Opioids are natural and semisynthetic alkaloids prepared from opium and synthetic compounds whose pharmacologic properties, rather than structure, mimic morphine.
Specific names: heroin, codeine, morphine, oxycodone, oxymorphone, hydrocodone, hydromorphone, buprenorphine, methadone, meperidine, propoxyphene (withdrawn from the US market), nalbuphine, fentanyl, levorphanol, butorphanol, pentazocine, tapentadol, tramadol.
There is no single test that will screen for/confirm all the opioids listed.
Normal range: drug and use dependent.
Use
Treatment of pain, usually moderate to severe
Preoperative sedation
Postoperative analgesia and surgical and medical emergencies including myocardial infarction, trauma, burns, orthopedic pain
Management of chronic pain associated with cancer
Antitussive and antidiarrheal agent
Detoxification and maintenance therapy of opiate addicts
Limitations
Screening
Typically performed in urine
Immunoassay-based technology performed on automated chemistry analyzers
EIA (KIMS, CEDIA), EMIT, RIA, FPIA
Qualitative
Target: morphine, morphine " “glucuronide
These "opiate " ¯ assays do not detect the semi/synthetic opioids, which include buprenorphine, methadone, meperidine, propoxyphene, nalbuphine, fentanyl, levorphanol, butorphanol, pentazocine, tapentadol, and tramadol.
These "opiate " ¯ assays have variable cross-reactivity with oxycodone, oxymorphone, hydrocodone, and hydromorphone.
Cutoff concentration " ”user defined.
300 ng/mL
2,000 ng/mL
Specific immunoassays are available for individual synthetic compounds.
Oxycodone: cutoff concentration 100 ng/mL; depending on the manufacturer, may exhibit approximately 100% cross-reactivity with oxymorphone
Methadone: cutoff concentration 300 ng/mL; depending on the manufacturer, may exhibit approximately 40% cross-reactivity with methadol
Buprenorphine: cutoff concentration 5 ng/mL; typically do not exhibit cross-reactivity with norbuprenorphine
Propoxyphene: cutoff concentration 300 ng/mL; depending on the manufacturer, may exhibit approximately 60% cross-reactivity with norpropoxyphene
Variable cross-reactivity with opioid metabolites
Several vendors offer assays in semiquantitative mode.
Immunoassay available specifically for heroin metabolite-6-acetylmorphine: cutoff concentration 10 ng/mL; <1% cross reactivity with morphine, codeine, and synthetic opioids
Screening in blood, serum
Immunoassay-based technology (FPIA, ELISA, RIA)
Opioid specific except for general "opiates, " ¯ which targets morphine with a cutoff concentration typically of 10 ng/mL
Target (cutoff concentration)
Fentanyl <1 ng/mL
Methadone 10 " “50 ng/mL; <5% cross-reactivity with methadol
Oxycodone 10 " “50 ng/mL; >50% cross-reactivity with oxymorphone
d-Propoxyphene 10 " “50 ng/mL; >400% cross-reactivity with norpropoxyphene
Confirmation/quantitation in serum, urine
Confirmation of urine samples often includes hydrolysis to cleave the glucuronide bond. In this case, the concentration provided is total drug (compared with free or unbound drug).
Common opioid confirmation profiles will include 6-acetylmorphine, morphine, codeine, oxycodone, oxymorphone, hydrocodone, and hydromorphone with limit of quantitation drug dependent but ranging 5 " “25 ng/mL.
Most synthetic opioids require individual specific tests for confirmation and quantitation; for potent low-dose synthetic opioids such as buprenorphine and fentanyl, the limit of quantitation is ≤1 ng/mL.
Sample preparation required: liquid " “liquid or solid-phase extraction.
Testing methodologies: gas chromatography, HPLC, GC/MS, LC/MSn (multiple Sn).