Effects of Pre-Session Supplemental Hydromorphone on Drug Seeking Behavior in Opioid Dependent Individuals

Drug dependence is a condition in which drug seeking holds a higher priority than behaviors
controlled by other reinforcers. Learning to understand, predict, and control this
maladaptive choice behavior may lead to improved prevention and treatment strategies. HYD is
a drug currently used as a cough suppressant and to relieve pain. The purpose of this study
is to determine the extent to which opioid drug seeking behavior in heroin dependent
individuals can be reduced by environmental factors, including supplemental opioid drug
availability, drug price, and non-drug alternative reinforcers. Specifically, this study
will determine whether pre-session opportunity to take "free" supplemental HYD influences
HYD seeking by using a choice progressive ratio schedule as well as by varying the dose of
HYD.

Participants in this observational study will undergo multiple test sessions in which they
will select between acquiring drug or money. Because participants may choose money on all 12
trials of test sessions as a way to avoid receiving an injection, a placebo injection will
be given when money is chosen. Prior to each test session, participants will receive a
sample of the drug dose. During each test session, participants will have 12 opportunities
to select either drug (administered as HYD) or money. Prior to each individual choice trial,
participants will receive supplemental HYD. Participants will use a computer to earn
choices. Respiration rate, oxygen saturation, heart rate, and blood pressure will be
monitored throughout choice trials. Pupil diameter will be measured with a digital camera.
Participants will complete self-report questionnaires at different times during the study.
Participants will be maintained on buprenorphine throughout the study, with a fixed 3-week
detoxification after study completion.

Inclusion Criteria:

- Current opiate dependence, verified by the structured clinical interview for DSM-IV
(SCID) and Addiction Severity Index (ASI)

- Positive urine test for opiates

- Agreement to use adequate contraception for the duration of the study

- Able to read and write English

Exclusion Criteria:

- DSM-IV diagnosis of a psychiatric illness

- History of or current neurological disease, including structural brain abnormalities,
seizures, infection, peripheral neuropathy, and head trauma

- History of cardiovascular disease, myocardial infarction, chest pain, edema, systolic
blood pressure greater than 160 mm Hg or less than 95 mm Hg, or diastolic blood
pressure greater than 95 mm Hg

- Pulmonary disease, including obstructive pulmonary disease, cor pulmonale,
tuberculosis, and asthma

- Systemic diseases, such as endocrinopathies, liver or kidney failure, myxedema,
hypothyroidism, Addison's disease, or autoimmune disease

- Current alcohol or sedative drug dependence

- Pregnant or breastfeeding

- Currently receiving treatment for opioid dependence

- Known phobia of injections