Test Catalog

Test ID: MTDNX    
Methadone Confirmation, Chain of Custody, Random, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

Monitoring for compliance of methadone treatment for analgesia or drug rehabilitation


Urine measurement of 2-ethylidene-1,5-dimethyl1-3,3-diphenylpyrrolidine is particularly useful for assessing compliance with rehabilitation programs


Chain of custody is required whenever the results of testing could be used in a court of law. Its purpose is to protect the rights of the individual contributing the specimen by demonstrating that it was under the control of personnel involved with testing the specimen at all times; this control implies that the opportunity for specimen tampering would be limited

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Adulterants testing will be performed on all chain of custody urine samples as per regulatory requirements.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Methadone (dolophine) is a synthetic opioid, a compound that is structurally unrelated to the natural opiates but is capable of binding to opioid receptors. These receptor interactions create many of the same effects seen with natural opiates, including analgesia and sedation. However, methadone does not produce feelings of euphoria and has substantially fewer withdrawal symptoms than opiates such as heroin.(1) Methadone is used clinically to relieve pain, to treat opioid abstinence syndrome, and to treat heroin addiction in the attempt to wean patients from illicit drug use.


Metabolism of methadone to inactive forms is the main form of elimination. Oral delivery of methadone makes it subject to first-pass metabolism by the liver and creates interindividual variability in its bioavailability, which ranges from 80% to 95%. The most important enzymes in methadone metabolism are cytochrome P450 (CYP) 3A4 and CYP2B6.(1-4) CYP2D6 appears to have a minor role, and CYP1A2 may possibly be involved.(1-5) Methadone is metabolized to a variety of metabolites, the primary metabolite is 2-ethylidene-1,5-dimethyl1-3,3-diphenylpyrrolidine (EDDP).(1-4) The efficiency of this process is prone to wide inter- and intraindividual variability, due both to inherent differences in enzymatic activity as well as enzyme induction or inhibition by numerous drugs. Excretion of methadone and its metabolites (including EDDP) occurs primarily through the kidneys.(1,4)


Patients who are taking methadone for therapeutic purposes excrete both parent methadone and EDDP in their urine. Clinically, it is important to measure levels of both methadone and EDDP. Methadone levels in urine vary widely depending on factors such as dose, metabolism, and urine pH.(5) EDDP levels, in contrast, are relatively unaffected by the influence of pH and are therefore, preferable for assessing compliance with therapy.(5)


Some patients undergoing treatment with methadone have attempted to pass compliance testing by adding a portion of the supplied methadone to the urine.(6) This is commonly referred to as "spiking.'' In these situations the specimen will contain large amounts of methadone and no or very small amounts of EDDP.(6) The absence of EDDP in the presence of methadone in urine strongly suggests adulteration of the urine specimen by direct addition of methadone to the specimen.


Chain of custody is a record of the disposition of a specimen to document who collected it, who handled it, and who performed the analysis. When a specimen is submitted in this manner, analysis will be performed in such a way that it will withstand regular court scrutiny.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.



Cutoff concentrations:


<300 ng/mL



<100 ng/mL



<100 ng/mL

Interpretation Provides information to assist in interpretation of the test results

The absolute concentration of methadone and its metabolites found in patient urine specimen can be highly variable and do not correlate with dose. However, the medical literature and our experience show that patients who are known to be compliant with their methadone therapy have ratios of 2-ethylidene-1,5-dimethyl1-3,3-diphenylpyrrolidine (EDDP):methadone of >0.60.(7)


An EDDP: methadone ratio <0.090 strongly suggests manipulation of the urine specimen by direct addition of methadone to the specimen.(6)

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Urine pH has a considerable effect on the ability to detect methadone, thus 2-ethylidene-1,5-dimethyl1-3,3-diphenylpyrrolidine is preferable for urine measurements.


Urine concentrations of methadone show very poor correlation to serum levels or the amount of drug administered.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Chapter 23: Opioid analgesics. In Goodman and Gilman's: The Pharmacological Basis of Therapeutics. 10th edition. Edited by HB Gutstein, H Akil. McGraw-Hill Book Company, 2001, pp 569-619

2. Eap CB, Buclin T, Baumann P: Interindividual variability of the clinical pharmacokinetics of methadone: implications for the treatment of opioid dependence. Clin Pharmacokinet 2002;41:1153-1193

3. Ferrari A, Coccia CP, Bertolini A, Sternieri E: Methadone-metabolism, pharmacokinetics and interactions. Pharmacol Res 2004;50:551-559

4. Baselt RC: Disposition of Toxic Drugs and Chemicals in Man. Seventh edition. Foster City, CA, Chemical Toxicology Institute, 2005

5. Principles of Forensic Toxicology. Second edition. AACC Press, 2003, pp 385

6. Galloway FR, Bellet NF: Methadone conversion to EDDP during GC-MS analysis of urine samples. J Anal Toxicol 1999;23:615-619

7. George S, Braithwaite RA: A pilot study to determine the usefulness of the urinary excretion of methadone and its primary metabolite (EDDP) as potential markers of compliance in methadone detoxification programs. J Anal Toxicol 1999;23:81-85

8. Nader R, Horwath AR, Wittwer CT: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Sixth Edition. Elsevier 2018