Michel Luyckx

Antioxidant properties of albumin: effect on oxidative metabolism of human neutrophil granulocytes.

The present study aims at investigating the effect of bovine serum albumin (BSA) on the trial of oxidative-stress. The antioxidant effects of BSA were determined by human neutrophil granulocytes oxygen free radicals and their by-products (O2-, H2O2, HOCl) productions. BSA interacts with those reactive oxygen species (ROS) in a dose-dependent manner. The 50% inhibitory concentration (IC50) of BSA estimated, after phorbol-12-myristate-13-acetate (PMA) stimulation were: 33.5 mg/ml for O2-, 6.5 mg/ml for H2O2, and 6.85 mg/ml for HOCl. When neutrophils were washed after pre-incubation with BSA, there was no significant decrease of ROS after stimulation of PMA (maximal: 15 +/- 1.2%). In the free cell experiments, IC50 for H2O2 and HOCl were 7.86 mg/ml and 0.67 mg/ml, respectively. The mechanism at which BSA acts may result from a simple chemical interaction with ROS rather than an intracellular mechanism by intervention in PMA oxidative metabolism. These antioxidant activities confer to BSA properties, which might be used to prevent damage inflicted by these ROS during inflammatory disorders.

Data Mining to Generate Adverse Drug Events Detection Rules

Adverse drug events (ADEs) are a public health is sue. Their detection usually relies on voluntary reporting or medical chart reviews. The objective of this paper is to automatically detect cases of ADEs by data mining. 115 447 complete past hospital stays are extracted from six French, Danish, and Bulgarian hospitals using a common data model including diagnoses, drug administrations, laboratory results, and free-text records. Different kinds of outcomes are traced, and supervised rule induction methods (decision trees and association rules) are used to discover ADE detection rules, with respect to time constraints. The rules are then filtered, validated, and reorganized by a committee of experts. The rules are described in a rule repository, and several statistics are automatically computed in every medical department, such as the confidence, relative risk, and median delay of outcome appearance. 236 validated ADE-detection rules are discovered; they enable to detect 27 different kinds of outcomes. The rules use a various number of conditions related to laboratory results, diseases, drug administration, and demographics. Some rules involve innovative conditions, such as drug discontinuations.

Stability, compatibility and plasticizer extraction of miconazole injection added to infusion solutions and stored in PVC containers

The stability of miconazole in various diluents and polyvinyl chloride (PVC) containers was determined and the release of diethylhexyl phthalate (DEHP) from PVC bags into intravenous infusions of miconazole was measured. An injection formulation (80 ml) containing a 1% solution of miconazole with 11.5% of Cremophor EL was added to 250-ml PVC infusion bags containing 5% glucose injection or 0.9% sodium chloride injection, to give an initial nominal miconazole concentration of 2.42 mg ml-1, the mean concentration commonly used in clinical practice. Samples were assayed by stability-indicating high-performance liquid chromatography (HPLC) and the clarity was determined visually. Experiments were conducted to determine whether the stability and compatibility of miconazole would be compromised, and whether DEHP would be leached from PVC bags and PVC administration sets during storage and simulated infusion. There was no substantial loss of miconazole over 2 h simulated infusion irrespective of the diluent, and over 24 h storage irrespective of temperature (2-6 degrees C and 22-26 degrees C). All the solutions initially appeared slightly hazy. Leaching of DEHP was also detected during simulated delivery using PVC bags and PVC administration sets. There was a substantial difference between the amounts of DEHP released from PVC bags and from administration sets, and also between the amounts released in solutions stored in PVC bags at 2-6 degrees C and 22-26 degrees C over 24 h. At the dilution studied, miconazole was visually and chemically stable for up to 24 h. The storage of miconazole solutions in PVC bags seems to be limited by the leaching of DEHP rather than by degradation. To minimize patient exposure to DEHP, miconazole solutions should be infused immediately after their preparation in PVC bags.

