diisopropylfluorophosphate (DFP) damage in rat hippocampal slices and against DFP in rats in vivo.
Carol Green
SRI Author
Formulation Approaches to Improving the Delivery of an Antiviral Drug with Activity against Seasonal Flu
The main objective of the present study was to develop formulations of noscapine hydrochloride hydrate with enhanced solubility and bioavailability using co-solvent- and cyclodextrin-based approaches. Different combinations of co-solvents, which were selected on the basis of high-throughput solubility screening, were subjected to in vitro intestinal drug permeability studies conducted with Ussing chambers. Vitamin E tocopherol polyethylene glycol succinate and propylene glycol based co-solvent formulations provided the maximum permeability coefficient for the drug. Inclusion complexes of the drug were prepared using hydroxypropyl-β-cyclodextrin and sulphobutylether cyclodextrins. Pharmacokinetic studies were carried out in male Sprague-Dawley rats for the selected formulations. The relative bioavailabilities of the drug with the co-solvent- and cyclodextrin-based formulations were found to be similar.
Cyanide Detoxification by Molybdenum Sulfur Complexes
SRI Authors: Carol Green
Development of an Agonist of the TGF-Beta Signaling Pathway to Treat Alzheimer’s Disease
Alzheimer’s disease (AD) is a neurodegenerative disorder that leads to progressive cognitive dysfunction. Current knowledge of the processes leading to AD is still limited, and no effective treatments are available. Because neurodegeneration is associated with injury and activation of innate immune responses in the brain, drugs that could mimic the beneficial aspects of this response are potential therapeutic candidates. The cytokine transforming growth factor (TGF)-?1 is an organizer of the brain’s response to injury and has been shown to have neuroprotective effects in models of brain injury and degeneration. Recombinant TGF-?1 has been used to treat various forms of brain injury in vivo but delivery is not suitable for human use. Studies from our lab have demonstrated that TGF-?1 can reduce the overall accumulation of A?, a key factor in AD pathogenesis, in mouse models for AD and in cell culture. Numerous studies have also demonstrated that TGF-?1 is a potent neurotrophic factor, although high-level chronic TGF-?1 production can also be detrimental. Recently, we reported that reduced TGF-?1 expression in vivo or in cultured neurons increases neurodegeneration. Additional studies show that reducing TGF-? signaling in neurons of a mouse model for AD increases A? accumulation and neurodegeneration and that TGF-? receptor expression is reduced in human AD brains. We have identified bioactive small molecule chemical compounds that can activate the TGF-? signaling pathway in hippocampal neurons of mice and that pass the blood-brain barrier. With reporter cell lines for the TGF-? signaling pathway we screened a diverse small molecule drug library and identified several compounds that are able to activate the reporter system in vitro and in TGF-? reporter mice in vivo. The compounds induce specific TGF-?-responsive genes in cell culture consistent with Smad dependent activation of the TGF-? pathway. These chemicals share common properties from which we propose here to derive a lead compound within 5 years. This project includes structure activity relationship analysis of identified active compounds, medicinal chemistry, toxicology and pharmacology in a subcontract with SRI International. Compounds will be tested in neuroprotection and neurotoxicity assays in cell culture and in TGF-? reporter mice in vivo. The two most promising compounds will then be tested in an in vivo model of neurodegeneration and in a mouse model for AD. Part of the in vivo analysis on neurodegeneration will be done in collaboration with researchers at UCSD. At the end of our studies we propose to have for the first time a novel neuroprotective and amyloid reducing investigational new drug based on the TGF-? signaling pathway for testing in patients with AD.
Evaluating the Toxicity of Novel Zn-DTPA Tablet Formulation in Dogs and Rats
The purpose of this research work is to evaluate toxicity of diethylenetriamine pentaacetic acid zinc trisodium salt (Zn-DTPA) tablets, a novel oral solid dosage form containing permeation enhancers in beagle dogs and Sprague Dawley rats. (Zn-DTPA) in tablet dosage form was administered once daily for 7 days to beagle dogs at low (840 mg/dog/day), mid (2520 mg/dog/day), or high (7560 mg/dog/day). On day 8, all treated and control groups were necropsied. The novel Zn-DTPA tablet formulation showed rapid absorption with the Tmax at 1 h. Plasma concentrations as high as 270 μg/mL were observed after 7 days of administration. Exposure to DTPA, based on area under the curve (AUClast) and maximum concentration (Cmax), was dose dependent but not dose proportional. No biologically relevant changes in hematology or clinical chemistry that were related to DTPA exposure were observed, and there were no changes in body weight in treated dogs compared with controls. Zn-DTPA was well tolerated, with minor toxicological effects of emesis and diarrhea, following oral tablet administration for 7 consecutive days. Based on the endpoints evaluated in this study, the maximum tolerated dose is considered to be greater than 7560 mg/dog/day (2535 μmol/kg/day, 1325 mg/kg/day), and the no-observed-adverse-effect level (NOAEL) is considered to be approximately 1325 mg/kg/day per oral when given to male and female beagle dogs. For rats, the NOAEL was estimated to be greater than 1000 mg/kg/day when administered by oral gavage of the crushed Zn-DTPA tablets as suspension once daily (qd) to male and female Sprague Dawley rats.
Pharmacokinetics and Toxicity of a Neuroprotective Cembranoid
SRI Authors: Carol Green
Comparison of a New Cobinamide-Based Method to a Standard Laboratory Method for Measuring Cyanide in Human Blood
SRI Authors: Carol Green
Non-Clinical Safety Evaluation of Xoma 3AB, a Novel Triple Antibody Drug Product Targeting Botulinum Toxin Type a, in Sprague-Dawley Rats
SRI Authors: Carol Green, Jon C. Mirsalis
A Systematic Screen of FDA-Approved Drugs for Inhibitors of Biological Threat Agents
BACKGROUND: The rapid development of effective medical countermeasures against potential biological threat agents is vital. Repurposing existing drugs that may have unanticipated activities as potential countermeasures is one way to meet this important goal, since currently approved drugs already have well-established safety and pharmacokinetic profiles in patients, as well as manufacturing and distribution networks. Therefore, approved drugs could rapidly be made available for a new indication in an emergency.
METHODOLOGY/PRINCIPAL FINDINGS: A large systematic effort to determine whether existing drugs can be used against high containment bacterial and viral pathogens is described. We assembled and screened 1012 FDA-approved drugs for off-label broad-spectrum efficacy against Bacillus anthracis; Francisella tularensis; Coxiella burnetii; and Ebola, Marburg, and Lassa fever viruses using in vitro cell culture assays. We found a variety of hits against two or more of these biological threat pathogens, which were validated in secondary assays. As expected, antibiotic compounds were highly active against bacterial agents, but we did not identify any non-antibiotic compounds with broad-spectrum antibacterial activity. Lomefloxacin and erythromycin were found to be the most potent compounds in vivo protecting mice against Bacillus anthracis challenge. While multiple virus-specific inhibitors were identified, the most noteworthy antiviral compound identified was chloroquine, which disrupted entry and replication of two or more viruses in vitro and protected mice against Ebola virus challenge in vivo.
CONCLUSIONS/SIGNIFICANCE: The feasibility of repurposing existing drugs to face novel threats is demonstrated and this represents the first effort to apply this approach to high containment bacteria and viruses.
