Electrolyte Changes
Dear Valued Client,
In the spirit of continual improvement and to provide our clients with industry leading service, we are excited to announce an upcoming change in testing associated with our 32400: Electrolyte Panel. For years this testing has been a referred test to another laboratory, however, beginning on August 1st, 2022 the 32400: Electrolyte Panel will be performed as an in-house test.
Axis has worked hard to source industry leading equipment in order to offer this testing with a higher level of service, and no increase in price.
You can always find the most recent publication for our panel offerings on our Test Catalog, found at www.axisfortox.com.
For specific questions regarding our tests or tests not found on our Test Catalog, please contact our Lab Client Support Team at [email protected].
We look forward to serving you.
Sincerely,
Matt Zollman
Director of Operations & Product Management
- Published in Announcements
False Positives in Toxicology Testing
By Kevin Shanks, M.S., D-ABFT-FT
We talk about false positives in forensic toxicology a lot. Could a specific drug cause a false positive for another drug on a toxicology test?
The answer is a bit complex, but it is both yes and no.
First, we need to talk about the screening test. One of the most commonly used screening tests is immunoassay. Immunoassays are based on the principle that antibodies are able to recognize and bind to the drug of interest. These antibodies are designed to be highly selective – meaning they preferentially bind to the drug of interest. In the absence of the drug of interest, this preferential binding does not eliminate the possibility of binding to other drugs that have similar chemical characteristics. This secondary binding is commonly referred to as a “false positive” result. Unfortunately, it is not possible to design an antibody that binds to a single drug exclusively. Additionally, given the myriad of drugs and drug metabolites, it is also not possible to evaluate all possible “false-positives.”
Let’s look at an amphetamine and methamphetamine as an example for this false positive phenomena.

Amphetamine Family Chemical Structures Drawn by Kevin G. Shanks (2022).
Historically, an amphetamines immunoassay uses either amphetamine or methamphetamine as a target compound, but it is very susceptible to other cross-reacting substances leading to “false positive” screening results. The following drugs have been known to cross react with various amphetamine immunoassay tests:
- Amantadine (Gocovri)
- Bupropion (Wellbutrin)
- Chlorpromazine (Thorazine)
- Desipramine (Norpramin)
- Ephedrine (Ephedra)
- Labetalol (Trandate)
- Mexiletine (Mexitil)
- Phentermine (Adipex)
- Pseudoephedrine (Sudafed, Mucinex-D)
- Trazodone (Desyrel)
As you can see from the list, simple use of an over the counter nasal decongestant such as Mucinex-D or Sudafed (pseudoephedrine) could lead to a positive immunoassay screening test for amphetamines. Or the use of prescription medication Adipex (phentermine) or Wellbutrin (bupropion) could easily cause a positive immunoassay test for amphetamines.
Second, we need to talk about confirmatory tests. While the screening test can be valuable for interpretation of toxicology results, especially in an emergency medicine situation, the possibility of “false positive” results is the primary reason for submitting the specimen to a laboratory for confirmatory testing. The laboratory confirmation testing utilizes either gas chromatography (GC) or liquid chromatography (LC) coupled to mass spectrometry (MS). A properly validated confirmatory test is not susceptible to the “false positive” results associated with immunoassay screening techniques. The mass spectrometric analysis provides what is effectively a “chemical fingerprint” pattern that is unique for each drug.
Going back to the amphetamines example, while the scope of a confirmation assay is highly dependent on the individual laboratory doing the analysis, the routine confirmatory amphetamines test typically only monitors amphetamine, MDMA, and methamphetamine. Some labs offer an expanded amphetamines panel and may include compounds such as ephedrine, MDA, MDEA, and pseudoephedrine or even other novel psychoactive substances such as the substituted cathinones (Dimethylpentylone, Eutylone, N-ethylpentylone, etc.).
If a mass spectrometry-based confirmatory test is positive for amphetamine or methamphetamine, the individual being tested has been exposed to or consumed a drug that either contains amphetamine and/or methamphetamine or metabolizes to either drug. It is also important to note that a drug that contains amphetamine only or metabolizes to amphetamine only will not result in a mass spectrometry positive result for methamphetamine. The only way to have a confirmed positive methamphetamine result is to consume a drug containing methamphetamine or one that metabolizes to methamphetamine. Methamphetamine will then metabolize to amphetamine. The following list is comprised of drugs that would be considered as true positives for amphetamine and methamphetamine.
