Single Application Cold-Chain Independent Drug Delivery System for Outer Ear Infections.

Outer ear infections (OE) affect millions of people annually with significant associated healthcare costs. Incorrect administration or non-compliance with the treatment regimen can lead to infection persistence, recurrence, antibiotic resistance, and in severe cases aggravation to malignant otitis externa. Such issues are particularly pertinent for military personnel, patients in nursing homes, the geriatric population, for patients with head or hand tremors and for those with limited or no access to proper healthcare. With the intent of using traditional material science principles to deconvolute material design while increasing relevance and efficacy, we developed a single application, cold-chain independent thixotropic drug delivery system. This can be easily applied into the ear as a liquid, then gels to deliver effective concentrations of antibiotics against bacterial strains commonly associated with OE. The system maintains thixotropic properties over several stress/no stress cycles, shows negligible swelling and temperature dependence, and does not impact the minimum inhibitory concentration or bactericidal effects of relevant antibiotics. Moreover, the thixogels are biocompatible and are well tolerated in the ear. This drug delivery system can readily translate into a user-friendly product, could improve compliance via a single application by the diagnosing health care provider, is expected to effectively treat OE and minimize the development of antibiotic resistance, infection recurrence or exacerbation.

Cardiolipin Preferentially Partitions to the Inner Leaflet of Mixed Lipid Large Unilamellar Vesicles.

Cardiolipin (CL), an anionic phospholipid constituting 20% of the inner mitochondrial membrane (IMM) of eukaryotes, stabilizes electron transport chain (ETC) complexes and is a signaling agent in the early stages of apoptosis. For apoptosis, CL moves from the inner to the outer leaflet of the IMM via a poorly understood mechanism. Relative to cylindrically shaped lipids like dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylglycerol (DOPG), cone-shaped CL should prefer the concave surfaces of lipid bilayers. Using the fluorophore, 1,1,2,2-tetrakis[4-(2-trimethylammonioethoxy)phenyl]ethene, we have measured CL versus DOPG partitioning to the inner versus the outer leaflet of liposomes in mixed lipid systems with DOPC. DOPG shows no leaflet preference. However, CL has a 4:1 preference for the concave surface of the inner leaflet of liposomes. To further test the inner leaflet preference of CL, we show that cytochrome c binding to the outer convex surface of 20% CL/80% DOPC vesicles is strongly attenuated. Because the outer leaflet of intracristal regions of the IMM has a concave curvature, the preference of CL for concave surfaces may facilitate the transport of CL from the inner to the outer leaflet of the IMM needed for CL remodeling, the optimal functioning of the ETC, and signaling in the early stages of apoptosis.

The Berkeleylactones, Antibiotic Macrolides from Fungal Coculture.

A carefully timed coculture fermentation of Penicillium fuscum and P. camembertii/clavigerum yielded eight new 16-membered-ring macrolides, berkeleylactones A-H (1, 4, 6-9, 12, 13), as well as the known antibiotic macrolide A26771B (5), patulin, and citrinin. There was no evidence of the production of the berkeleylactones or A26771B (5) by either fungus when grown as axenic cultures. The structures were deduced from analyses of spectral data, and the absolute configurations of compounds 1 and 9 were determined by single-crystal X-ray crystallography. Berkeleylactone A (1) exhibited the most potent antimicrobial activity of the macrolide series, with low micromolar activity (MIC = 1-2 µg/mL) against four MRSA strains, as well as Bacillus anthracis, Streptococcus pyogenes, Candida albicans, and Candida glabrata. Mode of action studies have shown that, unlike other macrolide antibiotics, berkeleylactone A (1) does not inhibit protein synthesis nor target the ribosome, which suggests a novel mode of action for its antibiotic activity.

Pharmaceutical analysis of a novel propargyl-linked antifolate antibiotic in the mouse.

Antimicrobial resistance to current antibiotics is a significant public health problem and the need for new antibiotics is a compelling one. We have been developing a new series of antibiotics, propargyl-linked diaminopyrimidines, based on the structure of trimethoprim. To date we have discovered compounds that are effective inhibitors of dihydrofolate reductase (the target of trimethoprim), that are potent antibiotics in vitro against a range of Gram-positive pathogens including methicillin-resistant S. aureus, and that are non-toxic in mammalian cell culture. In this study we report the development of an LC-MS-based protocol for the quantification of our lead antibiotic 37D1-UCP1099 and the application of this assay to follow the concentration of the compound in mouse plasma after intraperitoneal administration. Extraction of 37D1-UCP1099 from mouse plasma was achieved through a liquid-liquid extraction with ethyl acetate. Separation was performed utilizing a reverse-phase C18 column with a ten minute isocratic elution using 47:53 (v/v) 10mM NH4HCO3:acetonitrile. The lower limit of quantitation for 37D1-UCP1099 was 50ngmL-1 and the assay showed a dynamic range of 50-4000ngmL-1 with good linearity (r2≥0.996 for all fits). Intra-day and inter-day precision and accuracy were within 11.3% (%RSD) and 6.6% (%RE) respectably. We have demonstrated that the compound is stable under the assay procedures. The compound was shown to have a mean residence time of 26.2±1.0min and a half-life of 18.2±0.7min after intraperitoneal delivery at 5mgkg-1. These studies now form the foundation of our work to develop additional analogs of 37D1-UCP1099 with improved pharmacokinetic properties.