Effect of flomoxef on blood coagulation and alcohol metabolism

Potential Antibiotics for the Treatment of Neonatal Sepsis Caused by Multidrug-Resistant Bacteria

Neonatal sepsis causes up to an estimated 680,000 deaths annually worldwide, predominantly in low- and middle-income countries (LMICs). A significant and growing proportion of bacteria causing neonatal sepsis are resistant to multiple antibiotics, including the World Health Organization-recommended empiric neonatal sepsis regimen of ampicillin/gentamicin. The Global Antibiotic Research and Development Partnership is aiming to develop alternative empiric antibiotic regimens that fulfil several criteria: (1) affordable in LMIC settings; (2) activity against neonatal bacterial pathogens, including extended-spectrum β-lactamase producers, gentamicin-resistant Gram-negative bacteria, and methicillin-resistant Staphylococcus aureus (MRSA); (3) a licence for neonatal use or extensive experience of use in neonates; and (4) minimal toxicities. In this review, we identify five antibiotics that fulfil these criteria: amikacin, tobramycin, fosfomycin, flomoxef, and cefepime. We describe the available characteristics of each in terms of mechanism of action, resistance mechanisms, clinical pharmacokinetics, pharmacodynamics, and toxicity profile. We also identify some knowledge gaps: (1) the neonatal pharmacokinetics of cefepime is reliant on relatively small and limited datasets, and the pharmacokinetics of flomoxef are also reliant on data from a limited demographic range and (2) for all reviewed agents, the pharmacodynamic index and target has not been definitively established for both bactericidal effect and emergence of resistance, with many assumed to have an identical index/target to similar class molecules. These five agents have the potential to be used in novel combination empiric regimens for neonatal sepsis. However, the data gaps need addressing by pharmacokinetic trials and pharmacodynamic characterisation.

Helicobacter pylori antibiotic eradication coupled with a chemically defined diet in INS-GAS mice triggers dysbiosis and vitamin K deficiency resulting in gastric hemorrhage

Infection with Helicobacter pylori causes chronic inflammation and is a risk factor for gastric cancer. Antibiotic treatment or increased dietary folate prevents gastric carcinogenesis in male INS-GAS mice. To determine potential synergistic effects, H. pylori-infected male INS-GAS mice were fed an amino acid defined (AAD) diet with increased folate and were treated with antibiotics after 18 weeks of H. pylori infection. Antibiotic therapy decreased gastric pathology, but dietary folate had no effect. However, the combination of antibiotics and the AAD diet induced anemia, gastric hemorrhage, and mortality. Clinical presentation suggested hypovitaminosis K potentially caused by dietary deficiency and dysbiosis. Based on current dietary guidelines, the AAD diet was deficient in vitamin K. Phylloquinone administered subcutaneously and via a reformulated diet led to clinical improvement with no subsequent mortalities and increased hepatic vitamin K levels. We characterized the microbiome and menaquinone profiles of antibiotic-treated and antibiotic-free mice. Antibiotic treatment decreased the abundance of menaquinone producers within orders Bacteroidales and Verrucomicrobiales. PICRUSt predicted decreases in canonical menaquinone biosynthesis genes, menA and menD. Reduction of menA from Akkermansia muciniphila, Bacteroides uniformis, and Muribaculum intestinale were confirmed in antibiotic-treated mice. The fecal menaquinone profile of antibiotic-treated mice had reduced MK5 and MK6 and increased MK7 and MK11 compared to antibiotic-free mice. Loss of menaquinone-producing microbes due to antibiotics altered the enteric production of vitamin K. This study highlights the role of diet and the microbiome in maintaining vitamin K homeostasis.

Use of Hypoprothrombinemia-Inducing Cephalosporins and the Risk of Hemorrhagic Events: A Nationwide Nested Case-Control Study

Objective

Existing data regarding the risk of hemorrhagic events associated with exposure to hypoprothrombinemia-inducing cephalosporins are limited by the small sample size. This population-based study aimed to examine the association between exposure to hypoprothrombinemia-inducing cephalosporins and hemorrhagic events using National Health Insurance Research Database in Taiwan.

Design

A nationwide nested case-control study.

Setting

National Health Insurance Research database.

Participants

We conducted a nested case-control study within a cohort of 6191 patients who received hypoprothrombinemia-inducing cephalosporins and other antibiotics for more than 48 hours. Multivariable conditional logistic regressions were used to calculate the adjusted odds ratio (aOR) and 95% confidence interval (CI) for hemorrhagic events associated with exposure to hypoprothrombinemia-inducing cephalosporins (overall, cumulative dose measured as defined daily dose (DDD), and individual cephalosporins).

