Cefazolin tissue concentrations with a prophylactic dose administered before sleeve gastrectomy in obese patients: a single centre study in 116 patients.

BACKGROUND: In obese patients undergoing sleeve gastrectomy, the blood and fatty-tissue concentrations of cefazolin required for adequate antibiotic prophylaxis are uncertain. METHODS: This was a single centre prospective study in obese (Group A: 40≤ BMI ≤50 kg m-2) and severely obese (Group B: 50< BMI ≤65 kg m-2) patients undergoing bariatric surgery. Blood and fatty-tissue samples were collected after a cefazolin 4 g i.v. injection. The primary aim was to compare cefazolin concentrations in subcutaneous fatty tissue with a targeted tissue concentration of 4 µg g-1 according to Staphylococcus aureus resistance breakpoint. RESULTS: One hundred and sixteen patients were included: 79 in Group A and 37 in Group B. At the beginning of the surgery, cefazolin concentration in subcutaneous fatty tissue was 12.2 (5.4) µg g-1 in Group A and 12 (6.1) µg g-1 in Group B (P=0.7). At the end, cefazolin concentrations in subcutaneous fatty tissue were 9.0 (4.9) and 7.8 (4.2) µg g-1 in Groups A and B, respectively (P=0.2). The plasma concentration of free cefazolin during surgery was higher in Group A than in Group B (P<0.0001). Fatty-tissue concentrations of 95% and 83% patients in Groups A and B, respectively, were above S. aureus resistance breakpoint. CONCLUSIONS: After a 4 g dose, the concentrations of cefazolin in fatty tissue were above the 4 µg g-1 tissue concentration target, providing adequate antibiotic tissue concentrations during bariatric surgery. As cefazolin concentration in fatty tissue is a surrogate endpoint, the results should be considered in conjunction with the results on free cefazolin concentrations in subcutaneous tissue. CLINICAL TRIAL REGISTRATION: NCT01537380.

Systematic review: human gut dysbiosis induced by non-antibiotic prescription medications.

BACKGROUND: Global prescription drug use has been increasing continuously for decades. The gut microbiome, a key contributor to health status, can be altered by prescription drug use, as antibiotics have been repeatedly described to have both short-term and long-standing effects on the intestinal microbiome. AIM: To summarise current findings on non-antibiotic prescription-induced gut microbiome changes, focusing on the most frequently prescribed therapeutic drug categories. METHODS: We conducted a systematic review by first searching in online databases for indexed articles and abstracts in accordance with PRISMA guidelines. Studies assessing the intestinal microbiome alterations associated with proton pump inhibitors (PPIs), metformin, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, statins and antipsychotics were included. We only included studies using culture-independent molecular techniques. RESULTS: Proton pump inhibitors and antipsychotic medications are associated with a decrease in α diversity in the gut microbiome, whereas opioids were associated with an increase in α diversity. Metformin and NSAIDs were not associated with significant changes in α diversity. ß diversity was found to be significantly altered with all drugs, except for NSAIDs. PPI use was linked to a decrease in Clotridiales and increase in Actinomycetales, Micrococcaceae and Streptococcaceae, which are changes previously implicated in dysbiosis and increased susceptibility to Clostridium difficile infection. Consistent results showed that PPIs, metformin, NSAIDs, opioids and antipsychotics were either associated with increases in members of class Gammaproteobacteria (including Enterobacter, Escherichia, Klebsiella and Citrobacter), or members of family Enterococcaceae, which are often pathogens isolated from bloodstream infections in critically ill patients. We also found that antipsychotic treatment, usually associated with an increase in body mass index, was marked by a decreased ratio of Bacteroidetes:Firmicutes in the gut microbiome, resembling trends seen in obese patients. CONCLUSIONS: Non-antibiotic prescription drugs have a notable impact on the overall architecture of the intestinal microbiome. Further explorations should seek to define biomarkers of dysbiosis induced by specific drugs, and potentially tailor live biotherapeutics to counter this drug-induced dysbiosis. Many other frequently prescribed drugs should also be investigated to better understand the link between these drugs, the microbiome and health status.

Simultaneous determination of ceftaroline, daptomycin, linezolid and rifampicin concentrations in human plasma by on-line solid phase extraction coupled to high-performance liquid chromatography-tandem mass spectrometry.

