Objectives Ceftolozane/tazobactam is approved for hospital-acquired/ventilator-associated bacterial pneumonia at double the dose (i.e. 2 g/1 g) recommended for other indications. We evaluated the bronchopulmonary pharmacokinetic/pharmacodynamic profile of this 3 g ceftolozane/tazobactam regimen in ventilated pneumonia patients. Methods This was an open-label, multicentre, Phase 1 trial (clinicaltrials.gov: NCT02387372). Mechanically ventilated patients with proven/suspected pneumonia received four to six doses of 3 g of ceftolozane/tazobactam (adjusted for renal function) q8h. Serial plasma samples were collected after the first and last doses. One bronchoalveolar lavage sample per patient was collected at 1, 2, 4, 6 or 8 h after the last dose and epithelial lining fluid (ELF) drug concentrations were determined. Pharmacokinetic parameters were estimated by non-compartmental analysis and pharmacodynamic analyses were conducted to graphically evaluate achievement of target exposures (plasma and ELF ceftolozane concentrations >4 mg/L and tazobactam concentrations >1 mg/L; target in plasma: ≥30% and ≥20% of the dosing interval, respectively). Results Twenty-six patients received four to six doses of study drug; 22 were included in the ELF analyses. Ceftolozane and tazobactam Tmax (6 and 2 h, respectively) were delayed in ELF compared with plasma (1 h). Lung penetration, expressed as the ratio of mean drug exposure (AUC) in ELF to plasma, was 50% (ceftolozane) and 62% (tazobactam). Mean ceftolozane and tazobactam ELF concentrations remained >4 mg/L and >1 mg/L, respectively, for 100% of the dosing interval. There were no deaths or adverse event-related study discontinuations. Conclusions In ventilated pneumonia patients, 3 g of ceftolozane/tazobactam q8h yielded ELF exposures considered adequate to cover ceftolozane/tazobactam-susceptible respiratory pathogens.

Maximal and durable viral load suppression is one of the most important goals of HIV therapy and is directly related to adequate drug exposure. Protease inhibitors (PIs), an important component of the antiretroviral armada, were historically associated with poor oral bioavailability and high pill burden. However, because the PIs are metabolized by cytochrome P450 (CYP) 3A enzymes, intentional inhibition of these enzymes leads to higher drug exposure, lower pill burden, and therefore simplified dosing schedules with this class of drug. This is the basis of pharmacokinetic enhancement. In HIV therapy, two pharmacokinetic enhancers or boosting agents are used: ritonavir and cobicistat. Both agents inhibit CYP3A4, with cobicistat being a more specific CYP inhibitor than ritonavir. Unlike ritonavir, cobicistat does not have antiretroviral activity. Cobicistat has been evaluated in clinical trials and was recently approved in the USA as a fixed-dose combination with the integrase inhibitor, elvitegravir and two nucleos(t)ide analogs. Additional studies are examining cobicistat in fixed-dose combinations with various PIs. In this review, we summarize current knowledge of these agents and clinically relevant drug regimens and ongoing trials. Studies with elvitegravir and the novel PI TMC319011 are also discussed.

Objective Postpartum infections are polymicrobial and typically include Ureaplasma, an intracellular microbe treated by macrolides such as azithromycin. The aim of this study was to evaluate the perinatal pharmacokinetics of azithromycin following a single pre-incision dose prior to cesarean delivery. Study Design Thirty women undergoing scheduled cesarean delivery were randomized to receive 500 mg of intravenous azithromycin initiated 15, 30, or 60 minutes prior to incision and infused over one hour. Serial maternal plasma samples were drawn from the end of infusion up to 8 hours after the infusion. Samples of amniotic fluid, umbilical cord blood, placenta, myometrium, and adipose tissue were collected intraoperatively. Breast milk samples were collected 12-48 hours after the infusion in 8 women who were breastfeeding. Azithromycin was quantified using high performance liquid chromatography separation coupled with tandem mass spectrometry detection. Plasma pharmacokinetic parameters were estimated using non-compartmental analysis and compartmental modeling and simulations. Results The maximum maternal plasma concentration was reached within 1 hour and exceeded the in vitro minimum inhibitory concentration (MIC50) of 250 ng/mL of Ureaplasma spp in all 30 patients. The concentrations were sustained with a half-life of 6.7 hours. The median concentration (Cmed) of azithromycin in adipose was 102 ng/g, which was below the MIC50. The Cmed in myometrium was 402 ng/g, which exceeded the MIC50. Azithromycin was detectable in both the umbilical cord plasma and amniotic fluid following the single pre-operative dose. Azithromycin concentrations in breast milk were high and sustained up to 48 hours following the single dose. Simulations demonstrated accumulation in breast milk following multiple doses. Conclusion A single dose of azithromycin achieves effective plasma and tissues concentrations and is rapidly transported across the placenta. The tissue concentrations achieved in the myometrium exceed the MIC50 for Ureaplasma spp

