Active impedance matching of a cryogenic radio frequency resonator for ion traps

A combination of direct current (DC) fields and high amplitude radio frequency (RF) fields is necessary to trap ions in a Paul trap. Such high electric RF fields are usually reached with the help of a resonator in close proximity to the ion trap. Ion trap based quantum computers profit from good vacuum conditions and low heating rates that cryogenic environments provide. However, an impedance matching network between the resonator and its RF source is necessary, as an unmatched resonator would require higher input power due to power reflection. The reflected power would not contribute to the RF trapping potential, and the losses in the cable induce additional heat into the system. The electrical properties of the matching network components change during cooling, and a cryogenic setup usually prohibits physical access to integrated components while the experiment is running. This circumstance leads to either several cooling cycles to improve the matching at cryogenic temperatures or the operation of poorly matched resonators. In this work, we demonstrate an RF resonator that is actively matched to the wave impedance of coaxial cables and the signal source. The active part of the matching circuit consists of a varactor diode array. Its capacitance depends on the DC voltage applied from outside the cryostat. We present measurements of the power reflection, the Q-factor, and higher harmonic signals resulting from the nonlinearity of the varactor diodes. The RF resonator is tested in a cryostat at room temperature and cryogenic temperatures, down to 4.3 K. A superior impedance matching for different ion traps can be achieved with this type of resonator.

THz microscope for three-dimensional imaging with superconducting Josephson junctions

Superconducting Josephson junctions have a wide range of applications ranging from quantum computing to voltage standards, and they may also be employed as versatile sensors for high-frequency radiation and magnetic fields. In this work, we present a unique measurement setup utilizing a single Josephson junction on a cantilever for high-resolution spatial measurements of spectroscopically resolved THz and microwave field distributions. This THz microscope can be utilized to measure power and frequency of electromagnetic radiation from ∼1 GHz to 5 THz. It may also be used to measure static magnetic fields and provide topological scans of samples. The samples can be both actively radiating or passively irradiated at either room temperature or cryogenic temperatures. We review the measurement setup of the THz microscope and describe the evaluation of its measurement data to achieve three-dimensional visualizations of the field distributions. The diverse capabilities of this unique tool are demonstrated by its different measurement modes with measurements of field distributions at 20 GHz and 1.4 THz, spectroscopically resolved THz measurements, and magnetic field measurements.

Participation, retention and uptake in a multicentre pre-exposure prophylaxis cohort using online, smartphone-compatible data collection

Objectives

The aim of the study was to assess the feasibility of a national pre‐exposure prophylaxis (PrEP) programme using smartphone‐compatible data collection.

Methods

This was a multicentre cohort study (NCT03893188) enrolling individuals interested in PrEP in Switzerland. All centres participate in the SwissPrEPared programme, which uses smartphone‐compatible data collection. Feasibility was assessed after centres had enrolled at least one participant. Participants were HIV‐negative individuals presenting for PrEP counselling. Outcomes were participation (number enrolled/number eligible), enrolment rates (number enrolled per month), retention at first follow‐up (number with first follow‐up/number enrolled), and uptake (proportion attending first visit as scheduled). Participant characteristics were compared between those retained after baseline assessment and those who dropped out.

Results

Between April 2019 and January 2020, 987 individuals were assessed for eligibility, of whom 969 were enrolled (participation: 98.2%). The median enrolment rate was 86 per month [interquartile range (IQR) 52–137]. Retention at first follow‐up and uptake were both 80.7% (782/969 and 532/659, respectively). At enrolment, the median age was 40 (IQR 33–47) years, 95% were men who have sex with men, 47% had a university degree, and 75.5% were already taking PrEP. Most reported multiple casual partners (89.2%), previous sexually transmitted infections (74%) and sexualized drug use (73.1%). At baseline, 25.5% tested positive for either syphilis, gonorrhoea or chlamydia. Participants who dropped out were at lower risk of HIV infection than those retained after baseline assessment.

Conclusions

In a national PrEP programme using smartphone‐compatible data collection, participation, retention and uptake were high. Participants retained after baseline assessment were at considerable risk of HIV infection. Younger, less educated individuals were underrepresented in the SwissPrEPared cohort.

Quantifying the drivers of HIV transmission and prevention in men who have sex with men: a population model-based analysis in Switzerland

OBJECTIVES

Despite the huge success of antiretroviral therapy (ART), there is an ongoing HIV epidemic among men who have sex with men (MSM) in resource-rich countries. Understanding the driving factors underlying this process is important for curbing the epidemic.

