BLOG & STORIES

By Kevin Shanks, M.S., D-ABFT-FT

As mentioned in several previous posts on this blog, novel psychoactive substances (NPS) are arranged into different families. Opioids, cannabinoids, stimulants, hallucinogens, and benzodiazepines are the main ones we encounter in forensic toxicology. Axis makes an effort to be able to detect the most newly emerged of these NPS as the drug market evolves over time. In this post, we will take a brief look at two stimulants which have recently appeared in the United States.  

Chemical structure of N-isopropyl butylone Drawn by Kevin G. Shanks (2025)

N-isopropyl butylone and N-cyclohexyl methylone are considered substituted cathinones, which are a class of compounds related to cathinone, a naturally occurring stimulant alkaloid found in the plant Catha edulis, also known as khat. Substituted cathinones are chemically and pharmacologically similar to amphetamine and methamphetamine and act as central nervous system stimulants. These compounds primarily act on monoamine transporters in the body and inhibit the reuptake of dopamine, norepinephrine, and/or serotonin and may also act as releasers of the same neurotransmitters. The result of this pharmacological action is an increased concentration of neurotransmitters in the nerve cell synapse, which leads to stimulant and empathogenic physiological effects on the body. Desired effects of stimulants include euphoria, increased energy, sociability, and alertness. Adverse effects include anxiety, agitation, paranoia, hallucinations, and aggression. Acute toxicity is manifested via hyperthermia, hypertension, and tachycardia, severe agitation, hallucinations, and potential seizure, rhabdomyolysis, kidney failure, and death. Chronic toxicity includes psychological dependence, cognitive impairment, sleep disorders, depression, and neurotoxicity within the dopaminergic and serotonergic neutrotransmitter systems. 

Chemical structure of N-cyclohexyl methylone Drawn by Kevin G. Shanks (2025)

N-isopropyl butylone was first identified in the United States in 2024 in the state of Georgia, where it was detected in drug material alongside methamphetamine. It was also detected in drug material sold as MDMA in New Zealand in 2024 and in drug material purported to be MDMA/ecstasy sold in Europe in 2025. In 2025, it was found alongside ketamine and methamphetamine. N-isopropyl butylone is a positional isomer of other substituted cathinones including N-ethylpentylone, N, N-dimethylpentylone, and N-propylbutylone. 

N-cyclohexyl methylone was first identified in the United States in 2022 in drug material in the state of Florida when it was sold as an ecstasy tablet and in Indiana sold as a beige/off-white crystalline powder. The substance is a derivative of the older cathinone, methylone, which is itself a derivative of MDMA (3,4-methylenedioxymethamphetamine). 

While not explicitly listed as controlled substances in the United States, both of the substances may be considered positional isomers of already controlled drugs and therefore be considered “analogues”. According to the Drug Enforcement Administration’s (DEA) National Forensic Laboratory Information System (NFLIS) March 2023 Drug Snapshot, N-cyclohexyl methylone was the third most common detected substituted cathinone in the United States with 257 reports. And in the December 2024 Drug Snapshot, N-isopropyl butylone was the most prevalent cathinone with 178 detections while N-cyclohexyl methylone was number 5 with 12 detections. There have not yet been any published reports of these two substances being implicated in human toxicity, including hospitalizations and fatalities. 

Axis qualitatively monitors both compounds in our Novel Emerging Compounds (NEC) panel (order code 13710) and Comprehensive Panel, Blood with Analyte Assurance™ (order code 70510) using liquid chromatography with quadrupole time of flight mass spectrometry (LC-QToF-MS).  Axis also monitors other NPS cathinones in the NEC panel including alpha-PHP, alpha-PiHP, and N, N-dimethylpentylone. Additional cathinone/stimulant compounds in our Novel Psychoactive Substances panel (order code 13610) include alpha-PVP, butylone, dibutylone, dimethylone, eutylone, MDPV, mephedrone, methcathinone, methedrone, methylone, N-ethylpentylone, pentylone, and TFMPP. As always, if you have questions about these substances and how they may play a role in your medical-legal investigation, please reach out to our subject matter experts by email ([email protected]) or phone (317-759-4869, Option 3). 

By Kevin Shanks, M.S., D-ABFT-FT

As we have discussed on this blog several times in the past, novel psychoactive substances (NPS) come in different varieties, which include cannabinoids, stimulants, opioids, benzodiazepines, and hallucinogens. One of Axis Forensic Toxicology’s objectives it to be able to detect the most recently emerged NPS on the street in a timely manner. With that said, a new fentanyl derivative has emerged! 

Chemical Structure of ortho-Methylfentanyl Drawn by Kevin G. Shanks (2025)

Ortho-Methylfentanyl is a fentanyl analog or derivative that has emerged in the United States as an NPS in both powders and counterfeit tablets. It has a chemical formula C23H30N2O and a molecular weight equal to 350.5 g/mol. It is structurally-related to fentanyl with the fundamental difference in chemical structure being in the position of a single methyl (-CH3) group, which is attached to the ortho- position of the phenyl ring. There are two other positional isomers: meta- and para-methylfentanyl. The ortho isomer of methylfentanyl was first detected in 2023 in British Columbia, Canada, but over the last two years, it was been detected across Canada and the United States. In the United States, the substance is considered a Schedule I controlled substance and is illegal to synthesize, possess, and distribute. 

Pharmacologically, it is a mu (µ) opioid receptor agonist, much like morphine, oxycodone, and fentanyl. It also shares a similar analgesic potency with fentanyl. As a mu opioid receptor agonist, the effects of the substance would include analgesia, tiredness, drowsiness, sedation, and in overdose, severe respiratory depression, hypoxia, apnea, coma, and potentially, death. 

