OBJECTIVES:The objective of the study was to explore the distribution of gepotidacin into prostate tissue by ex vivo microdialysis (MD) after a single oral dose of gepotidacin. METHODS:We developed and validated an ex vivo MD technique to quantify unbound gepotidacin concentrations in the interstitial fluid of human prostate tissue after a single oral dose of 1500 mg. Adult male patients scheduled for radical prostatectomy received gepotidacin at different timepoints before surgery. MD probes were inserted into prostate tissue immediately after surgical removal for sampling of tissue concentrations. Plasma samples were collected in parallel. Population pharmacokinetic (popPK) modelling was used to analyse the concentration data. RESULTS:Thirty participants were recruited, of whom 24 had at least one prostate MD sample with concentrations above the limit of quantification. A popPK model was successfully developed that described plasma and prostate gepotidacin concentration well. The model-predicted geometric mean of unbound area under the concentration-time curve from zero to infinity was 15 500 h∗ng/mL (geometric coefficient of variation (GCV): 15.7%) in both prostate and plasma (prostate penetration ratio = 1). The model-predicted geometric mean of the unbound peak concentration (Cmax) of 1340 ng/mL (GCV: 38.7%) was reached after 4.25 hours (range: 3.25-12.2 hours) in prostate tissue. The model-predicted geometric mean of unbound plasma Cmax of 2090 (GCV 48.2%) ng/mL was reached after 1.75 hours (range: 0.75-8.25 hours). Model-estimated median total apparent plasma clearance and terminal apparent volume of distribution were 65.0 L/h (GCV 15.7%) and 1310 L (GCV 11.2%), respectively. CONCLUSIONS:Ex vivo MD proved feasible for quantifying gepotidacin in human prostate tissue, interstitial fluid showing exposures comparable with plasma. However, defining pharmacokinetic/pharmacodynamic targets against relevant pathogens for bacterial prostatitis remains essential for predicting drug efficacy for treatment of this disease.

OBJECTIVES:COVID-19 vaccines are periodically updated to address SARS-CoV-2 evolution. Whether minor antigen changes provide immunological or even clinical benefit remains unclear. This study compared neutralizing antibody responses following vaccination with the JN.1-based or KP.2-based 2024/25 Pfizer-BioNTech mRNA vaccine. METHODS:Adults aged 18-64 years who received the JN.1 vaccine in Austria, or the KP.2 vaccine in the United States were enrolled. A single blood sample was obtained within 120 days post-vaccination. Pseudovirus neutralization assays against SARS-CoV-2 variants XBB.1.5, JN.1, KP.2, KP3.1.1, XEC and LP.8.1 were performed. Geometric mean titre (GMT) ratios were analysed using t-tests and multivariable regression adjusted for age, sex, vaccination intervals, and prior infection. RESULTS:Among 191 participants (78 JN.1, 113 KP.2), GMTs (95% CI) for XBB.1.5 variant were higher in the JN.1 cohort (3498 [2535-4826]) than in the KP.2 cohort (1901 [1386-2607]), GMT ratio 1.84 (1.16-2.92). For the JN.1 variant, GMTs were 1122 (819-1538) in the JN.1 cohort and 695 (510-948) in the KP.2 cohort (GMT ratio: 1.61 [1.03-2.54]). GMTs for other variants did not differ significantly. After adjustment, only the XBB.1.5 difference remained significant (p = 0.04). CONCLUSIONS:Comparable neutralizing responses across JN.1 lineage variants suggest that annual COVID-19 strain updates targeting variants with small differences within the same antigenic cluster may have limited impact on vaccine-induced protection. These findings may inform future public health policy and regulatory decision-making for COVID-19 vaccines.

