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Prescription Drug Testing FAQs

AIT offers answers for popular questions related to drug detection and prescription drug testing

If you have a question not included on this list, please contact our Client Services Department or send an e-mail to our full-time, expert toxicologists. We would be happy to assist you.

For questions related to our laboratory testing services, click here. 


Q: What is the difference between compliance monitoring performed in a laboratory and instant urine drug testing?
A: Historically, “instant” urine drug testing has been used for pre-employment, workplace monitoring, and law enforcement applications. In these instances, administrators are looking for negative test results to verify that individuals are not misusing narcotics or other illicit drugs. In this case, traditional cut-off levels (normally as high as 300 or 2,000ng/mL for opiates) are well suited for detecting drug concentrations typically associated with abuse. However, traditional cut-off levels are not effective in providing accurate assessments of patient compliance. Modern-day urine drug testing to monitor patient compliance requires much lower cut-off levels that typically are only achievable using instrumentation utilized in a laboratory setting. These lower cut-off levels (normally as low as 50ng/mL for opiates) provide a more reliable method for monitoring patient compliance.

In addition, traditional workplace urine drug testing achieved by point-of-care (POC) devices and routine hospital testing techniques are usually based on immunoassay technologies, which not only have elevated cut-offs but also are unable to identify specific drugs within a class. AIT Laboratories employs state-of-the-art confirmation technology that provides a unique “chemical fingerprint” for the drug in question, enabling positive identification and quantitation at very low levels.

For more information about the benefits of compliance monitoring utilized by a laboratory, please read our expert article published in Practical Pain Management.

Q:  What is the turnaround time on compliance testing?  
A: For urine specimens utilizing AIT's compliance monitoring panel (DetectiMed® Panel), the standard turnaround time is 3-5 business days. Request of additional tests not included in the DetectiMed Panel may extend turnaround time. For blood specimens utilizing DetectiMed, the standard turnaround time is 10 business days.

Q: Could the result be a false positive?  
A: The concept of false positive is limited to the screening test. AIT Laboratories reports results based on confirmation testing by GC/MS or LC/MS/MS. This type of testing provides what is effectively a “chemical fingerprint” pattern for each drug. As such, the possibility of a false positive result is eliminated.

Q: Why was the instant result positive for THC but the AIT Labs result negative? 
A:  Reason 1: Patient is taking a prescription medication known to cross react with the cup and result in a THC positive (e.g. Protonix). Reason 2: THC metabolizes into several metabolites between which the cup cannot differentiate, meaning that the cup response is an accumulative result. Laboratory analysis detects only one of the many cross-reacting compounds, carboxy-THC, which may be at a concentration below the reporting limit.

Q. Is there anything other than the drug itself that can cause someone to test positive for THC or cocaine?
A. This scenario is only possible when relying on point-of-care or “instant” testing devices such as urine cups or dipsticks. Such devices recognize drug classes based on their “chemical shape” and most commonly change color when that shape is recognized. If other drugs with similar chemical shapes are present in the sample, this can result in a "false positive." Sustiva, Protonix, and other proton pump inhibitors can cause individuals to test positive for THC on certain instant devices, while common antibiotics such as amoxicillin can cause a person to test positive for cocaine.

While these drugs can generate false-positive results on instant testing devices, they will not generate a positive result at the laboratory. Because of the sophisticated instrumentation available, laboratory testing is far more selective and looks for what is effectively a "chemical fingerprint" of each drug tested. Therefore, a drug will only test positive if the specific drug of interest is actually present.

Q:  My patient is taking high doses of morphine – why is codeine positive? 
A:  Morphine is not known to metabolize to codeine. Trace urinary codeine concentrations may be present in individuals on high doses of morphine due to codeine impurity in the morphine tablet. The presence of this codeine impurity is well documented and can account for low concentrations of codeine detected in the urine from patients who have been prescribed relatively high doses of morphine for extended periods of time. When the morphine concentration is low, this trace codeine impurity is undetectable; however, at high morphine concentrations, codeine may increase slightly above the minimum detection limit.

Q: I have two patients taking the same dose of hydrocodone – why are their urine levels different? 
A:  There are many variables associated with urine drug levels. Caution should be used when interpreting quantitative levels.  A few common reasons for the differences in urine levels for two patients on the same dose of drug include urine pH, co-administration of other drugs, hydration level, cardiac output, timing between dose and specimen collection, and possibly patient non-compliance.

