Establishing powder-handling workflow practices and standard operating procedures: compounding pharmacy and safety.

This is an ongoing discussion and analysis of powder-handling safety in the compounding pharmacy laboratory that started in the November/December 2013 issue of the International Journal of Pharmaceutical Compounding. In the previous technical article, we established that most chemical powders handled during compounding procedures have an established occupational exposure limits and that powders are micronized during manipulation. All micronized powders handled on an open bench create health hazards to the technicians and create a potential for cross-contamination to the lab environment. Proper identification of the chemical hazard and established standard operating procedures in direct correlation to Good Lab Practices when working inside a powder hood will positively improve the compounding pharmacy's work environment.

Exploring the UDP pocket of LpxC through amino acid analogs.

Lipopolysaccharide (LPS) biosynthesis is an attractive antibacterial target as it is both conserved and essential for the survival of key pathogenic bacteria. Lipid A is the hydrophobic anchor for LPS and a key structural component of the outer membrane of Gram-negative bacteria. Lipid A biosynthesis is performed in part by a unique zinc dependent metalloamidase, LpxC (UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase), which catalyzes the first non-reversible step in lipid A biosynthesis. The UDP portion of the LpxC substrate-binding pocket has been relatively unexplored. We have designed and evaluated a series of hydroxamate based inhibitors which explore the SAR of substitutions directed into the UDP pocket with a range of substituted α-amino acid based linkers. We also provide the first wild type structure of Pseudomonas aeruginosa LpxC which was utilized in the design of many of these analogs.

A growing codependency: compounding pharmacy and safety.

Pharmacists and pharmacy technicians are in constant contact with potent compounds. When compounding with powders, there is a susceptibility to environmental conditions such that proper containment be in place to keep the employees safe, the medicine free from cross contamination or the introduction of outside contaminants, and the workplace free from floating active pharmaceutical ingredient particles. Adapting powder hoods as safety devices that work in direct relation to clearly defined standard operating procedures and good lab practices will facilitate a safer lab environment for employees and ensure good-quality prescriptions. This article discusses the safety concerns of compounding with powders and the safety measures to consider when purchasing powder hoods.

Pyrrolamide DNA gyrase inhibitors: fragment-based nuclear magnetic resonance screening to identify antibacterial agents.

DNA gyrase is an essential enzyme in bacteria, and its inhibition results in the disruption of DNA synthesis and, subsequently, cell death. The pyrrolamides are a novel class of antibacterial agents targeting DNA gyrase. These compounds were identified by a fragment-based lead generation (FBLG) approach using nuclear magnetic resonance (NMR) screening to identify low-molecular-weight compounds that bind to the ATP pocket of DNA gyrase. A pyrrole hit with a binding constant of 1 mM formed the basis of the design and synthesis of a focused library of compounds that resulted in the rapid identification of a lead compound that inhibited DNA gyrase with a 50% inhibitory concentration (IC(50)) of 3 µM. The potency of the lead compound was further optimized by utilizing iterative X-ray crystallography to yield DNA gyrase inhibitors that also displayed antibacterial activity. Spontaneous mutants were isolated in Staphylococcus aureus by plating on agar plates containing pyrrolamide 4 at the MIC. The resistant variants displayed 4- to 8-fold-increased MIC values relative to the parent strain. DNA sequencing revealed two independent point mutations in the pyrrolamide binding region of the gyrB genes from these variants, supporting the hypothesis that the mode of action of these compounds was inhibition of DNA gyrase. Efficacy of a representative pyrrolamide was demonstrated against Streptococcus pneumoniae in a mouse lung infection model. These data demonstrate that the pyrrolamides are a novel class of DNA gyrase inhibitors with the potential to deliver future antibacterial agents targeting multiple clinical indications.