A rapid density gradient technique for separating polymorphonuclear granulocytes

A gradient separation technique followed by isotonic ammonium chloride haemolysis was compared with two methods for the isolation of polymorphonuclear neutrophils from blood. This technique provided a high yield, excellent purity without lymphocyte and erythrocyte contamination, and made it possible to isolate more than 50 times 106 human neutrophils from 15 ml of blood. The polymorphonuclear neutrophils isolated in this way were capable of generating a large amount of reactive oxygen species. This technique for the separation of polymorphonuclear neutrophils is an effective method for in vitro studies.

Investigations of new lead structures for the design of novel cyclooxygenase-2 inhibitors

On the basis of molecular modelling studies, five new compounds were synthesised and studied in an attempt to design new lead structures as selective COX-2 inhibitors.

Antioxidant Effects and Anti-Elastase Activity of the Calcium Antagonist Nicardipine on Activated Human and Rabbit Neutrophils—A Potential Antiatherosclerotic Property of Calcium Antagonists?

Activated neutrophils which produce certain proteases, such as elastase and reactive oxygen species (ROS) are involved in oxidative stress and inflammation. In the present study, we have shown that nicardipine, a calcium channel blocker, affects the release of elastase and superoxide anion radicals (O2−) in vitro during human and rabbit neutrophil respiratory bursts. The drug inhibited the release of elastase and O2− by fMLP (N-formyl-methionylleucin-phenylalaninin), calcium ionophore (A23187) and PMA (phorbol-myristate-acetate)-stimulated human and rabbit neutrophils. Besides the release of elastase, strongly inhibited in the fMLP and A23187 stimulated systems, nicardipine affected elastase and O2− in a dose-dependent manner. The corresponding 50% inhibitory concentration (IC50) of nicardipine for elastase, released in PMA-stimulated human and rabbit neutrophils, was 15.95 ± 0.17 μM and 18.06 ± 0.08 μM, respectively, whereas for O2−, the IC50 of nicardipine in PMA, fMLP and A23187-stimulated human and rabbit neutrophils was 55.41 ± 0.09 μM and 58.43 ± 0.03 μM, 45.21 ± 0.13 μM and 37.19 ± 0.53 μM, 33.54 ± 0.09 μM and 30.54 ± 0.29, respectively. The mechanisms underlying the inhibition of elastase and superoxide anion radicals by nicardipine appear related to an inhibiting effect on the mobilisation of cytosolic calcium and on activation of protein kinase C (PKC). These antioxidant and anti-elastasic activities contribute to the properties of nicardipine, as positive side effects of its antihypertensive activity and may be useful to prevent inflammatory disorders (tissue damage, oxidative injury) involved in the pathogenesis of hypertension.

Risperidone Drug Monitoring

AbstractBackground: Risperidone is an atypical antipsychotic drug that has been marketed in France since 1996. Therapeutic failures have been observed with risperidone. Objective: To investigate whether interactions with the cytochrome P450 (CYP) isoenzymes implicated in risperidone metabolism could explain these treatment failures. Design and Setting: This was a retrospective study of clinical and drug monitoring data from 50 patients treated by five psychiatrists in northern France. Methods: The concentration of active drug (risperidone + 9-hydroxy-risperidone) in serum was evaluated by high performance liquid chromatography and radio receptor assay. Clinical efficacy was assessed by the global improvement (CGI2) item of the Clinical Global Impression rating scale. Results: Statistical analysis revealed a significant increase in efficacy when the serum concentration of active drug was between 25 and 150 μg/L compared with when it was out of this range. Carbamazepine, a CYP3A4 inducer, dramatically decreased the concentration of the active moiety of risperidone; on the contrary, CYP3A4 inhibitors (alprazolam and valproic acid) increased the concentration of active drug. The metabolism of risperidone by CYP3A4 did not lead to the formation of metabolite(s) with anti-D2 dopaminergic activity. Drugs interacting with CYP2D6 altered the risperidone/9-hydroxy-risperidone ratio but did not change the total amount of active drug. Conclusions: We have established a therapeutic range for risperidone. CYP3A4 is a major pathway for risperidone metabolism. Consideration of these factors in clinical practice should lead to improved outcomes for patients treated with risperidone.

