Related Experiment Video
Updated: Jun 20, 2026
10:17
High-throughput and Comprehensive Drug Surveillance Using Multisegment Injection-Capillary Electrophoresis-Mass Spectrometry
Published on: April 23, 2019
[Urinary toxicological screening: analytical interference between niflumic acid and cannabis]
A Boucher1, P Vilette, N Crassard
1Centre d'évaluation et d'information sur la pharmacodépendance (CEIP), 162 avenue Lacassagne, Lyon cedex 03, France.
Summary
Niflumic acid can cause false-positive cannabis screening results in children. This analytical interference highlights limitations in immunoassay-based drug testing, necessitating confirmatory methods.
Area of Science:
- Clinical Chemistry
- Toxicology
- Pharmacology
Background:
- Immunoassays are widely used for initial toxicological screening due to their speed and cost-effectiveness.
- Nonsteroidal anti-inflammatory drugs (NSAIDs) can sometimes cause analytical interferences in various laboratory tests.
- Niflumic acid is an NSAID commonly prescribed for pain and inflammation, including in pediatric populations.
Observation:
- A 3-year-old girl presented with behavioral disturbances, and her medical history included niflumic acid treatment.
- Initial urinary drug screening yielded a false-positive result for cannabinoids.
- Subsequent analysis using chromatography confirmed the absence of cannabinoids and identified niflumic acid.
Findings:
- Demonstrated a case of analytical interference between niflumic acid and cannabinoid immunoassays.
- The interference led to a false-positive screening result for cannabis in a pediatric patient.
- Chromatographic methods successfully differentiated between the drug and the target analyte.
Implications:
- Highlights the limitations of immunoassay-based screening tests and the potential for false-positive results.
- Emphasizes the importance of considering drug interactions and interferences, especially in pediatric patients receiving common medications.
- Recommends confirmatory testing (e.g., chromatography) to avoid misleading conclusions in toxicological analysis.
Related Concept Videos
01:30Drug toxicity: Drug–Drug Interaction
Drug–drug interactions can precipitate toxicity through multiple mechanisms. Absorption interactions alter how drugs enter the body, exemplified when ranitidine increases the absorption of basic drugs, while cholestyramine decreases the levels of propranolol. Protein binding interactions occur when drugs share the same binding sites on plasma proteins. Drugs like aspirin and warfarin, when bound in excess, can lead to increased free drug concentrations, enhancing the potential for...
01:21Chemotherapy-Induced Nausea and Vomiting: Cannabinoids
Tetrahydrocannabinol (THC) is a phytocannabinoid that primarily interacts with the CB1 receptor, a type of G protein-coupled receptor (GPCR) predominantly in and around the chemoreceptor trigger zone (CTZ) and emetic center. THC also blocks the serotonin receptor activity in the dorsal vagal complex (DVC) by inhibiting serotonin release. THC exerts its anti-emetic effects through these interactions, which are beneficial for patients undergoing chemotherapy.
Two synthetic agonists of THC,...
Two synthetic agonists of THC,...
01:26Urine Studies II: Urine Culture and Sensitivity Test
A urine culture and sensitivity test is a diagnostic procedure used to identify urinary tract bacterial infections and determine the most effective antibiotics for treatment. This test is generally preferred when a patient shows manifestations of a urinary tract infection, such as frequent or painful urination, cloudy or foul-smelling urine, or lower abdominal pain.Purpose of the TestThe primary goals of a urine culture and sensitivity test are to:Determine the specific bacteria causing the...
01:27Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Phase II biotransformation reactions are essential for detoxifying and eliminating xenobiotics, including many pharmaceutical compounds. These reactions typically involve conjugation, the covalent attachment of polar endogenous groups such as glucuronic acid, sulfate, methyl, or acetyl moieties to functional groups introduced during Phase I metabolism. The resulting conjugates are more water-soluble, enabling efficient renal or biliary excretion.The major classes of Phase II enzymes include...