METHODS

We simulated the HIV epidemic in MSM in Switzerland by stratifying a mathematical model by CD4 count, the care cascade and condom use. The model was parametrised with clinical, epidemiological and behavioural data from the Swiss HIV Cohort Study and surveys in the HIV-negative population.

RESULTS

According to our model, 3.4% of the cases that would otherwise have occurred in 2008-2015 were prevented by early initiation of ART. Only 0.6% of the cases were attributable to a change in condom use in the HIV-positive population, as less usage is mainly seen in virally suppressed MSM. Most new infections were attributable to transmission from recently infected undiagnosed individuals. It was estimated that doubling the diagnosis rate would have resulted in 11.8% fewer cases in 2001-2015. Moreover, it was estimated that introducing pre-exposure prophylaxis (PrEP) for 50% of those MSM not using condoms with occasional partners would have resulted in 22.6% fewer cases in 2012-2015.

CONCLUSIONS

By combining observational data on the relevant epidemiological and clinical processes with a mathematical model, we showed that the 'test and treat' approach is most effective in reducing the number of new cases. Only a moderate population-level effect was estimated for early initiation of ART and a weak effect for the change in condom use of diagnosed MSM. Protecting HIV-negative individuals who are not using condoms with PrEP was shown to have a major impact.

Assessing the need for a pre-exposure prophylaxis programme using the social media app Grindr®

Objectives

HIV pre‐exposure prophylaxis (PrEP) is not approved in Switzerland and therefore must be paid for by the users themselves. We conducted a survey to find out whether men who have sex with men (MSM) in Switzerland are already taking PrEP, or are considering using it, and whether it is being taken under medical supervision or not.

Methods

Grindr® is a geosocial networking app for MSM. Between 5 and 24 January 2017, users of the app who were located in Switzerland by a global positioning system (GPS) were asked to participate in a ten‐question survey on PrEP use.

Results

Of the 2455 people who took part in the survey, 1893 were included in the analysis. Eighty‐two participants (4.3%) reported that they were currently taking PrEP, 64 of whom (78%) said that they were under medical supervision. Seven PrEP users (9%) declared that they had not taken an HIV test within the previous 12 months. Nine hundred and forty‐four (49.9%) were considering taking PrEP in the next 6 months, and 1474 (77.9%) were considering taking it at some point in the future.

Conclusions

In an online survey carried out among sexually active MSM in Switzerland, only a minority of the individuals approached responded that they were currently using PrEP. However, the majority of participants were considering taking PrEP in the future. We identified a substantial proportion of PrEP users taking PrEP outside a medical setting. Hence, a national programme facilitating access to medical care and providing PrEP is urgently needed.

Adipose tissue macrophages inhibit adipogenesis of mesenchymal precursor cells via wnt-5a in humans

In patients with obesity and type 2 diabetes, adipose tissue is infiltrated by macrophages known to alter adipogenesis of mesenchymal precursor cells via secretion of proinflammatory cytokines. Recently, it has been shown that under certain conditions, immune cells can also express wnt-5a, a factor known to inhibit adipogenesis in humans. Therefore, in this study we aimed to investigate whether macrophages affect adipogenesis of mesenchymal precursor cells via wnt-5a. Wnt-5a was found to be expressed in adipose tissue macrophages in obese and type 2 diabetic human subjects in vivo by immunohistochemistry of adipose tissue biopsies. Furthermore, wnt-5a was detectable in circulating CD14(+) blood monocytes of human subjects with obesity and type 2 diabetes on RNA level by real-time PCR. Besides expression analysis in vivo, we also performed functional studies to explore the role of wnt-5a in low-grade inflammation of adipose tissue. In a cell culture experiment, macrophage-conditioned differentiation medium inhibited adipogenesis of 3T3-L1 cells. This inhibitory effect was restored by adding neutralising anti-wnt-5a antibodies. In conclusion, our data indicate that macrophages alter adipogenesis of 3T3-L1 cells not only via classical proinflammatory cytokines, but also via wnt signalling molecules.

