Drug Discrimination in Methadone-Maintained Humans Study 3

Inclusion Criteria:

1. Must be between the ages of 18-65.

2. Participation in the UAMS Substance Abuse Treatment Clinic Methadone Maintenance
Program or the CATAR Clinic Little Rock with maintenance on a stable dose of
methadone (+ or - 10 mg) for at least 1 month prior to study entry.

3. Subjects would have to be in "good standing" in the methadone maintenance program in
order to participate; i.e., compliance with scheduled medication and group therapy
session hours. This would be defined as < 3 missed methadone medications and missed <
3 group and <3 individual therapy sessions in the two months prior to study
participation

4. Subjects must submit a urine sample negative for illicit drugs prior to study entry.

5. Subjects must be able to read and understand English.

Exclusion Criteria:

1. Unstable medical condition (e.g., major, unstable cardiovascular, renal, endocrine or
hepatic disease) or stable medical condition requiring treatment that would interact
with study medications (e.g., controlled hypertension on an antihypertensive) or
ability to participate in study sessions, (e.g.,chronic back pain that would preclude
being able to sit for long periods, etc), to be determined by history provided by the
prospective subject or laboratory evaluation and physical examination as outlined
below. These would be determined by the study physician alone or in consultation with
the PI.

2. Current diagnosis of other drug or alcohol physical dependence (other than tobacco).

3. History of major psychiatric disorder (psychosis, schizophrenia, bipolar) or current
psychiatric disorder that requires medication (e.g., current major depression).

4. Pregnancy, plans to become pregnant or inadequate birth control (adequate birth
control includes an IUD, condoms, birth control pills, etc). Male participants are
encouraged to use condoms because little has been studied on the effects of these
drugs on the male reproductive system.

5. Present or recent use of over-the-counter psychoactive drug, prescription
psychoactive drug (antidepressants, anxiolytics, antipsychotics and anticonvulsants
that may also be used for mood stabilization or sleep disruption) or drug (e.g.,
ciprofloxacin, fluvoxamine) that would have major interaction with drugs to be
tested.

6. Liver function tests greater than 3 times normal, BUN and Creatinine outside normal
range, or thyroid function tests outside normal range.

7. A supine or semi-recumbent blood pressure of 100/65mmHg, a seated blood pressure of
90/60mmHg, or orthostatic change of >20mmHg systolic or >10mmHg diastolic on standing
or heart rate less than 60 beats/min.

8. EKG abnormalities including but not limited to: bradycardia (<60 bpm); prolonged QTc
interval (>450 msec); Wolff-Parkinson White syndrome; wide complex tachycardia; 2nd
degree, Mobitz type II heart block; 3rd degree heart block; left or right bundle
branch block.

9. Participants who become arrested and/or incarcerated will not be allowed to continue
to participate.