BACKGROUND:This study aimed to investigate pharmacokinetic (PK)/pharmacodynamic (PD) target attainment, tissue and plasma PK and PK interactions of ampicillin/sulbactam. METHODS:Thirty healthy volunteers received a single intravenous 30-min infusion of ampicillin 2000 mg (n = 10), sulbactam 1000 mg (n = 10) or ampicillin 2000 mg/sulbactam 1000 mg (n = 10). Drug concentrations were determined in the interstitial fluid of subcutis and muscle using microdialysis and in plasma over 8 h. A non-compartmental analysis and an adjustment to the plasma protein binding determined by ultrafiltration were performed to calculate PK parameters and the proportion of participants achieving PK/PD targets. The PK/PD targets selected for ampicillin were fT>MIC >50% and fT>MIC >70%, reflecting established efficacy thresholds for β-lactam antibiotics across varying degrees of disease severity. RESULTS:Fewer than 90% of participants reached the PK/PD target of ampicillin fT>MIC > 50% at MICs ≥4 mg/L and the target of fT>MIC > 70% at MICs ≥0.5 mg/L in plasma, muscle and subcutis, assuming three times daily dosing. In the pooled analysis, the mean fAUC0-8 of ampicillin was 80 (S.D. 25), 84 (S.D. 29) and 80 (S.D. 20) mg/L × h in subcutis, muscle and plasma. The mean fAUC0-8 of sulbactam was 49 (S.D. 13), 54 (S.D. 15) and 60 (S.D. 17) mg/L × h in subcutis, muscle and plasma. While ampicillin concentrations were similar between the groups, sulbactam showed higher concentrations in the combined group than in the sulbactam alone group, including an increased plasma fAUC0-8 (68 [S.D. 12] vs. 51 [S.D. 18] mg/L × h, P = 0.027). CONCLUSION:Although tissue concentrations almost reached plasma levels, the target attainment of ampicillin may be suboptimal when administered three times daily. Sulbactam tissue and plasma levels were slightly higher after combined administration with ampicillin than after administration of sulbactam alone.

OBJECTIVES:This study measured the penetration of ceftaroline and ceftazidime/avibactam into cerebrospinal fluid (CSF) to evaluate the potential of both drugs for treatment of central nervous system (CNS) infections. METHODS:In this prospective, single-centre pharmacokinetic (PK) study, 24 healthy volunteers equally divided into two groups received four doses of either 600 mg ceftaroline fosamil or 2000/500 mg ceftazidime/avibactam as intravenous infusions over 2 h at 8 h intervals for 4 doses. Plasma samples were obtained on both study days and CSF was sampled once per subject at either 2 h, 4 h or 8 h after the start of the last infusion via lumbar puncture. PK data were analysed using non-compartmental analysis, as well as using a population PK modelling approach. Monte Carlo simulations were performed to calculate probability of PK-pharmacodynamic (PK-PD) target attainment. RESULTS:Two-compartment models described the plasma PK data for all three compounds. The ratios between the estimated distribution clearances into and out of the CSF were 0.021, 0.083 and 0.071 for ceftaroline, ceftazidime and avibactam, respectively, indicating limited CSF penetration. Ceftaroline and ceftazidime PK-PD targets were not attained in CSF for minimum inhibitory concentrations around commonly used susceptibility breakpoints, but exposure appears sufficient to treat several pathogens commonly causing CNS infections. Avibactam concentrations were well below reported threshold concentrations that are required for activity. CONCLUSION:In healthy subjects, ceftaroline, ceftazidime and avibactam poorly distribute to CSF. Nonetheless, CSF exposure of both cephalosporins might be sufficient to cover certain, but not all, pathogens causative of CNS infections.

Penicillin/beta-lactamase inhibitors are often used to treat aspiration pneumonia in patients resuscitated after cardiac arrest (CA). The impact of hypothermic temperature control on the pharmacokinetics of amoxicillin/clavulanate (AMO/CLAV) and ampicillin/sulbactam (AMP/SULB) has not been studied. Our objective was to evaluate the effects of hypothermic temperature control on the plasma and soft tissue pharmacokinetics of AMO/CLAV and AMP/SULB, including pulmonary concentrations of AMP/SULB, in patients resuscitated after CA. This prospective clinical study involved ten adult patients after CA receiving either AMO/CLAV 2 g/0.2 g or AMP/SULB 2 g/1 g intravenously every 8 h. Patients underwent hypothermic temperature control (33 ± 1 °C) for 24 h, followed by normothermia. Plasma, urine, muscle, and subcutaneous pharmacokinetics were measured and plasma protein-binding assessed for each subject. Microdialysis determined unbound drug concentrations in soft tissues. The pulmonary concentration of AMP/SULB was analyzed in the epithelial lining fluid. No significant differences in plasma pharmacokinetics or renal excretion of AMO/CLAV and AMP/SULB were observed between the two temperature conditions. Soft tissue concentrations showed no consistent trend. Pharmacokinetic/pharmacodynamic targets (time that the unbound plasma concentrations were above the minimal inhibitory concentration [MIC] for MIC up to 8 mg/L) were met but not for 16 mg/L. Pulmonary concentrations of AMP/SULB in the epithelial lining fluid showed no clear trend. This study indicates that hypothermic temperature control does not significantly affect plasma concentrations, soft tissue concentrations, or renal excretion of AMO/CLAV and AMP/SULB in patients resuscitated after CA. However, pulmonary concentrations of AMP/SULB exhibited interindividual variability.