Moxifloxacin for the treatment of patients with complicated intra-abdominal infections (the AIDA Study)

This prospective, randomized, open, international, multicenter study of adults with complicated intra-abdominal infections (cIAI) compared the efficacy and safety of sequential intravenous (i.v.) to oral (p.o.) moxifloxacin 400 mg once daily, with that of i.v. ceftriaxone 2 g once daily, plus metronidazole 500 mg three times daily, followed by p.o. amoxicillin/clavulanate 625 mg three times daily. The primary efficacy variable was clinical cure at test of cure (TOC) (day 28-42 after study entry) in the per protocol (PP) population. Of 595 patients in the study, 511 patients were valid for PP analysis (246 moxifloxacin, 265 ceftriaxone/metronidazole). Sequential moxifloxacin was noninferior to the comparator regimen--clinical cure rates at TOC were 80.9% versus 82.3% (moxifloxacin versus ceftriaxone/metronidazole; 95% CI -8.9, 4.2%). The incidence of adverse events was comparable between the two treatment groups. Therefore, sequential moxifloxacin monotherapy is as effective and safe as combination therapy with i.v. ceftriaxone plus i.v. metronidazole followed by oral amoxicillin/clavulanate for the treatment of cIAI.

Increased expression of extracellular proteins as a hallmark of human endothelial cell in vitro senescence

A convenient way to study processes of aging in distinct human tissues consists of a molecular analysis of cells from the tissue in question, that were explanted and grown in vitro until they reach senescence. Using human umbilical vein endothelial cells (HUVEC), we have established an in vitro senescence model for human endothelial cells. A major hallmark of HUVEC in vitro senescence is the increased frequency of apoptotic cell death, which occurs as a determining feature of HUVEC senescence. Senescent endothelial cells are also found in vivo in atherosclerotic lesions, suggesting that the presence of such cells may contribute to the development of vascular pathology. To elucidate mechanisms underlying endothelial cell senescence and age-associated apoptosis, gene expression analyses were carried out. In these experiments, we observed the up-regulation of genes coding for extracellular proteins in senescent HUVEC. In particular, a significant upregulation of interleukin-8, VEGI, and the IGF-binding proteins 3 and 5 was observed. Upregulation of these genes was confirmed by both RT-PCR and Western blot. In the case of interleukin-8, a roughly 50-fold upregulation of the protein was also found in cellular supernatants. The extracellular proteins encoded by these genes are well known for their ability to modulate the apoptotic response of human cells, and in the case of interleukin-8, clear links to the establishment of atherosclerotic lesions have been defined. The results described here support a new model, where changes in the secretome of human endothelial cells contribute to vascular aging and vascular pathology.

Metabolic stabilization of p27 in senescent fibroblasts correlates with reduced expression of the F-box protein Skp2

When mortal human cells reach their finite lifespan, they enter an irreversible G1 growth arrest status referred to as senescence. Growth suppression of senescent cells can be explained by the accumulation of several growth-suppressive proteins, acting on mitogenic signal transduction and cell cycle regulation, respectively. We show here that the cdk inhibitor p27(KIP1), which is involved in several forms of G1 checkpoint control, accumulates in senescent cells. Whereas, the rate of p27 synthesis is reduced, accumulation of p27 is accompanied by an increase of the metabolic stability in senescent cells. p27 is a substrate for ubiquitin-mediated proteolysis, and its stabilization in senescent cells correlates with a deregulation of the p27-specific E3 ubiquitin ligase referred to as the SCF complex. Whereas, the Skp1 component of the SCF complex is overexpressed in senescent fibroblasts, the abundance of the F-box protein Skp2 is strongly reduced. In contrast to our findings with p27, the synthesis of the cell cycle regulators p21 and cyclin D1 is increased in senescent cells; however, both proteins are also highly unstable in these cells.

Replicative senescence of human endothelial cells in vitro involves G1 arrest, polyploidization and senescence-associated apoptosis

Human ageing is characterized by a progressive loss of physiological functions, increased tissue damage and defects in various tissue renewal systems. Age-related decreases of the cellular replicative capacity can be reproduced by in vitro assays of cellular ageing. When diploid human fibroblasts reach their finite lifespan, they enter an irreversible G1 growth arrest status referred to as replicative senescence. While deregulation of programmed cell death (apoptosis) is a key feature of age-related pathology in several tissues, this is not reflected in the standard in vitro senescence model of human fibroblasts, and the role of apoptosis during cellular ageing remains unclear. We have analyzed replicative senescence of human umbilical vein endothelial cells (HUVEC) in vitro and found that senescent HUVEC also arrest in the G1 phase of the cell cycle but, unlike fibroblasts, accumulate with a 4N DNA content, indicative of polyploidization. In contrast to human fibroblasts, senescent endothelial cells display a considerable increase in spontaneous apoptosis. The data imply that age-dependent apoptosis is a regular feature of human endothelial cells and suggest cell type specific differences in human ageing.

