Research volunteers needed for a 16 week study for people using methamphetamine, looking to stop or reduce use. Eligible participants will attend 2 clinic visits a week, receive an oral and an injectable active drug or placebo, be randomly assigned to either the active drug or placebo, receive compensation for participation, and participate voluntarily, at no cost. Eligible participants will receive 12 weeks of medication, have clinic visits twice a week, and be compensated for study activities up to $1,610.