An important safety consideration for topically administered drugs is the extent of systemic exposure they achieve. The aim of this study was to evaluate whether a topically administered microdose of the model drug diclofenac can predict the systemic availability, plasma, and tissue pharmacokinetics of a topical therapeutic dose. Eight healthy participants (6 men and 2 women) participated in a 4-period, crossover study. In period 1, a topical microdose (62 ± 6 μg) was administered; in period 2, a single intravenous microdose (0.95 ± 0.03 μg) was administered; in period 3, a topical therapeutic dose (120 mg) was administered; and in period 4, a single intravenous therapeutic dose (75 mg) of [14C]diclofenac was administered, with or without the addition of unlabeled diclofenac. Venous blood, urine, and microdialysis samples from subcutaneous adipose tissue beneath the dermal application site were collected for 24 h post-dosing. Total 14C-concentrations in plasma and microdialysates were quantified using accelerator mass spectrometry. The disposition of intravenously administered [14C]diclofenac was dose-linear. However, after topical administration, the fraction of total 14C absorbed (geometric mean and 95% confidence interval) was higher (P = .0019, 2-tailed, paired t test) for the microdose (0.48% and 0.34%-0.67%) compared with the therapeutic dose (0.13% and 0.07%-0.22%) (geometric mean ratio and 90% confidence interval: 3.79 and 2.41-5.98). Dose-normalized 14C-concentrations in microdialysates were low, variable, and did not differ between doses. Our study demonstrates the feasibility of quantifying 14C-concentrations in plasma and microdialysates following the topical administration of a microdose of [14C]diclofenac. The observed nonlinearity in systemic availability after topical dosing suggests that microdosing may not accurately predict the disposition of certain topical drugs at therapeutic doses. SIGNIFICANCE STATEMENT: We assessed whether a topically applied microdose of diclofenac could predict the systemic availability of a therapeutic dose. Results showed that systemic absorption was not dose-linear, indicating that microdosing may have limited use for predicting the pharmacokinetics of some topical drugs.

OBJECTIVE:The objective of this study was to assess the safety and tolerability of the intratympanic delivery of AC102, a novel pharmaceutical therapy based on a thermosensitive gel for preventing and treating a range of hearing impairments, including sudden sensorineural hearing loss. We studied this in healthy, normal-hearing volunteers to evaluate any change in hearing thresholds. STUDY DESIGN:An open-label, placebo-controlled, ascending single-dose, multicenter phase 1 clinical trial. SETTING:The study was conducted in two centers (blinded for reviewing purposes). SUBJECTS:Forty-two normal-hearing healthy volunteers younger than 40 years of age were eligible for enrollment in the study. INTERVENTION:A single intratympanic injection of a thermosensitive gel, either a placebo or containing AC102, to the middle ear. MAIN OUTCOME MEASURE:The primary objective of this study was to assess the safety and tolerability of a single intratympanic injection of ascending volume of placebo and ascending volume and concentration of AC102. The secondary objective was to determine single-dose pharmacokinetics of intratympanically injected AC102 and to evaluate any change in hearing thresholds in healthy male and female subjects. RESULTS:The intratympanic delivery of AC102 thermogel was safe and well tolerated in healthy volunteers with normal hearing, with no permanent adverse events recorded. A mild and temporary volume-dependent conductive hearing loss in the higher frequencies was observed irrespective of AC102 or placebo, which did not result in long-term changes in hearing. Other transient adverse events related to the injection procedure were largely similar between placebo gel and AC102 suspension, consisting mainly of mild ear discomfort, tinnitus, otalgia, and the formation of a droplet of blood at the injection site. CONCLUSIONS:The results of this phase 1 clinical trial suggest that the intratympanic delivery of AC102 is a safe and well-tolerated approach for drug delivery to the inner ear in healthy volunteers with normal hearing. As temporary, volume-dependent, conductive hearing losses were observed in the higher frequencies, it is recommended that patients are counseled on a short-term increase in hearing thresholds following injection for conditions such as sudden hearing loss.