Background.Although the incidence of Clostridium difficile infection (CDI) is increasing, available CDI treatment options are limited in terms of sustained response after treatment. This phase 3 trial assessed the efficacy and safety of surotomycin, a novel bactericidal cyclic lipopeptide, versus oral vancomycin in subjects with CDI.Methods.In this randomized, double-blind, active-controlled, multicenter, international trial, subjects with CDI confirmed by a positive toxin result were randomized to receive surotomycin (250 mg twice daily) or vancomycin (125 mg 4 times daily) orally for 10 days. The primary endpoints were clinical response at end of treatment and evaluation of surotomycin safety. The key secondary endpoints were clinical response over time and sustained clinical response through a 30- to 40-day follow-up period. Clostridium difficile infection recurrence during follow-up and time to diarrhea resolution were also analyzed.Results.In total, 570 subjects were randomized and had confirmed CDI; 290 subjects received surotomycin and 280 subjects received vancomycin. Surotomycin clinical cure rates at end of treatment (surotomycin/vancomycin: 79.0%/83.6%; difference of −4.6%; 95% confidence interval, −11.0 to 1.9]), clinical response over time (stratified log-rank test, P = .832), and sustained clinical response at end of trial (Day 40–50) (60.6%/61.4%; difference of −0.8%; 95% CI, −8.8 to 7.1) in the microbiological modified intent to treat population did not meet noninferiority or superiority criteria versus vancomycin. Both treatments were generally well tolerated.Conclusions.Surotomycin failed to meet the criteria for noninferiority versus vancomycin for the primary and key secondary endpoints in this trial.

The doses evaluated in this study yielded ceftolozane/tazobactam exposure levels generally comparable with those in adults. Single doses of ceftolozane/tazobactam were well-tolerated, and no safety concerns were identified. These data informed pharmacokinetic/pharmacodynamic models to derive pediatric dose recommendations for phase 2 ceftolozane/tazobactam clinical trials.

Surotomycin demonstrated non-inferiority to vancomycin for CDI clinical response at EOT. Surotomycin did not demonstrate superiority to vancomycin for clinical response over time or sustained clinical response rate.

Our study demonstrates that a maternal multiple-dose AZI regimen is effective in eradicating U. parvum IAI by virtue of intra-amniotic accumulation and suggests that antenatal therapy has the potential to mitigate complications associated with U. parvum infection in pregnancy, such as preterm labor and fetal sequelae.

Ceftolozane-tazobactam, a combination of the novel antipseudomonal cephalosporin ceftolozane and the well-established extended-spectrum ␤-lactamase inhibitor tazobactam, is approved for treating complicated urinary tract infections (cUTI) and complicated intra-abdominal infections (cIAI) in adults. To determine doses likely to be safe and efficacious in phase 2 pediatric trials for the same indications, single-dose ceftolozane-tazobactam plasma pharmacokinetic data from a recently completed phase 1 trial in pediatric patients (birth to Ͻ18 years old) with proven/suspected Gram-negative bacterial infections, along with pharmacokinetic data from 12 adult studies, were integrated into a population pharmacokinetic (popPK) analysis. Two-compartment linear models with first-order elimination described the concentration-time profiles of ceftolozane and tazobactam in pediatric patients well. Renal function and body weight were identified to be significant predictors of ceftolozane-tazobactam pharmacokinetics. Renal function, as measured by the estimated glomerular filtration rate (eGFR), significantly affected the clearance of both ceftolozane and tazobactam. Body weight significantly affected clearance and the distribution volume, also of both ceftolozane and tazobactam. Patients with infections had a 32.3% lower tazobactam clearance than healthy volunteers. Using the final popPK models, simulations of various dosing regimens were conducted to assess each regimen's plasma exposure and the probability of pharmacokinetic/pharmacodynamic target attainment. Based on these simulations, the following doses are recommended for further clinical evaluation in phase 2 pediatric trials for cUTI and cIAI (in patients with an eGFR of Ն50 ml/min/1.73 m 2 only): for children Ն12 years old, 1.5 g ceftolozane-tazobactam (1 g ceftolozane with 0.5 g tazobactam), and for neonates/very young infants, infants, and children Ͻ12 years old, 20/10 mg/kg of body weight ceftolozane-tazobactam, both via a 1-h intravenous infusion every 8 h.