Confused asked
If anyone gets a false positive for the presence of amphetamine using a urinalysis while taking ranitidine, and that sample is sent out to the lab for further examination, is it still possible to come back positive for methamphetamine?
At a glance
- Zantac (ranitidine) has been known to cause 'false-positive' results on urine drug screenings for amphetamine products.
- Laboratory tests, such as gas chromatography, are available to confirm or refute urine lab test results.
Answer
Zantac (ranitidine), an H2-blocker, has been reported by various studies as a potential causative agent when it comes to 'false-positive' results for amphetamine (e.g. Adderall) on urine drug tests (i.e. urinalysis).
If you received a 'positive' result for amphetamine on a urine drug test, there are several other 'confirmatory' tests that can be utilized that can correctly determine if the positive test is accurate in regard to actually containing the offending compound (methamphetamine in your case).
Urine Drug Testing
Urine drug testing is often utilized in many situations, including for employment or as part of a pain management regimen.
Most commonly, the type of test used is an 'immunoassay' test, which works by utilizing antibodies to react to specific drug compounds, like amphetamine or opioids.
These immunoassay tests work as follows:
- When a specified drug compound is present in a urine sample, an antibody binds to it. This produces a reaction.
- When a reaction occurs, this is considered a 'positive' result.
Immunoassay urine tests are generally used as an initial screening only as they are associated with a relatively high rate of inadvertent 'cross-reactivity' and 'false-positives'.
Cross-reactivity refers to drugs that are not being tested for reacting with the wrong antibody, causing a positive result (but is actually a 'false positive').
Zantac-Amphetamine Drug Test
Zantac (ranitidine) is one of the many drugs that have been reported to cause false-positives for amphetamine products like Adderall. Others include:
- Amantadine
- Dimetapp (Brompheniramine)
- Wellbutrin (Bupropion)
- Chlorpromazine
- Chloroquine
- Desipramine
- Doxepin
- Labetalol
- Sudafed PE (Phenylephrine)
- Promethazine
- Pseudoephedrine
- Selegiline
- Thioridazine
- Trazodone
- Trimethobenzamide
- Venlafaxine
- Vicks inhaler (l-methamphetamine)
'False-Positive' Confirmatory Tests
If you believe that your urine test was falsely positive, there, fortunately, are more accurate tests that can be utilized for confirmation.
While immunoassay tests rely on antibody reactions, other tests can accurately identify specific drug compounds in a given sample, eliminating the risk of 'cross-reactivity'.
These confirmatory tests include:
- Gas chromatography with mass spectrometry
- Liquid chromatography with mass spectrometry
The above tests aren't generally used for initial screenings due to their expense and the fact the urine-based immunoassay drug tests provide far quicker results.
In the case you provided in your question, if Zantac (ranitidine) caused a false-positive, a confirmatory test would confirm or rule this out.
Since the 'confirmatory tests' actually isolate and identify all compounds present in a sample, methamphetamine will either be present or not (unless there is a contamination issue).
References
- Monitoring opioid adherence in chronic pain patients: tools, techniques, and utility. PubMed
- Interpretation of urine drug testing in pain patients. PubMed
- Urine Drug Screening: A Valuable Office Procedure. AAFP
- False-Positive Interferences of Common Urine Drug Screen Immunoassays: A Review. Oxford Academic
- Commonly prescribed medications and potential false-positive urine drug screens. PubMed
- Urine drug screening: a practical guide for clinicians. PubMed
