Guanfacine Extended-release for Adolescents With Cannabis Use

Inclusion Criteria:

1. 12-25 years of age (inclusive) at consent;

2. Seeking treatment for cannabis use;

3. DSM-5 Cannabis Use Disorder, mild, moderate or severe;

4. Self-reported cannabis use on average at least 5 days/week during the 28 days priorto screening with a THC positive urine drug screen on the day of screening; and

5. Able to provide informed consent (both adequate IQ and English fluency; <18-year-olds will provide consent themselves in addition to parent/guardianconsent).

Exclusion Criteria:

1. DSM-5 substance use disorder (moderate or severe) except cannabis or nicotine;

2. Any unstable medical, psychiatric or neurological condition or medicalcontraindicating study participation;

3. Diagnosis of a psychotic or bipolar illness;

4. Acute suicidality as assessed by clinician;

5. Prescribed antipsychotics, benzodiazepines or other sedative medications, or othermedications for the treatment of ADHD. If prescribed antidepressants, theparticipant must have been on a stable dose for more than 2 weeks at screening;

6. A history of heart disease or cardiac risk factors (e.g. arrhythmias);

7. Abnormal liver or thyroid function as indicated by clinically-significant findingson blood tests;

8. Pregnancy, breast feeding or, if sexually active and able to become pregnant, noeffective contraception.

9. Intention to enter residential rehabilitation after treatment in the YSASresidential withdrawal facility.