SPECIALTY LAB TEST FOR POTENT PAINKILLER
Fentanyl (Duragesic, Sublimaze) is an extremely fast-acting synthetic narcotic analgesic, of high potency (approximately 100 - 200 times that of morphine) and short duration of action. There are several analogues and derivatives of fentanyl which are also abused, and may have higher potencies. Pharmaceutical fentanyl has been available since 1963 as an anesthetic supplement, and is available as a citrate salt for I.V or I.M injection.
Transdermal patches are also available for management of chronic pain or for breakthrough cancer pain. Fentanyl abuse among healthcare workers has become popular due to the drugs euphoric effects and easy availability. Due to the lipophilicity of the drug, fentanyl rapidly crosses the blood-brain barrier, producing fast and pronounced CNS effect, such as a heightened euphoria and respiratory depression, and possible toxic effects which include muscle rigidity, seizures, coma, and hypotension. Fentanyl also has similar tolerance and physical dependence properties to those of morphine.
Illicit fentanyl which appears on the street in the U.S., is principally in the form of the transdermal patches, which can be cut up and eaten, or the gel can be extracted from the patches and smoked or injected by addicts. Illicitly synthesized fentanyl powder manufactured in Mexico has appeared in the U.S. recently, and may be abused by itself or mixed with heroin or cocaine, which has resulted in several deaths.
Fentanyl is rapidly metabolized by the liver to the inactive metabolites, norfentanyl, hydroxyfentanyl, and hydroxynorfentanyl. Approximately 85% of an intravenous dose is excreted in urine over a 3 - 4 day period, with 0.4 - 6% of the drug excreted unchanged, 26 - 55% excreted as norfentanyl, and unknown amounts of hydroxyfentanyl, and hydroxynorfentanyl excreted.
Fentanyl is administered I.V. or I.M. at single dosage levels of 25 - 100 μg as needed, transdermally at dosages of 25 - 100 μg/hr for 72 hours for chronic pain management, or by oral transmucosal dosages of 200 - 1600 μg for breakthrough cancer pain. Following a single 50 - 100 μg fentanyl dose, fentanyl was detected in the urine of 3 of 7 patients for 24 hours. Urine fentanyl concentrations ranged from 89 - 449 ng/mL in 4 adults who died following the excessive use of transdermal fentanyl. In another series of 7 adult deaths, fentanyl concentrations ranging from 5.0 - 93 ng/mL were found following self-administered intravenous injections.
Redwood Toxicology Laboratory has developed and validated a direct method for the detection of fentanyl in urine using liquid-liquid extraction, deuterated internal standards, and GC/MS SIM detection. Accuracy of the method is in excess of 99.5% at 3 different concentrations with an overall precision of <5.0%. Linearity of the method is 5-10,000 ng/mL with a limit of detection of 5ng/mL.
