Assessment of the impact of telehealth intervention in patients with bone and joint infection.

OBJECTIVES: Patients with bone and joint infections (BJI) are involved in a complex care pathway and require prolonged antimicrobial treatment. Some studies have suggested that a pharmacist-led telehealth intervention (TI) could help to ensure better follow-up of chronic diseases. To our knowledge, there are no data on the effects of pharmacist-led TI on patients with BJI. The aim of this study is to assess the impact of a TI on patients treated for BJIs at three weeks after hospital discharge. PATIENTS AND METHODS: Patients encountered during hospitalization and receiving standardized care including TI were included in the study. All adverse events (AE) reported by patients during TI were evaluated. Impact of pharmaceutical interventions (PIs) provided by a clinical pharmacist following TI was evaluated by CLEO© (CLinical, Economic and Organizational) scale. Patient satisfaction concerning TI was assessed by an anonymous questionnaire following medical consultation at the end of antimicrobial treatment. RESULTS: Over a 4-month period, 36 patients received TI. Fifty-two AEs were identified in 21 patients (58%). Two patients were hospitalized due to an AE. Clinical pharmacists provided 34 pharmaceutical interventions (PIs) for 23 patients (64%). According to CLEO scale, 11 PIs had a major clinical impact (32%), 6 PIs (18%) had a favorable impact on the direct cost of treatment and 27 PIs (79%) had positive organizational impact. Concerning TI process, patients were satisfied or very satisfied, with an average score of 9.6/10. CONCLUSION: TI led to a high number of pharmaceutical interventions (PIs), with a meaningful clinical, organizational, and economic impact. Patients were also highly satisfied with this intervention.

Measurement of the Immunosuppressant Possession Ratio by Transplant Clinical Pharmacists Captures a Non-Adherence Associated With Antibody-Mediated Rejection.

Our objective was to calculate an immunosuppressant possession ratio (IPR) to diagnose non-adherence at the time of antibody-mediated rejection (ABMR). IPR was defined as the ratio of number of pills collected at the pharmacy to the number of pills prescribed over a defined period. In a first cohort of 91 kidney transplant recipients (KTRs), those with an IPR < 90% had more frequently a tacrolimus through level coefficient of variation >30% than patients with an IPR = 100% (66.7% vs. 29.4%, p = 0.05). In a case-control study, 26 KTRs with ABMR had lower 6 months IPRs than 26 controls (76% vs. 99%, p < 0.001). In KTRs with ABMR, non-adherence was more often diagnosed by a 6 months IPR < 90% than by clinical suspicion (73.1% vs 30.8%, p = 0.02). In the multivariable analysis, only de novo DSA and 6 months IPR < 90% were independently associated with ABMR, whereas clinical suspicion was not (odds ratio, 4.73; 95% CI, 1.17-21.88; p = 0.03; and odds ratio, 6.34; 95% CI, 1.73-25.59; p = 0.007, respectively). In summary, IPR < 90% is a quantifiable tool to measure immunosuppressant non-adherence. It is better associated with ABMR than clinical suspicion of non-adherence.

Hospital Production of Sterile 2% Propofol Nanoemulsion: Proof of Concept.

In the context of essential drug shortages, this article reports a proof of concept for the hospital preparation of a 2% propofol injectable nanoemulsion. Two processes for propofol were assessed: mixing propofol with the commercial Intralipid® 20% emulsion and a "de novo" process performed using separate raw materials (i.e., oil, water, and surfactant) and optimized for droplet size reduction with a high-pressure homogenizer. A propofol HPLC-UV stability-indicating method was developed for process validation and short-term stability. In addition, free propofol in the aqueous phase was quantified by dialysis. To envision routine production, sterility and endotoxin tests were validated. Only the "de novo" process using high-pressure homogenization gave satisfactory physical results similar to commercialized Diprivan® 2%. Both terminal heat sterilization processes (121 °C, 15 min and 0.22 µm filtration) were validated, but an additional pH adjustment was required prior to heat sterilization. The propofol nanoemulsion was monodisperse with a 160 nm mean droplet size, and no droplets were larger than 5µm. We confirmed that free propofol in the aqueous phase of the emulsion was similar to Diprivan 2%, and the chemical stability of propofol was validated. In conclusion, the proof of concept for the in-house 2% propofol nanoemulsion preparation was successfully demonstrated, opening the field for the possible production of the nanoemulsion in hospital pharmacies.

