Methadone, Serum

Test ID: 


CPT code:



  • Dolophine®
  • Methadose®

Clinical Use:

Therapeutic monitoring of methadone (Dolphine®/Methadose®) treatment.

Test Information:

Methadone possesses many of the pharmacologic properties of morphine and is approximately equipotent as an analgesic when administered parenterally. Unlike morphine, however, methadone produces marked sedative effects with repeated administration as a result of drug accumulation. This undesirable property restricted clinical usage of the drug until 1965 when Dole and Nyswander began narcotic maintenance treatment of former heroin addicts using large daily oral doses of dl-methadone.2 Whereas maintenance patients may receive as much as 180 mg of the drug daily, doses ≤50 mg have been known to prove fatal to nontolerant adults. The pharmacologic activity is due almost entirely to the l-isomer. The d-methadone isomer does have analgesic properties in large doses and this may be due to conversion to minor amounts of α-l-methadone and α-l-normethadol, both of which are potent analgesics.

Specimen Type:

Serum or plasma

Requested Volume: 

1 mL

Minimum Volume: 

0.3 mL

Container Type: 

Red-top tube, lavender-top (EDTA) tube, or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.


Transfer separated serum or plasma to a plastic transport tube.

Storage Instructions:

Room temperature

Stability Requirements:



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Rejection Criteria

Gel-barrier tube

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