Sorted By Test Name - Mayo Medical Laboratories

DMETH
505343
DPCP
505339
EMIT cutoff concentration: 150 ng/mL
Positives are reported with a quantitative GC-MS result.
Clinical References: Baselt RC, Cravey RH: Disposition of Toxic Drugs and Chemicals in Man.
Third edition. Chicago, Year Book Medical Publishers, 1989
Drug of Abuse, Methadone Screen with GC-MS Confirmation,
Urine
Clinical Information: Methadone (Dolophine) is a synthetic narcotic with analgesic and
pharmacological properties similar to morphine. It can be administered orally and provides analgesia for
approximately 24 hours. The I-racemate of the drug is active, while the d-racemate has little activity.
Methadone has properties that make it useful for treating heroin addiction. Sedation ensues with higher
doses, which is an undesirable side effect. Administered in small doses of 5 to 20 mg, the drug occupies
the opioid receptor for prolonged periods of time, blocking the action of morphine, precluding the
euphoric effect that heroin addicts seek. Addicts who self-administer heroin while taking methadone
doses do not experience euphoria, only sedation, miosis, respiratory depression, hypotension, and
dry-mouth. Tolerant patients may require doses up to 200 mg per day. Methadone is metabolized by
demethylation (cytochrome P [450] 2D6 [CyP 2D6]) to 2-ethylidene-1, 5-dimethyl-3,
3diphenylpyrrolidine (EDDP) and to 2-ethyl-5-methyl-3, 3-diphenylpyrrolidine (EMDP). Individuals with
genetic deficiencies of CyP 2D6 or coadministered amiodarone, paroxetine protease inhibitor
antiretrovirals, chlorpheniramine, or other drugs that inhibit CyP 2D6 will accumulate methadone with
associated toxicity.
Useful For: Compliance monitoring of methadone therapy in patients being treated for heroin
addiction
Interpretation: A positive result derived by this testing indicates that the patient has used methadone
in the recent past. Because the urine output of methadone associated with minimal effective therapy can
range between 1,000 to 50,000 ng/mL and only 5% is excreted unmetabolized, there is poor correlation of
urine concentration with dose.
Reference Values:
Negative
EMIT cutoff concentration: 300 ng/mL
Positives are reported with a quantitative GC-MS result.
Clinical References: 1. Goodman LS, Gillman A, Hardman JG, et al: The pharmacological basis of
therapeutics. 9th edition. Edited by JG Hardman, LE Limbird. New York, McGraw Hill, 2001, pp 544-55
2. Baselt RC: In Disposition of Toxic Drugs and Chemicals in Man, 5th edition. Chemical Toxicology
Institute, Foster City, CA 2000
Drug of Abuse, Phencyclidine Screen With GC-MS
Confirmation, Urine
Clinical Information: Phencyclidine (PCP) is a drug of abuse. This compound affects diverse neural
pathways and interacts with cholinergic, adrenergic, GABA-secreting, serotoninergic, opiate neuronal
receptors, and gamma receptors. It has analgesic, anesthetic, and stimulatory effects, giving bizarre
behavior, ranging from depression through catatonia, euphoria, violent rage, and hallucinations. Most
fatalities result from its hypertensive effect. Diagnosis of PCP usage depends on drug screen. PCP is
excreted in the urine.
Useful For: Detection of drug abuse involving PCP (angel dust or angel hair)
Interpretation: The presence of PCP in urine at concentrations >10 ng/mL is a strong indicator that
the patient has used PCP.
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