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Individuals who are moderate drinkers are at increased risk to abuse alcohol. Moreover, women are more vulnerable than men to the adverse consequences of alcohol consumption and recent data indicate that the drinking pattern in women is becoming more similar to that of men. However, few studies have determined whether female moderate drinkers (MD) show a differential response to the subjective and performance effects of alcohol, compared to female light drinkers (LD). Fifteen female MD who consumed an average of 34.7 drinks/month were compared to 15 female LD who consumed an average of 6.7 drinks/month. None of the participants had a first-degree family history of alcoholism or substance abuse. The acute effects of alcohol (0, 0.25, 0.50, 0.75 mg/kg) were evaluated using a double-blind, placebo-controlled outpatient design. Drug effects were assessed using a full range of performance measures, subjective-effects questionnaires and observer ratings. Alcohol impaired performance in a dose-related manner on all performance tasks for both groups of females. However, MD were less impaired than LD on balance and Digit Symbol Substitution Test (DSST). This reduced response was also evident from the observer ratings, with MD being viewed as less impaired by alcohol than LD. While ratings of Drug Liking increased in both groups of women on the ascending limb of the breath alcohol curve, alcohol was disliked by LD on the descending limb and LD reported increased ratings of Bad Drug Effects following the high dose of alcohol. The reduced performance impairment, coupled with the positive subjective effects and relative absence of adverse subjective effects, suggestive of behavioral tolerance, could result in a progression towards increased alcohol consumption among moderate female social drinkers.

Tolerance to the analgesic effects of opioids has been demonstrated in laboratory animals after repeated drug administration; yet, this effect has been studied less frequently under controlled laboratory conditions in humans. This within-subject, double-blind, placebo-controlled study was designed to determine whether tolerance developed to the analgesic, subjective, and physiological effects of the commonly prescribed opioid oxycodone when it was administered daily for 5 days. The effects of oxycodone (0, 5, and 20 mg/70 kg, orally) were compared, using a within-session cumulative dosing procedure, on the first and fifth days of the 'daily' dosing phase to assess for tolerance; active oxycodone was administered on the second and fourth days of the daily dosing phase. Changes in the effects of oxycodone were also compared when the medication was only administered on the first and the fifth day of a 5-day 'intermittent' dosing phase; placebo medication was administered on the second and fourth days of the intermittent dosing phase. A 9-day 'washout' period occurred between phases during which no medication was administered. Healthy volunteers (N=10) with no history of drug dependence or current drug use participated in this outpatient study. Analgesia was assessed using the cold pressor test, pain and drug effects were measured using a variety of questionnaires, and pupil diameter was monitored as an index of physiological effects. When administered daily, no differences were observed in oxycodone-induced analgesia between the first and the fifth days, but tolerance did develop to some of the positive subjective effects of oxycodone. In contrast, oxycodone-induced analgesia and participant ratings of some positive subjective drug effects were greater on the fifth compared with the first day of the intermittent dosing phase. No differences in the miotic effects of oxycodone between the first and the fifth days of either dosing phase were detected. Although obtained under limited experimental conditions, these findings suggest that tolerance may not develop to the analgesic effects of therapeutic doses of oxycodone under short-term daily dosing conditions, even though some of its subjective effects may decrease. These data also suggest that intermittent administration may enhance the analgesic effects of oxycodone, while also increasing some of the drug's positive subjective effects related to abuse liability.

Individuals who are moderate/heavy drinkers are at increased risk to abuse benzodiazepines and this risk is increased in women compared to men. However, no studies have determined whether female moderate drinkers (MD) show a differential response to the subjective and performance effects of benzodiazepines compared to female light drinkers (LD). Fourteen female MD who consumed an average of 36 drinks/month were compared to 14 female LD who consumed an average of 4.2 drinks/month. None of the participants had either a first- or second-degree family history of alcoholism. The acute effects of placebo, alprazolam (0.25, 0.50, 0.75 mg) and buspirone (5, 10, 15 mg) were evaluated using a double-blind, placebo-controlled outpatient design. Drug effects were assessed using a full range of performance measures and subjective-effects questionnaires. Alprazolam impaired performance in a dose-related manner on all performance tasks for both groups of females, whereas buspirone had minimal effects on performance. There were few differences between LD and MD with respect to subjective response or performance impairment following either alprazolam or buspirone. Although MD reported greater ratings of Good Drug Effect and Drug Liking than LD, this was neither dose-related, nor specific to alprazolam. The results of the present study suggest that female MD without a family history of alcoholism experience the same level of performance impairment as female LD, although they tend to report greater positive subjective effects from alprazolam.