Targeting of under-75 years for the optimization of medication reconciliation with an approach based on medication risks: An observational study.

PURPOSE: To date, how medication reconciliation (MR) could be prioritized in younger patients remains poorly evaluated. This study aimed at assessing whether a MR prioritization strategy based on the identification of high-risk medication at patients' admission treatment could be of interest in non-elderly patients. METHOD: This prospective study was conducted between July and September 2017 in an internal medicine unit at Bordeaux teaching hospital. All patients aged 16 to 74 years and receiving at least two long-term treatments at admission were considered eligible. High-risk medications were defined on the basis of a pharmacovigilance study, which identified the drugs most involved in serious adverse effects reported in the Nouvelle-Aquitaine region in non-elderly adults. They included antithrombotics, analgesics, antipsychotics and cardiac therapies. MR-induced treatment changes were compared according to the existence of high-risk medications at admission in study participants. RESULTS: Among the 92 study participants, 46 presented with high-risk medications at admission (median age 66 years, IQR 58-70) and 46 without such (median age 54 years, IQR 47-64). High risk-medications (HRM) existing at admission were antithrombotics (52.2%) and antipsychotics (22.4%). MR resulted in treatment changes in 37% of patients admitted with at-risk medications vs. 8.7% of those admitted without such (P=0.001). Overall, the mean number of treatment changes performed after MR was of 1 (95%CI 0.4-1.6) in patients with high-risk medication at admission and of 0.2 (95%CI 0-0.4) in patients without such. MR-induced treatment changes assessed as clinically major at least once by pharmacists or clinicians was greater in HRM group (43.5%) than in non-HRM group (31.6%). However, the consistency was low between clinicians and pharmacists, especially to distinguish the clinical importance of significant and minor interventions. CONCLUSION: Targeting high-risk medications at admission appeared efficient for the prioritization of MR in non-elderly patients hospitalised in internal medicine.

Benefit of a pharmacist-led intervention for medication management of renal transplant patients: a controlled before-and-after study.

AIMS: To assess the effect of a pharmacist-led intervention, using Barrows cards method, during the first year after renal transplantation, on patient knowledge about their treatment, medication adherence and exposure to treatment in a French cohort. METHODS: We conducted a before-and-after comparative study between two groups of patients: those who benefited from a complementary pharmacist-led intervention [intervention group (IG), n = 44] versus those who did not [control group (CG), n = 48]. The pharmacist-led intervention consisted of a behavioral and educational interview at the first visit (visit 1). The intervention was assessed 4 months later at the second visit (visit 2), using the following endpoints: treatment knowledge, medication adherence [proportion of days covered (PDC) by immunosuppressive therapy] and tacrolimus exposure. RESULTS: At visit 2, IG patients achieved a significantly higher knowledge score than CG patients (83.3% versus 72.2%, p = 0.001). We did not find any differences in treatment exposure or medication adherence; however, the intervention tended to reduce the proportion of non-adherent patients with low knowledge scores. Using the PDC by immunosuppressive therapy, we identified 10 non-adherent patients (10.9%) at visit 1 and six at visit 2. CONCLUSIONS: Our intervention showed a positive effect on patient knowledge about their treatment. However, our results did not show any improvement in overall medication adherence, which was likely to be because of the initially high level of adherence in our study population. Nevertheless, the intervention appears to have improved adherence in non-adherent patients with low knowledge scores.

