Fentanyl and its Medical uses

Fentanyl, also spelled fentanyl,is a highly potent synthetic opioid used as an analgesic.Fentanyl is used with other medicines for anesthesia.It is also used recreationally,sometimes in combination with heroin,cocaine,benzodiazepines or methamphetamine. Excess of it can be neutralized by naloxone.Fentanyl is sometimes used as an additive in counterfeit medicines masquerading as legitimate medicines.It works quickly and its effects usually last less than two hours.In medicine, it is administered by injection,nasal spray, or transdermal patch.Common adverse effects of fentanyl include nausea, vomiting, constipation, pruritus, sedation, confusion, and injury related to poor coordination.Serious adverse reactions may include hypoventilation, hallucinations, serotonin syndrome, hypotension, or the development of an opioid use disorder.Fentanyl acts by activating mu-opioid receptors.It is about 100 times stronger than morphine and about 50 times stronger than heroin.Fentanyl was first synthesized by Paul Janssen in 1960 and approved for medical use in the United States in 1968.In 2015, 1,600 kg (3,500 lb) were used in healthcare worldwide.As of 2017, fentanyl was the most widely prescribed synthetic opioid in medicine;[10] in 2019, it was the 278th most commonly prescribed drug in the United States, with over one million prescriptions.It is on the World Health Organization’s list of essential medicines.Fentanyl and fentanyl analogs accounted for the majority of drug overdose deaths in the United States in 2021, with 71,238 deaths.Compared to heroin, it is more potent, has higher profit margins, and has simpler logistics due to its smaller size.It can cut off or even completely replace the supply of heroin and other opiates.The flow of fentanyl mainly originates from factories in China that produce fentanyl or fentanyl precursors; they are then trafficked to other countries for illicit production and sale. In the U.S., finished fentanyl arrives mainly from Mexico via cartels.The U.S. Drug Enforcement Administration (DEA) intercepted and seized more than 10,000 pounds (4,500 kilograms) of fentanyl and more than 50 million fentanyl tablets in 2022, more than double the amount seized in 2021.

Medical use 

Anesthesia

Intravenous fentanyl is usually used for anesthesia and pain relief.To induce anesthesia, it is used together with sedative-hypnotics (such as propofol or thiopental) and muscle relaxants.To maintain anesthesia, an inhaled anesthetic with additional fentanyl may be used.These are usually performed at 15-30 minute intervals throughout procedures such as endoscopy and surgery and in the emergency department.To reduce pain after surgery, use an inhaled anesthetic to reduce the amount of anesthesia needed to emerge from anesthesia.Balancing this drug and titrating the drug according to the expected stimulus and the person’s response stabilizes blood pressure and heart rate throughout the procedure and allows for faster emergence from anesthesia with minimal pain.

Regional anesthesia

Fentanyl is the most commonly used intrathecal opioid because its lipophilicity allows for a rapid onset (5-10 minutes) and moderate duration (60-120 minutes).Spinal administration of hyperbaric bupivacaine with fentanyl may be the optimal combination.Fentanyl works almost immediately,reducing visceral discomfort and even nausea during the procedure.

Obstetrics

Fentanyl is sometimes given intrathecally as part of a spinal anesthesia, or epidurally for epidural anesthesia and pain relief.Due to fentanyl’s high lipid solubility, its action is more localized than that of morphine,which some clinicians prefer for broader analgesic effects.It is widely used in obstetric anesthesia because of its short onset and peak time (about 5 minutes),rapid termination of effect after a single administration, and relatively stable cardiovascular system.In obstetrics, the dose must be strictly controlled to prevent substantial transfer from the mother to the fetus.At high doses, this drug may work on the fetus, causing postpartum respiratory distress.Therefore, short-acting agents such as alfentanil or remifentanil may be more suitable for induction of general anesthesia.

Pain management

The bioavailability of intranasal fentanyl is about 70-90%, but there is some imprecision due to nasal congestion, pharyngeal swallowing, improper administration, etc.For acute and palliative care, doses of intranasal fentanyl are 50, 100, and 200 µg. In emergency medicine, a prospective observational study of approximately 900 out-of-hospital patients demonstrated that intranasal fentanyl was safe, had low side effects, and was effective in analgesia.In children, intranasal fentanyl can be used to treat moderate and severe pain and is well tolerated.Furthermore, a 2017 study showed that fentanyl lozenges were also effective in children as young as 5 years old, who weighed only 13 kg.Lozenges are more likely to be used because the child can control an adequate dose than buccal tablets.

Chronic pain

It is also used to treat chronic pain, including cancer pain.Transdermal patches are often used.The patch works by slowly releasing fentanyl through the skin into the bloodstream over 48 to 72 hours, allowing for long-lasting pain management.Dosage depends on the size of the patch because,in general, the rate of transdermal absorption is constant at constant skin temperature.Each patch should be replaced every 72 hours.Absorption rates depend on many factors. Body temperature, skin type, amount of body fat, and placement of the patch all have a major impact.Different delivery systems used by different manufacturers can also affect individual absorption rates. In general, the patch achieves its full effect within 12 to 24 hours; therefore,a fentanyl patch is often prescribed with a fast-acting opioid such as morphine or oxycodone to treat sudden onset pain.It is unclear whether fentanyl provides long-term pain relief in patients with neuropathic pain.