A Study To Evaluate The Abuse Potential Of Single Oral Doses Of Dimebon (Latrepirdine) In Healthy Recreational Polydrug Users

Primary outcomes

1. Balance of Effects- Drug Liking VAS: Peak Effect (Maximum Effect [Emax]) and Minimum Effect (Emin)

   Time frame: 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

   Drug liking VAS is one of the measures of balance of effects that assesses the degree that a participant likes a drug effect at the time the question is being asked (that is, at the moment). It is scored using a 100 millimeter (mm) bipolar visual analogue scale (VAS) anchored in the center with a neutral anchor of "neither like nor dislike" (score of 50 mm), on the left with "strong disliking" (score of 0 mm) and on the right with "strong liking" (score of 100 mm).

   Emax is largest effect score between 0.5 to 24 hours post-dose. Emin is smallest effect score between 0.5 to 24 hours post-dose.

2. Balance of Effects- Overall Drug Liking VAS: Peak Effect (Maximum Effect [Emax]) and Minimum Effect (Emin)

   Time frame: 6, 12, 24 hours post-dose

   Overall drug liking VAS is one of the measures of balance of effects that assesses the participant's global perception of drug liking (that is, effects over the whole course of the drug experience including any carryover effects). A 100 mm bipolar VAS is used to assess response based on a score ranging from 0 mm to 100 mm (0 mm = "strong disliking", 50 mm= "neither like nor dislike", and 100 mm= "strong liking").

   Emax is the largest effect score between 6 to 24 hours post-dose. Emin is the smallest effect score between 6 to 24 hours post-dose.

3. Balance of Effects- Take Drug Again VAS: Peak Effect (Maximum Effect [Emax])

   Time frame: 6, 12, 24 hours post-dose

   Take drug again VAS is one of the measures of balance of effects. It is a subjective assessment of the degree to which a participant would desire to take the drug again if given the opportunity. It is presented on a 100 mm bipolar VAS with score ranging from 0 mm to 100 mm (score of 0 mm = "definitely not", 50 mm = "do not care", and 100 mm = "definitely so").

   Emax is largest effect score between 6 hours to 24 hours.

4. Balance of Effects- Good and Bad Effects VAS: Peak Effect (Maximum Effect [Emax]) and Minimum Effect (Emin)

   Time frame: 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

   Good and Bad effects VAS is one of the measures of balance of effects that assesses the effect experienced by the participant on a 100 mm bipolar VAS, anchored in the center with a neutral anchor of neither good nor bad effects (score of 50 mm), on the left with bad effects(score of 0 mm) and on the right with good effects (score of 100 mm).

   Emax is largest effect score between 0.5 to 24 hours post-dose. Emin is smallest effect score between 0.5 to 24 hours post-dose.

5. Balance of Effects- Subjective Drug Value (SDV): Maximum Effect (Emax)

   Time frame: 6, 12, 24 hrs post-dose

   SDV is one of measures of balance of effects. It is a proxy measure of reinforcing efficacy that involves a series of independent, theoretical forced choices between drug administered and different monetary values. Participants were asked to choose between receiving another dose of same drug or an envelope containing specified amount of money, but they did not receive drug or money as described. Possible score range from 0.25 to 50. Higher score range indicates higher SDV. Emax: largest effect score between 6-24 hours post-dose.

6. Positive Effects- Addiction Research Center Inventory (ARCI) Morphine Benzedrine Group (MBG): Maximum Effect (Emax)

   Time frame: 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8 12, 24 hours post-dose

   ARCI (MBG) is one of the measures of positive effects. It is a set of 16 questions in which each question contributes to total score. Participants indicate their responses by selecting 'False' or 'True'. One point is given for each response that agrees with the scoring direction on scale i.e, true items receive a score of 1 if answer is 'True', false items receive a score of 1 if answer is 'False'. No points are given when the answer is opposite to the scoring direction. Score range: 0 to 16, higher score indicated positive effects. Emax: largest effect score between 0 to 24 hours post-dose.

7. Positive Effects- Good Drug Effects: Peak Effect (Maximum Effect [Emax])

   Time frame: 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

   Good drug effects VAS is one of the measures of positive effects that assesses the effect experienced by the participant on a 100 mm unipolar VAS, where responses are unidirectional and range from a response of 'none' (score of 0 mm= definitely not) to 'extremely' (score of 100 mm= definitely so).

   Emax is the largest effect score between 0.5 to 24 hours post-dose.