Methicillin-resistant Staphylococcus aureus infection is a serious clinical problem worldwide. Ceftaroline, daptomycin, linezolid in combination with rifampicin are particularly used in this indication. To allow monitoring of these antibiotics, an on-line solid phase extraction coupled to high-performance liquid chromatography-tandem mass spectrometry assay requiring a 100 µL aliquot of human plasma has been developed. Besides, significance of 25-O-desacetylrifampicin concentrations was evaluated. Sample pre-treatment is limited to protein precipitation with methanol. After centrifugation 10 µL of supernatant are injected into the chromatographic system, which consists of an on-line solid phase extraction followed by a separation on a phenyl-hexyl column and detected by a tandem mass spectrometer. Plasma drug concentrations were determined by multiple reaction monitoring in positive ion mode, and assay performance was evaluated. 25-O-Desacetylrifampicin activity, was compared to rifampicin using a microbiological method. Sample preparation using methanol precipitation followed by solid-phase extraction yielded good recovery and ionization efficiency, with chromatographic separation achieved within 3 min per sample. Within-run and between-run precisions ranged respectively from 1.22% to 9.35% and from 1.61% to 9.36%. Lower limits of quantification were 0.04 mg/L for linezolid, 0.1mg/L for rifampicin, 0.2mg/L for ceftaroline and 0.5mg/L for daptomycin. It appears that 25-O-desacetylrifampicin displays a substantial intrinsic bactericidal activity against S. aureus. This assay provides simple, rapid, sensitive and accurate quantification of the four antibiotic drugs and one metabolite and can be routinely used to monitor drug concentration in methicillin-resistant S. aureus infected patients.

A liquid chromatography-tandem mass spectrometry assay for quantification of rilpivirine and dolutegravir in human plasma.

A liquid chromatography-tandem mass spectrometry assay requiring a 100µL aliquot of human plasma for simultaneous determination of rilpivirine, a second generation non-nucleoside reverse transcriptase inhibitors of HIV and dolutegravir, a novel integrase stand transfer inhibitors of HIV concentrations has been developed. Sample pre-treatment is limited to protein precipitation with a mixture of methanol and zinc sulfate. After centrifugation the supernatant is injected in the chromatographic system, which consists of on-line solid phase extraction followed by separation on a phenyl-hexyl column. This 2.5min method, with its simple sample preparation provides sensitive (the limit of quantitation is 25ng/mL for each compound), accurate and precise (the intra-day and inter-day imprecision and inaccuracy are lower than 15%) quantification of the plasma concentration of these drugs and can be used for therapeutic drug monitoring in patients infected with HIV.

Switching from tenofovir/emtricitabine and nevirapine to a tenofovir/emtricitabine/rilpivirine single-tablet regimen in virologically suppressed, HIV-1-infected subjects.

OBJECTIVES: Nevirapine is an inducer of hepatic metabolism. After discontinuation, nevirapine has an inductive effect on cytochrome P450 3A4, which persists for a few weeks and which, after switching to rilpivirine, may reduce rilpivirine exposures and have a negative clinical impact. This study evaluates the virological outcome, pharmacokinetics and safety of switching virologically suppressed, HIV-1-infected patients from nevirapine to rilpivirine. PATIENTS AND METHODS: This 24 week open-label single-centre study included HIV-1-infected adults with HIV-1 RNA <50 copies/mL for >6 months on tenofovir/emtricitabine and nevirapine, who were willing to simplify their regimen to tenofovir/emtricitabine/rilpivirine. Virological suppression, safety and nevirapine and rilpivirine pharmacokinetics were assessed. RESULTS: At weeks 12 and 24, all 32 subjects remained virologically suppressed. One subject discontinued at week 1 for rilpivirine-associated insomnia and two patients chose to resume tenofovir/emtricitabine and nevirapine after week 12 because of rilpivirine-associated food constraint. There was no grade 3/4 laboratory abnormality. Rilpivirine trough concentrations were above the mean trough concentrations observed in Phase 3 studies by 1 week post-switch. Twenty-seven out of 32 patients had no measurable levels of nevirapine by 2 weeks post-switch. The meal accompanying tenofovir/emtricitabine/rilpivirine intake satisfied food requirements in 81% of cases. Overall general satisfaction was improved in 90% of the subjects despite food constraints. CONCLUSION: Nevirapine has a short and limited inductive effect on rilpivirine metabolism, which is not clinically significant. Tenofovir/emtricitabine/rilpivirine is an efficacious and safe option for virologically suppressed HIV-infected patients on nevirapine wishing to simplify their regimen.

