Current topics in medicinal chemistry
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Benzodiazepine site agonists (such as diazepam) are well-known to impair cognition. Since benzodiazepines exert their effects via modulation of α1-, α2-, α3- and α5-containing GABA(A) receptors, the cognition-impairing effects of diazepam must be associated with one or several of these subtypes. Of these different subtypes, α5-containing GABA(A) receptors represent an attractive option as the "cognition" subtype based upon the preferential localization of these receptors within the hippocampus and the well-established role of the hippocampus in learning and memory. ⋯ By appending features of the prototypic α2/α3-selective triazolopyridazine L-838417 (t-butyl and 1,2,4 triazole) along with the isoxazole of α5IA to a pyrazolotriazine core, an additional clinical candidate, MRK-016, was identified. Finally, a degree of α5 efficacy selectivity was achieved the pyridazine series but metabolic instability within this chemotype limited its further optimization. Overall, these studies demonstrate the feasibility of adopting a selective efficacy approach in the identification of α5 selective GABA(A) receptor inverse agonists.
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Congress carefully crafted the Hatch-Waxman Act to address two competing goals: to spur new pharmaceutical development and to encourage greater public access to generic drugs. To that end, the Act contains important provisions directed to fulfilling each goal, including provisions favorable to either branded drug or generic drug manufacturers. This article addresses those provisions in the context of issues pertaining to patent rights and in light of the congressional goals.
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Macrolides currently play a major role in the management of severe infections. Evidence derives from several retrospective studies have shown a significant reduction of mortality from community-acquired pneumonia upon treatment with a macrolide. Apart from other explanations, their effect is probably mediated through modulation of the immune function of the host. ⋯ The present review focuses on how the concept of macrolide function within the human immune system has evolved in recent years. Particular emphasis is on the role of macrolides in the treatment of sepsis syndrome. Many of the findings herein discussed have created a novel perspective for the management of sepsis syndrome with 14-membered macrolide, specifically clarithromycin.
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Emerging data indicates the existence of novel molecular targets for cannabinoid ligands and recently it has been suggested that the orphan G-protein coupled receptor, GPR55 can be activated by a range of endogenous, plant and synthetic cannabinoids. However, to date, the most potent ligand identified for GPR55 is the endogenous phospholipid, lysophosphatidylinositol (LPI). GPR55 is thought to link predominantly G-protein alpha(13), where it promotes Rho-dependent signalling. ⋯ Although GPR55 has only a low sequence identity with the CB1 or CB2 cannabinoid receptors, it clearly interacts with certain cannabinoid ligands. However, the nature and scope of these effects are presently unclear and they may be influenced by the assay and cellular background used for their study. This article reviews the current status of GPR55 pharmacology and its putative endogenous ligand, lysophosphatidylinositol LPI.
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Since the discovery of rimonabant (Acomplia: 1), a large effort has been directed at the discovery of new, potent and selective CB(1)R antagonists that serve as anti obesity drugs. As a result, a number of compounds reached various stages of clinical trials by late 2008. However, the announcement by Sanofi-Aventis that they were discontinuing all ongoing trials with rimonabant, as a result of the finding that risks associated with depression and anxiety outweighed its benefits, had a major impact on this area. ⋯ Various approaches have been employed to design these analogs, such as bioisosteric replacement, introduction of conformational constraints, scaffold hopping and ligand-based molecular modeling. In addition, current approaches that have been uncovered to avoid psychiatric side effects of CB(1)R antagonists are summarized. Finally, the design of non-brain penetrating and peripherally acting CB(1)R antagonists, allosteric modulators of CB(1)R, and neutral antagonists for CB(1)R is also discussed in this review.