Many people who are suffering from cancer will experience regular pain. This ongoing and continuous pain is sometimes called “background pain”. However, people that experience background pain may also experience periods of particularly severe and intense pain that “breaks through” the regular or background pain. This is known as breakthrough cancer pain(BTcP).
Fentanyl is an opioid analgesic used in anesthesia, for breakthrough cancer pain, or round the clock pain management; was developed in the 1950s to fill a need for strong and rapid analgesia. Because of these characteristics, fentanyl is commonly used to treat chronic cancer pain or in anesthesia.
Fentanyl sublingual tablets, transmucosal lozenges, buccal tablets, sublingual sprays, transdermal systems, and nasal sprays are indicated for the management of breakthrough pain in opioid tolerant cancer patients who require around the clock pain management.
Fentanyl produces strong analgesia through its activation of opioid receptors.
It has a duration of action of several hours and a wider therapeutic index as patients develop tolerance to opioids.
Fentanyl is associated with a risk of addiction and abuse and should not be mixed with alcohol or benzodiazepines.
Fentanyl is 80-85% bound to plasma proteins. In one study, a 0.1µg/L solution of fentanyl was 77.9±1.1% bound to human serum albumin and 12.0±5.4% bound to α-1 acid glycoprotein. A 0.1µg/L solution of norfentanyl, the primary metabolite of fentanyl, was 7.62±1.2% bound to human serum albumin and 7.24±1.9% bound to α-1 acid glycoprotein.
Fentanyl binds to opioid receptors, especially the mu opioid receptor, which are coupled to G-proteins.
Activation of opioid receptors causes GTP to be exchanged for GDP on the G-proteins which in turn down regulates adenylate cyclase, reducing concentrations of cAMP.
Reduced cAMP decreases cAMP dependant influx of calcium ions into the cell. The exchange of GTP for GDP results in hyperpolarization of the cell and inhibition of nerve activity.
Metabolism: Fentanyl is metabolized to a number of inactive metabolites. Fentanyl is 99% N-dealkylated to norfentanyl by cytochrome P450. It can also be amide hydrolyzed to despropionylfentanyl, or alkyl hydroxylated to hydroxyfentanyl which is N-dealkylated to hydroxynorfentanyl.
Absorption: Fentanyl sublingual tablets are 54% bioavailable. Fentanyl sublingual spray reached a Cmax of 0.20±0.06ng/mL for a 100µg dose and 1.61±0.60ng/mL for an 800µg dose with a Tmax of 0.69-1.25 hours, decreasing as the dose increased. The AUC was 1.25±0.67ng*h/mL for a 100µg dose and 10.38±3.70ng*h/mL for a 800µg dose.
Route of elimination: Within 72 hours, 75% of a dose of fentanyl is excreted in the urine with <7% unchanged, and 9% is excreted in the feces with <1% unchanged.
Half life: The half life of fentanyl is 7 hours. The half life of fentanyl sublingual spray is 5-12 hours.
All medicines may cause side effects, but many people have no, or minor, side effects.Some medical conditions may interact with Fentanyl.
Tell your doctor or pharmacist if you have any medical conditions.
Common side effects may include: respiratory depression, somnolence, stupor, coma, skeletal muscle flaccidity, cold and clammy skin, pupillary constriction, pulmonary edema, bradycardia, hypotension, airway obstruction, atypical snoring.
In case of overdose, patients should receive naloxone or nalmefene to reverse the action of the opioids as well as supportive measures to maintain the airway or advanced life support in the case of cardiac arrest.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.
