ADL 08-0011 is an active metabolite of the μ-opioid receptor antagonist alvimopan. It is produced from alvimopan via amide hydrolysis by gut microbiota. ADL 08-0011 is a μ-opioid receptor antagonist (Ki = 0.25 nM). It is selective for μ-opioid receptors over κ- and δ-opioid receptors (Kis = 15.8 and 31.6 nM, respectively). ADL 08-0011 inhibits endomorphin 1-induced inhibition of electrically induced contraction of isolated guinea pig ileum (pA2 = 9.4). In vivo, ADL 08-0011 (0.03-1 mg/kg) reverses loperamide-induced delayed gastric emptying in a rat model of castor oil-induced diarrhea.

Acyline is a novel GnRH antagonist found in animal studies to be a potent suppressor of circulating gonadotropin and testosterone (T) levels. Acyline inhibits basal and GnRH-stimulated serum testosterone concentrations in male dogs. Acyline prevented ovulation, but did not affect ovarian follicular development or gestational corpora lutea in the domestic cat. A single dose of the potent gonadotropin-releasing hormone antagonist acyline suppresses gonadotropins and testosterone for 2 weeks in healthy young men.