Results

Within the cohort, we identified 704 patients with hemorrhagic events and 2816 matched controls. Use of hypoprothrombinemia-inducing cephalosporins was associated with increased risk of hemorrhagic events (aOR, 1.71; 95% CI, 1.42–2.06), which increased with higher cumulative doses (<3 DDDs, aOR 1.62; 3–5 DDDs, aOR 1.78; and >5 DDDs, aOR 1.89). The aOR for individual cephalosporin was 2.88 (95% CI, 2.08–4.00), 1.35 (1.09–1.67) and 4.57 (2.63–7.95) for cefmetazole, flomoxef, and cefoperazone, respectively. Other risk factors included use of anticoagulants (aOR 2.08 [95% CI, 1.64–2.63]), liver failure (aOR 1.69 [1.30–2.18]), poor nutritional status (aOR 1.41 [1.15–1.73]), and history of hemorrhagic events (aOR 2.57 [1.94–3.41]) 6 months prior to the index date.

Conclusions

Use of hypoprothrombinemia-inducing cephalosporins increases risk of hemorrhagic events. Close watch for hemorrhagic events is recommended when prescribing these cephalosporins, especially in patients who are at higher risk.

Safety Evaluation and Drug Development based on Biological Fate of Drugs —Efforts Made to Overcome Drug Interaction in Drug Development—

1. Assay methods to detect drug interaction in toxicological samples were established by determining cytochrome P450 content and its activity in liver samples. The O-dealkylation reaction of 7-alkoxycoumarin was indicated to reflect changes in the molecular forms of P450s, and the enzyme induction or inhibition in the toxicological samples was easily detected by using the established methods. 2. During toxicological studies of 450191-S or the sleep inducer rilmazafone, a phenobarbital type-induction of hepatic drug metabolizing enzymes was observed in animals, and the doses required for the induction differed markedly between rats and dogs. Enzyme induction was caused by some specific metabolites of 450191-S, and the plasma concentrations of these metabolites were comparable when the enzyme induction was developed in both animals. 3. A nonsteroidal antiinflammatory compound 480156-S showed a slight or no effect on microsomal drug metabolizing activity in rats. On the other hand, repeated administration of this compound to humans resulted in a marked decrease in the oxidative metabolism of 480156-S, followed by a marked increase in the plasma concentrations of the compound. When volunteers were given 480156-S followed by several drugs, such as tolubutamide, the plasma clearance was delayed remarkably, indicating a severe drug interaction. 4. Cytochrome P450 belonging to the CYP2C family was indicated to participate in the oxidative metabolism of 480156-S in both rat and human liver microsomes. The preincubation of microsomes with 480156-S caused a concentration-dependent inhibition of CYP2C-dependent tolubutamide hydroxylation reaction in both rats and humans. There was a marked species difference in the susceptibility to the inhibitory effect of 480156-S, and the concentration required to inhibit rat CYP2C was almost 10 times higher than that required in humans. 5. The cephem antibiotics having N-methyltetrazolethiol (NMTT) at the 3'-position substituent were demonstrated to inhibit mitochondrial low K(m) aldehyde dehydrogenase (ALDH), and produced disulfiram-like (Antabuse) reaction during alcohol metabolism. Pharmacokinetic studies indicated that NMTT released from the antibiotics in bile duct or intestine cause the inhibitory action followed by the development of disulfiram-like reaction. 6. Attempts had been made to develop new cephem antibiotics lacking the disulfiram-like reaction by changing the chemical structure of 3'-position substituents, and a hydroxyethyltetrazolethiol was found not to inhibit the enzyme. Based on this result, together with the antibacterial activity, we have developed a new oxacephem antibiotic flomoxef (6315-S). Flomoxef showed no disulfiram-like reaction both in rats and human.

Comparison of flomoxef with latamoxef in the treatment of sepsis and/or Gram-negative bacteremia in adult patients

The safety and efficacy of flomoxef and latamoxef were compared in the treatment of hospitalized patients with sepsis and/or Gram-negative bacteremia in a prospective, open-labelled clinical trial. Patients were randomized to receive 1 to 2 g intravenous doses of either flomoxef every 6 to 12 h, or latamoxef every 8 to 12 h. Data from 21 patients given flomoxef and 23 patients given latamoxef were included in the evaluation of efficacy. Flomoxef produced clinical cure and satisfactory microbiological responses in 85.7% and 100% of patients, respectively. These results were similar to those obtained with latamoxef (87% and 100%, respectively). In addition, no significant difference was found in mean age, sex, severity of infection, distribution of pathogens and focus of infection between the two groups. However, the flomoxef group included more patients with ultimately fatal diseases. Six patients given flomoxef and two patients given latamoxef developed superinfections caused by yeast, enterococci and Pseudomonas aeruginosa in the urinary tract. Mild and reversible adverse reactions probably related to flomoxef and latamoxef were noted in 14.3% and 13% of patients, respectively. The results of this study demonstrated that flomoxef is a safe and effective antimicrobial agent in the treatment of patients with sepsis and/or Gram-negative bacteremia.