THC-COOH

11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) is the terminal, pharmacologically inactive oxidation metabolite of Δ9-THC, produced via sequential hepatic CYP450-mediated hydroxylation (to 11-OH-THC) and further oxidation. Because it is highly lipophilic, THC-COOH accumulates in adipose tissue and is released slowly into plasma, producing extended detection windows: plasma/urine detectable for 2–7 days after single use and up to 30+ days after chronic heavy use (Huestis 2007). It is the primary analyte in urinary cannabis drug testing: SAMHSA's Mandatory Guidelines for Federal Workplace Drug Testing Programs specify an immunoassay screening cutoff of 50 ng/mL and GC-MS/LC-MS confirmatory cutoff of 15 ng/mL for THC-COOH (SAMHSA 2017/2023). Because THC-COOH is inactive, its presence indicates prior exposure but does not establish current impairment — a distinction central to DUID policy debates. Citations: Huestis MA. Chem Biodivers. 2007;4:1770-1804; SAMHSA. Mandatory Guidelines for Federal Workplace Drug Testing Programs — Urine. 2023; Hartman RL, Huestis MA. Clin Chem. 2013;59:478-492. ---