These are drugs that contain amphetamine or metabolize to amphetamine:
- Adderall
- Benzedrine
- Dexedrine
- Durophet
- Procentra
- Zenzedi
- Ethylamphetamine
- Captagon (Fenethylline)
- Tegisec (Fenproporex)
- Pondinil (Mefenorex)
- Vyvanse (Lisdexamphetamine)
These are drugs that contain methamphetamine or metabolize to methamphetamine:
- Desoxyn (d-methamphetamine)
- Vick’s vapo-inhaler (l-methamphetamine)
- Illicit methamphetamine
- Didrex (Benzphetamine)
- Dimethylamphetamine
- Gewodin (Femprofazone)
- Altimina (Fencamine)
- Deprenyl (Selegiline)
At Axis Forensic Toxicology, we do not do preliminary screening by immunoassay testing. We have moved to more specific and selective initial screening using liquid chromatography with quadrupole time of flight mass spectrometry (LC-QToF-MS). All confirmatory testing is completed by either gas chromatography with mass spectrometry (GC-MS) or liquid chromatography with triple quadrupole mass spectrometry (LC-MS/MS).
Axis’ Comprehensive Panel includes Analyte Assurance™ for novel and designer compounds. While Axis’ screening methodology dramatically reduces “false positive” results, the confirmation of these compounds via a second test remains important if the results are to be used in forensic findings.
If you have any questions or concerns about potential false positives in your forensic toxicology casework, please contact our toxicologist subject matter experts at [email protected].
To stay current with the scope of testing for all realms of toxicology offered by Axis Forensic Toxicology, please consult the online test catalog.
References
Guidelines for the Interpretation of Analytical Toxicology Results. Disposition of Toxic Drugs and Chemicals in Man. Twelfth Edition. Randall C. Baselt. Biomedical Publications. Pages xxx-xlii. (2020).
Postmortem Forensic Toxicology. Principles of Forensic Toxicology. Fifth Edition. Barry Levine and Sarah Kerrigan. Springer. Pages 3-14. (2020).
Forensic Drug Testing. Principles of Forensic Toxicology. Fifth Edition. Barry Levine and Sarah Kerrigan. Springer. Pages 45-64. (2020).
Chromatography. Principles of Forensic Toxicology. Fifth Edition. Barry Levine and Sarah Kerrigan. Springer. Pages 135-162. (2020).
Immunoassay. Principles of Forensic Toxicology. Fifth Edition. Barry Levine and Sarah Kerrigan. Springer. Pages 177-196. (2020).
Mass Spectrometry. Principles of Forensic Toxicology. Fifth Edition. Barry Levine and Sarah Kerrigan. Springer. Pages 197-220. (2020).
- Published in General
Interferences in Toxicology Testing
By Kevin Shanks, D-ABFT-FT
In toxicology testing, qualitative and quantitative testing are the norm, but every so often something prevents a result from being acquired. This “something” is called interference and will be displayed on the Axis Forensic Toxicology report as unsuitable due to interference. Interferences can originate from both endogenous and exogenous sources.

Blood samples in test tubes
Image taken by Charlie-Helen Robinson (2021)
Endogenous sources of interference such as drug metabolites and components in the biological matrix may affect the ability of the analytical test to measure the analyte of interest with accuracy and precision. Forensic and postmortem specimens are more susceptible to endogenous interferences. These interfering substances present in the specimen may lead to competition for charge from the mass spectrometer and cause fluctuation or differences in the signal of the drug of interest. During analytical method validation, we assess potential sources of endogenous interferences by testing multiple sources of matrix (i.e. ten sources of authentic postmortem blood), but this testing may not encapsulate all of the variations that could be present.
Exogenous sources of interference include agents used by the person such as prescription and over the counter medications, various ingested substances, environmental contaminants, and sample additives. During the validation of the analytical method prior to implementation in the laboratory, we assess any common known exogenous interferences by spiking blood, urine, or tissues with the most commonly encountered substances in the forensic toxicology laboratory. While we test the most common compounds, the testing does not cover all known prescription and over the counter medications that are available on the market.