Long-term physicochemical stability of acyclovir 5 mg/mL solution stored in polypropylene bags as a simulated hospital stock preparation.

PURPOSE: To investigate the long-term chemical and physical stability of 5-mg/mL acyclovir solution in polypropylene bags stored at 5°C ± 3°C for 2 months in order to determine the feasibility of batch production by a centralized intravenous additive service. METHODS: Eight empty 100-mL polypropylene bags (bags A) and 8 empty 250-mL bags (bags B) were respectively filled with 60 mL and 200 mL of 5-mg/mL acyclovir and 0.9% sodium chloride injection (NaCl) under aseptic conditions through a semiautomated manufacturing process and vacuum packed before storage at 5°C ± 3°C. Four bags A and 4 bags B were tested for chemical stability via a stability-indicating high-performance liquid chromatography (HPLC) method immediately after preparation (time 0) and after 7, 14, 21, 28, 35, 42, and 63 days. Samples for microbiological assay were collected on days 0 and 63 from 4 bags A and 4 bags B immediately after breaking the vacuum. Osmolality, pH, and physical stability were assessed by visual examination, Subvisible particle counting was performed on 6 additional bags (3 each of bags A and B). RESULTS: Mean percentage loss of acyclovir relative to the mean experimental concentration at time 0 was below 5% over the 63-day study period.. No significant differences of pH, no change in color and no precipitate were observed during the study. Subvisible particle counts were compliant with European Pharmacopoeia requirements. Acyclovir solutions remained sterile over the 63 days of the study. CONCLUSION: Extemporaneously prepared acyclovir 5 mg/mL solutions in 0.9% NaCl stored in polypropylene bags were chemically and physically stable over 63 days when stored at 5°C ± 3°C.

Implementation of infliximab standardized doses after pharmacokinetic modelization in a cohort of patients with Crohn's disease.

BACKGROUND: According to infliximab (IFX) license in Crohn's disease (CD), infusion doses are based on patient's body-weight. Dose banding providing standardized doses (SD) has been implemented in parenteral chemotherapy in order to optimize aseptic unit capacity and reduce drug expenditure, duration of hospital stay and costs without decreasing efficacy. MATERIAL AND METHOD: The first part was a single-center retrospective analysis of consecutive CD patients receiving IFX maintenance therapy to determine standardized doses covering more than 50% of infusions. The second part was a prospective cohort study assessing the impact of SD compared to body-weight doses (BWD) on admission duration and costs. RESULTS: Six IFX SD covering more than 90% of infusion doses were implemented for dose banding. According to the Monte-Carlo simulation, there was no significant difference between IFX SD and BWD maintenance regimens. When assessed prospectively in 116 patients (75 patients treated with SD and 41 with BWD) corresponding to 128 infusions, hospitalization duration was shortened by 70 min per patient (p < 0.001). CONCLUSION: According to a pharmacokinetic model, IFX SD has a pharmacokinetic profile close to BWD and is associated with reduced length of hospitalization in a cohort of patients with CD. IFX SD implementation could optimize infusion units functioning and, save time and costs without decreasing efficacy.

Are Standard Dosing Regimens of Ceftriaxone Adapted for Critically Ill Patients with Augmented Creatinine Clearance?

