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How Long Does Fentanyl Stay in Your System?

Fentanyl is an opioid that was first synthesized by Paul Janssen in 1960s. The drug was initially used for anesthesia purposes in the operative rooms. Later on, it was approved for the clinical uses as a potent analgesic. Fentanyl binds to the mu-opioid receptors and stimulates the release of endorphins and enkephalins. This leads to alleviation of pain and generation of pleasant feelings. The mood improvements and neurophysiologic relaxation have also led to its abuse by many people. The long-term use of drug is also associated with certain adverse effects like confusion, dizziness, sedation, constipation, and memory impairment. The side-effects of Fentanyl can continue as long as drug particles stay within the system. It is important to know the time durations of drug elimination from the system.

How long does Fentanyl stay in your system?

When a person stops taking Fentanyl after a prolonged duration of use, a set of withdrawal symptoms start to appear in an individual. They occur due to physical and psychological dependence on the drug. Users are usually interested in knowing the time duration taken by their system to become completely free from the drug. To determine how long the drug particles can linger in our bodies, it is necessary to consider the half-life of drug. The half-life of intravenous Fentanyl is 2-4 hours in adults. It will take 11 to 12 hours to get eliminated from the system. The transdermal Fentanyl patch exhibits a half-life of about 7 hours. It will take almost 1.6 days to get out of the body system. The Transmucosal Fentanyl has a half life ranging from 5-15 hours. So, approximately 3.89 days are required to eliminate the drug. For the transdermal form of Fentanyl, 1.51 days are needed to clear from the body.

It can be concluded that the intravenous form will be eliminated more rapidly than transdermal and transmucosal formats. Furthermore, Transmucosal Fentanyl is subjected to earlier elimination than transdermal patches.

Factors that influence how long Fentanyl stays in your system:

The drugs elimination time is dependent on many factors. They can bring a considerable change in the duration of clearance of Fentanyl from the body. Such variables play a major role when more accurate durations are required as in detoxification centers for the drugs.

Individual Factors: The following individual attributes contribute to the changes in the time intervals in different individuals.

  • Age:The half-life in elderly people is about 15 hours in comparison to almost 5 hours in younger individuals. This shows the elderly may require up to 4 days for complete excretion of the intravenous drug. It is as a result of age related factors like low tissue perfusion, low plasma proteins, hepatic, and renal dysfunction.
  • Body fat: Fentanyl has a propensity for fatty tissues so it will get accumulated in adipose tissues of the body.
  • Genetics: Fentanyl is metabolized by the CYP3A4 enzymes. Some people have a poor metabolism due to the inefficiency of enzymes. Many people have powerful functioning of enzymes which leads to a faster metabolism.
  • Hydration:A proper intake of water is necessary to regulate the flow of drug through the kidneys into the urine. Therefore, individuals who stay optimally hydrated tend to eliminate the drug at faster rates.
  • Hepatic Functions:Any disease condition like cirrhosis can affect the rate of metabolism. The hepatic enzymes play a key role in the processing of drug. Any factor disturbing hepatic enzymes can alter the rate of metabolism.
  • Metabolic Rate:It is also known as BMR. People with a high BMR have a more rapid metabolism and more burning of fat sources. These both act to speed up the elimination process.

Route of Administration: This acts as an important factor in determining the time of elimination. As already discussed, the half-life of an intravenous route is the shortest, followed by transmucosal and transdermal. So the full elimination time is different for all these routes.

Dosages: The higher doses are related to storage and slow metabolism. A person continuously abusing Fentanyl would have developed tolerance and increased-up the doses for euphoric effects.

Frequency: More frequent use is associated with high plasma concentration of Fentanyl and slow excretion from the body.

Co-administered agents: Any medicines or supplements that act as CYP3A4 enhancers and inhibitors will increase or decrease the metabolism respectively. Carbamazepine, Phenytoin, phenobarbital, and rifampicin act as inducers. Ketoconazole, Ritonavir, and Clarithromycin act as CYP3A4 inhibitors.