During routine testing, if we encounter a sample that displays interference for a specific test, we attempt to achieve a valid result by rerunning the specimen at a dilution. This theory behind diluting the sample is to remove some of the biological matrix which may be causing the interference. If a valid result is attained using the dilution, then it will be reported as such on the final toxicology report. But, if we still cannot achieve a valid quantitative or qualitative result, then the result will be reported as unsuitable due to interference.
In the end, the quality of the analytical toxicology results acquired through testing is dependent on the quality of the sample being analyzed. Due to the inherent nature of forensic toxicology and the effects of postmortem biology, interferences can and do happen.
If you have a question about potential endogenous or exogenous interferences or a specific result on an Axis toxicology report, please reach out to our toxicologists at [email protected].
References
Guidelines for the Interpretation of Analytical Toxicology Results. Disposition of Toxic Drugs and Chemicals in Man. Twelfth Edition. Randall C. Baselt. Biomedical Publications. Pages xxx-xlii. (2020).
Introduction to Forensic Toxicology. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 1-12. (2008).
Postmortem Toxicology. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 191-218. (2008).
Postmortem Forensic Toxicology. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 3-14. (2017).
Forensic Drug Testing. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 31-48. (2017).
- Published in General
Drug Primer: Nitazenes
By Kevin Shanks, D-ABFT-FT
Over the last several years, the Drug Enforcement Administration (DEA) has moved to ban various newly emerged illicit opioids as Schedule I controlled substances. From 2015-2017, they controlled 19 fentanyl analogs and other opioids. In 2018, the DEA banned any substitutions to the fentanyl core chemical structure and classified them as “fentanyl-related substances”.

Waves of Federal Legislation for Opioids
DEA, 2015 – 2017
After this legislation in 2018, compounds that were chemically dissimilar from fentanyl and analogs began to emerge. The major family of non-fentanyl related compounds to emerge is known as the nitazenes, which are based on a benzimidazole chemical structure. This family of opioids was first synthesized in the 1950s in the pharmaceutical industry as potential analgesic and anesthetic medications. The first compound, also the most potent, is etonitazene. Other compounds in this family include butonitazene, flunitazene, isotonitazene, metonitazene, and N-pyrrolidinoetonitazene. Pharmacologically, these compounds are mu opioid receptor agonists, much like morphine, heroin, and fentanyl. In vitro data suggests that these compounds have analgesic potentcies similar to or greater than fentanyl, and because of this potency and potential for respiratory depression, they have never been investigated further or approved for use in medicine.

Chemical Structure of Isotonitazene.
Kevin G. Shanks (2022)
We screen for nitazene compounds by liquid chromatography with quadrupole time of flight mass spectrometry (LC-QToF-MS) and confirm their identity by liquid chromatography with triple quadrupole mass spectrometry (LC-MS/MS) test. Test specifics can be found in the Axis online catalog.
From June 1, 2021 to May 1, 2022, we detected a total of four nitazene compounds (metonitazene, isotonitazene, flunitazene, and N-pyrrolidinoetonitazene) in 128 postmortem toxicology blood samples across eight states (Florida, Illiniois, Indiana, Michigan, Nebraska, Ohio, Texas, and Wisconsin). Fentanyl was most commonly found alongside nitazene compounds, but other substances included 4-ANPP, acetylfentanyl, naloxone, methamphetamine, THC, cocaine/benzoylecgeonine, and morphine.
If you have any questions about these newly emerged nitazene compounds, please reach out to subject matter experts at Axis by email at [email protected].
References
Axis Forensic Toxicology internal data for nitazene analysis. 06/01/2021 – 05/01/2022.
- Published in Drug Classes
Nitazene Analog Panel Coming Soon
Dear Valued Client,
In the spirit of continual improvement, to provide the most relevant panels and tests in the industry, our products are periodically updated as new compounds emerge and older compounds cease to be relevant over the years. It is with that goal in mind that we announce the creation of the 13910: Nitazene Analog Panel. Beginning with orders placed on or after June 27th, 2022, the 13910: Nitazene Analog Panel will include the following compounds:
- Butonitazene
- Etodesnitazene
- Etonitazene
- Flunitazene
- Isotodesnitazene
- Isotonitazene
- Metodesnitazene
- Metonitazene
- N-Pyrrolidino Etonitazene
- Protonitazene
In addition, as part of this change, these compounds will be removed from the 13710: Novel Emerging Compounds Panel. All of these compounds will still be included as part of the 70510: Comprehensive Panel, Blood with Analyte Assurance™.