8. Positive Effects- High VAS: Peak Effect (Maximum Effect [Emax])

   Time frame: 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

   High VAS is one of the measures of positive effects that assesses the effect experienced by the participant on a 100 mm unipolar VAS, where responses are unidirectional and range from a response of 'none' (score of 0 mm= definitely not) to 'extremely' (score of 100 mm= definitely so).

   Emax is largest effect score between 0 to 24 hours.

9. Negative Effects- Bad Drug Effects: Peak Effect (Maximum Effect [Emax])

   Time frame: 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

   Bad effects VAS is one of the measures of negative effects that assesses the effect experienced by the participant on a 100 mm unipolar VAS, where responses are unidirectional and range from a response of 'none' (score of 0 mm= definitely not) to 'extremely' (score of 100 mm= definitely so).

   Emax is largest effect score between 0.5 to 24 hrs.

10. Negative Effects- Addiction Research Center Inventory (ARCI) Lysergic Acid Diethylamide (LSD): Maximum Effect (Emax)

    Time frame: 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

    ARCI (LSD) is one of the measures of negative effects. It is a set of 14 questions in which each question contributes to total score. Participants indicate their responses by selecting 'False' or 'True'. One point is given for each response that agrees with scoring direction on scale i.e, true items receive a score of 1 if answer is 'True', false items receive a score of 1 if answer is 'False'. No points are given when the answer is opposite to scoring direction. Score range: 0 to 14, higher score indicated higher negative effects. Emax: largest effect score between 0 to 24 hours post-dose.

11. Sedative Effects- Addiction Research Center Inventory (ARCI) Pentobarbital Chlorpromazine Group (PCAG): Maximum Effect (Emax)

    Time frame: 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

    ARCI (PCAG) is one of the measures of sedative effects. It is a set of 15 questions in which each question contributes to total score. Participants indicate their responses by selecting 'False' or 'True'. One point is given for each response that agrees with the scoring direction on scale i.e, true items receive a score of 1 if answer is 'True', false items receive a score of 1 if answer is 'False'. No points are given when answer is opposite to scoring direction. Score range: 0 to 15, higher score indicated higher sedative effects. Emax: largest effect score between 0 to 24 hours post-dose.

12. Sedative Effects- Alertness/Drowsiness: Minimum Effect (Emin)

    Time frame: 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

    Alertness/Drowsiness VAS is one of the measures of sedative effects. It is scored using a 100 mm bipolar VAS anchored in the center with a neutral anchor of "neither drowsy nor alert" (score of 50 mm), on the left with "very drowsy" (score of 0 mm) and on the right with "very alert" (score of 100 mm). Emin is the smallest effect score between 0 to 24 hours post-dose.

13. Other Subjective Effects- Any Drug Effects: Peak Effect (Maximum Effect [Emax])

    Time frame: 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

    Any drug effects VAS is one of the measures of other subjective effects. It assesses the effect experienced by the participant on a 100 mm unipolar VAS, where responses are unidirectional and range from a response of 'none' (score of 0 mm= definitely not) to 'extremely' (score of 100 mm= definitely so). Emax is the largest effect score between 0.5 to 24 hours post-dose.

14. Other Subjective Effects- Drug Similarity

    Time frame: 12 hours post-dose

    Drug similarity VAS is one of the measures of other subjective effects. It assesses the similarity of the drug recently received by the participant on a 100 mm unipolar VAS, where responses are unidirectional and range from a response of 'none' (score of 0 mm= not at all similar) to 'extremely' (score of 100 mm= very similar). Recently received drugs were compared with placebo, benzodiazepines, codeine/morphine, Tetrahydrocannabinol (THC), pseudoephedrine.

15. Other Subjective Effects- Addiction Research Center Inventory (ARCI) Benzedrine Group (BG): Maximum Effect (Emax) and Minimum Effect (Emin)

    Time frame: 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8, 12, 24 hours post-dose

    ARCI (BG) is measure of other subjective effects. It is a set of 13 questions in which each question contributes to total score. Participants select 'False' / 'True' for response. One point given for each response that agrees with scoring direction, true items receive score of 1 if answer 'True', false items receive score of 1 if answer 'False'. No points if answer is opposite to scoring direction. Score range: 0 to 13, higher score indicated higher other subjective effects. Emax: largest effect score between 0 - 24 hours post-dose. Emin: smallest effect score between 0 - 24 hours post-dose.