Fentanyl and fentanyl analogs are increasingly entering the drug supply as counterfeit tablets or substituted for heroin or other drugs. These analogs include drugs such as alfentanil, remifentanil, and sufentanil, as well as drugs that are not approved for use in humans, such as carfentanil, furanylfentanyl, and others. Fentanyl is 50 to 100 times more potent than morphine and some analogs are even stronger. Today, street drugs are commonly cut, mixed, or exchanged with fentanyl and, undenounced to the user, ill effects and even death can occur. Fentanyl analogs, such as carfentanil, which are over 100 times more potent than fentanyl are becoming more prevalently mixed with street drugs. Carfentanil is a synthetic opioid approximately 10,000 times more potent than morphine and the DEA has warned about contact with these substances and to avoid touching mucous membranes after touching these substances.
Fentanyl is widely used in clinical medicine and has been commercially available as sublingual tablets and in a lollipop formation, etc., because of its rapid onset following oral absorption. Buccal, intranasal, lozenge, and sublingual fentanyl formulations are used in clinical practice but always with caution for potential fear of side effects. The food and drug administration (FDA) prescribing information includes
Serious, life-threatening, or fatal respiratory depression has occurred with use of fentanyl, including following use in opioid non-tolerant patients and improper dosing. […] Accidental exposure of even one dose of fentanyl, especially by children, can result in a fatal overdose of fentanyl. Death has been reported in children who have accidentally ingested transmucosal immediate-release fentanyl products. Deaths due to a fatal overdose of fentanyl have occurred when children and adults were accidentally exposed to fentanyl transdermal patch.
Concentrations of fentanyl sold on the street vary greatly regarding concentration and formulations. It is well known that substantial differences exist in the pharmacokinetic profile of buccal, intranasal, lozenge, and sublingual fentanyl compared with other fentanyl products. The pharmacokinetic differences in the extent of absorption of fentanyl can result in fatal overdose even in the hospital setting and even when taken as prescribed by health care providers. It is understandable how street drugs that are mixed with fentanyl can result in acute consequences such as respiratory depression, coma, and death.
Depending on the formulation, oral exposure of fentanyl will peak within 10 minutes with an onset < 1 minute.- Oral exposure is discouraged in opioid-naïve patients in clinical practice such that it carries a boxed warning from the FDA. The US Boxed Warning states, “Transmucosal and nasal fentanyl formulations are contraindicated in the management of acute or postoperative pain and in opioid nontolerant patients.”