Search

The authors tested a leading theory of bubble formation, insufficient learning, in a laboratory asset market using a drug, Naltrexone, which inhibits reinforcement learning. We found that asset price bubbles in Naltrexone sessions were larger compared with placebo sessions, averaging 60% higher in amplitude and 77% larger in the deviation from fundamental value in the final 12-period trading round. There was no difference between conditions in understanding of the trading rules, overconfidence, or confusion. Participants on Naltrexone appeared unable to determine appropriate trading strategies as prices changed. The findings indicate that specific neural mechanism of reinforcement learning is involved in the formation of asset market bubbles.

Objectives The objective of this study was to investigate lofexidine urine and plasma pharmacokinetics using three different dosing regimens in opioid dependent subjects. To date, there have been no published studies on lofexidine appearance and excretion in urine of opioid dependent subjects. Methods Subjects were stabilized with 100 mg morphine sulphate on days 3-8 of the study. The dosing regimens of lofexidine hydrochloride were .8 mg twice a day (BID), 1.2 mg BID, or .8 mg three times a day (TID) on days 9 through 16 of the study. Plasma and urine samples were collected at appropriate time points. Area under the concentration-time curve (AUC), maximum concentration in plasma (C(max)), time when maximum concentration was reached (T(max)) and fraction excreted unchanged in urine (Fe) were calculated. Results The average half-life obtained from all profiles was 12.1 +/- 6.3 hr. Steady-state (SS) was reached by study day 15. The plasma pharmacokinetic parameters for 1.2 mg BID and .8 mg TID dosing regimens did not seem to be different at steady state (day 15). T(max) was not statistically significantly different across dosing regimens. Fe values ranged between .01% and 34% with high variability within the same dosing regimen. For the total dose of 2.4 mg/day the two dosing regimens that were evaluated, namely 1.2 mg BID and .8 mg TID, did not show a significant statistical difference in plasma and urine pharmacokinetic parameters. Conclusion Although preliminary due to the limited number of subjects, these findings are the first to document lofexidine urine pharmacokinetics in opiate addicts using a highly sensitive liquid chromatography tandem mass spectrometric analysis.

Objectives: The objective of this investigation was to characterize the pharmacokinetic profile of lofexidine. Lofexidine is an orally bioavailable α 2-adrenergic receptor agonist analogue of clonidine that acts centrally to suppress opiate withdrawal symptoms. Methods: During the detoxification period of a phase 3 placebo-controlled, randomized, double-blind trial, six subjects were entered in this preliminary pharmacokinetic study. Results: Pharmacokinetic analysis of plasma samples collected during study day 7 indicated that Cmax was 3242 ± 917 ng/L. The mean trough levels between the study days were not significantly different (p >. 05), suggesting that the subjects were at steady-state. Conclusions: Although preliminary due to the limited number of subjects, these findings are the first to document lofexidine clinical pharmacokinetics in opiate addicts using a highly sensitive liquid chromatography tandem mass spectrometric analysis.

A six-session cognitive behavioral protocol has been developed for substance abusers who meet the description "hazardous users." This category includes individuals evidencing mild to moderate use of alcohol or other drugs, whose lifestyles are minimally disrupted, or who are displaying signs of problem use or abuse, but are unwilling to enter intensive treatment. The treatment model is nonconfrontational and is designed to motivate the individual to recognize the problems associated with his or her substance use and initiate treatment-seeking behavior. The intervention may be particularly useful in situations where employees have tested positive for substances but deny having a problem, where friends or family members report help is needed but the individual denies any problem, or where an alcohol or other drug problem is clearly evidenced but the individual doesn't acknowledge a problem. A positive outcome is indicated by the client taking action which is consistent with an increased awareness of the problem as conceptualized by Prochaska and DiClemente (1982). This model is an alternative to the traditional confrontational models of "breaking through denial." The philosophies employed by William Miller and associates and by the Matrix treatment models form the basis of the intervention.