You can always find the most recent publication for our panel offerings on our Test Catalog, found at www.axisfortox.com.
For specific questions regarding our tests or tests not found on our Test Catalog, please contact our Lab Client Support Team at [email protected].
We look forward to serving you.
Sincerely,
Matt Zollman
Director of Operations & Product Management
- Published in Announcements
Drug Primer: Mitragynine (Kratom)
By Kevin Shanks, D-ABFT-FT
Mitragyna speciosa is a tree or shrub that grows in southeast Asia, particularly Thailand and Malaysia. The plant is locally known as kratom or biak-biak. It exists in the Rubiaceae family of plants, which includes the genera Coffea or caffeine-containing plants, with the most-widely known species being Coffea arabica and Coffea canephora (coffee plants). In regions of Asia, the plant has been used by either chewing the leaves or brewing them into a liquid beverage such as a tea. The leaves can also be pulverized and fashioned into a powder and then smoked or consumed orally in a capsule.

Mitragyna speciosa
Image by Ahmad Fuad Morad (CC BY-SA 2.0)
Mitragyna contains the alkaloids, mitragynine and 7-hydroxymitragynine. Approximately 60% of the plant’s alkaloid content is mitragynine and 7-hydroxymitragynine makes up about 2% of the overall alkaloid content. In lower dosages, the alkaloids produce stimulant-type effects, but at larger dosages, both compounds function as mu opioid receptor agonists. Mitragynine is considered to be approximately 13 times more potent than morphine as an analgesic, but 7-hydroxymitragynine is considered to be approximately 4 times more potent than mitragynine. 7-hydroxymitragynine is also a product of mitragynine biotransformation in the human body, thus mitragynine can be considered a prodrug for 7-hydroxymitragine. The alkaloids have also been shown to have other effects such as the blocking of serotonergic receptors and inhibition of CYP1A2, CYP2D6, and CYP3A4 enzymes.

Chemical structures of Mitragynine and 7-hydroxymitragynine
Structure drawn by Kevin G. Shanks (2022)
An interesting pharmacological characteristic of mitragynine and 7-hydroxymitragynine is that when binding to opioid receptors, they exhibit biased agonism. Normally, when an opioid binds to an opioid receptor, the β-arrestin pathway is initiated – the β-arrestin pathway is responsible for most of the respiratory depression and sedation observed in opioid use and overdose. There exists evidence that shows mitragynine and 7-hydroxymitragynine do not initiate this pathway.
The United States Federal government moved to control mitragynine and 7-hydroxymitragynine as Schedule I controlled substances in 2016-2018, but backed off the legislation after public comment on the matter. They remain uncontrolled at the Federal level, but some states have passed legislation making them controlled substances in their locale.
Most forensic toxicology laboratories include only mitragynine in the scope of their testing and do not include the 7-hydroxymitragynine alkaloid/metabolite. Typical detection limits for the compound are 5-20 ng/mL in blood. At Axis Forensic Toxicology, mitragynine is included in the Comprehensive Panel (order code 70510) and/or as a directed confirmation test for mitragynine (order code 42090). Specific information about our testing can be found in the online test catalog.
Experts at Axis, alongside the Coconino County (Arizona) Medical Examiner’s Office, recently published a manuscript in the Journal of Analytical Toxicology titled “Two Single-Drug Fatal Intoxications by Mitragynine”. There have been many mitragynine-associated or related intoxications and fatalities reported over the last several years, but most have involved multiple drugs including other central nervous system depressants such as opioids, benzodiazepines, and ethanol. Sole intoxications with mitragynine leading to fatality are rare. In the published article, an analytical method for the detection of mitragynine by liquid chromatography with triple quadrupole mass spectrometry (LC-MS/MS) is detailed as well as presentation of two cases where mitragynine was certified as the single agent in the cause of death of an individual. To request a copy of this new manuscript, please contact us at [email protected].
References
Opioids. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 271-291. (2017).
Mitragynine. Disposition of Toxic Drugs and Chemicals in Man. Twelfth Edition. Randall C. Baselt. Biomedical Publications. Pages 1414-1415. (2020).