Pharmacokinetics of ertapenem in burns patients.

The aims of this study were to evaluate pharmacokinetic (PK) parameters of total and unbound ertapenem (ERT) in burns patients and to identify which covariates influence these PK parameters. ERT plasma concentrations were measured in burns patients (n = 8) who received a 0.5-h infusion of ERT (1000 mg) every 24 h. PK parameters were estimated by a non-compartmental approach and the influence of covariates was estimated by multivariate analysis using a population approach. Clearance (CL) and the volume of distribution (V) of total ERT were lower than the results for unbound ERT [CL, 22.2 ± 5.6 mL/min vs. 279.4 ± 208.2 mL/min; V, 9.7 ± 1.4L vs. 120.6 ± 130.6L (mean ± standard deviation)]. Creatinine clearance (CL(Cr)) and the burned surface area (BSA) were the covariates identified that significantly (P<0.01) affected the pharmacokinetics of total ERT [CL (L/h)=0.373 +{0.00666 x CL(Cr) (mL/min)}] and unbound ERT [peripheral volume of distribution (L) = 3.05 + {0.959 x BSA (% of the total body surface)}], respectively. The influences of albuminaemia, glomerular filtration and burn wound on ERT pharmacokinetics are proposed to explain these results. These first results support that the ERT plasma concentration should be closely monitored particularly for patients with high values of BSA and/or CL(Cr) to avoid suboptimal exposure.

A liquid chromatography assay for a quantification of doripenem, ertapenem, imipenem, meropenem concentrations in human plasma: application to a clinical pharmacokinetic study.

A simple chromatographic assay based on ultra high performance liquid chromatography with ultraviolet detection at 295 nm is proposed to determinate simultaneously human plasma concentrations of imipenem, doripenem, meropenem and ertapenem. After deproteinization by acetonitrile, carbapenems are separated on a PentaFluoroPhenyl column with a binary gradient elution. This method is specific, accurate, precise (the intra-day and inter-day imprecision and inaccuracy are lower than 15%), sensitive (the limit of quantitation is equal to 0.50 mg/L for imipenem, doripenem, ertapenem, meropenem) and not time consuming (run time=7 min). An application of this method to measure ertapenem plasma concentrations in burn patients is presented.

A liquid chromatography-tandem mass spectrometry assay for quantification of nevirapine, indinavir, atazanavir, amprenavir, saquinavir, ritonavir, lopinavir, efavirenz, tipranavir, darunavir and maraviroc in the plasma of patients infected with HIV.

A liquid chromatography-tandem mass spectrometry assay for simultaneous determination of the plasma concentration of 11 antiretroviral agents (nevirapine, indinavir, atazanavir, amprenavir, saquinavir, ritonavir, lopinavir, efavirenz, tipranavir, darunavir and maraviroc) has been developed. Sample pre-treatment is limited to protein precipitation with a mixture of methanol and zinc sulfate. After centrifugation the supernatant is injected in the chromatographic system, which consists of on-line solid phase extraction followed by separation on a phenyl-hexyl column. This method, with its simple sample preparation provides sensitive, accurate and precise quantification of the plasma concentration of antiretroviral drugs and can be used for therapeutic drug monitoring in patients infected with HIV.

Influence of darunavir coadministration on nevirapine pharmacokinetics in HIV-infected patients: a population approach.