Q: Will oxycodone metabolize to hydrocodone? 
A: Oxycodone is not known to metabolize to hydrocodone. However, similar to the presence of codeine as an impurity in pharmaceutical-grade morphine, the same phenomena can be used to explain the presence of hydrocodone in the urine of patients who are prescribed high doses of oxycodone for extended periods of time.

Q: My patient said he missed his dose of oxycodone last night – should the test result be negative? 
A: It will depend largely on three factors: Dose, frequency of dose, and metabolism/excretion capabilities. If the patient is prescribed oxycodone TID or QID then the urine should still test positive for the drug. If the patient is only prescribed single daily doses and they are capable of rapid metabolism/excretion, then the result may be negative due to screening cutoffs. The patient may also test positive for oxymorphone only as the detection window in the urine for this metabolite is longer than the parent drug.

Q: I am not prescribing Serax and the results were positive for oxazepam. The patient claims she is not taking Serax – could this be a false positive? 
A: Oxazepam is a terminal metabolite for several benzodiazepines. The presence of oxazepam and no other drugs could indicate the use of Serax, or it could indicate recent use of another benzodiazepine that was discontinued long enough ago that only oxazepam remains.

Q: I am prescribing 40 mg methadone TID – the result is positive for methadone and EDDP. The methadone level is 1800 ng/mL and the EDDP level is 2200 ng/mL. Is this consistent? 
A: Concentrations of methadone and its metabolite, EDDP, vary widely and depend on many factors such as metabolism/excretion rates, dose and dose frequency, and urine pH. Compliance cannot be determined solely from urinary methadone/metabolite concentrations.

Q: The levels of oxymorphone are higher than oxycodone. Is my patient abusing Opana? 
A: Not necessarily. Clinical trials indicate that the ratio of oxymorphone to oxycodone can vary from 0-184 percent and that there is no direct correlation between the dose and the resulting ratio. Oxymorphone also has a slightly longer detection window in the urine than oxycodone, meaning that oxymorphone may still be detectable following complete excretion of any oxycodone.

Q: My patient tested negative for benzodiazepines and they are prescribed one tablet every night. Are they taking it? 
A: It is possible. Low doses of benzodiazepines (especially alprazolam and lorazepam) can sometimes screen below the cutoff and therefore be reported as negative. If your client provides this information and they wish to determine if there is a small amount of drug in the urine, we can order a confirmation test and utilize the lower detection limits.

Q: Could the low level of morphine on this report be from dietary intake? 
A: Individuals who ingest poppy seeds may test positive for low levels of morphine — codeine and thebaine are present at significantly lower levels in the poppy seeds and usually go undetected in the urine. This is dependent upon the extent of ingestion and the timing between ingestion and specimen collection. Toxicologists at AIT generally consider 100 ng/mL as potentially resulting from poppy seed ingestion, which applies only when the patient is not prescribed morphine or codeine.

To learn more about opiate anomalies in compliance monitoring, read our expert article in Practical Pain Management. 

Q: My patient is on a high dose of oxycodone and tested positive for trace levels of hydrocodone. Is it a secondary metabolite or are they using? 
A: Similar to the presence of codeine as an impurity in pharmaceutical-grade morphine, the same phenomena can be used to explain the presence of hydrocodone in the urine of patients who are prescribed high doses of oxycodone for extended periods of time. AIT has tested various oxycodone formulations in which low levels of hydrocodone were detected. This study does not preclude the possibility of hydrocodone being an abnormal and unexpected metabolite; however, it provides an explanation for the positive result. In these cases, hydrocodone concentrations are typically fewer than 100 ng/mL, its metabolite hydromorphone is absent, and high concentrations of oxycodone are present.

To learn more about opiate anomalies in compliance monitoring, read our expert article in Practical Pain Management. 

Q: My patient tested positive for methamphetamine and amphetamine. Is that due to their Adderall prescription? 
A: No. Adderall is a formulation containing amphetamine – not methamphetamine. Adderall use will cause a patient to test positive for amphetamine but not methamphetamine. Amphetamine does not metabolize to methamphetamine.

Q: Does phentermine cause a positive result for amphetamines? 
A: Yes. Phentermine (Adipex) is a member of the same family of drugs as amphetamines and, it DOES cross react with the point-of-care or "instant" testing devices. Phentermine is easily distinguished from amphetamine and methamphetamine during confirmation analysis. Mass spectrometry provides a chemical fingerprint for phentermine, which is independent of those obtained for amphetamine and methamphetamine.

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