Andrew Lamont Larkin

Opioid receptor modulation of hedonic taste preference and food intake: a single-dose safety, pharmacokinetic, and pharmacodynamic investigation with GSK1521498, a novel μ-opioid receptor inverse agonist.

Endogenous opioids and μ‐opioid receptors have been linked to hedonic and rewarding aspects of palatable food intake. The authors examined the safety, pharmacokinetic, and pharmacodynamic profile of GSK1521498, a μ‐opioid receptor inverse agonist that is being investigated primarily for the treatment of overeating behavior in obesity. In healthy participants, GSK1521498 oral solution and capsule formulations were well tolerated up to a dose of 100 mg. After single doses (10–150 mg), the maximum concentration (Cmax) and area under the curve (AUC) in plasma increased in a dose‐proportional manner. GSK1521498 selectively reduced sensory hedonic ratings of high‐sugar and high‐fat dairy products and caloric intake of high‐fat/high‐sucrose snack foods. These findings provide encouraging data in support of the development of GSK1521498 for the treatment of disorders of maladaptive ingestive behavior or compulsive consumption.

Regulation of Ingestive Behaviors in the Rat by GSK1521498, a Novel μ-Opioid Receptor-Selective Inverse Agonist

μ-Opioid receptor (MOR) agonism induces palatable food consumption principally through modulation of the rewarding properties of food. N-{[3,5-difluoro-3′-(1H-1,2,4-triazol-3-yl)-4-biphenylyl]methyl}-2,3-dihydro-1H-inden-2-amine (GSK1521498) is a novel opioid receptor inverse agonist that, on the basis of in vitro affinity assays, is greater than 10- or 50-fold selective for human or rat MOR, respectively, compared with κ-opioid receptors (KOR) and δ-opioid receptors (DOR). Likewise, preferential MOR occupancy versus KOR and DOR was observed by autoradiography in brain slices from Long Evans rats dosed orally with the drug. GSK1521498 suppressed nocturnal food consumption of standard or palatable chow in lean and diet-induced obese (DIO) Long Evans rats. Both the dose-response relationship and time course of efficacy in lean rats fed palatable chow correlated with μ receptor occupancy and the plasma concentration profile of the drug. Chronic oral administration of GSK1521498 induced body weight loss in DIO rats, which comprised fat mass reduction. The reduction in body weight was equivalent to the cumulative reduction in food consumption; thus, the effect of GSK1521498 on body weight is related to inhibition of food consumption. GSK1521498 suppressed the preference for sucrose-containing solutions in lean rats. In operant response models also using lean rats, GSK1521498 reduced the reinforcement efficacy of palatable food reward and enhanced satiety. In conclusion, GSK1521498 is a potent, MOR-selective inverse agonist that modulates the hedonic aspects of ingestion and, therefore, could represent a pharmacological treatment for obesity and binge-eating disorders.