OBJECTIVE: The influence of ritonavir-boosted darunavir coadministration on nevirapine pharmacokinetics was investigated in HIV-infected patients using a population-based approach. METHODS: The population was composed of 51 patients (89 samples; 42 patients treated with an antiretroviral regimen containing nevirapine and nucleoside/nucleotide reverse transcriptase inhibitors and nine patients treated with a regimen containing a combination of nevirapine and darunavir). A one-compartment model with first-order absorption was fitted to the data using nonmem version V (GloboMax, Ellicott City, MD, USA). RESULTS: Relationships were established between nevirapine clearance (Cl) and age (Cl/F=2.42+47.2/age, where F denotes bioavailability) and between nevirapine volume of distribution (V(d)) and the presence of darunavir in the antiretroviral regimen [V(d)/F=38.0+75.0 (1 - darunavir coadministration), where darunavir coadministration is 1 for patients treated with a combination of nevirapine and darunavir and 0 for other patients]. According to this final model, a significant decrease in the means of Cl/F (3.84 +/- 0.92 vs. 2.76 +/- 1.00 L/h; P<0.05) and V(d)/F (93.2 +/- 31.10 vs. 39.8 +/- 6.97 L; P<0.0001) and an increase in the mean of nevirapine trough plasma concentrations (3.68 +/- 1.69 vs. 5.35 +/- 3.20 mg/L; P<0.05) are observed if nevirapine is used in combination with darunavir. CONCLUSIONS: These results suggest that nevirapine exposure is increased when nevirapine is administered in combination with darunavir and that therapeutic drug monitoring of nevirapine should be performed if this antiretroviral regimen is considered.

Population pharmacokinetics of domperidone in preterm neonates.

PURPOSE: A population pharmacokinetic analysis was performed to define domperidone pharmacokinetic parameters in preterm neonates, as no pharmacokinetic data are available in this population. METHODS: An oral domperidone solution was administered (0.75 mg/kg per day) in 32 preterm neonates (64 samples). Domperidone plasma concentration was measured by high-performance liquid chromatography (HPLC) assay, and a one-compartment model with first-order absorption was fitted to the data using NONMEM version V level 1.1. RESULTS: The mean peak and trough plasma concentration values of domperidone were, respectively, 25.3 +/- 20.5 ng/ml and 15.4 +/- 11.4 ng/ml (mean +/- standard deviation). The pharmacokinetic parameters (interindividual variability%) were clearance (Cl/F) = 0.92 L/h (51.6%), volume of distribution (Vd/F) = 0.405 L (68%), and absorption constant rate (Ka) = 0.0843 h(-1) (55.8%). The clearance is not lower than values reported in adults. No influence of covariates (postnatal age, prematurity, weight, gender) on domperidone pharmacokinetic parameters was found. CONCLUSION: This pilot study designed with a limited sampling strategy showed that domperidone plasma concentrations were consistent with those reported in adults, suggesting that domperidone dosage regimen currently used in preterm neonates is suitable.

Effect of antidepressant drugs on 6-OHDA-treated mice in the FST.

There is growing evidence suggesting that dopamine could be indirectly involved in the appearance of behavioural effects of antidepressants. In this study, we induced a partial (over 70%) and non-reversible depletion of dopamine-containing neurons in mice by i.c.v. infusion of 6-OHDA. Then, we compared the antidepressant-like effect of drugs (citalopram, paroxetine, desipramine and imipramine) with or without dopamine depletion in the mice forced swimming test. Our results clearly show that lesion with 6-OHDA does not modify the response of mice to desipramine and imipramine, whereas dopamine depletion abolished the antidepressant-like effect of citalopram and paroxetine. It could then be suggested that antidepressant-like effect of selective serotonin reuptake inhibitors (paroxetine and citalopram) in the mice FST requires the activation of dopaminergic pathways to occur.

A simple high performance liquid chromatography assay for monitoring plasma concentrations of tipranavir in HIV infected patients.

A simple HPLC assay to determine plasma concentration of tipranavir is presented. A liquid/liquid extraction of the drugs in ethyl acetate/hexane from 250 microL of plasma is followed by a reversed phase isocratic HPLC assay with UV detection at 205 nm. The imprecision and inaccuracy are lower than 10%, the low limit of quantitation is 0.4 mg/L. Thus, this method can be used for therapeutic drug monitoring of tipranavir in HIV infected patients.

Low initial trough plasma concentrations of lopinavir are associated with an impairment of virological response in an unselected cohort of HIV-1-infected patients.

