2025 Medical Review Officer Online Course with Live Discussion (Includes Digital Syllabus)-Tab 8:Toxicology of Drugs of Abuse

Tab 8:Toxicology of Drugs of Abuse

Pdf Summary

This document provides a comprehensive overview of toxicology related to drug testing, focusing on interpretation, metabolism, and detection of various substances.<br /><br />Interpretation of drug test results emphasizes that a negative result may indicate no recent drug use, but can also be due to urine dilution or adulteration. Positive results confirm drug use but do not correlate with impairment, route, amount, or timing.<br /><br />Cannabinoids: Marijuana contains about 90 cannabinoids, with delta-9-tetrahydrocannabinol (THC) being the main psychoactive compound. Two major metabolites are 11-nor-delta-9-THC-OH (short-lived, psychoactive) and 11-nor-delta-9-THC-9-carboxylic acid (THCA), the primary urine test target. Detection depends on assay specificity, cut-off levels, and use type. Issues include passive inhalation, medicinal usage, and synthetic cannabinoids. Exposure to hemp products can cause low or variable urine test readings, as shown by studies with hemp snack bars and oils.<br /><br />Cocaine: Metabolized mainly to benzoylecgonine and ecgonine methyl ester; benzoylecgonine is detectable for days post-use. The drug’s plasma half-life is short, but metabolites persist. Routes of use include smoking, snorting, and injection. Notable issues are passive inhalation, unknowing ingestion, and degradation after collection.<br /><br />Opiates and Opioids: Opiates are derived from opium (e.g., morphine, heroin, codeine), while opioids are synthetic narcotics (e.g., hydrocodone, oxycodone). Heroin metabolizes to 6-monoacetylmorphine (6-AM), morphine, and others. Poppy seed consumption can yield morphine-positive tests. Opioid testing considers complex metabolism and potential for only metabolites being detected.<br /><br />Amphetamines: Reportable drugs include methamphetamine (with amphetamine as a metabolite) and MDMA. Detection is influenced by urine pH. Differentiation of illicit methamphetamine from legitimate sources (e.g., Vicks inhaler) is possible through chiral analysis. Issues include false positives from other sympathomimetic drugs and emerging “bath salts” (cathinones).<br /><br />PCP has no legitimate use and shows pH-dependent excretion. Other drugs discussed include benzodiazepines, barbiturates, and opioids like tramadol and fentanyl, with some drugs posing workplace-specific concerns.<br /><br />The document concludes with Medical Review Officer (MRO) self-assessment questions addressing interpretation of complex test results, reinforcing understanding of metabolism and detection profiles across drug classes.

Keywords

toxicology

drug testing

drug metabolism

drug detection

cannabinoids

cocaine metabolites

opiates and opioids

amphetamines

PCP

Medical Review Officer