A multinational, multicentre, non-blinded, randomized study of moxifloxacin oral tablets compared with co-amoxiclav oral tablets in the treatment of acute exacerbation of chronic bronchitis

The aim of this study was to compare the efficacy and safety of once daily dosing with moxifloxacin (BAY 12-8039) with that of coamoxiclav given three times daily for the treatment of acute exacerbation of chronic bronchitis (AECB). Moxifloxacin (one 400 mg tablet daily) was administered orally for 5 days and co-amoxiclav (three 625 mg tablets daily) was given orally for 7 days. The study was randomized, non-blinded, multinational (12 countries) and multicentre (68 centres). A total of 575 patients, all with clear signs of AECB, were treated, 292 with moxifloxacin and 283 with co-amoxiclav. Of these, 512 patients were evaluable for efficacy (261 in the moxifloxacin group and 251 in the co-amoxiclav group). The primary efficacy parameter was clinical response at 14 days in the evaluable population. A clinical success was classified as resolution or improvement of symptoms. Variables used to assess clinical response included wheeze, cough, dyspnoea, sputum volume, rales and rhonchi. The success rate for moxifloxacin in the evaluable patients was 96.2% and that for co-amoxiclav was 91.6%. The 95% confidence intervals for this difference (0.4%; 8.7%) indicate equivalence in the treatments. Sputum samples were taken from patients and 140 of these contained a pathogen, Haemophilus influenzae being the most frequently isolated. Moraxella catarrhalis and Streptococcus pneumoniae were also commonly isolated pathogens. The eradication rate at 14 days in the evaluable patients was 87.7% in the moxifloxacin group and 89.6% in the coamoxiclav group. Both drugs were well tolerated with no significant differences in the numbers of drug-related adverse events or the numbers of patients withdrawing because of an adverse event. These results and the broad spectrum of antibacterial activity make moxifloxacin a promising and safe alternative to conventional therapy for the empirical treatment of AECB.

A comparison of the safety and efficacy of moxifloxacin (BAY 12-8039) and cefuroxime axetil in the treatment of acute bacterial sinusitis in adults. The Sinusitis Study Group

The aim of this multicentre, randomized study was to compare the efficacy and safety of moxifloxacin (BAY 12-8039), a new 8-methoxy fluoroquinolone, with that of cefuroxime axetil for the treatment of acute bacterial sinusitis in adults. Diagnosis was made on a range of clinical signs and symptoms combined with radiology and microbiology. A 400 mg dose of moxifloxacin was administered once daily for 7 days to 242 patients and 250 mg twice daily of cefuroxime axetil was administered to 251 patients for 10 days. The clinical success rate at the end of treatment in the evaluable population was significantly higher (96.7%) in the moxifloxacin group (204/211) than in the cefuroxime axetil group (204/225, 90.7%; 95% confidence intervals 1.5%; 10.6%). At follow-up the success rate in the moxifloxacin group was 90.7% and that for the cefuroxime axetil group was 89.2% (95% confidence intervals -4.3%; 5.4%). The predominant pathogens isolated were Streptococcus pneumoniae and Haemophilus influenzae, followed by Moraxella catarrhalis and Staphylococcus aureus. The bacteriological eradication rates were higher for moxifloxacin (94.5%, 103/109) than for cefuroxime axetil (83.5%, 96/115; 95% CI 3.6%; 19.7%). Only one S. pneumoniae infection persisted following moxifloxacin therapy in contrast with three in individuals on cefuroxime axetil. There were slightly more adverse events in the moxifloxacin group than in the cefuroxime axetil group, but there were fewer serious adverse events following moxifloxacin treatment (three vs. eight). The drug was discontinued because of adverse events in 14 moxifloxacin patients and in 11 cefuroxime axetil patients. Overall, in all assessments, moxifloxacin was at least as effective clinically and bacteriologically, and as well tolerated, as cefuroxime axetil in the treatment of acute sinusitis.

Ciprofloxacin as antipseudomonal treatment in patients with cystic fibrosis

OBJECTIVE

The efficacy and safety of oral ciprofloxacin as a maintenance antipseudomonal therapy were evaluated in 44 patients with cystic fibrosis who had completed a 14-day regimen of intensive hospital therapy with intravenous ceftazidime and amikacin, supplemented by amikacin inhalation therapy.