The objective of the present study was to determine whether augmented renal clearance (ARC) impacts negatively on ceftriaxone pharmacokinetic (PK)/pharmacodynamic (PD) target attainment in critically ill patients. Over a 9-month period, all critically ill patients treated with ceftriaxone were eligible. During the first 3 days of antimicrobial therapy, every patient underwent 24-h creatinine clearance (CLCR) measurements and therapeutic drug monitoring of unbound ceftriaxone. ARC was defined by a CLCR of ≥150 ml/min. Empirical underdosing was defined by a trough unbound ceftriaxone concentration under 2 mg/liter (percentage of the time that the concentration of the free fraction of drug remained greater than the MIC [fT>MIC], 100%). Monte Carlo simulation (MCS) was performed to determine the probability of target attainment (PTA) of different dosing regimens for various MICs and three groups of CLCR (<150, 150 to 200, and >200 ml/min). Twenty-one patients were included. The rate of empirical ceftriaxone underdosing was 62% (39/63). A CLCR of ≥150 ml/min was associated with empirical target underdosing with an odds ratio (OR) of 8.8 (95% confidence interval [CI] = 2.5 to 30.7; P < 0.01). Ceftriaxone PK concentrations were best described by a two-compartment model. CLCR was associated with unbound ceftriaxone clearance (P = 0.02). In the MCS, the proportion of patients who would have failed to achieve a 100% fT>MIC was significantly higher in ARC patients for each dosage regimen (OR = 2.96; 95% CI = 2.74 to 3.19; P < 0.01). A dose of 2 g twice a day was best suited to achieve a 100% fT>MIC When targeting a 100% fT>MIC for the less susceptible pathogens, patients with a CLCR of ≥150 ml/min remained at risk of empirical ceftriaxone underdosing. These data emphasize the need for therapeutic drug monitoring in ARC patients.

Higher than standard dosing regimen are needed to achieve optimal antibiotic exposure in critically ill patients with augmented renal clearance receiving piperacillin-tazobactam administered by continuous infusion.

PURPOSE: To determine whether augmented renal clearance (ARC) impacts negatively on piperacillin-tazobactam unbound concentrations in critically ill patients receiving 16 g/2 g/day administered continuously. MATERIAL AND METHODS: Fifty nine critically ill patients without renal impairment underwent 24-h creatinine clearance (CrCL) measurement and therapeutic drug monitoring during the first three days of antimicrobial therapy by piperacillin-tazobactam. The main outcome was the rate of piperacillin underexposure, defined by at least one of three samples under 16 mg/L. Monte Carlo simulation was performed to predict the distribution of piperacillin concentrations for various CrCL and minimal inhibitory concentration (MIC) values. RESULTS: The rate of piperacillin underexposure was 19%, significantly higher in ARC patients (0 vs. 31%, p = .003). A threshold of CrCL ≥ 170 mL/min had a sensitivity and specificity of 1 (95%CI: 0.79-1) and 0.69 (95%CI: 0.61-0.76) to predict piperacillin underexposure. In ARC patients, a 20 g/2.5 g/24 h PTZ dosing regimen was associated with the highest probability to reach the 16 mg/L empirical target, without risk of excessive dosing. CONCLUSIONS: When targeting a theoretical MIC at the upper limit of the susceptibility range, the desirable target (100%fT>16) may not be achieved in patients with CrCL ≥ 170 mL/min receiving PTZ 16 g/2 g/day administered continuously.

A new reliable, transposable and cost-effective assay for absolute quantification of total plasmatic bevacizumab by LC-MS/MS in human plasma comparing two internal standard calibration approaches.

The quantification of monoclonal antibodies (mAbs) such as bevacizumab, a recombinant humanized immunoglobulin G1 (hIgG1), in biological fluids, is an essential prerequisite to any pharmacokinetic preclinical and clinical study. To date, reference techniques used to quantify mAbs rely on enzyme-linked immunosorbent assay (ELISA) lacking specificity. Furthermore, the commercially available ELISA kit to quantify bevacizumab in human plasma only assesses the free fraction of the drug. However, the conditions of storage and analysis of plasma samples could alter the physiological equilibrium between the free, bound and partially bound forms of bevacizumab and this could result in over- or underestimation of drug concentration. We developed a new assay for absolute quantification of total fraction of bevacizumab by liquid chromatography tandem mass spectrometry (LC-MS/MS) basing identification and quantification of bevacizumab on two specific peptides. In this report we compare our assay with two internal standard (IS) calibration approaches: one using a different human mAb (Trastuzumab) and the other using a stable isotope labeled specific peptide. After enrichment by affinity chromatography on protein A and concentration by ultrafiltration, human plasma samples were proteolyzed by trypsin. Linearity was established from 12.5 to 500µg/mL with an interday accuracy ranging from 101.7 to 110.6% and precision from 7.0% to 9.9%. This study demonstrates the importance of the choice of the IS in quantifying bevacizumab in human plasma and highlights the difficulty of reaching a reliable proteolysis with a sufficient recovery. We developed a reliable and cost-effective LC-MS/MS method to quantify total plasmatic fraction of bevacizumab in human plasma. Through our development we proposed a generic methodology easily transposable to quantify all IgG1 subclass very useful for clinical pharmacokinetics studies.

