The results of the present study demonstrate that in septic shock patients, piperacillin concentrations in the interstitial space may be subinhibitory, even though effective concentrations are attained in plasma. The lack of success of antimicrobial therapy in these patients thus might be attributable to inadequate target site penetration of antibiotics.

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Summary: Purpose and Methods: Regional overexpression of the multidrug transporter P-glycoprotein (P-gp) in epileptic brain tissue may lower target site concentrations of antiepileptic drugs and thus contribute to pharmacoresistance in epilepsy. We used the P-gp substrate R-[11 C]verapamil and positron emission tomography (PET) to test for differences in P-gp activity between epileptogenic and nonepileptogenic brain regions of patients with drug-resistant unilateral temporal lobe epilepsy (n = 7). We compared R-[11 C]verapamil kinetics in homologous brain volumes of interest (VOIs) located ipsilateral and contralateral to the seizure focus. Results: Among different VOIs, radioactivity was highest in the choroid plexus. The hippocampal VOI could not be used for data analysis because it was contaminated by spill-in of radioactivity from the adjacent choroid plexus. In several other temporal lobe regions that are known to be involved in seizure generation and propagation ipsilateral influx rate constants K 1 and efflux rate constants k 2 of R-[11 C]verapamil were descriptively increased as compared to the contralateral side. Parameter asymmetries were most prominent in parahippocampal and ambient gyrus (K 1 , range: −3.8% to +22.3%; k 2 , range: −2.3% to +43.9%), amygdala (K 1 , range: −20.6% to +31.3%; k 2 , range: −18.0% to +38.9%), medial anterior temporal lobe (K 1 , range: −8.3% to +14.5%; k 2 , range: −14.5% to +31.0%) and lateral anterior temporal lobe (K 1 , range: −20.7% to +16.8%; k 2 , range: −24.4% to +22.6%). In contrast to temporal lobe VOIs, asymmetries were minimal in a region presumably not involved in epileptogenesis located outside the temporal lobe (superior parietal gyrus, K 1 , range: −3.7% to +4.5%; k 2 , range: −4.2% to +5.8%). In 5 of 7 patients, ipsilateral efflux (k 2 ) increases were more pronounced than ipsilateral influx (K 1 ) increases, which resulted in ipsilateral reductions (10%-26%) of R-[11 C]verapamil distribution volumes (DV). However, for none of the examined brain regions, any of the differences in K 1 , k 2 and DV between the epileptogenic and the nonepileptogenic hemisphere reached statistical significance (p > 0.05, Wilcoxon matched pairs test). Conclusions: Even though we failed to detect statistically significant differences in R-[11 C]verapamil model parameters between epileptogenic and nonepileptogenic brain regions, it cannot be excluded from our pilot data in a small sample size of patients that regionally enhanced P-gp activity might contribute to drug resistance in some patients with temporal lobe epilepsy.

To characterize the penetration of moxifloxacin (BAY 12-8039) into peripheral target sites, the present study aimed at measuring unbound moxifloxacin concentrations in the interstitial space fluid by means of microdialysis, an innovative clinical sampling technique. In addition, moxifloxacin concentrations were measured in cantharides-induced skin blisters, saliva, and capillary plasma and compared to total- and free-drug concentrations in venous plasma. For this purpose, 12 healthy volunteers received moxifloxacin in an open randomized crossover fashion either as a single oral dose of 400 mg or as a single intravenous infusion of 400 mg over 60 min. An almost-complete equilibration of the free unbound plasma fraction of moxifloxacin with the interstitial space fluid was observed, with mean area under the concentration-time curve (AUC)interstitial fluid/AUCtotal-plasma ratios ranging from 0.38 to 0.55 and mean AUCinterstitial fluid/AUCfree-plasma ratios ranging from 0.81 to 0.86. The skin blister concentration/plasma concentration ratio reached values above 1.5 after 24 h, indicating a preferential penetration of moxifloxacin into inflamed lesions. The moxifloxacin concentrations in saliva and capillary blood were similar to the corresponding levels in plasma. Our data show that moxifloxacin concentrations attained in the interstitial space fluid in humans and in skin blister fluid following single doses of 400 mg exceed the values for the MIC at which 90% of isolates are inhibited for most clinically relevant bacterial strains, notably including penicillin-resistant Streptococcus pneumoniae. These findings support the use of moxifloxacin for the treatment of soft tissue and respiratory tract infections in humans.