A mutually exclusive choice procedure was used to evaluate the reinforcing effects of caffeine in eleven normal subjects with histories of regular caffeine consumption (mean 256mg/day). Subjects participated for 24 weeks; each week consisted of three consecutive daily sessions (two sampling days followed by a choice day) during which subjects were required to abstain from dietary sources of caffeine. On each sampling day subjects ingested four capsules, one every 2h. Capsules contained placebo on one sampling day and caffeine (50 or 100mg/capsule) on the other sampling day. Placebo and caffeine were associated with different color-coded capsules. At the beginning of the choice day subjects chose one of the two color-coded capsules they wished to take on that day; they were required to ingest one capsule and, thereafter, they could ingest up to six additional capsules of the same color throughout the day. Across subjects and dose, caffeine was chosen over placebo on 80% of choice occasions; nine of 11 subjects (82%) chose caffeine on more than 70% of choice occasions and caffeine choice was replicable despite changes in capsule colors across blocks. This is the first study in a relatively uncontrolled outpatient context to demonstrate significant caffeine reinforcement in the majority of normal subjects.

DN-2327 (pazinaclone) is a new non-benzodiazepine compound which has high affinity for benzodiazepine receptors. The acute behavioral effects and abuse liability of DN-2327 (2, 4 and 8mg) were compared to those of the benzodiazepine anxiolytic alprazolam (0.25, 0.5 and 1mg) in ten normal adult male volunteers using a double-blind, placebo-controlled, outpatient design. For both drugs, the neck effect occurred approximately 1.5h after drug administration. Both drugs also produced comparable dose-related effects on several measures related to sedation, as well as on subject- and observer-rated strength of drug effect. Both alprazolam and DN-2327 produced dose-related impairments on various performance measures; on some tasks, the impairment was greater for DN-2327. In contrast, there were no differences between DN-2327 and alprazolam on observer-rated measures. Although no measures of drug-taking were made in this study, to the extent that self-reported effects predict reinforcing effects, the data suggest little liability for abuse of the two compounds in this subject population. Ratings of 'drug liking' and 'willing to take the drug again' were not increased following alprazolam. Although DN-2327 did not increase ratings of 'willing to take the drug again', DN-2327 did produce small but significant increases on ratings of 'drug liking'. Overall, these results suggest that the non-benzodiazepine DN-2327 has a pharmacological profile that is similar to that of benzodiazepines.

Two groups of pigeons were trained to discriminate a histamine H(1)-antagonist (chlorpheniramine or promethazine) from saline with responding maintained under a fixed-ratio 30 schedule of food delivery. There was no cross-substitution with these two histamine H(1)-antagonists: that is, promethazine failed to substitute reliably for chlorpheniramine in chlorpheniramine-trained pigeons, and chlorpheniramine failed to substitute reliably for promethazine in promethazine-trained pigeons. Among the other histamine H(1)-antagonists tested, tripelennamine consistently produced greater than 80% responding in chlorpheniramine-trained pigeons but not in promethazine-trained pigeons. In contrast, diphenhydramine consistently produced greater than 80% responding in promethazine-trained pigeons but not in chlorpheniramine-trained pigeons. Similarly, chlorcyclizine partially substituted for promethazine and failed to substitute for chlorpheniramine. d-Amphetamine substituted for chlorpheniramine in 2 of 4 pigeons and partially in a third pigeon, whereas d-amphetamine substituted for promethazine in only 1 of 4 pigeons. Pentobarbital failed to produce greater than 80% responding in either chlorpheniramine- or promethazine-trained pigeons. The results of the present study demonstrate that the histamine H(1)-antagonists, chlorpheniramine and promethazine, have differential discriminative stimulus effects in pigeons. These findings suggest that the discriminative stimulus effects of this class of compounds are not based entirely on their ability to act as antagonists at histamine H(1)-receptors.