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Q: Nicotine and Cotinine tests ( Answered,   0 Comments )
Subject: Nicotine and Cotinine tests
Category: Health > Conditions and Diseases
Asked by: realtorcoombes-ga
List Price: $10.00
Posted: 29 Jun 2006 16:36 PDT
Expires: 29 Jul 2006 16:36 PDT
Question ID: 742181
I stopped chewing tobacco almost 3 months ago after chewing for over
20 years.  I took a blood test to check my nicotine levels a couple
weeks ago.  My results show: range at 11 ng/ml.  My range at 260 ng/ml.  What do these levels mean?  (I am
not around anyone who smokes.) I would like to know if the nicotine is
out of my body and if not, how long will it take to be free and clear
of this horrible drug.
Subject: Re: Nicotine and Cotinine tests
Answered By: crabcakes-ga on 29 Jun 2006 22:07 PDT
Hello Realtorcoombs,

  Congratulations on giving up chewing tobacco!

   It?s hard for me to say this, but perhaps there was a lab error.
While I found no drugs that interefere with this test, there may be
supplements or a food that could have caused a false elevation of
cotinine in your urine. You weren?t wearing a nicotine patch were you?
Unless you have a genetic defect that causes your liver to very slowly
metabolize nicotine, your results for cotinine should have been far
lower, or even negative. This genetic defect appears to be more common
in people of Asian heritage.

?A comparison of Latino, white, and Chinese-American smokers suggests
that people of East Asian descent are apt to clear nicotine from their
blood more gradually than the other smokers do, thereby staving off a
craving for the next cigarette.
Researchers recruited 131 smokers?37 Chinese-Americans, 40 Latinos,
and 54 whites?for the analysis. Each volunteer gave a blood sample
before receiving an intravenous infusion of nicotine. The substance
was labeled with deuterium atoms, a heavy form of hydrogen, to make it
detectable in the blood. After the injection, the participants
provided 10 blood samples at specific intervals over the next 8 hours,
then one per day for 4 days.

Nicotine is cleared from the blood by liver enzymes that convert it to
its metabolite cotinine. Blood analysis showed that it took an average
of 152 minutes for half the injected nicotine to degrade in the blood
of the Chinese-Americans in this study. Nicotine's half-life in whites
and Latinos was 134 and 122 minutes, respectively. Slow metabolism of
nicotine draws out its effects, says Neal L. Benowitz, a clinical
pharmacologist at the University of California, San Francisco. He and
his colleagues report their work in the Jan. 16 Journal of the
National Cancer Institute.? 

?Nicotine metabolism is complex. Nicotine, a highly lipid-soluble
alkaloid, is converted to cotinine in a two-step process involving
cytochrome P450 and aldehyde oxidase. Nicotine is eliminated primarily
by hepatic metabolism by way of C-oxidation to cotinine, the major
metabolite. While nicotine has a relatively short half-life of about 2
hours, cotinine has a half-life of approximately 20 hours. Therefore,
cotinine provides a more stable marker of exposure in the person since
there is less variability in cotinine throughout the day than that
observed for nicotine.?

A half life means that half of the cotinine is out of your system in
about 20 hours. In another 20 hours, half of that is gone, and in
another 20 hours, half of that remaining cotinine is cleared. This
means barring a genetic defect, all traces of cotinine should be gone
within a week.

?Depending on how high your level is to begin with, your level could
drop to that of a nonsmoker in 7 to 10 days.?

?However, according to  Julie Possner, a paramedical examiner with Exam
& Profile Services in Wisconsin,  "Cigarettes [nicotine] will show up
many days or even weeks after use in somebody's urine. It will
probably still show up if someone has refrained from smoking for a
short time prior to the exam." (SOURCE: "The Lowdown on Life Insurance
Medical Exams", Yahoo!,

?Different people metabolize nicotine at different rates. Some people
even have a genetic defect in the enzymes in their liver that break
down nicotine, whereby the mutant enzyme is much less effective at
metabolizing nicotine than the normal variant. If a person has this
gene, their blood and brain nicotine levels stay higher for longer
after smoking a cigarette. Normally, people keep smoking cigarettes
throughout the day to maintain a steady level of nicotine in their
bodies. Smokers with this gene usually end up smoking many fewer
cigarettes, because they don't constantly need more nicotine.?

?A GENETIC defect which slows down the liver's capacity to clear
nicotine from the body increases the chances of tobacco addiction,
research revealed today.

Another study concluded that almost five million people around the
world died from smoking in 2000, in line with previous estimates.

The research came after the Government declared a ban on smoking in
the majority of public places within four years and increased efforts
to encourage smokers to kick the habit.?

?Over a period of about a month, these symptoms and the physiological
changes subside. But for many smokers, even a day without nicotine is
excruciating. Every year, millions of people try to break the nicotine
habit; only 10 percent of them succeed.?

?The elimination half-life of nicotine averages 2 hours
(Benowitz, 1982;) Feyerabend, 1985). The half-life of a drug 
is useful in predicting the rate of accumulation of that drug 
in the body with repetitive dosing and the time course of 
decline after cessation of dosing. Consistent with a half-life 
of 2 hours, accumulation of nicotine over 6 to 8 hours during 
regular smoking and persistence of significant levels of 
nicotine in the blood for 6 to 8 hours after cessation of 
smoking, i.e. overnight, has been observed (Benowitz, 1982b). 
Thus, cigarette smoking represents a situation where the 
smoker is exposed to significant concentrations and possibly 
pharmacological effects of nicotine for 24 hours a day.?

?Nicotine and its metabolites (cotinine and nicotine 1-N-oxide)
are excreted in the urine. At a pH of 5.5 or less, 23% is
excreted unchanged. At a pH of 8, only 2% is excreted in the
urine. The effect of urinary pH on total clearance is due
entirely to changes in renal clearance. (Ellenhorn, 1988).

Nicotine is secreted into saliva. Passage of saliva containing
nicotine into the stomach, combined with the trapping of
nicotine in the acidic gastric fluid and reabsorption from the
small bowel, provides a potential route for enteric nicotine
recirculation. This recirculation may account for some of the
oscillations in the terminal decline phase of nicotine blood
levels after I.V. nicotine infusion or cessation of smoking.

I hope this has helped you! Please check each link for complete
information. Consider getting retested if you need clean results for
employment or insurance purposes.

If any part of this answer is unclear, please request an Answer
Clarification, and allow me to respond, before you rate.

Sincerely, Crabcakes

Search Terms
Cotinine clearance
Cotinine nicotine + metabolism
Cotinine urine GC/MS test
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