Stability, compatibility and plasticizer extraction of quinine injection added to infusion solutions and stored in polyvinyl chloride (PVC) containers

The stability of quinine was determined in various diluents and in polyvinyl chloride (PVC) containers. The release of diethyhexyl phthalate (DEHP) from PVC bags into intravenous infusions of quinine was also measured. We used an injection of two doses of quinine; quiniforme at 500 mg and quinimax at 400 mg in either 250- or 500-ml PVC infusion bags containing 5% dextrose, to give initial nominal concentrations of 2 or 1 mg ml(-1) quiniforme and 1.6 or 0.8 mg ml(-1) quinimax, the mean concentrations commonly used in clinical practice. Samples were assayed by stability-indicating high-performance liquid chromatography (HPLC) and the clarity was determined visually. Experiments were conducted to determine whether the stability and compatibility of quinine would be compromised, and whether DEHP would be leached from PVC bags and PVC administration sets during storage and simulated infusion. There was no substantial loss of quiniforme and quinimax over 1- or 2-h simulated infusion irrespective of the diluent, and storage during 8 h at 22 degrees C, 48 or 72 h at 4 degrees C and 96 h at 45 degrees C. Leaching of DEHP was also detected during simulated infusion delivery using PVC bags and PVC administration sets. The quantity was less than 2 microg ml(-1). During storage at 4 degrees C and room temperature the leaching of DEHP was low, but when the temperature was 45 degrees C the quantity was high, 21 microg ml(-1). To minimise patient exposure to DEHP, quinine solutions with all drugs should be infused immediately or stored for a maximum of 48 h at 4 degrees C.

High-performance liquid chromatographic determination of naltrexone in plasma of hemodialysis patients.

A simple, sensitive, selective and reliable reversed-phase high-performance liquid chromatographic (HPLC) method with UV detection is described for the determination of naltrexone in plasma samples. Naltrexone and the internal standard, naloxone, were isolated from plasma either with a liquid-liquid extraction method using ethyl acetate or with a solid-phase extraction method using Sep-Pack C18 cartridge before chromatography. The extracts were dried under a stream of nitrogen and the samples were reconstituted in the mobile phase, then 20 microL were injected on a Waters Symmetry C18 column (5 microm particle size, 4.6 x 150 mm). The mobile phase consisted of 0.06% triethylamine (pH 2.8)-acetonitrile (92:8, v/v) pumped at 1 mL/min. The peak-area ratio versus plasma concentration was linear over the range of 10-500 ng/mL and the detection limit was less than 8 ng/mL. Quantification was by ultra-violet detection at 204 nm. The present method was applied to the determination of the plasma concentration of naltrexone in dialyzed patients. Patients (n = 8) with severe generalized pruritus received 50 mg of naltrexone orally per day for 2 weeks. The variability in the therapeutic response in treated patients required plasma concentration investigations of this opioid antagonist.

Pharmacokinetics of midazolam: comparison of sublingual and intravenous routes in rabbit

SummaryIn France, the legal routes used to administer midazolam to a patient are intravenously and intramuscularly. For anaesthetists, these routes are not well adapted to paediatric use; they lead to pain at injection site and stress on children. The sublingual route should be a good compromise between stress and quick efficiency. We have developed a sublingual tablet of midazolam. The aim of the present investigation is to compare the pharmacokinetic parameters of midazolam tablets administered by the sublingual and intravenous routes in 6 rabbits to determine the bioequivalence between these routes. We have estimated the 1-hydroxy-midazolam serum level by difference between RRA and HPLC values.By the sublingual route, midazolam absorption is substantial and fast. The statistical analysis, on data obtained with HPLC dosage, shows no significant difference between pharmacokinetic parameter values calculated after intravenous and sublingual administration (0.5 mg). The absolute bioavailability was close to 100%. With RRA dosage, however, AUCs were greater than those obtained by HPLC dosage (174%). 1-hydroxy-midazolam seems to have a great importance in BZD activity. To estimate the bioequivalence between intravenous and sublingual midazolam administration, it is necessary to take into account the active metabolites.