Pre-dose plasma concentration monitoring of mycophenolate mofetil in patients with autoimmune diseases.

AIM: To date, neither the benefit of mycophenolic acid (MPA) therapeutic drug monitoring (TDM), the prodrug of mycophenolate mofetil (MMF), nor the optimal monitoring technique have been established in autoimmune diseases. This study was undertaken to confirm, in a cohort of new patients, the plasma MPA thresholds previously published in patients with systemic lupus erythematosus (SLE) or vasculitis. METHODS: MPA areas under the concentration-time curves between 0 and 12 h, 12 h trough concentrations and pre-dose concentrations (C0 ) were determined for 23 patients with SLE and 21 with systemic vasculitis. The relationship between patients' pharmacokinetic (PK) variables and their clinical outcomes during follow-up were analyzed. RESULTS: In both autoimmune diseases, at PK assessment, median MPA C0 for patients with uncontrolled disease was significantly lower than that of patients with stable disease or in remission, 1.6 mg l(-1) (IQR 0.9-2.1 mg l(-1)) vs. 2.95 mg l(-1) (IQR 1.38-3.73 mg l(-1)) for SLE (P = 0.048) and 1.55 mg l(-1) (IQR 0.98-2.18 mg l(-1)) vs. 3 mg l(-1) (IQR 2.2-4.4 mg l(-1)) for vasculitis (P = 0.016). According to our receiver operating characteristics curve analysis, a C0 threshold of 2.5-3 mg l(-1) was best able to discriminate a flare (SLE: 88% sensitivity, 80% specificity; vasculitis: 100% sensitivity, 90% specificity). Patients with C0 ≥ 2.5-3 mg l(-1) at inclusion had better clinical outcomes during the 12 months following PK assessment. CONCLUSION: Provided that the benefit of TDM in patients with autoimmune diseases could be confirmed by randomized, controlled trials, it might be based on the C0 measured approximately 12 h post-dose.

Chemical stability of azacitidine suspensions for injection after cold-chain reconstitution of powder and storage.

PURPOSE: The 72-hour chemical stability of refrigerated syringes of azacitidine suspension prepared via a cold-chain method is investigated. METHODS: Three 25-mg/mL azacitidine suspensions were prepared from different lots of powdered drug. The suspensions were stored in 2-mL polypropylene syringes at 2-8 °C and protected from light. The concentrations of azacitidine and the mean area under the concentration-time curve (AUC) values for its degradation products were determined after 0, 1, 2, 3, 4, 6, 8, 12, 24, 48, and 72 hours using high-performance liquid chromatography with ultraviolet detection. RESULTS: The degradation process was slow during the first 48 hours and then accelerated. During the first 48 hours of storage, 4.23% of the azacitidine was lost relative to the mean concentration measured at time zero, which complied with International Conference on Harmonisation (ICH) guidance specifying a maximum change of 5% from the initial measured value. Two degradation products were present immediately after syringe preparation; N-formylribosylguanylurea formed rapidly (as indicated by a 35.62% increase from the baseline AUC in the first 12 hours), whereas ribosylguanylurea formation occurred more slowly (a 7.69% mean increase from the baseline AUC at 12 hours) but then rapidly accelerated. The study results indicate that properly prepared azacitidine syringes for injection can be administered up to two days later while maintaining conformance with ICH stability standards. CONCLUSION: Azacitidine 25-mg/mL suspensions reconstituted with refrigerated water (2-8 °C) and stored in propylene syringes were chemically stable during the first 48 hours when stored protected from light at 2-8 °C.

