CFI-to-CFI Newsletter - Volume 12 Issue 4 - 10

COMMON CAUSES OF FALSE POSITIVES
There are many commonly used prescription
and over the counter (OTC) medications that
are allowed by the FAA that may cause a false
positive urine test. There are five categories
(besides cannabinoids as mentioned earlier)
of medications that cause false positive drug
levels. The categories of main concern to the
pilot and civilian population are: amphetamines,
benzodiazepines, opioids, PCP, and tricyclic
antidepressants. All amphetamine medications
are disallowed for pilot use by the FAA.
Medications that could cause a falsely elevated
amphetamine level are metformin, labetalol,
pseudoephedrine, and ranitidine. Metformin
(Glucophage®) is a medication used in diabetes
type II for glycemic control. Pseudoephedrine
(Sudafed®) is an OTC medication taken for
nasal congestion. Pseudoephedrine is also
manufactured in combination with non-sedating
antihistamines like Claritin-D (loratadine and
pseudoephedrine), Allegra-D® (fexofenadine and
pseudoephedrine), and Zyrtec-D (certirizine
and pseudoephedrine). Labetolol (Normodine®)
is a beta-blocker medicine that mainly controls
the patient's heart rate. Labetolol is used for
hypertension and is indicated in hypertensive
urgency when the blood pressure is very high
for long periods of time. Ranitidine (Zantac®)
is an H2 blocking agent used for ulcers and
gastroesophageal reflux disease (GERD).
Ranitidine is available OTC so be aware that
chronic use could possibly cause a false positive
urine test for amphetamine.
Benzodiazepines are medications used in
patients with anxiety. They include diazepam
(Valium®), lorazepam (Ativan®), and alprazolam
(Xanax®). All benzodiazepines are no-fly
medications. Medications that could cause
a falsely elevated benzodiazepine level are
Sertraline, Oxaprozin, and Efavirenz. Sertraline
(Zoloft®) is an FAA-allowed serotonin reuptake
inhibitor (SSRI) for depression that requires
a Special Issuance Authorization. Oxaprozin
(Daypro®) is a non-steroidal anti-inflammatory
(NSAID) that is used for pain and inflammation.
Efavirenz (Sustiva®) is an antiviral medication
prescribed for patients with HIV.
We know there is an opioid crisis in the United
States. Pain medications that contain opioids
including codeine, morphine, oxycodone, and
hydrocodone-when used chronically-have a
high abuse potential. Medications that could
cause a falsely elevated opioid level include
dextromethorphan, quinolones, and verapamil.
Dextromethorphan is an active ingredient in
many OTC cough and cold products and in high
doses may cause hallucinations. Quinolones
are antibiotics that are prescribed to treat
URINE TESTING FOR DRUGS IS VERY COMMON
IN THE OUTPATIENT CLINIC SETTING AND
OUTSIDE LABORATORIES. IT IS FASTER AND
CHEAPER BUT HAS A HIGHER FALSE POSITIVE
RATE THAN BLOOD TESTING OR OTHER MORE
TECHNOLOGICALLY ADVANCED TESTS.
CFI-to-CFI Newsletter - Volume 12 Issue 4

Table of Contents for the Digital Edition of CFI-to-CFI Newsletter - Volume 12 Issue 4
