Urine Testing: The Basics

March 19th, 2009 Allen Trapp Posted in Driving under the Influence of Drugs, Urine Test No Comments »

     Urine samples are usually tested for drugs by using a screening test followed by gas chromatography-mass spectroscopy (GCMS).  The screening test is normally an enzymatic method of analysis that determines if the “signal strength” is at or above a cut-off level.  These tests employ reagents that interact with several different but related compounds (e.g., metabolites) and measure the total “signal strength” of all those compounds. 

     GCMS should be able to identify both the parent drug and any metabolite(s).  If a parent drug is identified, the metabolite should also be present.  For example, if a urine sample is positive for methamphetamine, it should also be positive for amphetamine. 

     In order for a test result to be reported as positive the amount of a compound should equal or exceed the cut-off level.  If the cut-off limit for the GCMS is not met, the result should be reported as negative.   In other words, sound science dictates that reports reading “lower than the lowest calibrator” should not be reported as positive.

     One final word about metabolites: Most metabolites are less psychoactive than the parent drug or are inactive, which means that they have no impact on the person.  If only an inactive metabolite such as carboxy THC is found in a urine sample, the metabolite did not affect driving. 

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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Urine Tests: False Positive Results for Drugs

August 14th, 2006 Allen Trapp Posted in Urine Test No Comments »

Substances that cause False Positive Drug Test Results

THC – Substances or Conditions which can cause false positives
Dronabinol (Marinol)
Ibuprofen; (Advil, Nuprin, Motrin, Excedrin IB etc)
Ketoprofen (Orudis KT)
Kidney infection (Kidney disease, diabetes) Liver Disease
Naproxen (Aleve)
Promethazine (Phenergan, Promethegan)
Riboflavin (B2, Hempseed Oil)

Amphetamines – Substances or Conditions which can cause false positives
Ephedrine, pseudoephedrine, propylephedrine, phenylephrine, or desoxyephedrine
(Nyquil, Contact, Sudafed, Allerest, Tavist-D, Dimetapp, etc)
Phenegan-D, Robitussin Cold and Flu, Vicks Nyquil
Over-the-counter diet aids with phenylpropanolamine (Dexatrim, Accutrim)
Over-the-counter nasal sprays (Vicks inhaler, Afrin)
Asthma medications (Marax, Bronkaid tablets, Primatine Tablets)
Prescription medications (Amfepramone, Cathne, Etafediabe, Morazone,phendimetrazine, phenmetrazine, benzphetamine, fenfluramine, dexfenfluramine,dexdenfluramine,Redux, mephentermine, Mesocarb, methoxyphenamine, phentermine,amineptine, Pholedrine, hydroymethamphetamine, Dexedrine, amifepramone, clobenzorex,fenproyorex, mefenorex, fenelylline, Didrex, dextroamphetamine, methphenidate, Ritalin,pemoline, Cylert, selegiline, Deprenyl, Eldepryl, Famprofazone) Kidney infection, kidney disease, Liver disease, diabetes

Opiates – Substances or Conditions which can cause false positives
Poppy Seeds
Tylenol with codeine
Most prescription pain medications
Cough suppressants with Dextromethorphan (DXM)
Nyquil
Kidney infection, Kidney Disease
Diabetes, Liver Disease

Ecstacy – Substances or Conditions which can cause false positives
Ephedrine, pseudoephedrine, propylephedrine, phenylephrine, or desoxyephedrine
(Nyquil, Contact, Sudafed, Allerest, Tavist-D, Dimetapp, etc)
Phenegan-D, Robitussin Cold and Flu, Vicks Nyquil
Over-the-counter diet aids with phenylpropanolamine (Dexatrim, Accutrim)
Over-the-counter nasal sprays (Vicks inhaler, Afrin)
Asthma medications (Marax, Bronkaid tablets, Primatine Tablets)
Prescription medications (Amfepramone, Cathne, Etafediabe, Morazone,phendimetrazine, phenmetrazine, benzphetamine, fenfluramine, dexfenfluramine, dexdenfluramine,Redux, mephentermine, Mesocarb, methoxyphenamine, phentermine, amineptine, Pholedrine, hydroymethamphetamine, Dexedrine, amifepramone, clobenzorex, fenproyorex, mefenorex, fenelylline, Didrex, dextroamphetamine, methphenidate, Ritalin, pemoline, Cylert, selegiline, Deprenyl, Eldepryl, Famprofazone) Kidney infection, kidney disease
Liver disease, diabetes

Cocaine – Substances or Conditions which can cause false positives
Kidney infection (kidney disease)
Liver infection (liver disease)
Amoxicillin, tonic water

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Blood and Urine tests for Methamphetamine

August 11th, 2006 Allen Trapp Posted in Blood Test, Chemical Test, Urine Test No Comments »

     If a person has taken methamphetamine, that individual should also have its metabolite amphetamine in his or her system. In other words, levels of both methamphetamine and amphetamine should be detected in both the blood and urine. Some GC/MS assays can falsely yield positive methamphetamine levels when high concentrations of ephedrine or pseudoephedrine are present in the specimen. Depending on the temperature of the injection port, the ephedrine or pseudoephedrine can be converted (or cooked) to methamphetamine. Therefore, sound scientific practice requires a negative report for methamphetamine if only methamphetamine is found in blood or urine. The absence of amphetamine means that the person had not consumed methamphetamine, which would in the ordinary course of metabolism would produce amphetamine. Therefore, in a case where only methamphetamine is found in the blood or urine the person probably had a cold and taken cold medicine containing ephedrine or pseudoephedrine.

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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