“Two Single-Drug Fatal Intoxications by Mitragynine” (2022) G.S. Behonick, C. Vu, L. Czarnecki, M. El-Ters, K. Shanks. J Anal Tox, DOI: https://doi.org/10/1093/jat/bkac016
- Published in Drug Classes
Drug Primer: 4-ANPP
By Kevin Shanks, D-ABFT-FT
The presence of fentanyl in the street drug supply has rapidly exploded throughout the United States since approximately 2014. Drug overdose deaths have increased as well over the last several years and topped 100,000 deaths in the USA in 2021, with the major driving factor being fentanyl.

Fentanyl Trends. DEA Annual Report, 2020. NFLIS.
We discussed fentanyl in a previous blog post, but briefly, fentanyl is a mu opioid receptor agonist and is metabolized in the human body by the cytochrome P450 enzyme system, primarily CYP3A4, into various products. It can be dealkylated, hydroxylated, methylated, and hydrolyzed.
In the modern forensic toxicology laboratory, we monitor for the presence of unchanged fentanyl, alongside its primary metabolite, norfentanyl, in blood and urine. But, over the last several years, laboratories have added a third substance to their scope of analysis for fentanyl – 4-ANPP.

Chemical structure of 4-ANPP
Drawn by Kevin G. Shanks (2022)
4-ANPP, also known as N-phenyl-1-(2-phenylethyl)-4-piperidinamine or despropionyl fentanyl, is formed via amide hydrolysis. It is a minor metabolite of fentanyl, but it is also a precursor or starting material used in the synthesis of illicitly manufactured fentanyl and various related fentanyl analogs. 4-ANPP is reacted with propionyl anhydride to form fentanyl or some other reagent to form a related fentanyl analog such as acetylfentanyl (acetic anhydride) or cyclopropylfentanyl (cyclopropane carbonyl chloride).
Pharmacologically, 4-ANPP is inactive – it does not produce any specific effect on the body. Ultimately, its presence is merely a marker for fentanyl use or exposure. Detection of this substance in the body is highly dependent on the dose and purity of the product consumed by the individual. The toxicology alone cannot determine if 4-ANPP is present due to metabolism or if it was ingested by using an impure illicit product.
Axis Forensic Toxicology tests for the presence of 4-ANPP in our Designer Opioids panel (order code 13810), which is completed by liquid chromatography with triple quadrupole mass spectrometry (LC-MS/MS). The reporting limit is 50 pg/mL and the substance is reported as qualitatively positive or negative.
If you have any questions regarding the presence or absence of 4-ANPP or its role in your toxicology casework, please reach out to Axis’ subject matter experts at [email protected].
References
Fentanyl. Disposition of Toxic Drugs and Chemicals in Man. Twelfth Edition. Randall C. Baselt. Biomedical Publications. Pages 844-847. (2020).
Opioids. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 271-291 (2017).
2020 Annual Drug Report. National Forensic Laboratory Information System (NFLIS). Drug Enforcement Administration. Springfield, VA. NFLIS-Drug 2020 Annual Report (usdoj.gov). (Accessed March 20, 2022).
Labroo, R.B., Paine, M.F., Thummel, K.E., Kharasch, E.D. (1997) Fentanyl Metabolism by Human Hepatic and Intestinal Cytochrome P450 3A4: Implications for Interindividual Variability in Disposition, Efficacy, and Drug Interactions. Drug Metabolism and Disposition, 25: 9. 1072-1080.
Drug Primer: Fentanyl (2021). Axis Forensic Toxicology Blog. Drug Primer: Fentanyl – Axis Forensic Toxicology (axisfortox.com).
- Published in Drug Classes
Pharmacodynamics
By Kevin Shanks, D-ABFT-FT
Pharmacodynamics (PD) is the study of the effect of substances on the body. The word is derived from Greek – Pharmakon and dynamikos which means “force” or “power”. PD includes concepts such as receptor affinity, receptor activity, and potency.

“Whelp” by NoelMichelle. Licensed under CC BY-SA 4.0.
Receptor affinity is the measure of how well a substance binds to a receptor. As an example, let’s look at the opioids, morphine and fentanyl. Both substances bind to the mu (µ) opioid receptor. Morphine binds to the receptor with an affinity (Ki) equal to 1.8 nM, whereas fentanyl binds to the receptor with an affinity (Ki) equal to 0.39 nM. This essentially means that fentanyl has a 4-5 stronger hold at the receptor than morphine does.
