Understanding the Clinical Pharmacology of Marijuana-Tobacco Co-administration

Inclusion Criteria: * Heart rate \< 105 beats per minute (BPM)\* * Systolic Blood Pressure \< 160 and \> 90\* * Diastolic Blood Pressure \< 100 and \> 50\* \*Considered out of range if both machine and manual readings are above/below these thresholds. * Body Mass Index (BMI) ≤ 38.0 (at investigator's discretion for higher BMI if no other concurrent health issues) * Current regular user of cannabis who smokes or vapes cannabis or THC extracts at least three days a week for the past 3 months or more * Test positive for D-9-tetrahydrocannabinol (THC) at screening and self-report of cannabis use * Current user of inhaled forms of tobacco/nicotine (cigarette, cigars, e-cigarettes) who use the product daily for the past 3 months or more * Saliva cotinine ≥ 30 ng/mL Exclusion Criteria: * Unstable medical conditions: * Heart disease * Seizures * Cancer * Thyroid disease (okay if controlled with medication) * Diabetes * Hepatitis B or C or Liver disease * Glaucoma * Kidney disease or urinary retention * An ulcer in the past year * Active use of an inhaler for asthma or Chronic Obstructive Pulmonary Disease (COPD) * Hypertension if uncontrolled (meaning participant has a diagnosis, but they are not taking medication/under treatment (e.g., diet or exercise plan) * Drug/Alcohol Dependence * Alcohol or illicit drug dependence within the past 12 months (currently in treatment) with the exception of those who recently completed an alcohol/drug treatment program * Positive toxicology test at the screening visit (THC \& prescribed medications okay) * Opioid replacement therapy (including methadone, buprenorphine, or other) * Psychiatric conditions * Current or past schizophrenia, and/or current or past bipolar disorder * Major depression, current or within the past year * Major personality disorder * Participants with current or past minor or moderate depression and/or anxiety disorders will be reviewed by the PI \[study physician\] and considered for inclusion * History of psychiatric hospitalizations are not exclusionary, but study participation will be determined as per PI's \[study physician's\] approval * Current regular use of any psychiatric medications with the exception of Selective serotonin reuptake inhibitors (SSRI) and serotonin-norepinephrine reuptake inhibitors (SNRI) and current evaluation by the PI that the participant is otherwise healthy, stable, and able to participate * Congenital or acquired immunodeficiency disorders (i.e. HIV, congenital immune deficiency syndrome, chronic diseases) * Other disorders (i.e. ICU, malnutrition, immunosuppressive therapy) * Traumatic brain injury * Recent onset or change (worsening) in cough, fever and/or abdominal symptoms (vomiting or pain) in the past two weeks * Medications * Use of medications that are inducers of nicotine metabolizing enzyme CYP2A6 (Example: rifampicin, dexamethasone, phenobarbital, and other anticonvulsant drugs) * Concurrent use of nicotine-containing medications * Any stimulant medications (ex. Adderall) generally given for attention deficit hyperactivity disorder (ADHD) treatment * Other/Misc. Chronic Health Problems * Oral thrush * Fainting * Other "life threatening illnesses" as per study physician's discretion * Pregnancy * Pregnancy (self-reported and urine pregnancy test) * Breastfeeding (determined by self-report) * Concurrent participation in another clinical trial * Inability to communicate in English * History of marijuana-induced psychosis or paranoia after smoking marijuana * Scoring a 7 or higher on the Severity of Dependence Scale (SDS) for cannabis use * Planning to quit smoking or vaping within the next 60 days * Planning to quit cannabis use within the next 60 days * Uncomfortable with getting blood drawn * Willingness to abstain from tobacco smoking and all combustible products for 13 hours before admission * Willingness to abstain from smoking/ingestion of cannabis 13 hours before * Willingness to abstain from nicotine products 13 hours before each admission