Fentanyl Drug Information

Classification

Fentanyl (Duragesic, Sublimaze, "China White") 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 anaesthetic 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.

Metabolism

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.

Abuse

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 have resulted in several deaths.

With increased dose or prolonged abuse (either binge or chronic) an individual may experience a set of secondary effects that can include increased anxiety, irritability, aggressiveness, paranoia and hypersexuality. Physiological effects can include dilated pupils, dry mouth, hippus, increased body temperature and tachycardia. In overdose situations, a person my experience hallucinations, coma or death. Crash symptoms typically follow binge abuse of cocaine. This phase is marked by extreme fatigue, depression, mental exhaustion and prolonged periods of sleep.

Laboratory drug testing: Methods of Analysis

Immunoassay screens are commercially available for detecting fentanyl in urine specimens. Confirmation of the presumptive positives is generally performed using a specific technique such as gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/tandem mass spectrometry (LC/MS/MS). Redwood Toxicology Laboratory utilizes a direct method for the detection of fentanyl in urine using liquid-liquid extraction, deuterated internal standards, and GC/MS detection.


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Drug information data is not definitive and should be used for reference guidelines only.