Predicting the efficacy of opioid sequestration by intravenous lipid emulsion using biologically relevant in vitro models of drug distribution.

Intravenous lipid emulsions (ILE), among other uses, are utilized in the treatment of poisonings caused by lipophilic substances. The body of evidence regarding the benefits of this treatment is growing but information about opioids-ILE interaction is still very scarce. In this work, the impact of ILE on the distribution of buprenorphine, fentanyl and butorphanol used in various concentrations (100-500 ng/ml) was investigated. Two different in vitro models were used: disposition of the drugs in plasma after ultracentrifugation and distribution into the simulated biophase (cell monolayer of 3T3 fibroblasts or J774.E macrophages). We confirmed the ability of ILE to sequester the three drugs of interest which results in their decrease in the aqueous part of the plasma by 34.2-38.2%, 11.7-28.5% and 6.0-15.5% for buprenorphine, fentanyl and butorphanol, respectively. Moreover, ILE affected the drug distribution to the biophase in vitro, however, in this case the drug concentration in cells decreased by 97.3 ± 3.1%, 28.6 ± 5.4% and 13.0 ± 7.5% for buprenorphine, fentanyl and butorphanol, respectively. The two models revealed notable differences in ILE's potential for drug sequestration, especially for buprenorphine. Similar, but not as pronounced tendencies were observed for the two other drugs. These discrepancies may result from the difference in protein abundance and resulting drug-protein binding in both systems. Nevertheless, the results obtained with both in vitro models correlated well with the partition coefficient (logP) values for these drugs.

Tylosin Dosage Adjustment Based on Allometric Scaling in Male Turkeys.

Turkeys' body weight (BW) increases 10-fold within only 2.5 months, leading to a change in the pharmacokinetics (PK) of drugs according to allometric principles. Thus, the same dosage may lead to age-dependent variability in efficacy, in particular, to treatment failure and/or selection for resistance. The study aimed to investigate whether a non-linear dosage based on a published allometric model for tylosin clearance, may optimize the internal exposure in growing turkeys. The single dose PK study was performed on turkeys aged 6, 9.5, 13 and 17 weeks (BW from 1.75 kg to 15.75 kg). Tylosin was administered intravenously (i.v.) or orally (p.o.) according to following protocols: Dose = 31.6 × BW0.58 or Dose = 158 × BW0.58, respectively. Plasma tylosin was measured using high-performance liquid chromatography and non-compartmental PK analysis was performed. The area under the curve (AUClast) after i.v. administration was 8.90 ± 1.01; 7.51 ± 1.11; 6.54 ± 1.20 and 8.01 ± 1.75 mg × h/L in 6-; 9.5-; 13- and 17-week-old turkeys, respectively. After p.o. administration AUClast was 4.80 ± 2.92; 4.60 ± 2.45; 3.00 ± 1.49 and 3.24 ± 2.00 mg × h/L in respective age groups indicating high variability. For i.v. administration, the non-linear dosage allowed to minimize the age-dependent variability in AUC. However, due to low oral bioavailability (8-12%) and resulting interindividual variability, the proposed approach may not improve tylosin efficacy in turkeys under farm conditions.

Interspecies Outer Membrane Vesicles (OMVs) Modulate the Sensitivity of Pathogenic Bacteria and Pathogenic Yeasts to Cationic Peptides and Serum Complement.

The virulence of bacterial outer membrane vesicles (OMVs) contributes to innate microbial defense. Limited data report their role in interspecies reactions. There are no data about the relevance of OMVs in bacterial-yeast communication. We hypothesized that model Moraxella catarrhalis OMVs may orchestrate the susceptibility of pathogenic bacteria and yeasts to cationic peptides (polymyxin B) and serum complement. Using growth kinetic curve and time-kill assay we found that OMVs protect Candida albicans against polymyxin B-dependent fungicidal action in combination with fluconazole. We showed that OMVs preserve the virulent filamentous phenotype of yeasts in the presence of both antifungal drugs. We demonstrated that bacteria including Haemophilus influenza, Acinetobacter baumannii, and Pseudomonas aeruginosa coincubated with OMVs are protected against membrane targeting agents. The high susceptibility of OMV-associated bacteria to polymyxin B excluded the direct way of protection, suggesting rather the fusion mechanisms. High-performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV) and zeta-potential measurement revealed a high sequestration capacity (up to 95%) of OMVs against model cationic peptide accompanied by an increase in surface electrical charge. We presented the first experimental evidence that bacterial OMVs by sequestering of cationic peptides may protect pathogenic yeast against combined action of antifungal drugs. Our findings identify OMVs as important inter-kingdom players.