Fentanyl absorption, metabolism, and excretion:

The transdermal and transmucosal forms are rapidly absorbed into the blood circulation. The intravenous form is directly entered into the blood so it has the highest efficiency among the routes of administration. The analgesic effects get instantaneously initiated within few minutes of an IV injection. The effects can last up to 30 to 60 minutes. The intramuscular form has a slow onset of action as compared to intravenous form. The effects get initiated in 10-15 minutes and stay up to 1 to 2 hours via the intramuscular route. Transmucosal and transdermal get swiftly absorbed through the buccal mucosa and skin respectively.

Through the transmucosal route, 25% of the drug enters through the mucosal lining and 75% gets dissolved in saliva and undergoes gastrointestinal absorption. This results in a total bioavailability of 50% transmucosal drug. Through the transdermal patch, bioavailability becomes 90%. Regardless of the route of administration of Fentanyl, 85% of the drug binds to the plasma proteins (alpha-1-acid glycoprotein) and gets distributed to various organs like brain, lungs, heart, spleen, and kidneys. Due to a high lipophilicity, Fentanyl has a greater propensity for accumulation in adipose tissues of the body.

After the process of absorption, the drug undergoes the hepatic metabolism. CYP3A4 enzymes act and convert Fentanyl into norfentanyl through N-dealkylation. It is then subjected to further metabolism and forms inactive metabolites. The process of hydroxylation is involved in the formation of inactive metabolites such as propionic acid and 4-N-anilinopiperidine.

About 90% of metabolites and 7-10% unchanged Fentanyl gets excreted through the kidneys. Almost 1% of the drug is eliminated through feces as an unchanged Fentanyl. The research studies have shown 75 % of Fentanyl gets cleared from the body within 4 days of the last dose.

Different types of Fentanyl drug tests:

The SAMHSA-5 tests are not used for the detection of Fentanyl. These are useful for opioids that are converted to morphine and Fentanyl doesn’t get metabolized into morphine. Some of the tests that are used for Fentanyl include:

  • Urine Tests:The gas chromatography/mass spectrometry (GC/MS) is utilized for finding the levels of unchanged Fentanyl and its metabolites in urine samples. The documented levels depend upon the consumed drug. A 25 mcg/hr patch yields 175 ng/ml of norfentanyl and 47 ng/ml of fentanyl in the urine sample. The exact window of detection is variable among individuals. In some people, the drug was not detectable even after 24 hours and it was identifiable up to 72 hours in other individuals.
  • Hair Tests:The hair follicles are collected and analyzed for the presence of drug. The therapeutic doses result in 0.1 ng/mg-0.5 ng/mg accumulation of drug particles in hair follicles. Hair tests are regarded as highly convenient and non-invasive tests. Small amounts of drug remain embedded in hair follicles even after few months of the last dose. The tests are not as reliable as the amount ingested and the levels of drug detected in hair follicles differ to a large extent.
  • Saliva Tests: Some drugs become readily detectable in the oral fluids sample but it is not the case with Fentanyl. The transdermal or intravenous formats are not visible in the saliva. The oral lozenges have a higher chance of getting easily detected in salivary samples. Not many chemicals and techniques are available that can easily spot Fentanyl in oral samples. The test is not so popular for Fentanyl and lacks precision and accuracy as compared to other modalities for testing.
  • Blood Tests:The collection of blood samples is another common method but is mostly reserved for cases admitted to the hospital. Such cases may be of overdoses or other severe intoxications. Intravenous Fentanyl can be detected within minutes and remain detectable for less than 24 hours. The transmucosal and transdermal formats can remain identifiable for about 1-4 days. Blood tests are invasive and offer a shorter window period for detection.

Tips to clear Fentanyl from the system faster:

There are some techniques that can speed up the clearance of drug from the body. However, all of these are not for general adoption and must be consulted from the doctor before implementation.

  • The basic step is to stop consuming Fentanyl in any form.
  • Reduce the body fat through exercise and diet control. Fentanyl gets stored in the fat tissues.
  • Calcium-D-Glucarate acts as a useful supplement for the detoxification process.
  • Activated Charcoal is administered to absorb the undigested Fentanyl. Thus, it prevents the further absorption of the drug.