Model development data were obtained from daily cannabis smokers with positive cannabinoid immunoassay results greater than 100 ng/mL THCCOOH equivalents upon entry into inpatient research protocols approved by the National Institute on Drug Abuse (NIDA) Institutional Review Board. Participants resided continuously on the closed clinical research unit for up to 30 days. Participants’ physical and psychological health was verified by medical history and physical examination, psychological tests, ECG, CBC and blood chemistries, and urinalysis. All belongings were searched prior to unit entry and no visitors were allowed. All voided urine was collected ad libitum and analyzed for THCCOOH by GCMS following alkaline hydrolysis (4 (link)) with a 2.5 ng/mL LOQ, with concentrations normalized to urine creatinine determined by a modified Jaffe method.
Models were validated with specimens from a separate group of long-term daily cannabis smokers (reporting ≥5000 lifetime episodes of cannabis use) who were engaged in an outpatient research study evaluating neurocognitive performance during extended drug abstinence (16 (link)). This study was approved by the McLean Hospital and NIDA IRBs; written informed consent was obtained from all participants after a complete description of the study. These participants agreed to maintain cannabis abstinence for 28 days, with compliance evaluated by urine CN-THCCOOH concentrations in daily urine specimens collected under direct observation. The ratio of Specimen 2/Specimen 1 normalized concentrations was determined; a 50% increase (ratio of 1.5) compared to the preceding concentration indicated new cannabis use. Participants were not currently taking psychoactive medications and had ≤100 lifetime cocaine, stimulant, opioid, sedative-hypnotic, hallucinogen and inhalant uses.
Models were validated with specimens from a separate group of long-term daily cannabis smokers (reporting ≥5000 lifetime episodes of cannabis use) who were engaged in an outpatient research study evaluating neurocognitive performance during extended drug abstinence (16 (link)). This study was approved by the McLean Hospital and NIDA IRBs; written informed consent was obtained from all participants after a complete description of the study. These participants agreed to maintain cannabis abstinence for 28 days, with compliance evaluated by urine CN-THCCOOH concentrations in daily urine specimens collected under direct observation. The ratio of Specimen 2/Specimen 1 normalized concentrations was determined; a 50% increase (ratio of 1.5) compared to the preceding concentration indicated new cannabis use. Participants were not currently taking psychoactive medications and had ≤100 lifetime cocaine, stimulant, opioid, sedative-hypnotic, hallucinogen and inhalant uses.
