Arena Pharmaceuticals' lorcaserin demonstrates low abuse potential

Arena Pharmaceuticals, Inc. (Nasdaq: ARNA) reported that positive data from a clinical trial evaluating the abuse potential of lorcaserin were presented in a poster session at the 48th Annual Meeting of the American College of Neuropsychopharmacology. Data from the trial demonstrate that the risk for abuse associated with lorcaserin is very low.

"Human abuse liability studies of the type done by Arena provide critical data to the FDA and DEA for decisions about any post-marketing scheduling and control under the Controlled Substance Act," said Edward M. Sellers, M.D., Ph.D., Vice President of Kendle International Inc., and Principal Investigator.

Investigational drugs that act through mechanisms in the brain are generally required to undergo an evaluation to determine abuse potential. This determination will be made by the US Drug Enforcement Administration (DEA), with input from the US Food and Drug Administration (FDA), as part of the regulatory review process. Lorcaserin was studied in a standard paradigm at doses well above the intended therapeutic dose of 10 mg twice daily. The clinical trial compared the relative abuse potential of lorcaserin against three comparators: placebo, zolpidem (a schedule IV controlled substance) and ketamine (a schedule III controlled substance).

The trial was a randomized, placebo-controlled, double-blind, seven-way crossover trial conducted in 35 healthy male and female recreational drug users. Subjects received single doses of lorcaserin (20 mg, 40 mg and 60 mg), zolpidem (15 mg and 30 mg), ketamine (100 mg) and placebo in a blinded fashion. Following dosing, subjects completed tests that assessed their subjective states and the drugs' effects (both positive and negative). The primary endpoint was derived from the scores on a "drug liking" scale.

The subjects reported neutral "drug liking" scores for placebo and positive "drug liking" scores for zolpidem and ketamine, which confirmed study validity. The subjective effects of the 20 mg lorcaserin dose were similar to those of placebo. "Drug liking" was significantly lower for the 40 mg and 60 mg lorcaserin doses as compared to zolpidem and ketamine, and subjects demonstrated significant disliking of these supratherapeutic doses of lorcaserin compared to placebo. The subjects' willingness to take lorcaserin again for recreational purposes was significantly lower for 40 mg and 60 mg doses as compared to placebo.

Data from the trial demonstrate that the risk for abuse associated with lorcaserin is very low and less than that of zolpidem or ketamine. At the supratherapeutic doses, lorcaserin was associated with distinct, primarily negative, subjective effects. Although the majority of subjects who took lorcaserin at the supratherapeutic doses in this trial reported adverse events, most often headache, only two subjects withdrew from the trial because of an adverse event.