Von Willebrand factor (vWF) and thrombospondin-1 (TSP-1) are glycoproteins with procoagulant and prothrombotic properties, playing additional roles in inflammation and cell adhesion [1,2]. They are stored in granules of platelets and endothelial cells (ECs) and are released upon cell activation by agonists like lipopolysaccharide (LPS) or desmopressin [1,2]. In vivo changes in blood concentrations of vWF have previously been studied in human models of desmopressin or low-dose LPS administration to healthy volunteers [3–5], while little is known about the time course of TSP-1 plasma concentrations in these settings [6].

Background Cefiderocol may potentially be used to treat skin and soft tissue infections (SSTIs). However, the pharmacokinetics of cefiderocol in human soft tissues have not yet been determined. The objective of the present PK study was to investigate whether target-site concentrations of cefiderocol are sufficiently high for the treatment of SSTIs.Methods In this pharmacokinetic study, a single intravenous dose of 2 g cefiderocol was administered to eight healthy male volunteers. Drug concentrations were determined in plasma, muscle and subcutis over 8 h. Free plasma concentrations were calculated using the plasma protein binding determined with ultrafiltration. Free tissue concentrations were obtained using microdialysis. Penetration ratios were calculated as AUC0-8h_free_tissue/AUC0-8h_free_plasma. A population pharmacokinetic model was developed, and the probability of target attainment (PTA) was determined using Monte Carlo simulations.Results Cefiderocol showed good tissue penetration, with mean penetration ratios +/- standard deviation of 0.99 +/- 0.33 and 0.92 +/- 0.30 for subcutis and muscle, respectively. Cefiderocol pharmacokinetics in plasma were best described with a two-compartment model, and tissue concentrations were described by scaling the tissue concentrations to concentrations in the peripheral compartment of the plasma model. For a thrice-daily regimen with 2 g doses intravenously infused over 3 h, PTA was >= 90% for MIC values up to 4 mg/L, both based on free plasma and soft tissue pharmacokinetics.Conclusions This study indicates that a dose of 2 g cefiderocol achieves concentrations in plasma considered sufficient for treating relevant bacterial species. Assuming a comparable PK/PD target for soft tissues, sufficiently high concentrations would also be achieved in soft tissues.

Background Pathophysiological changes in severely burned patients alter the pharmacokinetics (PK) of anti-infective agents, potentially leading to subtherapeutic concentrations at the target site. Albumin supplementation, to support fluid resuscitation, may affect pharmacokinetic properties by binding drugs. This study aimed to investigate the PK of piperacillin/tazobactam in burn patients admitted to the ICU before and after albumin substitution as total and unbound concentrations in plasma.Patients and methods Patients admitted to the ICU and scheduled for 4.5 g piperacillin/tazobactam administration and 200 mL of 20% albumin substitution as part of clinical routine were included. Patients underwent IV microdialysis, and simultaneous arterial plasma sampling, at baseline and multiple timepoints after drug administration. PK analysis of total and unbound drug concentrations under steady-state conditions was performed before and after albumin supplementation.Results A total of seven patients with second- to third-degree burns involving 20%-60% of the total body surface were enrolled. Mean (SD) AUC0-8 (h center dot mg/L) of total piperacillin/tazobactam before and after albumin substitution were 402.1 (242)/53.2 (27) and 521.8 (363)/59.7 (32), respectively. Unbound mean AUC0-8 before and after albumin supplementation were 398.9 (204)/54.5 (25) and 456.4 (439)/64.5 (82), respectively.Conclusions Albumin supplementation had little impact on the PK of piperacillin/tazobactam. After albumin supplementation, there was a numerical increase in mean AUC0-8 of total and unbound piperacillin/tazobactam, whereas similar Cmax values were observed. Future studies may investigate the effect of albumin supplementation on drugs with a higher plasma protein binding.

Rabbits are frequently used for the examination of the pharmacokinetics and effectiveness of antibiotic substances. However, antibiotics vary substantially in protein binding affecting the concentration of the antimicrobially effective unbound drug. We hypothesized that the binding properties of vancomycin, meropenem and ceftriaxone might vary between human and rabbit plasma. In an in-vitro study we observed dose dependent variability in protein binding of antibiotics between species. Thus, in-vitro-pre-studies are required to guarantee for translational conditions.