In early 2025, we first detected ortho-methylfentanyl in our postmortem toxicology sample population and have now added it to our Designer Opioids panel (order code 13810) and the Comprehensive Panel, Blood with Analyte Assurance™ (order code 70510) using liquid chromatography with quadrupole time of flight mass spectrometry (LC-QToF-MS). Reporting limit is 50 pg/mL.  

Axis also has the ability to monitor other novel opioids to include acetylfentanyl, acrylfentanyl, AP-237, AP-238, betahydroxythiofentanil, brorphine, carfentanil, cis-3-methylfentanyl, cyclopropylfentanyl, furanylfentanyl, isobutrylfentanyl, methoxyacetylfentanyl, ocfentanil, para-fluorobutyrylfentanyl, para-fluoroisobutyrylfentanyl, tetrahydrofuranfentanyl, tianeptine, U-47700, and valerylfentanyl. 

As always, if you have questions about ortho-methylfentanyl and how it (or any other novel emerging compound) may play a role in your medical-legal investigation, please reach out to our subject matter experts by email ([email protected]) or phone (317-759-4869, Option 3). 

Stay tuned to this blog for more quick drug primers on more novel compounds we have recently added to our testing scope! 

By Kevin Shanks, D-ABFT-FT

1,1-Difluoroethane (DFE) is a chemical compound that belongs to the family of hydrofluorocarbons, also known as HFCs. DFE has a chemical formula C2H4F2 and is a colorless, odorless gas at room temperature and is commonly used as a refrigerant (HFC-152a or R-152a) in air conditioning and refrigeration systems. It is also used as a propellant in aerosol products, such as cleaning sprays for electronics, computer keyboards, and other sensitive equipment. DFE has a relatively low environmental toxicity and does not deplete the ozone layer, therefore is considered a more environmentally friendly alternative to older refrigerants like CFC-12 (dichlorodifluoromethane) because it has a lower global warming potential (GWP). 

Chemical Structure of 1,1-difluoroethane (DFE)
Drawn by Kevin G. Shanks (2025)

The pharmacology of DFE is primarily related to its toxicological effects, as it is not used for any therapeutic or medical application. It is often misused by individuals seeking to experience a high through inhalation, sometimes called “huffing”, which can be highly dangerous and lead to severe health consequences. The substance acts as a volatile anesthetic that depresses the central nervous system leading to a sedative effect via the GABAA and glutamate receptors. Symptoms of acute exposure to DFE are coughing, wheezing, difficulty breathing, drowsiness, dizziness, light-headedness, headache, nausea, euphoria, and loss of coordination. In more severe cases, it can cause slurred speech, altered judgement, unconsciousness, pulmonary edema, suffocation, and death. Chronic exposure to DFE may lead to more long-term effects, including potential neurological damage and heart damage, including coronary disease, angina, and arrhythmias, and potential psychological addiction. 

Electronic cleaning spray with DFE as an ingredient  Images by Kevin G. Shanks (2025)

There have been several case reports of DFE toxicity and fatality published in scientific literature over the years. In reports published by Broussard et al. and Hahn et al., 3 adults died in vehicle accidents and had blood DFE levels ranging from 35-86 mcg/mL. In another report published by Frazee et al., two men were found dead after using DFE – they had postmortem blood DFE concentrations of 61 and 230 mcg/mL. In another report published by Vance et al., 14 adults who died following acute ingestion of DFE had postmortem blood concentrations ranging from 3-380 mcg/mL.  

As DFE is not a pharmaceutical medication or substance approved for use in the human body, there is no amount considered safe for use, therefore, there is also no unequivocal corresponding postmortem blood concentration that is considered therapeutic, toxic, or fatal. All postmortem blood concentrations can and should be considered relevant in a medical-legal investigation surrounding impairment, toxicity, and/or fatality. 

Axis Forensic Toxicology tests for DFE by gas chromatography with flame ionization detection (GC-FID) under order code 46590, and has just added the screen to the Comprehensive Panel with Analyte Assurance™. Minimum sample size is 0.5 mL. Due to the previously mentioned lack of relevancy of postmortem blood concentrations, all results are reported as qualitative (positive or negative). No quantitation is performed. 

As always, if you have questions about DFE and how it may have played a role in your medical-legal investigation, please reach out to our subject matter experts by email ([email protected]) or phone (317-759-4869, Option 3).

References

• Randall C. Baselt. Fluorocarbons. Disposition of Toxic Drugs and Chemicals in Man.12th Edition. Pages 878-880. 
• Larry Brousard, Barry S. Levine, Sarah Kerrigan. Chapter 31. Inhalants. Principles of Forensic Toxicology. 5th Edition. Pages 561-568. 
• L. Brousard, T. Brustowicz, T. Pittman et al. Two traffic fatalities related to the use of difluoroethane. Journal of Forensic Science, 42: 1186-1187 (1997).
• T. Hahn, J. Avella, and M. Lehrer. A motor vehicle accident fatality involving the inhalation of 1,1-difluoroethane. Journal of Analytical Toxicology, 30: 638-642 (2006).
• C.C. Frazee III, S. Fleming, and U. Garg et al. Huffing: Two deaths involving 1,1-difluoroethane. Society of Forensic Toxicologists Annual Meeting, 2010. 
• C. Vance, C. Swalwell, and I. McIntyre. Deaths involving 1,1-difluoroethane at the San Diego County Medical Examiner’s Office. Journal of Analytical Toxicology, 36: 626-633 (2012).