Once a substance binds to a receptor, it will produce a response or effect. A substance can bind to the receptor a produce an effect – this is called agonism. A substance can also bind to the receptor and block a response from occurring – this is called antagonism. A drug such as morphine or fentanyl binds to mu opioid receptors and acts as an agonist – it produces analgesia and central nervous system depression. Naloxone, on the other hand, is a receptor antagonist as it binds to mu opioid receptors and does not produce a biological response – it blocks other opioids from binding to the same receptors.
Potency refers to the amount of a substance that is needed to produce a desired effect. To compare drug potencies, we look at the EC50, or the concentration of drug at which 50% of the maximum effect is achieved. When two substances are tested in the same person, the drug with the lower EC50 would be considered more potent. A lesser amount of a more potent drug is needed to achieve the same effect as a less potent drug.
Within the study of the pharmacodynamics of drugs, we are also concerned with the route of administration, onset of action, and duration of action.
The route of administration is the path by which a substance is taken into the body. Common routes of administration include oral (by mouth), dermal absorption, mouth inhalation, nasal inhalation, nasal insufflation, smoking, vaping, intravenous injection, intramuscular injection, intrathecal injection, sublingual absorption, buccal absorption, and rectal absorption. Tablets such as Xanax (alprazolam) and Vicodin (hydrocodone) are to be consumed orally. Cocaine can be nasally insufflated or snorted. Heroin may be injected intravenously. Methamphetamine may be smoked. Nicotine can be vaped.
The onset of action of a drug is the amount of time it takes for a drug’s effects to occur after administration. The onset is dependent on the route of administration, but there are other factors including drug formulation, dosage, and the individual consuming the substance. Substances that are orally consumed typically have an onset of action 30-90 minutes and those substances that are smoked or inhaled have onset of action typically within minutes. Substances that are injected directing into the blood stream have effects that occur within seconds to minutes of administration. As an example, when someone smokes or vapes cannabis, the effects normally occur within minutes, but when someone consumes a THC-infused edible foodstuff by mouth, the onset of action is normally 30-90 minutes after ingestion.
The duration of action of a drug is the length of time that a substance is effective or how long effects are felt. As an example of duration, morphine’s effects are typically felt for 4-5 hours after administration, while fentanyl’s effects are felt for 1-2 hours after use. As with onset of action, the duration of action can also be influenced by route of administration and formulation of drug used. Substances such as Oxycontin (extended release oxycodone) will have a duration approximately 12 hours.
The branch of pharmacology known as pharmacokinetics can help to answer questions such as ‘Are drugs involved in the incident?’ or ‘How much substance did a living individual consume?’ or ‘When was the substance taken?’, but the knowledge of pharmacodynamics can help to answer questions such as ‘During the incident, was an individual impaired?’ or ‘Was the person suffering from toxic drug effects?’ or “Did this substance play a role in the death of the individual?’.
If you have any questions or concerns regarding the role of pharmacodynamics in your toxicology case, please reach out to our Axis Forensic Toxicology subject matter experts at [email protected].
References
Guidelines for the Interpretation of Analytical Toxicology Results. Disposition of Toxic Drugs and Chemicals in Man. Twelfth Edition. Randall C. Baselt. Biomedical Publications. Pages xxx-xlii. (2020).
Pharmacokinetics and Pharmacodynamics. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. American Association for Clinical Chemistry (AACC). 2017. 77-93.
Introduction to Forensic Toxicology. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 1-12. (2008).
Postmortem Toxicology. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 191-218. (2008).
Postmortem Forensic Toxicology. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 3-14. (2017).
- Published in General
Reference Ranges
By Kevin Shanks, D-ABFT-FT
Many forensic toxicology tests are qualitative and provide a positive-negative or present-not detected result. The interpretation of those results is relatively simple. A substance is there or it is not. But, a quantitative test with a numerical result must be put into context of the case to aid in determining its overall meaning. Is the concentration of drug measured significant to the investigation or is it an incidental finding? Forensic toxicologists do this by compiling reference ranges, or sets of blood, serum, or plasma drug or metabolite concentrations which are used as a baseline for interpretation of results.