The herpes simplex virus type 1 (HSV-1) mutant in 1814 contains an insertion mutation in the coding sequence for the virion transactivator protein VP16 and is thus impaired for the activation of immediate early (IE) gene expression. This virus was modified further by introducing the Moloney murine leukemia virus LTR promoter in place of the upstream sequences controlling expression of the IE regulatory protein ICPO, to yield mutant in 1820. In almost all cell types tested, in 1820 initiated infection less efficiently than in 1814, behaving as if lacking both VP16 and ICPO functions, but in BHK cells in 1820 was less impaired than in 1814. A rescuant of in 1820 at the VP16 locus, in 1825, also exhibited a host range phenotype, initiating replication as efficiently as wild-type HSV-1 in BHK cells but inefficiently in other cell types. In 1825 was unable to complement an ICPO null mutant in restricted cells, demonstrating that the promoter exchange prevented the expression of ICPO protein in functionally significant amounts. The novel host range properties of in 1820 provided a basis for the construction of additional viruses conditionally impaired for IE gene expression and assessment of their value as prototype vectors. Production of an HSV-1 mutant multiply defective in the expression of IE gene products was achieved by introduction of the temperature-sensitive mutation of HSV-1 tsK, which inactivates the IE transcription activator ICP4 at nonpermissive temperatures, into in 1820 to produce in 1820K. This mutant could be propagated effectively in BHK cells at 31 degrees but was effectively devoid of the major regulators ICPO, ICP4, and VP16 in other cells types at 38.5 degrees. Cultures could withstand infection with 5 PFU of in 1820K per cell without detectable cytopathology and could be reseeded to form colonies at approximately 90% efficiency. A derivative of in 1820K containing the Escherichia coli lacZ gene controlled by the human cytomegalovirus (HCMV) major IE promoter expressed low but detectable levels of beta-galactosidase in almost all cells after infection of cultures at 5 PFU per cell and incubation at 38.5 degrees. Cultures infected with 5 PFU per cell of an in 1820K derivative expressing neomycin phosphotransferase (npt) controlled by the HCMV IE promoter were resistant to killing by the antibiotic G418 for up to 3 days, and cell survival correlated with the retention of functional levels of npt. Mutants based on in 1820K can thus express foreign gene products in virtually all cells in a culture under conditions in which cytotoxicity is eliminated, demonstrating that progressive reduction of IE gene expression is an important step in the design of HSV-1-derived vectors.

Several studies investigated diclofenac tissue concentrations using microdialysis (MD). However, thorough evaluations of the optimal MD set‐up for diclofenac are unavailable. Thus, this in vitro MD study aimed to compare different set‐ups to improve quantitative recovery of diclofenac. In forward and reverse in vitro MD experiments with diclofenac at two concentrations (1 and 100 ng/ml), the perfusion solutions physiological saline 0.9% (PS) and human albumin 1% (HSA) were compared using tissue probes (10‐mm membrane) and customized intravenous (iv) probes (30‐mm membrane). Using PS, the mean relative recovery of diclofenac at 1 ng/ml was 1.6% ± 0.04% and 3.12% ± 0.00% with the tissue probe and the iv probe, respectively. The respective mean relative recovery for diclofenac at 100 ng/ml was 0.02% ± 0.01% and 0.21% ± 0.11%. Using HSA, the mean relative recovery was 314% ± 25% (tissue probe) and 1064% ± 97% (iv probe) for diclofenac at 1 ng/ml and 444% ± 91% and 1415% ± 217% for diclofenac at 100 ng/ml. In reverse dialysis using PS, the mean relative loss of diclofenac was 99.2% ± 0.5% (tissue probe) and 95.8% ± 1.7% (iv probe). Using HSA, the mean relative loss was −4.4% ± 7.2% and 0.2% ± 7.5%, respectively. PS and HSA were not suitable perfusion solutions for quantification of absolute diclofenac concentrations. Despite methodological challenges, HSA may be used for comparative experiments or bioequivalence studies.