OBJECTIVES: The relationship between lopinavir trough plasma concentration at baseline and virological efficacy 3 months after the beginning of the therapy was investigated in an unselected cohort of HIV-1-infected patients METHODS: According to initial trough lopinavir plasma level, patients were classified into three groups: the subtherapeutic group (<3 mg/L, n=18), the therapeutic group (between 3 and 8 mg/L, n=50) and the toxic group (>8 mg/L, n=16). The virological response after 3 months of lopinavir treatment, defined as a viral load <200 HIV-1 RNA copies/mL, was compared amongst these groups. RESULTS: The virological response was significantly different (P<0.05) between the subtherapeutic group (22.% of patients with viral load<200 copies/mL) and the other groups (56.0% of patients with a viral load<200 copies/mL in the therapeutic group and 56.2% in the toxic group). CONCLUSIONS: A lower virological efficacy should be expected for experienced or naive patients with plasma trough lopinavir concentrations<3 mg/L at the beginning of treatment.

Determination of atazanavir and other antiretroviral drugs (indinavir, amprenavir, nelfinavir and its active metabolite M8, saquinavir, ritonavir, lopinavir, nevirapine and efavirenz) plasma levels by high performance liquid chromatography with UV detection.

A global method is proposed for therapeutic drug monitoring of atazanavir, a novel protease inhibitor and of all other protease inhibitors (PI) and non nucleoside reverse transcriptase inhibitors (NNRTI) which are currently used to treat HIV patients. All drugs are extracted after a liquid-liquid extraction and separated on a C18 column with a binary gradient elution except lopinavir which is separated without this gradient. The absorbance is measured at 259 nm except for lopinavir (205 nm) and nevirapine (320 nm). This method is specific, accurate, precise (the intra-day and inter-day imprecision and inaccuracy are lower than 15%) and the limits of quantitation (0.40 mg/L for nevirapine, 0.10 mg/L for indinavir, 0.10 mg/l for M8, 0.05 mg/L for amprenavir, 0.10 mg/L for nelfinavir, 0.10 mg/L for saquinavir, 0.10 mg/L for ritonavir, 0.10 mg/L for efavirenz, 0.10 mg/L for atazanavir and 0.20 mg/L for lopinavir) are consistent with trough plasma concentrations allowing to use this method for therapeutic drug monitoring of PI and NNRTI.

Relationship between cerebral pharmacokinetics and anxiolytic activity of diazepam and its active metabolites after a single intra-peritoneal administration of diazepam in mice.

The relationship between the cerebral pharmacokinetics of diazepam and its active metabolites (desmethyldiazepam, oxazepam) and the anxiolytic effect evaluated by the four-plates test and the light/dark test were investigated after a single intra-peritoneal injection of diazepam (1 mg/kg or 1.5 mg/kg). For up to 30 min after administration, the sedative effect interfered with the anxiolytic effect, thus the results of the anxiolytic effect were not interpretable. From 30 min to 60 min after administration, this interference disappeared, the cerebral level of benzodiazepines was stable (the brain elimination of diazepam was compensated for by the appearance of desmethyldiazepam followed by oxazepam) but the anxiolytic effect decreased dramatically in all the tests with diazepam 1 mg/kg or 1.5 mg/kg. The acute tolerance to benzodiazepines and the difference of affinity for subtypes of GABA(A) receptors between diazepam, desmethyldiazepam, oxazepam could explain this result.

A follow-up study of a population of schizophrenic patients treated with clozapine.

1. Clozapine is a dibenzodiazepine neuroleptic which presents the advantage of not having undesirable neurological side-effects. Its efficacy for the treatment of the symptoms of schizophrenia is known, but the use of clozapine is limited to treatment-resistant schizophrenic patients as it induces agranulocytosis with a higher incidence than that of other neuroleptic drugs. 2. The present study was designed in order to evaluate the benefit/risk of chronic treatment. The analysis was performed using the files of schizophrenic patients. These patients were not stabilized by a classical neuroleptic treatment and/or presented individual secondary effects. 3. Clozapine induced neutropenia and 1 case of agranulocytosis in 3 females. Analysis of leukocyte expression highlighted some premonitory symptoms in patients who presented neutropenia. The observation of 2 to 3 early successive peaks in leukocyte expression (between the third and tenth week of treatment) could be predictive of neutropenia in the 3 to 4 months of treatment. 4. The patients who presented a lower leukocyte base-line following a peak had a higher risk, of developing neutropenia. This might explain some late accidents beyond the first six months of treatment. 5. The present study confirmed the advantages of clozapine treatment and demonstrated that the risk of neutropenia may be diminished by the detection of premonitory symptoms and the early monitoring of patients at risk i.e. female patients and subjects with a lower leukocyte base-line.