Alveolar diffusion and pharmacokinetics of linezolid administered in continuous infusion to critically ill patients with ventilator-associated pneumonia.

OBJECTIVES: This study aimed to determine the steady-state serum and alveolar concentrations of linezolid administered by continuous infusion to critically ill patients with ventilator-associated pneumonia (VAP). PATIENTS AND METHODS: This was a prospective, open-label study performed in an intensive care unit and research ward in a university hospital. Twelve critically ill adult patients with VAP received 600 mg of linezolid as a loading dose followed by 1200 mg/day by continuous infusion. After 2 days of therapy, the steady-state serum and alveolar (collected by a mini-bronchoalveolar procedure) concentrations of linezolid were determined by HPLC. RESULTS: The median (IQR) serum and epithelial lining fluid (ELF) linezolid concentrations at steady state (C(ss)) were 7.1 (6.1-9.8) and 6.9 (5.8-8.6) mg/L, respectively, and the median (IQR) AUC (AUC(0-24)) values were 169 (146-235) and 164 (139-202) mg · h/L, respectively, corresponding to a median (IQR) linezolid alveolar diffusion of 97% (80%-108%). CONCLUSIONS: Our study shows that the continuous infusion of 1200 mg of linezolid daily in critically ill patients with VAP provides satisfactory pharmacokinetic results, with a linezolid alveolar diffusion of 100% and concentrations exceeding almost twice the susceptibility breakpoint for Staphylococcus aureus (4 mg/L) in both serum and ELF for 100% of the time. However, the clinical benefit of continuous infusion in comparison with standard intermittent infusion is still to be determined.

A sensitive liquid chromatography coupled with mass spectrometry method for the intracellular and plasma quantification of raltegravir after solid-phase extraction.

INTRODUCTION: Liquid chromatography coupled with mass spectrometry for the quantification of raltegravir in human plasma and peripheral blood mononuclear cells has been developed. METHODS: Sample preparations were based on a fully automated solid-phase extraction process. Mass spectrometric data were acquired in a single-ion monitoring method. Raltegravir and quinoxaline, the internal standard, were well separated in a gradient mode over 15 min. KEY FINDINGS: Validation study exhibited excellent linearity, with good intra- and inter-day precision and accuracy. CONCLUSIONS: The assay was successfully applied to the raltegravir quantification in HIV-infected patients.

Quantitative analysis of erythropoietin in human plasma by tandem mass spectrometry.

The extended use of protein drugs in therapeutics has created the need for their quantification in human plasma. A methodology using the therapeutic protein itself as internal standard for quantitative analysis by multiple reaction monitoring (MRM) has been designed and applied to epoetin beta, a recombinant human erythropoietin (rhEPO). After depletion of major proteins, plasma samples were desalted and enriched in rhEPO by reversed phase liquid chromatography prior to tryptic cleavage. Differential isotopic labeling of peptides was performed by derivatization with 2-methoxy-4,5-dehydro-imidazole. A light version (four hydrogen atoms) of this reagent was used for plasma peptides. Tryptic peptides obtained from pure rhEPO were derivatized with a heavy version (four deuterium atoms) of the same reagent and used as internal standards. Two rhEPO tryptic peptides with three MRM transitions per peptide were selected for quantification. This strategy provided a quantification limit close to 50 amol of epoetin beta per microliter of plasma (equivalent to 1.7 ng/mL), i.e., well below the expected therapeutic concentrations in plasma (around 100-500 amol/µL).