During antibiotic drug development, media are frequently spiked with either serum/plasma or protein supplements to evaluate the effect of protein binding. Usually, previously reported serum or plasma protein binding values are applied in the analysis. The aim of this study was to evaluate this approach by experimentally measuring free, unbound concentrations for antibiotics with reportedly high protein binding and their corresponding antimicrobial activities in media containing commonly used protein supplements. Free, unbound ceftriaxone and ertapenem concentrations were determined in bacterial growth medium with and without bovine/human serum albumin, as well as adult bovine serum and human plasma using in vitro microdialysis. The corresponding antimicrobial activity was determined in MIC and time-kill curve experiments using Escherichia coli ATCC 25922 and Streptococcus pneumoniae ATCC 6303 as test strains. A semimechanistic maximum effect model was simultaneously fitted to the data and respective EC 50 (concentration at half-maximum effect) values compared. Protein binding differed significantly for ceftriaxone (P < 0.05) between human plasma (76.8 ؎ 11.0%) and commercially available bovine (20.2 ؎ 8.3%) or human serum albumin (56.9 ؎ 16.6%). Similar results were obtained for ertapenem (human plasma, 73.8 ؎ 11.6%; bovine serum albumin, 12.4 ؎ 4.8%; human serum albumin, 17.8 ؎ 11.5%). The MICs and EC 50 s of both strains were significantly increased (P < 0.05) for ceftriaxone when comparing human and bovine serum albumin, whereas the EC 50 s were not significantly different for ertapenem. Free, unbound antibiotic concentrations differed substantially between plasma and protein supplements and correlated well with antimicrobial efficacy. Therefore, free, active concentrations should be measured in the test system instead of correcting for literature protein binding values.

AimsThe aims of the study were to: (1) evaluate the gastrointestinal transit, release and absorption of budesonide from tablets with a new multimatrix formulation (M MX®) designed to release the drug throughout the whole colon, and (2) assess the influence of food on budesonide bioavailability. MethodsTwo phase I studies, each comprising 12 healthy males, were performed. Gastrointestinal transit of 153 Sm-labelled tablets containing 9 mg budesonide was evaluated by means of pharmaco-scintigraphy. The effect of food was tested by comparing plasma pharmacokinetics after intake of a high fat and high calorie breakfast with fasting controls. Results153 Sm-labelled tablets reached the ascending colon after a mean ± SD 9.8 ± 6.9 h. Initial tablet disintegration was observed in the ileum in 42% and the ascending and transverse colon in 33% of subjects. Ninety-six per cent of the dose was absorbed into the systemic circulation during passage through the whole colon including the sigmoid. Food significantly decreased C max values from 1429 ± 1014 to 1040 ± 601 pg mL − 1 ( P = 0.028) and AUC values from 14 814 ± 11 254 to 13 486 ± 9369 pg h − 1 mL − 1 ( P = 0.008). Mean residence time and t max increased by 12-29%. There was no drug accumulation after 1 week of once daily oral administration of budesomide. ConclusionsMMX®-budesonide tablets appear suitable for targeted colonic drug delivery. Transit parameters and low systemic bioavailability warrant further studies with the new formulation.

Ropivacaine is well tolerated and provides effective analgesia when given for caudal blockade in small children for inguinal hernia repair.

SUMMARYBackground: Mesalazine (5-aminosalicylic acid, 5-ASA)-containing formulations represent a cornerstone in the treatment of inflammatory bowel diseases. Recently, a new formulation has been developed to provide selective and more homogeneous release of 5-ASA compared to traditional systems. Methods: In a first study, gastrointestinal transit was followed by gamma-scintigraphy after single-dose application of tablets containing 1200 mg mesalazine to 12 healthy male volunteers. 5-ASA release was verified by the assessment of plasma pharmacokinetics. In a second, 7-day, multiple-dose study, the steady state plasma pharmacokinetics, urinary excretion and safety profile were characterized after twice-daily tablet administration to 12 healthy volunteers.