Luminal Delivery of Pectin-Modified Oxygen Microbubbles Mitigates Rodent Experimental Intestinal Ischemia.

INTRODUCTION: Ischemic gut injury is common in the intensive care unit, impairs gut barrier function, and contributes to multiorgan dysfunction. One novel intervention to mitigate ischemic gut injury is the direct luminal delivery of oxygen microbubbles (OMB). Formulations of OMB can be modified to control the rate of oxygen delivery. This project examined whether luminal delivery of pectin-modified OMB (OMBp5) can reduce ischemic gut injury in a rodent model. METHODS: The OMBp5 formulation was adapted to improve delivery of oxygen along the length of small intestine. Adult Sprague-Dawley rats (n = 24) were randomly allocated to three groups: sham-surgery (SS), intestinal ischemia (II), and intestinal ischemia plus luminal delivery of OMBp5 (II + O). Ischemia-reperfusion injury was induced by superior mesenteric artery occlusion for 45 min followed by reperfusion for 30 min. Outcome data included macroscopic score of mucosal injury, the histological score of gut injury, and plasma biomarkers of intestinal injury. RESULTS: Macroscopic, microscopic data, and intestinal injury biomarker results demonstrated minimal intestinal damage in the SS group and constant damage in the II group. II + O group had a significantly improved macroscopic score throughout the gut mucosa (P = 0.04) than the II. The mean histological score of gut injury for the II + O group was significantly improved on the II group (P ≤ 0.01) in the proximal intestine only, within 30 cm of delivery. No differences were observed in plasma biomarkers of intestinal injury following OMBp5 treatment. CONCLUSIONS: This proof-of-concept study has demonstrated that luminal OMBp5 decreases ischemic injury to the proximal small intestine. There is a need to improve oxygen delivery over the full length of the intestine. These findings support further studies with clinically relevant end points, such as systemic inflammation and vital organ dysfunction.

MitoQ and CoQ10 supplementation mildly suppresses skeletal muscle mitochondrial hydrogen peroxide levels without impacting mitochondrial function in middle-aged men.

PURPOSE: Excess production of reactive oxygen species (ROS) from the mitochondria can promote mitochondrial dysfunction and has been implicated in the development of a range of chronic diseases. As such there is interest in whether mitochondrial-targeted antioxidant supplementation can attenuate mitochondrial-associated oxidative stress. We investigated the effect of MitoQ and CoQ10 supplementation on oxidative stress and skeletal muscle mitochondrial ROS levels and function in healthy middle-aged men. METHODS: Skeletal muscle and blood samples were collected from twenty men (50 ± 1 y) before and following six weeks of daily supplementation with MitoQ (20 mg) or CoQ10 (200 mg). High-resolution respirometry was used to determine mitochondrial respiration and H2O2 levels, markers of mitochondrial mass and antioxidant defences were measured in muscle samples and oxidative stress markers in urine and blood samples. RESULTS: Both MitoQ and CoQ10 supplementation suppressed mitochondrial net H2O2 levels during leak respiration, while MitoQ also elevated muscle catalase expression. However, neither supplement altered urine F2-isoprostanes nor plasma TBARS levels. Neither MitoQ nor CoQ10 supplementation had a significant impact on mitochondrial respiration or mitochondrial density markers (citrate synthase, mtDNA/nDNA, PPARGC1A, OXPHOS expression). CONCLUSION: Our results suggest that neither MitoQ and CoQ10 supplements impact mitochondrial function, but both can mildly suppress mitochondrial ROS levels in healthy middle-aged men, with some indication that MitoQ may be more effective than CoQ10.

Comparative pharmacokinetics of spectinamide 1599 after subcutaneous and intrapulmonary aerosol administration in mice.

