title: Measurement of Drug Liking in Abuse Potential Studies: A Comparison of Unipolar and Bipolar Visual Analog Scales.
abstract: Abuse liability studies usually measure drug liking using 100-mm visual analog scales (VAS), presented as unipolar (liking measured on entire scale) or bipolar (liking and disliking measured with a neutral midpoint). These 2 types of VAS were compared using drug liking ratings from a randomized double-blind crossover study of immediate-release and controlled-release oxycodone in 2 cohorts of nondependent recreational opioid users. Cohort 1 (n = 19) received intact oxycodone 40 mg, intact OxyContin®40 and 80 mg, crushed OxyContin®40 mg, and placebo, while cohort 2 (n = 16) received intact oxycodone 20, 40, and 80 mg and placebo. In general, bipolar and unipolar ratings were positively correlated (r = 0.72) for all values (n = 2,477). Emaxfor both scales generally had higher correlation than individual responses for active drug or placebo. The correlation for individual scores after placebo treatment for the 2 scales was poor in both cohorts (r = -0.11, cohort 1 and r = 0.17, cohort 2). Both scales performed similarly within the context of the study, but bipolar scales can also assess disliking, which may be a consideration depending on anticipated drug effects. Appropriate participant training on the use of these scales is also necessary to reduce variability.
authors.affiliation: Pfizer Inc, Durham, NC, USA.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Setnik
authors.affiliation: Pfizer Inc, Durham, NC, USA.
authors.forename: Carl L
authors.initials: CL
authors.lastname: Roland
authors.affiliation: Pfizer Inc, Durham, NC, USA.
authors.forename: Glenn
authors.initials: G
authors.lastname: Pixton
authors.affiliation: PRA Health Sciences, Salt Lake City, UT, USA.
authors.forename: Lynn
authors.initials: L
authors.lastname: Webster
mesh_terms: D000293:Adolescent; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology; D018592:Cross-Over Studies; D003627:Data Interpretation, Statistical; D003692:Delayed-Action Preparations; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008875:Middle Aged; D009293:Opioid-Related Disorders / Q000523:psychology; D010098:Oxycodone / Q000008:administration & dosage / Q000494:pharmacology; D015203:Reproducibility of Results; D012107:Research Design; D019966:Substance-Related Disorders / Q000523:psychology*; D064232:Visual Analog Scale; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D003692:Delayed-Action Preparations; D010098:Oxycodone
keywords: bipolar VAS; drug liking; human abuse potential studies; unipolar VAS; visual analog scales