New mu-opioid receptor agonists with phenoxyacetic acid moiety

DARK Classics in Chemical Neuroscience: Loperamide

Loperamide, a popular and inexpensive over-the-counter antidiarrheal medicine, is a potent μ-opioid receptor agonist approved by the U.S. Food and Drug Administration (FDA). It has been on the market since 1976 and is relatively safe with no central nervous system-related side effects when used for a short period of time at the recommended therapeutic dose (2-8 mg/day). In recent years, loperamide has become notoriously known as the "poor man's methadone" for people with substance dependence due to the increase in loperamide overdoses from self-administered medication to treat opioid withdrawal symptoms. As a result, in 2018, the FDA decided to limit the available packaged dose of loperamide to stop prominent abuse. This review provides the synthesis and chemical properties of loperamide as well as the pharmacology and adverse effects of its use and the social effects of such abuse.

A facile synthesis for novel loperamide analogs as potential μ opioid receptor agonists

A facile synthesis for novel loperamide analogs as potential μ opioid receptors is described. The synthetic procedure for compound 5, which contains two 4-phenyl piperidine scaffolds, was optimized, and this compound was synthesized in excellent yield. We also describe a mild and highly efficient protocol for the synthesis of compounds 6 and 7.

1-(4-Bromo-phen-yl)-2-(2-chloro-phen-oxy)ethanone

In the title compound, C14H10BrClO2, a twofold halogenated derivative of phenyl-ated phenyl-oxyethanone, the least-squares planes defined by the C atoms of the aromatic rings subtend an angle of 71.31 (17)°. In the crystal, C-H⋯O contacts connect the mol-ecules into chains along the b-axis direction.

Design and synthesis of 4-phenyl piperidine compounds targeting the mu receptor

Small molecule mu agonists based on the 4-phenyl piperidine scaffold were designed and synthesized to further investigate the therapeutic potential of loperamide analogs. The resulting compounds show excellent agonistic activity towards the human mu receptor with interesting SAR trends within the series.