title: New generalized poisson mixture model for bimodal count data with drug effect: An application to rodent brief-access taste aversion experiments.
abstract: Pharmacodynamic (PD) count data can exhibit bimodality and nonequidispersion complicating the inclusion of drug effect. The purpose of this study was to explore four different mixture distribution models for bimodal count data by including both drug effect and distribution truncation. An example dataset, which exhibited bimodal pattern, was from rodent brief-access taste aversion (BATA) experiments to assess the bitterness of ascending concentrations of an aversive tasting drug. The two generalized Poisson mixture models performed the best and was flexible to explain both under and overdispersion. A sigmoid maximum effect (Emax ) model with logistic transformation was introduced to link the drug effect to the data partition within each distribution. Predicted density-histogram plot is suggested as a model evaluation tool due to its capability to directly compare the model predicted density with the histogram from raw data. The modeling approach presented here could form a useful strategy for modeling similar count data types.
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, London, United Kingdom.|Center for Drug Clinical Research, Shanghai University of Chinese Medicine, Shanghai, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Sheng
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, London, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Soto
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, London, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Orlu Gul
authors.affiliation: Population, Policy, and Practice Programme, Institute of Child Health, UCL, London, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Cortina-Borja
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, London, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Tuleu
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, London, United Kingdom.
authors.forename: J F
authors.initials: JF
authors.lastname: Standing
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D016208:Databases, Factual / Q000706:statistics & numerical data*; D008954:Models, Biological; D016012:Poisson Distribution; D011803:Quinine / Q000494:pharmacology; D011897:Random Allocation; D051381:Rats; D013649:Taste / Q000187:drug effects / Q000502:physiology; D055697:Taste Perception / Q000187:drug effects / Q000502:physiology*
chemical_list: D011803:Quinine