NOVEL NEUROSTEROIDS FOR ALCOHOL-RELATED CONDITIONS

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Alcoholism and alcohol abuse pose serious health problems in the United States and around the world. A great deal of effort has been directed toward developing therapies, but success has been limited and relapse is common. Relapse is often precipitated by withdrawal symptoms and/or intense craving, even after prolonged abstinence. Therefore, simultaneous neuromodulation of withdrawal symptoms and alcohol seeking behavior could be therapeutic. The endogenous neuroactive steroids, including 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP or epiallopregnanolone), have profound effects on stress, anxiety, alcohol and drug seeking behavior. Several lines of evidence suggest that 3alpha,5alpha-THP participates in these actions through GABAergic mechanisms in brain areas that are important in the regulation of alcohol withdrawal, craving and reward. Preliminary results from our laboratories demonstrate that 3alpha, 5alpha-THP and its amino-analog (NPI-113) stimulate GABA receptor-mediated C1- uptake, protect against bicuculline-induced seizures and reduce alcohol drinking in alcohol preferring rats. Other researchers have demonstrated that 3alpha,5alpha-THP reduces anxiety and aggression, symptoms that may promote alcohol-drinking behavior. Collectively, these observations suggest a crucial role for 3alpha,5alpha-THP in the regulation of brain mechanisms that are relevant to the management of alcohol-seeking behavior and withdrawal. However, these naturally occurring neurosteroids are ultra short acting (20-30 minutes) because of metabolic degradation. The objective of this project is to develop a model for neurosteroid medication development that includes synthesis of novel compounds, in vitro and in vivo screening, pharmacokinetic and toxicological evaluation and a pilot clinical trial of the most promising compound. We have recently tested specific amino- and cyano-analogs of 3alpha,5alpha-THP containing chemical moieties that block metabolic sites. These compounds have partial agonist activity modulating GABAA receptor-mediated C1- flux and a longer duration of action (4-6 hrs) in the reduction of alcohol drinking behavior. These properties should provide therapeutic benefits and have theoretical usefulness for development of novel agents with GABAA modulating and anti-craving activity. Specifically, we plan to (1) synthesize novel amino- and cyano-analogs of 3alpha,5alpha-THP using structural information derived from our previous studies, (2) characterize GABAA receptor agonist/antagonist activities in vitro using a C1- uptake assay in subcellular synaptoneurosome preparations from rat cerebral cortices, (3) test for reduction of alcohol consumption in alcohol preferring P and HAD rats and reversal of alcohol reinforcement in monkeys, (4) test for reversal of alcohol withdrawal symptoms and seizures in rats, (5) establish toxicity, tolerance, and pharmacokinetic profiles of the most active analogs, and (6) conduct a pilot scale double-blind placebo- controlled clinical trial to determine the efficacy of the most active analog in alcohol-seeking behavior in human subjects. We predict that this comprehensive medication development program will establish an integrated screening system for the discovery and development of therapeutic neurosteroids for the management of problem alcohol drinking and withdrawal.