An in vitro study of epoetin beta intravenous injection site at the end of hemodialysis.

The aim of this study (SITEPO) is to evaluate the influence of the intravenous injection site (drip chamber injection site, venous injection site or venous fistula needle) on plasma concentration of epoetin beta (Neorecormon, Roche), a recombinant Human Erythropoietin (rHuEPO), at the end of in vitro hemodialysis sessions. No practical administration guidelines are available. Twenty 1-h dialysis sessions are performed. Before each dialysis, the circuit is filled with 270ml, of heparinized total human blood whose hematocrit is adjusted to 35%. A common dosage of epoetin beta in clinical practice (3000IU) is studied for the three injection sites and for reference experiments in which rHuEPO is not injected into the dialysis circuit. Plasma concentrations of erythropoietin are measured by ELISA. The physiologically endogenous erythropoietin concentration is systematically determined and removed from the total epoetin beta concentration. Average epoetin beta plasma levels returned are not significantly different between the three injection sites and no significant rHuEPO loss is observed after injection into the drip chamber, the venous injection site and the venous fistula needle compared with reference experiments. The three intravenous injection sites of rHuEPO can be used at the end of dialysis without significant epoetin beta loss.

Alveolar concentrations of piperacillin/tazobactam administered in continuous infusion to patients with ventilator-associated pneumonia.

OBJECTIVES: To determine the steady-state serum and alveolar concentrations of piperacillin/tazobactam administered in continuous infusion to critically ill patients with ventilator-associated pneumonia and various degrees of renal failure. DESIGN: Prospective comparative study. SETTING: An intensive care unit and research ward in a university hospital. PATIENTS: Forty patients with microbiologically documented ventilator-associated pneumonia. INTERVENTIONS: Patients were randomized to receive piperacillin/tazobactam daily continuous infusions of 12/1.5 g or 16/2 g after a loading dose of 4/0.5 g. The serum and alveolar piperacillin/tazobactam concentrations were determined at steady-state with high performance liquid chromatography. MEASUREMENTS AND MAIN RESULTS: The median (interquartile) serum and alveolar piperacillin concentrations were respectively 25.3 mg/L (23.1-32.6) and 12.7 mg/L (6.7-18.0) for 12/1.5 g/day, and 38.9 mg/L (32.9-59.6) and 19.1 mg/L (14.0-21.5), respectively, for 16/2 g/day in patients with no/mild renal failure. In patients with moderate/advance renal failure, the median (interquartile) serum and alveolar piperacillin concentrations were 102.4 mg/L (97.4-112.6) and 44.1 mg/L (33.4-48.3), respectively, for 12/1.5 g/day, and 135.3 mg/L (119.5-146.2) and 54.9 mg/L (45.2-110.3), respectively, for 16/2 g/day. Our results show great variability in piperacillin/tazobactam concentrations, with an alveolar percentage penetration of 40-50% for piperacillin and 65-85% for tazobactam and a negative association between serum or alveolar concentrations and creatinine clearance. CONCLUSIONS: A target piperacillin serum concentration of at least 35-40 mg/L is probably required to provide alveolar concentrations exceeding the susceptibility breakpoint for gram-negative bacteria (16 mg/L) during ventilator-associated pneumonia. In patients with no/mild renal failure, a continuous daily dose of piperacillin/tazobactam 16/2 g allows reaching this target concentration, which might be not observed with 12/1.5 g/day. In patients with moderate/advanced renal failure, both dosages achieve serum concentrations far above the 35-40 mg/L threshold, suggesting that in that case, therapeutic drug monitoring should be performed in order to adjust the daily dose.

Reliability of mini-bronchoalveolar lavage for the measurement of epithelial lining fluid concentrations of tobramycin in critically ill patients.

