Early THC-COOH Concentrations Were Higher in Capillary Blood While Parent THC Was Generally Lower
Capillary sampling did not change every cannabinoid concentration in the same direction. Ten-minute THC-COOH comparisons favored capillary blood across the study groups, unlike the general parent-THC pattern.
The metabolite showed an early difference
The paired study reported significantly higher capillary THC-COOH concentrations at ten minutes for daily concentrate, daily flower and occasional flower users. At subsequent times, concentrations matched more closely and the reported metabolite comparisons were not statistically significant.
Parent and metabolite cannot share an assumed correction
Parent THC was generally lower in capillary blood after inhalation. Treating the capillary specimen as uniformly diluted or concentrated would fail to preserve these opposing analyte-specific observations. The measured compounds have different disposition patterns; the paper does not isolate one universal physiological explanation for every difference.
An analyte-specific result remains necessary
The upper-arm collection method and specimen handling belong to the comparison. Agreement later in the sampling period should not be projected backward to the early interval, and a nonsignificant difference is not formal proof of equivalence. The study supplies human paired-specimen evidence. It does not establish that an early metabolite excess means more severe intoxication or that a lower parent result signifies less impairment in an individual.
Related analysis: the study’s broader findings and limitations.
