Effects of Cannabis Administration Routes on Human Performance and Pharmacokinetics

Background: \- Marijuana (cannabis) is an illegal drug. Researchers want to study people s reactions, attention, and behavior after they take marijuana in different ways. They want to learn better ways to detect drugs in a person s body They also want to know how long marijuana can be found in blood, urine, saliva, and breath. Objectives: \- To learn how people respond to delta-9-tetrahydrocannabinol (THC, a marijuana component) and how their bodies handle it after it is given in different ways. Eligibility: \- Adults age 18 50 who use marijuana. Design: * Participants are screened under another NIDA protocol. * This study involves up to 6 visits to NIDA. * At the first visit, participants will practice the tasks and tests they will do at their dosing sessions. They will learn how to give breath and saliva samples. * Dosing sessions 1 4 will last 3 5 days each. All participants will be admitted to a research clinic the night before these sessions. Some participants can stay at the clinic and some must go home between sessions. * At each session, participants will eat a brownie with placebo or marijuana. Then they will smoke a placebo or marijuana cigarette. Some will inhale placebo or marijuana after it is vaporized. * Throughout the sessions: * Participants will give urine, saliva, and breath samples. Their blood will be taken with a tube in a vein and finger pricks. Their vital signs will be checked. * Participants will answer questionnaires and take thinking tests. They will also take tests that assess eye movement, balance, and time estimation. * Participants may have a 5th dosing session. They will eat a marijuana brownie and have the above tests and samples.