METHODS

Twenty-one patients were randomly assigned to oral ciprofloxacin alone (Group I) and 23 received ciprofloxacin plus inhaled amikacin (Group II).

RESULTS

Negative sputum cultures were achieved in 34 patients (77%) at the end of intensive therapy (19 Group I and 15 Group II) and were sustained after 3 months of maintenance therapy in 5 of the 19 responders in Group I (26%) and in 8 of the 15 responders in Group II (53%). Resistance to ciprofloxacin was found in 7 of 31 (23%) sputum isolates at the end of ciprofloxacin therapy. During maintenance therapy, continued improvement in clinical symptoms was observed in 14 patients in both treatment groups; 6 in each group had further improvements whereas only 4 patients were clinical failures. There was no correlation between clinical outcome and either elimination of Pseudomonas aeruginosa from sputum culture or development of ciprofloxacin resistance. Both maintenance regimens were well-tolerated by this population of patients which included 28 children younger than 15 years of age. There were no severe or serious adverse events, no signs of quinolone-related arthropathy and no growth impairment.

CONCLUSION

Ciprofloxacin was efficacious, safe and well-tolerated as maintenance antipseudomonal therapy in cystic fibrosis patients. These results suggest further evaluation of ciprofloxacin as an oral maintenance therapy is warranted.

Ciprofloxacin in pediatrics: worldwide clinical experience based on compassionate use--safety report

BACKGROUND

Quinolone-induced cartilage toxicity has been observed in experimental juvenile animal studies and is species- and dose-specific. Accordingly these findings have led to the contraindication of fluoroquinolones in children. Previous data in 634 adolescents and children treated with compassionate use ciprofloxacin demonstrated low rates of reversible arthralgia and a safety profile similar to that for adult patients.

OBJECTIVE

This report describes the safety findings in 1795 children who received 2030 treatment courses of intravenous or oral ciprofloxacin.

RESULTS

The average doses of intravenous and oral ciprofloxacin in the study population were 8 and 25 mg/kg/day, respectively. Treatment-associated events were reported in 10.9% of children receiving oral ciprofloxacin compared with 18.9% among intravenous recipients. Overall arthralgia occurred during 31 ciprofloxacin treatment courses (1.5%) and the majority of events were of mild to moderate severity and resolved without intervention. More than 60% of arthralgia episodes were in children with cystic fibrosis.

CONCLUSION

The adverse event pattern in children receiving ciprofloxacin in this analysis was similar to that observed in adults. Rates of reversible arthralgia were low and unchanged from previously published surveillance data in children.

Characterization of indole-negative Bacteroides fragilis group species with use of polymerase chain reaction fingerprinting and resistance profiles

Biochemical tests alone do not adequately differentiate the various Bacteroides species, groups, and antimicrobial-resistant variants. Consequently, we used a polymerase chain reaction (PCR) fingerprinting technique, with either a single nonspecific primer derived from the t-DNA intergenic spacer region (T3B) or a single primer that anneals to minisatellite DNA sequences (M13 core), to identify and characterize 58 clinical isolates of Bacteroides fragilis group species (B. fragilis, B. distasonis, and B. caccae). In addition to species- and subspecies-specific differences, 4 strains of B. fragilis, 1 of B. distasonis, and 3 of B. caccae that showed increased resistance to imipenem, ampicillin, and ampicillin/sulbactam also produced unique PCR fingerprint profiles. Analysis by the clinical source of isolation (i.e. blood or intraabdominal, skin, or soft-tissue infection) indicated that no particular PCR fingerprint type was associated with greater pathogenicity of any individual clinical source. The PCR fingerprinting technique proves to be a useful tool for species identification and taxonomic studies, as well as for epidemiological studies of Bacteroides species.