The effects of the human endotoxin challenge on tissue pharmacokinetics are unknown. In the present study, we aimed to assess the effect of the endotoxin challenge on interstitial fluid pharmacokinetics of tedizolid in healthy volunteers using intramuscular microdialysis. Eight healthy male subjects were treated with 200 mg of tedizolid phosphate for 6 days. On Day 6, an intravenous bolus of lipopolysaccharide (LPS) (2 ng/kg body weight) was administered. LPS infusion did not affect plasma pharmacokinetics of tedizolid. In contrast, following LPS infusion, median muscle tissue fAUC (0.83 [0.75-1.15] vs. 1.14 [1.11-1.43] mg × h/L, P = .0078) and muscle tissue fCmax (0.15 [0.14-0.19] vs. 0.19 [0.18-0.24] mg/L, P = .0078) were significantly increased by 38% and 24%, respectively. The human endotoxin challenge was associated with increased tissue concentrations of tedizolid, without affecting its plasma concentration-time profile. The human endotoxin challenge combined with microdialysis may be used to investigate the influence of systemic inflammation on tissue pharmacokinetics.

BACKGROUND Preclinical data suggested anti-inflammatory properties of tedizolid. OBJECTIVES To investigate the influence of tedizolid on the cytokine response to the human endotoxin challenge and the effect of endotoxaemia on the pharmacokinetics and protein binding of tedizolid. METHODS In this cross-over trial, 14 male healthy volunteers underwent two treatment periods: (A) 200 mg of tedizolid phosphate once daily for 6 days (3 days orally and 3 days intravenously), followed by an intravenous bolus of 2 ng/kg body weight of LPS on the last treatment day; and (B) intravenous bolus of LPS (2 ng/kg body weight) without concomitant tedizolid treatment. Participants underwent first period A or B, separated by at least 6 weeks. Plasma was sampled to assess cytokines and the pharmacokinetics of tedizolid. RESULTS Following the endotoxin challenge, the peak plasma concentration (median [IQR]; 280 [155-502] versus 287 [132-541]  pg/mL; P = 0.875) and AUC0-24 (979 [676-1319] versus 1000 [647-1632]  pg·h/mL; P = 0.638) of interleukin-6 remained unchanged with and without concomitant tedizolid treatment. The peak concentration and AUC0-24 of TNF-α remained also unchanged with and without tedizolid (47 [31-61] versus 54 [27-69]  pg/mL; P = 0.73 and 197 [163-268] versus 234 [146-280]  pg·h/mL; P = 0.875, respectively). The total maximum concentration (mean ± SD; 2.94 ± 0.69 versus 2.96 ± 0.62 mg/L), total AUC0-24 (22.3 ± 3.8 versus 21.1 ± 3.6 mg·h/L) and protein binding (21.4% ± 1.7% versus 21.6% ± 1.9%) of tedizolid were similar with and without the endotoxin challenge. CONCLUSIONS Tedizolid did not attenuate the LPS-induced cytokine response in healthy volunteers. Furthermore, endotoxaemia did not influence the plasma pharmacokinetics of tedizolid.

OBJECTIVES The efficacy and quality of generic antibacterial drug formulations are often questioned by both healthcare specialists and patients. Therefore, the present study investigated the interchangeability of generic drugs with their originators by comparing bioequivalence parameters and stability data of generic cefepime, linezolid and piperacillin/tazobactam with their respective originator drugs. METHODS In this open-label, randomized, crossover bioequivalence study, three groups of 12 healthy volunteers each received a single intravenous infusion of either 2 g of cefepime or 4.5 g of piperacillin/tazobactam and two generic formulations, or 600 mg of linezolid and one generic formulation. Plasma sampling was performed, with a 5 day washout period between study days. Stability was tested by storing reconstituted generic and originator products according to their own storage specifications and those of the comparator products. All concentrations were measured by LC-MS. RESULTS Similar ratios of generic/originator (90% CI) Cmax were observed for Cefepime-MIP/Maxipime [93.7 (88.4-99.4)], Cefepime Sandoz/Maxipime [95.9 (89.1-103.2)], Linezolid Kabi/Zyvoxid [104.5 (91.1-119.9)], Piperacillin Kabi/Tazobac [95.9 (90.4-101.7)], Piperacillin Aurobindo/Tazobac [99.7 (84.9-104.7)], Tazobactam Kabi/Tazobac [93.4 (87.4-99.8)] and Tazobactam Aurobindo/Tazobac [97.4 (89.7-105.8)]. Accordingly, similar ratios of AUC0-t were observed for Cefepime-MIP/Maxipime [91.1 (87.6-94.8)], Cefepime Sandoz/Maxipime [97.9 (92.5-103.5)], Linezolid Kabi/Zyvoxid [99.7 (93.3-106.6)], Piperacillin Kabi/Tazobac [92.2 (88.3-96.3)], Piperacillin Aurobindo/Tazobac [99.9 (97.0-102.8)], Tazobactam Kabi/Tazobac [91.4 (86.4-96.7)] and Tazobactam Aurobindo/Tazobac [98.8 (94.3-103.6)]. Stable and similar concentrations were measured for all contiguous substances, regardless of storage conditions. CONCLUSIONS Compared with their respective originator drugs, generic cefepime, linezolid and piperacillin/tazobactam met the predetermined bioequivalence criteria. All formulations were stable under the storage conditions of their respective comparators.

