Urinary excretion profiles of 11-nor-9-carboxy- Delta super(9)-tetrahydrocannabinol Study III. A Delta super(9)-THC-COOH to creatinine ratio study

• Published in: Forensic science international Vol. 137; no. 2-3; pp. 196 - 202
• Main Authors: Fraser, AD, Worth, D
• Format: Journal Article
• Language: English
• Published: 26.11.2003
• ISSN: 0379-0738
• DOI: 10.1016/j.forsciint.2003.07.011

Huestis and Cone reported in that serial monitoring of Delta super(9)-THC-COOH/creatinine ratios in paired urine specimens collected at least 24 h apart could differentiate new drug use from residual Delta super(9)-THC-COOH excretion following acute marijuana use in a controlled setting. The best accuracy (85.4%) for predicting new marijuana use was for a Delta super(9)-THC-COOH/creatinine ratio greater than or equal to 0.5 (dividing the Delta super(9)-THC-COOH/creatinine ratio of specimen no. 2 by the specimen no. 1 ratio). In previous studies in this laboratory, urine specimens were collected from chronic marijuana users greater than or equal to 24 h or greater than or equal to 48 h apart in an uncontrolled setting. Subjects with a history of chronic marijuana use were screened for cannabinoids with the EMIT registered II Plus cannabinoids assay (cut-off 50 ng/ml) followed by confirmation for Delta super(9)-THC-COOH by GC-MS (cut-off 15 ng/ml). Creatinine was analyzed as an index of dilution. The objective of the present study was to evaluate whether creatinine corrected specimens could differentiate new marijuana or hashish use from the excretion of residual Delta super(9)-THC-COOH in chronic marijuana users based on the Huestis 0.5 ratio. Urine specimens (N = 376) were collected from 29 individuals greater than or equal to 96 h between urine collections. The mean urinary Delta super(9)-THC-COOH concentration was 464.4 ng/ml, mean Delta super(9)-THC-COOH/creatinine ratio (ng/(ml Delta super(9)-THC-COOH mmol 1 creatinine)) was 36.8 and the overall mean Delta super(9)-THC-COOH/creatinine ratio of specimen 2/mean Delta super(9)-THC-COOH/creatinine ratio of specimen 1 was 1.37. The Huestis ratio calculation indicated new drug use in 83% of all sequentially paired urine specimens. The data were sub-divided into three groups (Groups A-C) based on mean Delta super(9)-THC-COOH/creatinine values. Interindividual mean Delta super(9)-THC-COOH/creatinine values ranged from 4.7 to 13.4 in Group A where 80% of paired specimens indicated new drug use (N = 10) and 20.4-39.6 in Group B where 83.6% of paired specimens indicated new drug use (N = 7). Individual mean Delta super(9)-THC-COOH/creatinine values ranged from 44.2 to 120.2 in Group C where 84.5% of paired urine specimens indicated new marijuana use (N = 12). Correcting Delta super(9)-THC-COOH excretion for urinary dilution and comparing Delta super(9)-THC-COOH/creatinine concentration ratios of sequentially paired specimens (collected greater than or equal to 96 h apart) may provide an objective indicator of ongoing marijuana or hashish use in this population.