Spectinamides are a novel series of spectinomycin analogs being developed for the treatment of tuberculosis. Intrapulmonary aerosol (IPA) administration of lead spectinamide 1599 has previously been shown to be more efficacious than subcutaneous (SC) administration at comparable doses. The objective of the current study was to characterize the disposition of 1599 in plasma and lungs in mice in order to provide a potential rationale for the observed efficacy differences. 200 mg/kg of 1599 was administered to healthy BALB/c mice by SC injection or by IPA delivery. Plasma and major organs were collected at specified time points until 8 h after dosing. Drug concentrations were measured by LC-MS/MS and analyzed by noncompartmental pharmacokinetic analysis. 1599 demonstrated rapid absorption into plasma after IPA and SC administration, resulting in very similar plasma exposure for both routes. In contrast, drug exposure in the lungs was 48 times higher following IPA as compared to SC administration, which is highly desirable as the lungs are the main site of infection in pulmonary TB. The higher local exposure in the lungs is likely the basis for the increased efficacy after IPA compared to SC administration. Overall, this study supports the pulmonary route as a potential pathway for the treatment of tuberculosis with 1599.

Thermodynamic analysis questions claims of improved cardiac efficiency by dietary fish oil.

Studies in the literature describe the ability of dietary supplementation by omega-3 fish oil to increase the pumping efficiency of the left ventricle. Here we attempt to reconcile such studies with our own null results. We undertake a quantitative analysis of the improvement that could be expected theoretically, subject to physiological constraints, by posing the following question: By how much could efficiency be expected to increase if inefficiencies could be eliminated? Our approach utilizes thermodynamic analyses to investigate the contributions, both singly and collectively, of the major components of cardiac energetics to total cardiac efficiency. We conclude that it is unlikely that fish oils could achieve the required diminution of inefficiencies without greatly compromising cardiac performance.

Inhaled Pyrazinoic Acid Esters for the Treatment of Tuberculosis.

PURPOSE: Analog development of existing drugs and direct drug delivery to the lungs by inhalation as treatments for multiple and extensively drug resistant (MDR and XDR) tuberculosis (TB) represent new therapeutic strategies. Pyrazinamide (PZA) is critical to drug sensitive TB therapy and is included in regimens for MDR TB. However, PZA-resistant Mycobacterium tuberculosis (Mtb) strains threaten its use. Pyrazinoic acid esters (PAEs) are PZA analogs effective against Mtb in vitro, including against the most common PZA resistant strains. However, PAEs require testing for TB efficacy in animal models. METHODS: PAEs were delivered daily as aqueous dispersions from a vibrating mesh nebulizer to Mtb infected guinea pigs for 4 weeks in a regimen including orally administered first-line TB drugs. RESULTS: PAEs tested as a supplement to oral therapy significantly reduced the organ bacterial burden in comparison to infected, untreated control animals. Thus, PAE aerosol therapy is a potentially significant addition to the regimen for PZA resistant MDR-TB and XDR-TB treatment. Interestingly, low dose oral PZA treatment combined with standard therapy also reduced bacterial burden. This observation may be important for PZA susceptible disease treatment. CONCLUSION: The present study justifies further evaluation of PZA analogs and their lung delivery to treat TB.

Lipid-based carriers for pulmonary products: preclinical development and case studies in humans.

A number of lipid-based technologies have been applied to pharmaceuticals to modify their drug release characteristics, and additionally, to improve the drug loading for poorly soluble drugs. These technologies, including solid-state lipid microparticles, many of which are porous in nature, liposomes, solid lipid nanoparticles and nanostructured lipid carriers, are increasingly being developed for inhalation applications. This article provides a review of the rationale for the use of these technologies in the pulmonary delivery of drugs, and summarizes the manufacturing processes and their limitations, the in vitro and in vivo performance of these systems, the safety of these lipid-based systems in the lung, and their promise for commercialization.

Dry powder PA-824 aerosols for treatment of tuberculosis in guinea pigs.