Background: Microdialysis sampling after drug microdosing may provide tissue pharmacokinetic data early in clinical drug development. However, low administered doses and small sample volumes pose an analytical challenge, particularly for highly protein-bound drugs. Materials & methods: Carbon-14 [14C]diclofenac was used as a model drug to assess the technical and analytical feasibility of in vivo microdialysis after microdose administration in an in vitro setup. Results: [14C]diclofenac dialysate concentrations were accurately quantified with accelerator MS. [14C]diclofenac dialysate recoveries were similar in the presence and absence of therapeutic diclofenac concentrations but were considerably decreased when albumin was added to the immersion solution, suggesting high protein binding. Conclusion: These results demonstrate the feasibility of combining microdosing and microdialysis to assess tissue pharmacokinetics.

Ablative fractional laser treatment facilitates epidermal drug delivery, which might be an interesting option to increase the topical efficacy of biological drugs in a variety of dermatological diseases. This work aims at investigating safety and tolerability of this new treatment approach in patients with plaque-type psoriasis. Eight patients with plaque-type psoriasis were enrolled in this study. All patients received (i) ablative fractional laser microporation (AFL) of a psoriatic lesion with an Er:YAG laser + etanercept (ETA; Enbrel® solution for injection) (AFL-ETA), (ii) ETA alone on another lesion, and, if feasible, (iii) AFL alone on an additional lesion. Overall, all treatment arms showed a favorable safety profile. AFL-ETA improved the lesion-specific TPSS score by 1.75 vs. baseline, whereas ETA or AFL alone showed a TPSS score improvement of 0.75 points, a difference that was not statistically significant and might be attributable to differences in baseline scores. Topical administration of ETA to psoriatic plaques via AFL-generated micropores was generally well-tolerated. No special precautions seem necessary in future studies. Clinical benefit will need assessment in sufficiently powered follow-up studies.

OBJECTIVES:The efficacy of an anti-infective drug is influenced by its protein binding (PB), since only the free fraction is active. We hypothesized that PB may vary in vitro and in vivo, and used clindamycin, a drug with high and concentration-dependent PB to investigate this hypothesis.METHODS:Six healthy volunteers received a single intravenous infusion of clindamycin 900 mg. Antibiotic plasma concentrations were obtained by blood sampling and unbound drug concentrations were determined by means of in vivo intravascular microdialysis (MD) or in vitro ultrafiltration (UF) for up to 8 h post dosing. Clindamycin was assayed in plasma and MD fluid using a validated HPLC-UV (ultraviolet) method. Non-linear mixed effects modelling in NONMEM® was used to quantify the PB in vivo and in vitro.RESULTS:C max was 14.95, 3.39 and 2.32 mg/L and AUC0-8h was 41.78, 5.80 and 6.14 mg·h/L for plasma, ultrafiltrate and microdialysate, respectively. Calculated ratio of AUCunbound/AUCtotal showed values of 13.9%±1.8% and 14.7%±3.1% for UF and microdialysate, respectively. Modelling confirmed non-linear, saturable PB for clindamycin with slightly different median (95% CI) dissociation constants (Kd) for the alpha-1 acid glycoprotein (AAG)-clindamycin complex of 1.16 mg/L (0.91-1.37) in vitro versus 0.85 mg/L (0.58-1.01) in vivo. Moreover, the estimated number of binding sites per AAG molecule was 2.07 (1.79-2.25) in vitro versus 1.66 in vivo (1.41-1.79).CONCLUSIONS:Concentration-dependent PB was observed for both investigated methods with slightly lower levels of unbound drug fractions in vitro as compared with in vivo.