High-performance liquid chromatographic assay to determine the plasma levels of HIV-protease inhibitors (amprenavir, indinavir, nelfinavir, ritonavir and saquinavir) and the non-nucleoside reverse transcriptase inhibitor (nevirapine) after liquid-liquid extraction.

A single HPLC assay was developed for therapeutic drug monitoring of 5 HIV protease inhibitors (indinavir, amprenavir, saquinavir, ritonavir, nelfinavir) and a non-nucleoside reverse transcriptase inhibitor (nevirapine) in human plasma. After liquid-liquid extraction in a mixture ethyl acetate-hexane, compounds are separated on a C18 column with a gradient elution of solvent A [acetonitrile and 0.025 M tetramethylammonium perchlorate in 0.2% aqueous trifluoroacetic acid (55:45 (v/v))] and solvent B [methanol and 0.025 M tetramethylammonium perchlorate in 0.2% aqueous trifluoroacetic acid (55:45 (v/v))]. The compounds are detected at various wavelengths: 320 nm (nevirapine), 259 nm (indinavir), 254 nm (amprenavir, nelfinavir, saquinavir) and 239 nm (ritonavir). The intra-day and inter-day precision and accuracy are lower than 15%. The limits of quantitation are 0.05 mg/l (amprenavir), 0.2 mg/l (indinavir, saquinavir, nelfinavir) and 0.4 mg/l (ritonavir, nevirapine). This method which allows to estimate simultaneously plasma levels of protease inhibitors and nevirapine can be used for therapeutic drug monitoring.

[Study of lipid peroxidation inhibition in human blood by several endogenous and exogenous compounds]. / Etude de l'inhibition de la peroxydation lipidique dans le sang humain par diverses molécules endogènes et exogènes.

Numerous studies suggest that lipid peroxidation is involved in the atherosclerosis and hemolytic disease processes. Nicanartine improves in vitro resistance of LDL (low density lipoproteins) to oxidation in the conjugated dienes model. Polarographic assays show that hemin-bound drugs inhibit erythrocyte membrane peroxidation. A method to measure the antioxidant capacity of plasma is proposed and tested in sickle cell disease. These in vitro results suggest drugs and drugs combination which could be efficient to inhibit lipid peroxidation in vivo.

Role of bilirubin in the regulation of the total peroxyl radical trapping antioxidant activity of plasma in sickle cell disease.

Alpha-tocopherol and bilirubin antioxidant properties were evaluated in sickle cell disease. The total peroxyl radical trapping antioxidant activity of plasma (TRAP) was measured with a polarographic method using hemin as oxidative stress initiator. The TRAP was not correlated with plasma alpha-tocopherol concentration. The TRAP was correlated with plasma total bilirubin concentration [TRAP = 8.1 (total bilirubin) +363.7 (r = 0.67)] and the correlation was even better with the sum (alpha-tocopherol + total bilirubin) plasma concentration [TRAP = 9.1(alpha-tocopherol + total bilirubin)+ 170.5(r = 0.77)]. The alpha-tocopherol contribution in the antioxidant capacity of plasma was significant but bilirubin level acted as the limiting factor of plasma antioxidant capacity in sickle cell anemia. This result can be explained by the antioxidant property of bilirubin but also by coantioxidant activity towards oxidized alpha-tocopherol.

Chain-breaking antioxidants and ferriheme-bound drugs are synergistic inhibitors of erythrocyte membrane peroxidation.

Induced erythrocyte membrane peroxidation (EMP) is considered as an accurate model of reperfusion injuries and as such was used to investigate protective effects of various drugs. EMP was induced by an azo initiator and monitored by oxygen uptake. Both hydrophilic (ascorbic acid) and lipophilic (alpha-tocopherol, probucol, nicanartine) chain-breaking antioxidants as well as ferriheme-bound drugs (deferoxamine, chloroquine) inhibited EMP. When antioxidants and ferriheme-bound drugs were combined, synergistic effects were observed. It is proposed that ferriheme compounds which catalyse peroxide induced lipid peroxidation were blocked by deferoxamine and/or chloroquine. So these drugs inhibited at least partly the membrane peroxidation process and added their effects to the ones of chain-breaking antioxidants.