSG peptide into tumoral tissue is low but seems non-heterogeneous between central and peripheral tumor region.

Population Pharmacokinetics Modelling and Simulation of Mitotane in Patients with Adrenocortical Carcinoma: An Individualized Dose Regimen to Target All Patients at Three Months?

Mitotane is the most effective agent in post-operative treatment of adrenocortical carcinoma. In adults, the starting dose is 2–3 g/day and should be slightly increased to reach the therapeutic index of 14–20 mg/L. This study developed a population PK model for mitotane and to simulate recommended/high dosing regimens. We retrospectively analyzed the data files of 38 patients with 503 plasma concentrations for the pharmacokinetic analysis. Monolix version 2019R1 was used for non-linear mixed-effects modelling. Monte Carlo simulations were performed to evaluate the probability of target attainment (PTA ≥ 14 mg/L) at one month and at three months. Mitotane concentration data were best described by a linear one-compartment model. The estimated PK parameters (between-subject variability) were: 8900 L (90.4%) for central volume of distribution (V) and 70 L·h⁻¹ (29.3%) for clearance (Cl). HDL, Triglyceride (Tg) and a latent covariate were found to influence Cl. The PTA at three months for 3, 6, 9, and 12 g per day was 10%, 55%, 76%, and 85%, respectively. For a loading dose of 15 g/day for one month then 5 g/day, the PTA in the first and third months was 57 and 69%, respectively. This is the first PKpop model of mitotane highlighting the effect of HDL and Tg covariates on the clearance as well as a subpopulation of ultrafast metabolizer. The simulations suggest that recommended dose regimens are not enough to target the therapeutic threshold in the third month.

Dexmedetomidine versus sufentanil with high- or low-concentration ropivacaine for labor epidural analgesia: A randomized trial

AIM

To study analgesic effects of dexmedetomidine or sufentanil, both combined with ropivacaine, in epidural analgesia during labor.

METHODS

We recruited 160 primigravidae with full-term pregnancy who received epidural anesthesia during labor and randomized them into four groups to receive epidural administration of ropivacaine combined with sufentanil (RS₁ and RS₂ groups) or with dexmedetomidine (RD₁ and RD₂ groups). Systolic blood pressure, diastolic blood pressure and heart rate before anesthesia (T₁ ), 15 min after anesthesia induction (T₂ ), on delivery (T₃ ) and 2 h postpartum (T₄ ), together with visual analogue scale scores, Bromage scores, Ramsay scores, adverse reactions during analgesia and urinary retention at 6 and 24 h postpartum were recorded; the pH, PCO₂ and PO₂ of umbilical cord arterial blood and Apgar scores at 1, 5 and 10 min after childbirth were assessed.

RESULTS

RS₁ group had significantly lower systolic blood pressure, diastolic blood pressure and heart rate than RD₁ group at T₂ and T₃ (all P < 0.05), but not at T1. At T₂ and T₃ , the other three groups were lower than RS₂ group in visual analogue scale and Ramsay scores (all P < 0.05). After childbirth, RD₂ group had significantly higher PO₂ result than other three groups (P < 0.05). At 6 h postpartum, RD₂ group had significantly fewer cases of urinary retention than RD₁ and RS₁ groups (both P < 0.05).

CONCLUSION

A relatively low concentration of ropivacaine, combined with dexmedetomidine, is better in analgesia during labor.

Complementary Role of P2 and Adenosine Receptors in ATP Induced-Anti-Apoptotic Effects Against Hypoxic Injury of HUVECs

BACKGROUND

Vascular endothelial injury during ischemia generates apoptotic cell death and precedes apoptosis of underlying tissues. We aimed at studying the role of extracellular adenosine triphosphate (ATP) on endothelial cells protection against hypoxia injury.

METHODS

In a hypoxic model on endothelial cells, we quantified the extracellular concentration of ATP and adenosine. The expression of mRNA (ectonucleotidases, adenosine, and P2 receptors) was measured. Apoptosis was evaluated by the expression of cleaved caspase 3. The involvement of P2 and adenosine receptors and signaling pathways was investigated using selective inhibitors.

RESULTS

Hypoxic stress induced a significant increase in extracellular ATP and adenosine. After a 2-h hypoxic injury, an increase of cleaved caspase 3 was observed. ATP anti-apoptotic effect was prevented by suramin, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), and CGS15943, as well as by selective A2A, A2B, and A3 receptor antagonists. P2 receptor-mediated anti-apoptotic effect of ATP involved phosphoinositide 3-kinase (PI3K), extracellular signal-regulated kinases (ERK1/2), mitoK_ATP, and nitric oxide synthase (NOS) pathways whereas adenosine receptor-mediated anti-apoptotic effect involved ERK1/2, protein kinase A (PKA), and NOS.

CONCLUSIONS

These results suggest a complementary role of P2 and adenosine receptors in ATP-induced protective effects against hypoxia injury of endothelial. This could be considered therapeutic targets to limit the development of ischemic injury of organs such as heart, brain, and kidney.

Challenges and innovations of drug delivery in older age

Both drug delivery performance and various age-related physical, mental and physiological changes can affect drug effectiveness and safety in elderly patients. The many drug delivery systems developed over the years include recent novel transdermal, nasal, pulmonary and orally disintegrating tablets that provide consistent, precise, timely and more targeted drug delivery. Certain drug delivery systems may be associated with suboptimal outcomes in the elderly because of the nature of drug present, a lack of appreciation of the impact of age-related changes in drug absorption, distribution and clearance, the limited availability of pharmacokinetic, safety and clinical data. Polypharmacy, patient morbidity and poor adherence can also contribute to sub-optimal drug delivery systems outcomes in the elderly. The development of drug delivery systems for the elderly is a poorly realised opportunity, with each system having specific advantages and limitations. A key challenge is to provide the innovation that best meets the specific physiological, psychological and multiple drug requirements of individual elderly patients.