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Gastroparesis is a chronic neuromuscular disorder of the upper gastrointestinal tract in which episodic exacerbation can lead to frequent hospitalizations and severe disability. Dopamine D2/D3 receptor antagonists have been used to treat patients with gastroparesis with some efficacy; however, their chronic use is limited owing to associated central nervous system (CNS) or cardiovascular safety concerns. Trazpiroben (TAK‐906) is a dopamine D2/D3 receptor antagonist under development for the long‐term treatment of gastroparesis. Preclinical studies in rat and dog have shown trazpiroben to have minimal brain penetration and low affinity for the human ether‐à‐go‐go‐related gene (hERG) potassium channel (IC50, 15.6 µM), thereby reducing the risk of the CNS and cardiovascular adverse effects seen with other dopamine D2/D3 receptor antagonists. This phase 1 trial evaluated the safety, pharmacokinetics, and pharmacodynamics of trazpiroben in healthy participants. Trazpiroben was rapidly absorbed and eliminated (Tmax, ∼1.1 hours; t1/2, 4–11 hours) after administration of single (5–300 mg) and multiple (50 or 100 mg) doses. Receptor target engagement was confirmed for all doses, as indicated by an increase in serum prolactin levels compared with placebo (mean prolactin Cmax, 134.3 ng/mL after administration of trazpiroben 10 mg vs 16.1 ng/mL with placebo). Therapeutically relevant single and multiple doses of trazpiroben were well tolerated in healthy participants, and no clinically meaningful cardiovascular adverse effects were observed across the whole dose range. These data support the further development of trazpiroben for the treatment of gastroparesis. [ABSTRACT FROM AUTHOR]

Background: Selective kappa opioid receptor antagonism is a promising experimental strategy for the treatment of depression. The kappa opioid receptor antagonist, LY2456302, exhibits ~30-fold higher affinity for kappa opioid receptors over mu opioid receptors, which is the next closest identified pharmacology., Methods: Here, we determined kappa opioid receptor pharmacological selectivity of LY2456302 by assessing mu opioid receptor antagonism using translational pupillometry in rats and humans., Results: In rats, morphine-induced mydriasis was completely blocked by the nonselective opioid receptor antagonist naloxone (3mg/kg, which produced 90% mu opioid receptor occupancy), while 100 and 300 mg/kg LY2456302 (which produced 56% and 87% mu opioid receptor occupancy, respectively) only partially blocked morphine-induced mydriasis. In humans, fentanyl-induced miosis was completely blocked by 50mg naltrexone, and LY2456302 dose-dependently blocked miosis at 25 and 60 mg (minimal-to-no blockade at 4-10mg)., Conclusions: We demonstrate, for the first time, the use of translational pupillometry in the context of receptor occupancy to identify a clinical dose of LY2456302 achieving maximal kappa opioid receptor occupancy without evidence of significant mu receptor antagonism., (© The Author 2015. Published by Oxford University Press on behalf of CINP.)

Objective: The efficacy and tolerability of alosetron in women with diarrhea-predominant irritable bowel syndrome (IBS) have been established in double-blind, placebo-controlled trials. However, the degree to which alosetron fulfills the needs of those suffering from IBS has not been thoroughly examined from the patient's perspective. This randomized, double-blind, placebo-controlled study conducted in women with diarrhea-predominant IBS evaluated patients' overall satisfaction with treatment as well as their satisfaction with respect to several specific medication attributes., Methods: Patients randomized to receive either alosetron 1 mg b.id. (n = 532) or placebo (n = 269) were administered a questionnaire on which they rated on 7-point Likert scales their prestudy IBS treatment (at the screening visit) or study medication (on wk 12 or final study visit) with respect to overall satisfaction and 11 specific medication attributes., Results: Whereas approximately 10% of patients were satisfied or very satisfied overall with prestudy IBS medication, 69% of patients were satisfied or very satisfied overall with alosetron and 46% with placebo (p < 0.001) at the end of 12 wk of therapy. The majority of alosetron-treated patients (61-87%) were satisfied or very satisfied with each of 11 specific medication attributes (p < 0.001 vs placebo for each attribute). Favorable satisfaction ratings for alosetron were assigned to the five medication attributes that patients considered to be most important, including relief of urgency (68% alosetron vs 41% placebo), speed of relief (71% vs 40%), time to return to normal activities (75% vs 49%), relief of abdominal pain (62% vs 44%), and prevention of return of urgency (68% vs 42%)., Conclusions: Women with diarrhea-predominant IBS are satisfied with alosetron 1 mg b.i.d. treatment overall and also with respect to specific attributes of IBS medication they consider most important.