Pharmacokinetics of ciprofloxacin in pediatric cystic fibrosis patients

The pharmacokinetic characteristics of ciprofloxacin were studied in 10 children with cystic fibrosis, aged from 6 to 16 years, who had completed the standard regimen of intravenous ceftazidime and amikacin. The aim of the investigation was to derive dosing guidelines for young cystic fibrosis patients to be treated with ciprofloxacin. Each child received ciprofloxacin given as two 30-min infusions (10 mg/kg of body weight each) 12 h apart; this was followed by the administration of oral ciprofloxacin (15 mg/kg every 12 h). Blood samples were taken after both infusions and after the first oral dose. A total of 232 ciprofloxacin concentrations (203 concentrations in plasma and 29 concentrations in urine) were analyzed by use of NONMEM and a two-compartment body model with seven parameters: total body clearance (CL), volume of the central compartment (V2), volume of the peripheral compartment (V3), intercompartmental clearance, renal clearance, absorption rate constant, and bioavailability. The influences of weight (range, 18 to 42 kg) and age (range, 6 to 16 years) were investigated. CL (in liters per hour) was found to be linearly correlated with weight (typical value of CL = 8.8 + 0.396. WT, where WT is weight; (interindividual coefficient of variation, 7.8%). V2 and V3 were directly proportional to weight, with slopes of 0.7 and 1.3 liters/kg, respectively. Interindividual variabilities were calculated to be 22.6 and 14.9% for V2 and V3, respectively. No dependency of the other pharmacokinetic parameters on age or weight was seen. Because of the high correlations between age and weight, only one covariable was necessary. Weight had the strongest effect. Bioavailability (population mean) was estimated to be 61.8%, and renal clearance (population mean) was estimated to be 11.4 liters/h. The residual (intraindividual) variability was 31.9%. The protein binding was about 34%, which is similar to the results obtained for adults. In order to define the appropriate dosage regimen for children suffering from cystic fibrosis, a formula was derived so that steady-state concentrations, similar to those obtained in adults after the administration of dosages of 400 mg three times daily intravenously and 750 mg twice daily orally, could be reached. The calculated total daily dose increased with increasing body weight. Given as milligrams per kilogram of body weight, the calculated dosage regimens suggest that for younger children (weight range, 14 to 28 kg), 28 to 20 mg/kg orally twice daily should be given, and for older children (weight range, 28 to 42 kg), 20 to 15 mg/kg orally twice daily should be given. For intravenous administration, dosages of 15 to 10 mg/kg twice daily are sufficient.

Pharmacokinetics of FCE 22891, a new oral penem

FCE 22891 is the oral prodrug of FCE 22101, a new broad-spectrum penem. The pharmacokinetics of FCE 22891 after single-dose administration, its absolute bioavailability, and the effect of food intake on its absorption were investigated in three different randomized crossover studies in healthy volunteers. Drug levels in blood and urine were measured by high-pressure liquid chromatography and bioassay. For optimal comparison of the results of all studies, and since there was good agreement of both methods, only the high-pressure liquid chromatography results are included. The pharmacokinetics of the penem were linear, and its bioavailability after oral administration was 42 +/- 11%. Food intake increased the total area under the curve from 0 h to infinity from 11.9 +/- 3.5 to 14.1 +/- 2.4 mg.h/liter. A specific side effect, i.e., bladder complaints, was registered in some volunteers taking FCE 22891 at doses greater than or equal to 1.0 g.

Comparative pharmacokinetics of sulbactam/ampicillin and clavulanic acid/amoxycillin in human volunteers

In this study, the pharmacokinetic parameters of 2 different beta-lactamase inhibitors (sulbactam and clavulanic acid) in combination with 2 different aminobenzylpenicillins (ampicillin and amoxycillin) were compared. The study involved 10 healthy volunteers who received sulbactam 250 mg plus ampicillin 500 mg intravenously, clavulanic acid 100 mg plus amoxycillin 500 mg intravenously, sultamicillin equivalent to sulbactam 294 mg plus ampicillin 440 mg orally, and clavulanic acid 125 mg plus amoxycillin 500 mg orally in a crossover, randomised trial. Serum and urine concentrations of ampicillin, amoxycillin and clavulanic acid were assayed by agar diffusion test, and the concentrations of sulbactam by gas chromatography with mass spectrometry. Pharmacokinetic parameters were calculated according to open 1- and 2-compartment models. Test results showed that the addition of sulbactam significantly increases the bioavailability of oral ampicillin when the 2 drugs are administered in the form of the prodrug sultamicillin. Also, sulbactam does not interfere with the kinetics of intravenous ampicillin but increases the absorption of oral ampicillin.

