TAKEAWAY: What is an enantiomer? What are amphetamine enantiomers? Why is it essential to conduct an enantiomer analysis? Get answers to these frequently asked questions and more!
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What is an enantiomer?
In chemistry terms, enantiomers are pairs of molecules that are chemically identical and exist as mirror images of one another. However, they cannot be superimposed on one another. The two isomers are designated as d- (Dextro) and l- (Levo), indicating the direction in which they rotate a beam of polarized light.
Despite their similarities, enantiomers often have very different effects on the human body. One enantiomer can be inactive, while another can have therapeutic effects. The enantiomers will also react with the body at different speeds and markedly different strengths. For example, methamphetamine is a controlled substance, but its L-isomer is used in several over-the-counter medications.
Because amphetamines are the primary metabolite of methamphetamine, assessing this drug is even more complex. For methamphetamines and amphetamines, the D-isomer is considered much more active biologically, and most illegal drugs are D-isomers.
Enantiomers are problematic in drug testing because standard drug tests, such as immunoassay, cannot distinguish between enantiomers. Because of this, they can deliver inconclusive results. Test results reported by a laboratory will not indicate the specific enantiomer because the laboratory procedure is set up to identify only the presence of amphetamine or methamphetamine. Labs must perform additional analysis to determine which enantiomer is present.
What are amphetamine enantiomers?
Amphetamine is a central nervous system stimulant with 2 enantiomers: levoamphetamine and dextroamphetamine. The effects of dextroamphetamine on the central nervous system are more pronounced than levoamphetamine. Physicians prescribe it to treat attention deficit hyperactivity disorder and narcolepsy. However, athletes also use it to enhance performance. It is also sold illegally as an aphrodisiac and to induce euphoria.
Amphetamine and methamphetamine exist in 2 isomeric structural forms known as enantiomers. Enantiomers are non-superimposable mirror images. The 2 isomers of each substance are designated as d- (Dextro) and l- (Levo), indicating the direction in which they rotate a beam of polarized light. As with many pharmacological enantiomers, the d- and l-isomers have distinct pharmacological properties. In this case, the d- isomer of each substance has a strong central nervous system stimulant effect, while the l-isomer of each substance has a primarily peripheral action. Illegally manufactured amphetamine and methamphetamine are principally found as the d-isomer. However, significant amounts of the l-isomer of each substance may be present depending on the starting materials used by the clandestine laboratories.
When does D- and L-enantiomer analysis need to be completed?
Enantiomer analysis can help determine if positive drug tests are due to a lawful use of prescription or over-the-counter medications rather than illegal consumption. These tests may be warranted if the test participant indicates the use of a legal substance that contains the l-enantiomer. Medical Review Officers (MROs) can also order enantiomer testing for all specimens with positive amphetamines initial test results and all specimens with a positive methamphetamine confirmatory test result or request additional testing on a case-by-case basis. The analysis will differentiate between the d- and l-enantiomers. Urine containing 20% or more d-enantiomer suggests exposure to the schedule 2 substance. However, a sample with less than 20% d-enantiomer may indicate another reason for the positive test.
Why is it essential to conduct an enantiomer analysis?
Although both are controlled drugs, the d- and l-enantiomers have very different effects on the body. From a safety perspective, l-enantiomers can be far much dangerous. Since standard drug tests do not distinguish between d- and l- enantiomers, enantiomer analysis is crucial in identifying the origin of a drug detected in a routine test. The test results will provide a percentage of the d- and l-enantiomers present in the sample. These percentages allow the MRO to more accurately determine whether the positive result was the illicit use of a banned substance or happened through a more innocent use of over-the-counter or prescribed medications.
This additional testing ensures that employers do not mistakenly rule out potential new hires or unfairly penalize employees inadvertently exposed to a drug.
What is SureHire’s process when enantiomer analysis is requested?
SureHire does not require enantiomer analysis for every specimen. However, it is necessary if the participant has disclosed specific medical information (e.g., use of nasal inhaler within days of drug test) to the MRO. SureHire will notify the employer or recruiter who booked the appointment of the additional testing requirements and arrange for the specimen to be shipped to a certified laboratory for further analysis.
It takes approximately 5 to 7 additional business days to ship the specimen, test it, and have the MRO review the laboratory test results and issue a final result.
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