Hi dely1234-ga, and thanks for your question.
Alprazolam is metabolized to 4-hydroxy-alprazolam (90%) (an inactive
benzophenone) and alpha-hydroxy-alprazolam (10%) and has a half-life
of about 12-14 hours. About 1% or less of alprazolam is excreted
unchanged into the urine. The half-life can rise to as high as 16.3
hours in healthy elderly patients. The half-life in patients with
alcoholic liver disease can be as high as 65.3 hours.
http://www.rxlist.com/cgi/generic/alpraz_cp.htm
See also, for example, Table 1 in this reference:
Yuan R, Flockhart DA, Balian JD. Pharmacokinetic and pharmacodynamic
consequences of metabolism-based drug interactions with alprazolam,
midazolam, and triazolam. J Clin Pharmacol. 1999 Nov;39(11):1109-25.
Review.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10579141&query_hl=10&itool=pubmed_docsum
If you are interested, you can request a reprint of this article from Dr. Yuan:
Dr. Rae Yuan
HFD-860, CDER-OPS-OCPB-DPE I
Food and Drug Administration, 5600
Fishers Lane, Woodmont-II building, Room 4076
Rockville, MD 20857.
You can also purchase a copy ($25) from this link:
http://jcp.sagepub.com/cgi/reprint/39/11/1109
You can see Table 1 here:
http://img476.imageshack.us/img476/3231/xanaxtable10jr.jpg
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Other benzodiazepines follow a different metabolic pathway, ending
with oxazepam as one of the final metabolites. See the figure at this
site for a summary:
http://www.norchemlab.com/reference/dtq/0103dtq02.htm
So, this explains why you received a DUI notice. Nordiazepam,
oxazepam, and temazepam are not metabolites of Xanax, and shouldn't be
present in the urine. With regard to vitamins or GABA analogs taken
orally leading to synthesis of any of these drugs, this has not been
described in the literature and would be highly unlikely. See the
next section for some information about interactions between Xanax and
other herbal remedies.
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You can find a great deal of information about Xanax in the official
prescibing information literature:
http://www.xanax.com/xanax.pdf
There is some information on possible interactions between natural and
herbal remedies and Xanax here, the main one being with Kava, which
can synergistically enhance the CNS activity of alprazolam:
http://www.mothernature.com/Library/Ency/Index.cfm/id/1308001
or here:
http://www.deliciouslivingmag.com/healthnotes/healthnotes.cfm?org=nh&lang=EN&ContentID=1308001#Dni-Supp
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There are varying statements on the activity of the metabolites of
alprazolam, in part because the initial metabolite is itself quickly
inactivated via metabolism. RxList.com states that
"[t]he biological activity of a-hydroxy-alprazolam is approximately
one-half that of alprazolam."
http://www.rxlist.com/cgi/generic/alpraz_cp.htm
The above article also includes an in depth discussion of the
interactions of alprazolam with other medications. These are
summarized in Table 2:
http://img145.imageshack.us/img145/3433/xanaxtable23vt.jpg
It does not appear that your were on any of the medications listed in
this table, nor does it seem that the medications that you were on
interact with alprazolam.
RxList.com also gives a summary of the possible effects of other
medications on alprazolam concentrations:
" * Fluoxetine: Coadministration of fluoxetine with alprazolam
increased the maximum plasma concentration of alprazolam by 46%,
decreased clearance by 21%, increased half-life by 17%, and decreased
measured psychomotor performance.
* Propoxyphene: Coadministration of propoxyphene decreased the
maximum plasma concentration of alprazolam by 6%, decreased clearance
by 38%, and increased half-life by 58%.
* Oral Contraceptives: Coadministration of oral contraceptives
increased the maximum plasma concentration of alprazolam by 18%,
decreased clearance by 22%, and increased half-life by 29%."
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In terms of possible false positive tests, one authoritative source states that...
"False-positive results have been reported when the metabolites of
certain nonsteroidal anti-inflammatory drugs (oxaprozin, etodolac,
fenoprofen calcium, naproxen sodium, tolmetin sodium) are present in
the urine.[5] [25] [33]"
Ford: Clinical Toxicology, 1st Ed., Copyright © 2001 W. B. Saunders Company
Here are the references cited in the above quote:
[5]. Camara PD, Audette L, Velletri K, et al: False-positive
immunoassay results for urine benzodiazepine in patients receiving
oxaprozin. Clin Chem 1995; 41(1):115.
[25]. Matuch-Hite T, Jones P, Moriarity J: Interference of oxaprozin
with benzodiazepines via enzyme immunoassay technique [Letter]. J Anal
Toxicol 1995; 19(2):130.
[33]. Pulini M: False-positive benzodiazepine urine test due to
oxaprozin [Letter]. JAMA 1995; 273(24):1905.
This statement is reiterated on page 919 of the source below, stating
that in general, ibuprofen ingestion can lead to false positive
benzodiazepine urine immunoassay tests.
Wallach J.: Interpretation of Diagnostic Tests. 7th Ed. Lippincott
Williams & Wilkins, 2000.
Further, there have been multiple journal articles published on this phenomenon:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Display&dopt=pubmed_pubmed&from_uid=9491969
You may be interested in this article from Clinical Chemistry in 1995:
http://www.clinchem.org/cgi/reprint/41/1/115
Of course, gas chromatography based tests would not show a false
positive in the presence of an anti-inflammatory, so the likelihood of
this in your case would depend on what type of test was performed. If
the test used was an immunoassay and you have been taking any of the
anti-inflammatory drugs listed above and truly haven't taken any of
the other benzodiazepines, then this would seem like the most likely
explanation for your test results.
Also, if you were felt to be sufficiently impaired that you should not
be driving, even if you only had a positive test for Xanax and its
metabolites, you could still be charged with DUI, whether you take the
prescribed dose or higher. This may also be the basis of the charges
against you, rather than the other benzodiazepines found in your
urine.
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I hope this information is helpful. Please feel free to request any
clarification prior to rating.
-welte-ga |
