Fentanyl Absorption, Distribution, Metabolism, and Excretion: Narrative Review and Clinical Significance Related to Illicitly Manufactured Fentanyl.

This review reexamines information yielded from decades of medicinal fentanyl research and applies elements of the pharmacokinetic profile to persons with IMF exposure. In persons who use drugs, peripheral accumulation of fentanyl may be leading to prolonged exposure. More focused research on the pharmacology of fentanyl in persons using IMF is warranted.