A therapeutic blood concentration is a concentration or level of drug or its active metabolite which is present in the blood, serum, or plasma following a therapeutically effective dosage. Most therapeutic ranges originate from data amassed during pharmaceutical medication clinical trials or controlled dosing studies. More often than not, the individuals tested to determine a therapeutic blood range consist of a healthy, non-disease stricken population. A toxic blood concentration is a concentration or level of drug or its active metabolite present in the blood, serum, or plasma that is associated with serious adverse or toxic symptoms. A lethal blood concentration is an amount of drug or its active metabolite present in the blood, serum, or plasma that has been reported to cause fatality, or is so far above reported therapeutic or toxic concentrations, that one may judge it might cause fatality.

Test tubes and other recipients in chemistry lab by Horia Varlan (CC BY 2.0)
Any value given for a therapeutic, toxic, or lethal blood concentration is not considered absolute, but is to be used as a frame of reference or guideline in evaluating a specific case in its context. Blood concentrations can be affected by dose of the substance used, route of administration, drug absorption differences, age and sex of the individual, potential tolerance to the substance, underlying pathology or observed disease states, postmortem redistribution (PMR), substance protein binding, and the accumulation of active metabolites.
Some substances have distinct therapeutic, toxic, and lethal blood reference ranges. This can be shown by looking at acetaminophen (Tylenol). Acetaminophen’s therapeutic reference range is 10-30 mcg/mL while it’s toxic and lethal reference ranges are greater than 150 mcg/mL. As you can see, there is a definite difference observed in the reference ranges.
On the other hand, some substances have overlapping therapeutic, toxic, and lethal blood reference ranges. The reported therapeutic reference range for fentanyl in blood is 1-3 ng/mL. But toxicity may occur at blood concentrations lower than 3 ng/mL. People using fentanyl as a therapeutic medication under the supervision of a physician may also regularly have blood concentration exceeding 3 ng/mL. Another example of this overlap in therapeutic and toxic/lethal ranges is methadone. Acute oral therapeutic dosing of methadone in treatment settings has resulted in blood concentrations 75-860 ng/mL and chronic oral dosing of methadone in medical treatment settings has led to blood concentrations 570-1,006 ng/mL. But, blood concentrations found in the postmortem blood of people who have died from methadone toxicity were 20-5,300 ng/mL.
There is no one size fits all type of reference range for forensic toxicology testing – the interpretation hinges on the context and circumstances of the case. Axis Forensic Toxicology understands that one should never practice toxicology strictly by the numbers and we are able to help with interpretation of the relevant toxicology in your casework.
Axis is making changes to its final toxicology reports to align with and provide a single source of values for the reported reference ranges. If you have any questions or concerns regarding a substance’s reference range or its role in your medical-legal death investigation, please reach out to our subject matter experts at [email protected].
References
Disposition of Toxic Drugs and Chemicals in Man. Twelfth Edition. Randall C. Baselt. Biomedical Publications. (2020).
Pharmacokinetics and Pharmacodynamics. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. American Association for Clinical Chemistry (AACC). 2017. 77-93.
Introduction to Forensic Toxicology. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 1-12. (2008).
Postmortem Toxicology. Clarke’s Analytical Forensic Toxicology. Sue Jickells and Adam Negrusz. Pharmaceutical Press. Pages 191-218. (2008).
Postmortem Forensic Toxicology. Principles of Forensic Toxicology. Fourth Edition. Barry Levine. AACC, Inc. Pages 3-14. (2017).
- Published in General
Shipping Best Practices
By Matt Zollman, Director of Operations and Product Management
From time to time, circumstances such as weather or pandemics can cause shipment delays. Here are some Best Practices to keep in mind as you prepare and track your packages:
Submissions:
- Submit smaller, more frequent shipments. If delays do occur, smaller, more frequent shipments minimize the overall impact to your cases.
- Review your Axis Case Management Portal. Cases are posted to your Case Management Portal once they are logged into our system, where you have visibility into when they are received.
- Record your outbound tracking numbers. We’re not able to see all of them in the system and recording them on your end aids in troubleshooting delays.
Supplies:
- You should receive outbound notification. You should receive an e-mail notification when outbound supplies are ready to be sent. If you do not receive a notification in a timely manner after supplies are requested, please notify Axis.
- Please reach out if you do not receive your order. You should receive your shipment in a timely manner. If you do not, please notify Axis for quick resolution.
Axis is committed to providing the same level of service to which you have become accustomed and, to that end, will continue to communicate any additional delays. As always, if you have any questions about your cases or supplies, please reach out to [email protected] or [email protected].
We look forward to serving you.
- Published in General