Tolerability of Vidaza (azacitidine) subcutaneous administration using a maximum volume of 3 ml per injection.

The azacitidine (Vidaza®) product monograph indicates that doses greater than 4 ml should be divided equally into two syringes and injected into different sites. Although 2 ml is a more commonly used maximum volume for subcutaneous injections, there is a lack of evidence to support the use of any given maximum volume with azacitidine. Applying the status quo of 2 ml to azacitidine results in patients receiving 3-4 injections per visit. This prospective study evaluated the frequency and type of injection site reactions when the maximum subcutaneous injection volume was increased from 2 to 3 ml per injection site. Among 30 patients, 309 doses were administered, and injection site reactions were noted in 92.9% of all doses, with the majority (82.2%) being grade 1; only 10.7% of doses resulted in grade 2 reactions, and there were no grade 3 or 4 reactions. There was no increase in frequency or severity of injection site reactions when the maximum volume was increased to 3 ml. The median number of injections that patients received per visit decreased from 3 to 2 after the volume was increased, and there was a statistically significant reduction in the incidence of pain. Decreasing the number of injections also facilitates ease of rotation of injection sites and decreases pharmacy preparation time. This is the first time that injection site reaction data relating to injection volume have been reported for azacitidine.

Metabolic suppression identifies new antibacterial inhibitors under nutrient limitation.

Characterizing new drugs and chemical probes of biological systems is hindered by difficulties in identifying the mechanism of action (MOA) of biologically active molecules. Here we present a metabolite suppression approach to explore the MOA of antibacterial compounds under nutrient restriction. We assembled an array of metabolites that can be screened for suppressors of inhibitory molecules. Further, we identified inhibitors of Escherichia coli growth under nutrient limitation and charted their interactions with our metabolite array. This strategy led to the discovery and characterization of three new antibacterial compounds, MAC168425, MAC173979 and MAC13772. We showed that MAC168425 interferes with glycine metabolism, MAC173979 is a time-dependent inhibitor of p-aminobenzoic acid biosynthesis and MAC13772 inhibits biotin biosynthesis. We conclude that metabolite suppression profiling is an effective approach to focus MOA studies on compounds impairing metabolic capabilities. Such bioactives can serve as chemical probes of bacterial physiology and as leads for antibacterial drug development.