How Many Gallons Of Water Do I Have To Drink To Be Clean Of Thc

MJ, a 40 years erstwhile female, presents to your pain clinic for a routine follow-upwardly visit. You determine to run a random urine drug screen past immunoassay (IA) and she tests positive for cannabinoids.

When asked, MJ admits "I only smoked 2 puffs five days ago".

Fact or Myth?

Mena Raouf, a star PharmD Candidate, took a closer look at this.
Here'due south what he had to say…

Marijuana Pharmacokinetics

Δ^nine-tetrahydrocannabinol (THC) is the major psychoactive metabolite of cannabinoids, which is highly lipophilic and distributes into adipose tissue, liver, lung, and spleen. [1,iii] Following inhalation, THC can be detected in the blood within seconds; withal, its bioavailability varies depending on the depth and elapsing of inhalation. It is estimated that the bioavailability of THC is approximately ten-fourteen% in occasional users and 23-27% in chronic users. [ane,2]

Equally seen in effigy 1 below, the psychoactive component (THC) of marijuana, undergoes hepatic hydroxylation to generate the equipotent metabolite Δ^9_tetra hydrocannabinol (11-OH-THC) catalyzed by CYP 2C19 and 8β-hydroxy-Δ⁹-tetrahydrocannabinol (8 β -OH-THC) catalyzed by CYP 3A4. [1,iii] eleven-OH-THC undergoes oxidation to generate the inactive carboxy-Δ⁹-tetrahydrocannbinol (THCCOOH). Carboxy-Δ⁹-tetrahydrocannbinol is conjugated with glucuronic acrid and excreted in the urine. 8β-OH-THC undergoes dehydroxylation to generate 8β,11-di-OH-THC, which indicates recent cannabinoid use if present. [1,3,4,5] However, carboxy-Δ⁹-tetrahydrocannbinol is the most abundant and prevalent metabolite and is ultimately the compound of involvement for urine drug screening. [one,3,five]

Figure ane: Metabolism of THC Following Smoking

Urine Detection

Figure ii illustrates how THC and its metabolites are eliminated in the urine and feces as shown in a study by Manno et al. [viii] where cannabinoids were measured in the urine in 8 subjects that smoked a marijuana cigarette containing 27mg of THC. THC urine concentrations peaked at 21.5 ng/mL in 2 hours and were undetectable (<1.v ng/mL) in 5 out of viii subjects after half-dozen hours. Urine concentrations of 11-OH-THC and THC-COOH peaked at iii hours and 4 hours respectively. THC-COOH, the compound of interest in urine drug screening, has a urinary half-life of 2-3 days. [5,6,8,x]

Figure two: concentrations of THC metabolites in the urine following smoking [1,8]

Post-obit a single marijuana utilise, THC is unlikely to exist detected in the urine beyond 3 days at the 50 ng/ml cut-off level and beyond 7 days for the 20 ng/mL cutoff level. [4] For a unmarried use based on the 50ng/mL cutoff, carboxy-Δ^nine-tetrahydrocannbinol can be detected in the urine within three days. For moderate employ (4 times/week), the detection winodw is 5-7 days. For daily use, the detection window is x-xv days with up to 30 days for long-term chronic smokers. [nine] Detection times are summarized below in table 1.

Tabular array 1: Marijuana Urine Detection (IA) Fourth dimension Based on Utilise [7]

Frequency of use	Detection window (days)
Single use	3 days
Moderate utilise (4 times/week)	5-7 days
Daily use	10-15 days
Chronic heavy use	>30 days

At present back to our patient MJ

If the patient truly smoked "2 puffs 5 days ago", then she should take tested negative based on the 50 ng/mL laboratory cutting-off by immunoassay. Her positive test at this cut-off translates to moderate employ (4 times/calendar week).

Marijuana is still the most commonly detected substance of abuse on urine drug screening by IA, but permit's not forget that faux positives are common with cannabinoids as elucidated and identified in Dr. Fudin's Urintel Drug Application after inputting concomitant medication data. Information technology remains a dilemma in pain management where patients with true pathologies and legitimate pain seek marijuana and other illicit substances for pain relief and anxiolytic effects. The presence of illicit substance does non necessarily negate the legitimacy of the patient'due south pain complaints, only it may propose the presence of concurrent disorder such every bit substance abuse or "chemical coping". The patient must be willing to work with the healthcare squad to receive handling for both disorders; that is a decision the patient has to brand.

This article was collaboratively written with Mena Raouf, a 2016 PharmD Candidate at the Albany College of Pharmacy and HealthSciences with a concentration in Nephrology. Mena moved out of Arab republic of egypt 5 years agone to kickoff chemist's shop schoolhouse and career in the U.S. He hopes to complete PGY1 and PGY2 Chemist's Residency and practice as a clinical pharmacist specialist. He is currently under the mentorship of Dr. Fudin studying hurting management.

References:

Lapoint JM. Cannabinoids. In: Hoffman RS, Howland M, Lewin NA, Nelson LS, Goldfrank LR. eds. Goldfrank's Toxicologic Emergencies, 10e. New York, NY: McGraw-Colina; 2015.
McBurney LJ, Bobbie BA, Sepp LA. GC/MS and EMIT analyses for delta ix-tetrahydrocannabinol metabolites in plasma and urine of human subjects. J Anal Toxicol. 1986;x:56–64.
Grotenhermen F: Pharmacokinetics and pharmacodynamics of cannabinoids. Clin Pharmacokinet. 2003;42:327–360.CrossRef [PubMed: 12648025]
Smith-kielland A, Skuterud B, Morlan J. Urinary Excretion of 11-nor-9-Carboxy-AgTetrahydrocannabinol and Cannabinoids in Frequent and Infrequent Drug Users. Journal of Analytical Toxicology, Vol. 23, September 1999
Huestis 1000, Mitchel JM, Cone EJ. Urinary Excretion Profiles of 11-Nor-9-Carboxy-AgTetrahydrocannabinol in Humans afterwards Single Smoked Doses of Marijuana. Journal of Belittling Toxicology, Vol. xx, October 1996
Goodwin RS, Darwin WD, Chaing Due north et al. Urinary Emptying of 11-Nor-9-carboxy- 9-tetrahydrocannnabinolin Cannabis Users During Continuously Monitored Forbearance. J Anal Toxicol. 2008 October ; 32(8): 562–569.
Moeller KE, Lee KC, Kissack JC. Urine Drug Screening:Applied Guide for Clinicians. Mayo Clin roc. January 2008;83(1):66-76

Manno JE, Manno BR, Kemp PM et al.: Temporal indication of marijuana employ can exist estimated from plasma and urine concentrations of delta9-tetrahydrocannabinol, eleven-hydroxy-delta9-tetrahydrocannabinol, and eleven-nor-delta9-tetrahydrocannabinol-ix-carboxylic acrid. J Anal Toxicol. 2001;25:538–549
Detection fourth dimension of drugs of abuse in urine.Vandevenne Thou, Vandenbussche H, Verstraete A Acta Clin Belg. 2000 Nov-December; 55(half-dozen):323-33.
Karschner EL, Schwilke EW, Lowe RH et al. Implications of plasma Delta9-tetrahydrocannabinol, 11-hydroxy-THC, and eleven-nor-9-carboxy-THC concentrations in chronic cannabis smokers. J Anal Toxicol. 2009 Oct; 33(viii):469-77.
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