Novel treatments for multidrug-resistant tuberculosis (MDR-TB), extensively drug-resistant tuberculosis (XDR-TB), or latent TB are needed urgently. Recently, we reported the formulation and characterization of the nitroimidazo-oxazine PA-824 for efficient aerosol delivery as dry powder porous particles and the subsequent disposition in guinea pigs after pulmonary administration. The objective of the present study was to evaluate the effects of these PA-824 therapeutic aerosols on the extent of TB infection in the low-inoculum aerosol infection guinea pig model. Four weeks after infection by the pulmonary route, animals received daily treatment for 4 weeks of either a high or a low dose of PA-824 dry powder aerosol. Animals received PA-824 cyclodextrin/lecithin suspensions orally as positive controls, and those receiving placebo particles or no treatment were negative controls. The lungs and spleens of animals receiving the high dose of inhaled PA-824 particles exhibited a lower degree of inflammation (indicated by wet tissue weights), bacterial burden, and tissue damage (indicated by histopathology) than those of untreated or placebo animals. Treatment with oral PA-824 cyclodextrin/lecithin suspension resulted in a more significant reduction in the bacterial burden of lungs and spleen, consistent with a dose that was larger than inhaled doses (eight times the inhaled low dose and four times the inhaled high dose). However, histopathological analysis revealed that the extent of tissue damage was comparable in groups receiving the oral or either inhaled dose. The present studies indicate the potential use of PA-824 dry powder aerosols in the treatment of TB.

Novel dry powder preparations of whole inactivated influenza virus for nasal vaccination.

The purpose of these studies was to enhance mucosal and systemic antibody production in response to increased local residence time of a whole inactivated influenza virus administered as a dry powder nasal vaccine formulation. Spray-freeze-drying (SFD) particles suitable for nasal delivery were characterized for physico-chemical properties and stability. Mucoadhesive compounds (MA) were characterized for their effects on nasal residence time of vaccine powders in rats compared with published in vitro data and elicited immune responses. SFD particles (D(50) = 26.9 microm) were spherical with a specific surface area of 1.25 m(2)/g. Thermal analysis indicated SFD powders were amorphous and demonstrated improved stability with respect to liquid formulations under various storage conditions. In vitro physico-chemical studies and in vivo scintigraphic imaging experiments indicated sodium alginate (SA) and carboxymethylcellulose-high molecular weight (CMC-HMW) powder formulations most significantly increased residence time in Brown Norway rats. Intramuscular delivery provided equivalent serum antibody titers to intranasal (IN) powder without MA, in the presence of CMC-HMW, SA, and hydroxypropyl methylcellulose (HPMC-HMW) after initial dosing and all formulations except IN powder with chitosan after boosting. IN liquid provided equivalent serum antibody titers to all IN powders after the initial vaccination and significantly greater serum antibody titers than IN powder with chitosan after boosting. Trends were consistent between residence time studies and immune response; however, no statistically significant differences between powder and liquid formulations were observed. It was concluded that enhanced serum and mucosal antibody responses were elicited by a dry powder nasal vaccine, specifically, administered in the presence of sodium alginate.

Manufacture, characterization, and pharmacodynamic evaluation of engineered ipratropium bromide particles.

PURPOSE: The intent of this research was to generate and characterize respirable particles of ipratropium bromide (IPB), a short-acting anticholinergic bronchodilator, to achieve demonstrable sustained-release properties. The value of a long-acting anticholinergic agent is evident in the use of tiotropium for the treatment of chronic obstructive pulmonary disease. METHODS: Hollow, spherical particles of ipratropium bromide suitable for inhalation were generated using a spray-drying process and characterized by laser diffraction particle size analysis, scanning electron microscopy, dynamic vapor sorption, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and dissolution testing. Experimental design techniques were used to identify critical process parameters and optimize the spray drying process. Pharmacodynamic studies were conducted to determine duration of effect. RESULTS: Crystalline, stable, respirable particles with a range of dissolution profiles were manufactured by application of polylactic acid (PLA) coatings of 1, 5, 10, 15, 30, and 50% w/w. A novel, robust, modified Type IV dissolution method discriminated between formulations and guided their development. Preliminary studies in guinea pigs indicated an increased duration of bronchodilatory effect for 30% PLA-coated particles (56.3 min) particles compared with IPB powders alone (11.0 min). CONCLUSIONS: Sustained-release respirable particles of ipratropium bromide were developed using a PLA spray coating approach and a trend for increased duration of effect was demonstrated in guinea pigs.