Pharmacokinetics of temocillin in volunteers

The pharmacokinetics of temocillin, a new semisynthetic parenteral penicillin, were studied in 10 healthy volunteers. Doses of 0.5, 1.0, and 2.0 g were administered by intravenous bolus injection at weekly intervals, and serum and urine samples were assayed by an agar diffusion method. Mean peak serum concentrations were: 77.9 (+/- 28.4) mg/L (0.5 g), 160.8 (+/- 58.2) mg/L (1.0 g), and 236.1 (+/- 93.3) mg/L (2.0 g), with serum concentrations still being measurable after 12 hours for all doses [7.9 (+/- 3.7) mg/L, 12.9 (+/- 5.2) mg/L, 14.8 (+/- 6.3) mg/L]. According to a 2-compartment open model, the mean terminal half-lives of 0.5, 1.0, and 2.0 g doses were 5.2 (+/- 0.3), 5.0 (+/- 0.2), and 5.0 (+/- 0.2) hours, respectively. The total volume of distribution averaged 0.15 (+/- 0.01), 0.17 (+/- 0.01), and 0.24 (+/- 0.01) L/kg bodyweight, respectively, mean renal clearances were 18.5 (+/- 3.2), 19.6 (+/- 5.0), and 29.8 (+/- 2.6) ml/min, respectively, and the area under the serum concentration time curve (AUC) was 344.1 (+/- 18.7), 573.3 (+/- 27.8), and 784.5 (+/- 47.1) mg X h/L, respectively. At 74 (+/- 12.9)%, the 24-hour urinary recovery was highest for the low dose, followed by 68.1 (+/- 6)% for the 2.0 g dose, and 66.1 (+/- 16.8)% for the 1.0 dose. No untoward side effects were recorded. Thus, temocillin appears to be a penicillin with a prolonged half-life and high AUC.

Comparative pharmacokinetics of ceftriaxone after subcutaneous and intravenous administration

The pharmacokinetics of ceftriaxone (CRO) after subcutaneous and intravenous administration was studied in 10 healthy volunteers (5 males, 5 females, age 22-43 years, body weight 64.3 +/- 9.5 kg). Each of them received 2.0 g CRO i.v., and then 0.5 g i.v. and 0.5 g CRO s.c. in a randomized cross-over design. Subcutaneous administration of ceftriaxone was tolerable in combination with lidocaine. Serum and urine concentrations were determined by high performance liquid chromatography and for comparison with a bioassay. Mean serum concentrations were high after intravenous administration: 258 +/- 40 mg/1 (0 min, 2 g i.v.) resp. 84 +/- 40 mg/1 (0 min, 0.5 g i.v.). They declined to 11.6 +/- 4.2 mg/1 (2 g) resp. 6.5 +/- 2.2 mg/1 (0.5 g i.v.) within 24 h. Following subcutaneous application peak serum concentrations of 37.1 +/- 5.6 mg/1 were found after 138 +/- 49 min and a mean serum concentration of 6.6 +/- 1.6 mg/1 after 24 h. Concentrations of free ceftriaxone, determined by ultrafiltration, were 9.2 +/- 2.7% of total concentrations from 25 to 200 mg/1. Cumulated urine recoveries over a period of 24 h were: 51.2 +/- 8.9% (2 g i.v.), 47.1 +/- 7.9% (0.5 g i.v.) and 39.7 +/- 9.5% (0.5 g s.c.). There was no evidence for the presence of a microbiologically active metabolite in urine. Comparison of pharmacokinetic parameters for the 0.5 g dose did not show relevant differences between intravenous and subcutaneous administration (using an open two-compartment model): t beta 1/2 (min) 514 +/- 104 (s.c.), 592 +/- 133 (i.v.), VD,Area (1) 11.9 +/- 3.8 (s.c.), 13.3 +/- 3.8 (i.v.) and AUCtot (mg X h/1) 515 +/- 106 (s.c.) and 549 +/- 125 (i.v.). Bioavailability of the subcutaneous application was 0.96 +/- 0.26. For the 2 g i.v. dose the known nondosis-dependent kinetics was observed. Subcutaneous administration of ceftriaxone appears to be a possible alternative to the intravenous route in selected clinical situations or cases.

Pharmacokinetics of cefadroxil and cefaclor during an eight-day dosage period

The concentrations of cefadroxil and cefaclor in serum were studied in eight healthy volunteers receiving 1,000 mg of both substances three times per day for 8 days. Intraindividual comparisons showed an increase in peak serum levels of cefadroxil from days 1 to 8 in seven of eight volunteers. Cefaclor peak concentrations did not rise during the 8 days.