
Detecting THC-COOH in a driver can be an important part of a field sobriety test. Typically, THC-COOH concentrations will peak at about one to three hours after oral administration. This declines quickly, as does THC itself. In chronic users, THC-COOH concentrations will decrease rapidly.
THC-COOH levels peak at 1-3 hours after oral administration
Glucuronide-bound THC-COOH is a major urinary metabolite of THC. It has potential for pharmacokinetic interactions with CYPs. It is an end product of THC biotransformation in most species. It is a more lipophilic metabolite than the parent drug.
THC-COOH concentrations in urine are high after a single oral dose. The peak concentration of THC-COOH in plasma occurred less than nine minutes after the last puff sequence. The half-life of THC-COOH in urine was estimated to be 3-4 days when sensitive analytical procedures were used.
The pharmacokinetics of oral THC is important to the successful application of new therapeutic approaches. A mechanistic static model predicts AUCRhep. A basic mechanistic model, predicts that the rate of AUCRsys is related to the initial peak plasma THC concentration. The plasma THC concentrations are higher than inhibitory concentrations for CYP450 enzymes.
The liver eliminated THC rapidly. The THC concentration in liver fell to levels below measurable levels after 6 h. The glucuronide-bound THC-COOH concentration in liver was lower than the THC-COOH concentration in blood.
THC-COOH levels decline rapidly like THC does
Compared to THC, 11-nor-9-carboxy-D9-tetrahydrocannabinol (THC-COOH) is less active. However, it is at least as effective in activating CB1R. This is important to consider when studying the effects of THC.
The 11-nor-9-carboxy-D9-tetrahydrocannabinol-glucuronide (THC-COOH) is the major end product of THC biotransformation. This metabolite is most commonly found at higher temperatures. It is the substrate for UDP-glucuronosyltransferase. The enzyme adds a glucuronide moiety to form 11-nor-9-carboxy-D9-tetrahydrocannabinol-glucuronide.
The pharmacokinetic profile of THC was different between injections and inhalation. Plasma THC concentrations were higher following injection than inhalation. Plasma THC concentrations remained higher at all other timepoints. Similarly, plasma 11-OH-THC concentrations were lower following inhalation. The differences in plasma THC concentrations were not statistically significant at all timepoints. However, the results suggest that 11-OH-THC levels in the brain are lower following inhalation than injection.
Plasma 11-OH-THC concentrations are highest following injection at 30 minutes. Plasma THC concentrations at all other timepoints were statistically similar to those at 30 minutes. However, plasma THC concentrations were lower at 240 minutes.
THC-COOH detection time on field sobriety tests
Detection time on field sobriety tests depends on the type of drug and the frequency of use. Occasional use is detectable for a couple of days and chronic use for weeks.
There is evidence that THC stays in the system for weeks after use. Chronic users may develop a tolerance to THC. Detection times for chronic users can extend for up to three months. However, anecdotal reports of higher day-after blood THC levels in chronic users haven't been confirmed in controlled studies.
One of the most commonly used field sobriety tests is the modified Romberg balance. It is a two-stage procedure that includes a balance phase and a counting phase. The underlying mechanism is that THC is a tacky substance when heated.
The NC State Crime Lab tests for THC-COOH. This is a metabolite formed by oxidizing hydroxy-THC. The level is hundreds of nanograms per milliliter. THC-COOH is found in saliva, breathalyzers and blood tests. It is also present in fatty tissue and blood.
THC-COOH detection time in chronic users
Detection time for marijuana in urine tests depends on how often the user has used marijuana. A chronic user will have higher detection time than an occasional user. This is due to the metabolic cross-reaction between active 11-hydroxy-THC and inactive metabolites.
The THC-COOH metabolite is present in the body for up to two hours after smoking. It rapidly disperses into fatty tissues and becomes detectable in the blood and urine within a couple of hours after smoking. In contrast, the THC metabolite appears in the urine after only 60 minutes.
Detection time for chronic users may be even longer. In a study of 25 frequent users, THC-COOH was detected in the blood and urine for at least 24 hours after consumption. A test for THC-COOH detected an average of 45 ng/mL in plasma 12 hours after consumption.
Although it is not an accurate predictor of impairment, high blood THC levels are an indicator that a driver is under the influence. A chronic user may drive safely with high blood THC levels.
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