A Metabolite Found Only in Natural Marijuana Can Distinguish It From Prescription THC in Drug Tests
THCV-COOH, a urinary metabolite of a compound found in natural marijuana but absent from synthetic Marinol, was detected only after marijuana use, providing a reliable way to distinguish marijuana from prescription THC in drug tests.
Quick Facts
What This Study Found
Because synthetic THC (Marinol) and natural marijuana produce identical urinary metabolites, drug tests cannot tell them apart. This creates a problem: people testing positive for cannabis can claim they were using a prescription.
Researchers identified a solution: delta-9-tetrahydrocannabivarin (THCV), a natural compound present in marijuana but absent from synthetic Marinol. THCV is metabolized to THCV-COOH, which can be detected in urine.
Four subjects received, in randomized order: oral Marinol (15 mg), smoked THC in a placebo marijuana cigarette (16.88 mg), or smoked marijuana (2.11% THC, 0.12% THCV). Urine was collected for one week.
THCV-COOH was detected only after smoking actual marijuana. Neither oral Marinol nor smoked pure THC produced THCV-COOH in urine. This confirmed THCV-COOH as a reliable marker to distinguish marijuana use from Marinol use.
Key Numbers
Four subjects, three sessions. Marinol: 15 mg oral. Smoked THC: 16.88 mg. Smoked marijuana: 2.11% THC, 0.12% THCV. Detection limit: 1.0 ng/mL. THCV-COOH only positive after marijuana.
How They Did This
Three-session, within-subject, crossover design with four subjects. Each received oral Marinol, smoked THC in placebo cigarette, and smoked marijuana in randomized order. GC-MS analysis of urine for THC-COOH and THCV-COOH.
Why This Research Matters
This study solved a practical problem in drug testing: distinguishing between legal prescription THC and illegal marijuana use. The THCV-COOH marker has since been used in forensic and workplace drug testing when this distinction matters.
The Bigger Picture
As more patients receive prescription cannabinoids, the ability to distinguish pharmaceutical from botanical cannabis use in drug testing has become increasingly important for workplace, legal, and clinical purposes.
What This Study Doesn't Tell Us
Only four subjects. THCV content varies among marijuana varieties, so very low-THCV marijuana might not produce detectable THCV-COOH. The study predates the availability of many modern cannabis products. Detection window for THCV-COOH may be shorter than for THC-COOH.
Questions This Raises
- ?Does THCV-COOH detection work with edible marijuana as well as smoked?
- ?How does THCV content vary across commercial cannabis strains?
- ?What is the detection window for THCV-COOH compared to THC-COOH?
Trust & Context
- Key Stat:
- THCV-COOH was detected only after smoking marijuana, never after Marinol
- Evidence Grade:
- A controlled crossover study with the strongest possible design for a biomarker validation study, though with only four subjects.
- Study Age:
- Published in 2001. The THCV marker approach has been adopted in some forensic testing protocols.
- Original Title:
- Delta9-tetrahydrocannabivarin as a marker for the ingestion of marijuana versus Marinol: results of a clinical study.
- Published In:
- Journal of analytical toxicology, 25(7), 565-71 (2001)
- Authors:
- ElSohly, M A(4), deWit, H, Wachtel, S R, Feng, S, Murphy, T P
- Database ID:
- RTHC-00104
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
Can drug tests tell marijuana from prescription THC?
Standard tests cannot, but testing for THCV-COOH (a metabolite of THCV, found only in natural marijuana) can distinguish the two, as this study demonstrated.
Why does this matter?
Patients with prescriptions for synthetic THC (Marinol) may test positive for cannabis on standard drug tests. The THCV marker allows drug testers to determine whether the person used marijuana or only their prescription.
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Cite This Study
https://rethinkthc.com/research/RTHC-00104APA
ElSohly, M A; deWit, H; Wachtel, S R; Feng, S; Murphy, T P. (2001). Delta9-tetrahydrocannabivarin as a marker for the ingestion of marijuana versus Marinol: results of a clinical study.. Journal of analytical toxicology, 25(7), 565-71.
MLA
ElSohly, M A, et al. "Delta9-tetrahydrocannabivarin as a marker for the ingestion of marijuana versus Marinol: results of a clinical study.." Journal of analytical toxicology, 2001.
RethinkTHC
RethinkTHC Research Database. "Delta9-tetrahydrocannabivarin as a marker for the ingestion ..." RTHC-00104. Retrieved from https://rethinkthc.com/research/elsohly-2001-delta9tetrahydrocannabivarin-as-a-marker
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.