Discussion
Martínez-Loredo
Across all substance administration studies, the Blinded-Dose Purchase Task yielded orderly demand data that showed significantly greater demand in the active dose conditions compared to the placebo conditions using a double-blind, placebo-controlled within-subject design. Demand was significantly correlated with substance use and monetary patterns of drug spending, as well as some subjective effects of the drugs. These relations differed by drug and dose administered. These data highlight the potential of the Blinded-Dose Purchase Task for assessing drug demand while controlling for drug expectancy effects.The results underscore the viability of this task as an addition to laboratory drug administration studies. The task takes approximately 3–5 min to administer, offering a simple and straightforward assessment that provides additional information on drug reinforcement beyond what is typically provided by a typical abuse liability study that only assesses subjective effects. The present findings significantly extend results from purely hypothetical purchase tasks, and represent an important preliminary step in extending the literature. Specifically, the present studies and analyses build on a noteworthy study in which stimulant-naïve individuals completed a blinded purchase task following a single dose of D-amphetamine or placebo (MacKillop et al., Contrary to previous work, in the present study, we used the novel Blinded-Dose Purchase Task to assess reinforcing value of the dose effects of cocaine and methamphetamine and a single dose of alcohol, The demand metrics evaluated appear to track real-world drug spending and drug use behavior, further highlighting the viability of the present task. In the cocaine administration study in which individuals who met Higher peak ratings in the 250 mg/70 kg cocaine dose condition were generally associated with less persistent consumption. Specifically, participants who reported higher peak subjective ratings also tended to report lower intensity and marginally lower In the methamphetamine administration study, in which individuals who recreationally used stimulants participated, money spent on stimulants each week was significantly and positively associated with demand metrics further validating this task. Specifically, money spent on stimulants each week was significantly and positively associated with intensity and Simulated methamphetamine purchasing did not appear to show indications of dose effects for the 20 mg or 40 mg doses for either intensity or rate of change of elasticity (Unit-price analyses indicated somewhat higher intensity and significantly lower Similar to the cocaine study, peak subjective effects for methamphetamine at the 20 and 40 mg doses were inversely associated with money spent on stimulants per week and the number of days stimulants were used in the last month, potentially representing tolerance with increased purchasing with decreased “liking” or “good” effects. These results highlight the importance of multidimensional evaluations of drug reinforcement when administering substances. More research is needed in this regard to understand drug administration in the context of dose effects of hypothetical purchasing and relations to subjective effects, as well as other informative demand metrics that may illuminate clinically relevant drug purchasing behaviors (e.g., understanding drug purchasing in the context of commonly co-used drugs, cross-price elasticity; Bergeria et al., In the alcohol administration study, in which individuals who reported at least occasionally drinking 4–5 drinks per episode participated, significant positive associations emerged between intensity and money spent on alcohol per week and weekly alcohol use as well as between Data from the present studies generally align with purely hypothetical tasks in which the doses are not administered, highlighting the versatility and viability of purchase tasks. However, more research is needed to understand potential differences of purchase task metrics across different drugs, doses, and populations. Far less research exists regarding methamphetamine or cocaine purchase tasks relative to alcohol purchase tasks, making conclusions as to the most critical and predictive demand metrics and how these might differ across drugs/drug classes difficult (see Martínez-Loredo et al., As with any study, these findings should be considered in the context of study limitations. These studies and analyses should be considered preliminary, but represent an important first step in evaluating forced sampling methods in cocaine, methamphetamine, and alcohol purchase tasks. An important future direction will be to directly compare purchasing results of forced sampling methodology as used in the present study, with results obtained from purely hypothetical purchase tasks with cocaine, methamphetamine, and alcohol purchasing. Currently, purely hypothetical purchase tasks are much more common in the literature (although see Bergeria et al., Furthermore, the sample size was limited and a portion of the findings are correlational in nature. Increased statistical power upon replication would allow for greater flexibility in analyses and increased credence to the present findings. Multi-level modeling which can incorporate multiple variables of interest into a single analysis (e.g., Kaplan et al., 