OBJECTIVE: To evaluate the reliability of mini-bronchoalveolar lavage (mini-BAL) for the measurement of tobramycin concentrations in epithelial lining fluid (ELF) in comparison with conventional bronchoscopic bronchoalveolar lavage (BAL). DESIGN: Prospective, open-label study. SETTING: An intensive care unit and research ward in a university hospital. PATIENTS: Twelve critically ill adult patients with ventilator-associated pneumonia (VAP). INTERVENTIONS: All subjects received intravenous infusions of tobramycin 7-10 mg/kg once daily. After 2 days of therapy, the steady-state serum and ELF concentrations (obtained from BAL and mini-BAL) of tobramycin were determined by means of high-performance liquid chromatography. MEASUREMENTS AND RESULTS: We observed poor penetration of tobramycin in ELF of approximately approximately 12% with ELF peak concentrations of approximately approximately 3 mg/l with both methods. Good agreement in Bland-Altman analysis (mean +/- SD bias = 0.04 +/- 0.38 mg/l) was observed between the two methods of sampling. CONCLUSION: Our results suggest that tobramycin 7-10 mg/kg once daily in critically ill patients with VAP might provide insufficient lung concentrations in the case of difficult-to-treat pathogens. Besides, mini-BAL, which is simple, non-invasive and easily repeatable at the bedside, appears to be a reliable method for the measurement of antibiotic concentrations in ELF in comparison with bronchoscopic BAL in critically ill patients with VAP.

Determination of linezolid in plasma and bronchoalveolar lavage by high-performance liquid chromatography with ultraviolet detection using a fully automated extraction method.

The aim of this study was to develop a specific and sensitive high-performance liquid chromatographic assay for the determination of linezolid in human plasma, and bronchoalveolar lavage. The sample extraction was based on a fully automated solid-phase extraction with an OASIS HLB cartridge. The method used ultraviolet detection set at a wavelength of 254 nm and a separation with a Zorbax Eclipse XDB C8 column. The assay has been found linear over the concentration range 0.02-30 microg/ml and 0.04-30 microg/ml for linezolid, respectively, in plasma and bronchoalveolar lavage. It provided good validation data for accuracy and precision (CV <4.64% and 5.08%, accuracy in the range 96.93-102.67% and 97.33-105.67%, respectively, for intra- and inter-day). The assay will be applied to determine the penetration of linezolid in human bronchoalveolar lavage during pharmacokinetic steady-state.

Simultaneous determination of the antiretroviral agents: amprenavir, lopinavir, ritonavir, saquinavir and efavirenz in human peripheral blood mononuclear cells by high-performance liquid chromatography-mass spectrometry.

A selective and accurate assay for the simultaneous quantitation of four protease inhibitors (PIs) (amprenavir (APV), lopinavir (LPV), ritonavir (RTV) and saquinavir (SQV)) and a non-nucleoside reverse transcriptase inhibitor (NNRTI) (efavirenz, EFV) in human peripheral blood mononuclear cells using high-performance liquid chromatography-mass chromatography (LC/MS) has been developed and validated. After liquid-liquid extraction, the antiretroviral agents were separated within 15 min. The calibration curves of each drug showed a good linearity in a range of concentration between 2 and 200 ng/3 x 10(6) cells for amprenavir, lopinavir, efavirenz, 1.60 and 128 ng/3 x 10(6) cells for ritonavir and saquinavir. Mean intra- and inter-assay coefficients of variation over the ranges of the standard curves were less than 15% and mean extraction recoveries ranged 88.7-112.1%. The limits of quantification were 2 ng/3 x 10(6) cells for amprenavir, lopinavir, efavirenz, 1 ng/3 x 10(6) cells for ritonavir and 1.6 ng/3 x 10(6) cells for saquinavir. This novel LC/MS assay, which provides an excellent method for simultaneous intra-cellular determination of amprenavir, lopinavir, ritonavir, saquinavir and efavirenz in human peripheral blood mononuclear cells, could be successfully applied for therapeutic drug monitoring and pharmacokinetic studies.