Fentanyl

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Benjamin Clanner-Engelshofen is a freelance writer in the medical department. He studied biochemistry and pharmacy in Munich and Cambridge / Boston (USA) and noticed early on that he particularly enjoyed the interface between medicine and science. That is why he went on to study human medicine.

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The active ingredient fentanyl is one of the most important remedies for severe to very severe pain. It is about 125 times more effective than morphine. Fentanyl is used in particular for breakthrough pain in the course of cancer as well as severe chronic pain. Different dosage forms such as nasal sprays, lozenges and plasters are available for this. Here you can read everything you need to know about fentanyl, dosage, effects and use.

This is how fentanyl works

Fentanyl is a strong pain reliever (analgesic) active ingredient from the group of opioids. Its analgesic potency is about 125 times that of morphine.

The nerves in the body conduct stimuli, including pain stimuli, from almost every part of the body to the central nervous system (= brain and spinal cord). The intensity of the stimulus depends on the trigger and the level of endorphins. These are natural hormones that reduce the perception of pain. When the endorphin level in the body is high, pain is less noticeable. The same effect, i.e. a reduced perception of pain, can be achieved with opiates and opioids.

Opiates are naturally occurring substances in the poppy plant that inhibit the sensation of pain. Opioids are chemically and synthetically produced substances based on the model of opiates, which have the same pain-relieving mechanism of action as opiates.

Fentanyl is one such opioid. Once absorbed into the body, it quickly crosses the blood-brain barrier into the central nervous system. At specific docking points, the opioid receptors, it can inhibit the transmission of pain stimuli. As a result, the brain no longer perceives the pain.

Onset of action depends on the dosage form

Since fentanyl has a strong pain-relieving effect, only very small amounts are needed to effectively suppress the pain. This enables a variety of dosage forms, all of which deliver the active ingredient into the body at different speeds.

Fentanyl injections (syringes) are the fastest to take effect. This is followed by dosage forms in which the active ingredient is absorbed through the oral or nasal mucosa, such as lozenges and nasal spray (onset of action within minutes).

If fentanyl is stuck to the skin in the form of a patch, the effect is slowest (only after several hours).

Uptake, breakdown and excretion

The amount of fentanyl that gets into the body depends - like the onset of action - on the dosage form (lozenge, nasal spray, plaster, etc.). Only 5 percent of the applied active ingredient is absorbed through the oral mucous membranes, while it is around 70 percent when taken orally.

In the body, after ingestion, fentanyl is largely metabolized in the liver to ineffective breakdown products and then excreted in the urine. About three to twelve hours after admission, half of the pain reliever is eliminated (half-life).

In the case of dosage forms with slow release of active ingredients (sustained release preparations) and fentanyl-containing patches, this period of time is correspondingly longer; in the case of infusions or injections, it is comparatively shorter.

When is fentanyl used?

Fast-acting dosage forms (such as fentanyl nasal spray, sucking tablet / lollipop or injections) are used to treat severe and extremely severe pain, such as those that occur in tumor diseases or intensive care patients (breakthrough pain).

In addition, fentanyl is used in conjunction with other active ingredients for anesthesia before operations. In such cases, it is only used for a short period of time.

Slow-release dosage forms such as fentanyl patches are used to treat chronic severe pain that can only be adequately treated with the help of opioid pain relievers. The application here usually extends over a longer period of time.

This is how fentanyl is used

In the case of fast-acting dosage forms (syringes, nasal spray, etc.), the fentanyl dosage is determined individually by the doctor. It starts with a low dose, which is then gradually increased until adequate pain relief is achieved. This fixed dose is then administered in each case in the case of acute pain.

When treating chronic pain with a fentanyl patch, the selected area of ​​skin (unshaven, uninjured) is cleaned with clean water and dried well before being applied. Any hair can be carefully cut off with scissors.

Then remove the protective film from the plaster and stick the plaster onto the desired area of ​​skin (press lightly for 30 seconds). It then releases the pain reliever constantly for usually three days. Then, if necessary, a new plaster can be applied to a different area of ​​skin.

When peeling off the old patch, care must be taken to ensure that no remnants of the patch stick to the skin. A fentanyl patch can be applied to the affected area of ​​skin after a week at the earliest.

Once removed, the patch is disposed of properly (as instructed by your doctor or pharmacist). Since used plasters still contain active ingredients, this step is important so that no uninvolved people come into contact with it (e.g. small children).

The fentanyl patch should not be removed and replaced with a new one before 48 hours have elapsed, as this can lead to increased side effects. The patch should only be divided to reduce the dose if your doctor has instructed you to do so. If you feel that the effects are too strong, you should speak to your doctor.

What are the side effects of fentanyl?

The side effects are strongly related to the mode of action of the substance and are therefore also dose-dependent. With low doses, there are often no or only minor side effects. The higher the dose, the more pronounced they become.

In more than one in ten people treated, fentanyl causes drowsiness, sleepiness, dizziness, constriction of the pupils, a slow heartbeat, drop in blood pressure, nausea and vomiting. These undesirable effects are to be expected especially at the beginning of therapy.

In addition, every tenth to one hundredth person treated has side effects such as sweating, rash, itching, central dullness, confusion, visual disturbances, cardiac arrhythmias, dulling of the respiratory reflex, indigestion (such as constipation) and urinary retention.

In addition, side effects such as skin reactions at the adhesive site of the patch are possible with the fentanyl patch.

What should be considered when using fentanyl?

Interactions

If other central depressant agents are taken in addition to fentanyl, the effects can mutually increase. For example, the use of sedatives such as diazepam, antipsychotics such as droperidol or alcoholic beverages should be avoided.

Note that alcohol combined with fentanyl can significantly reduce responsiveness in traffic.

It is also advisable not to take drugs that affect the level of the neurotransmitter serotonin at the same time. These include antidepressants (MAO inhibitors, SSRIs), migraine drugs such as sumatriptan and serotonin precursors such as tryptophan. Simultaneous use of such active ingredients and fentanyl can lead to a so-called serotonin syndrome (rapid pulse rate, sweating, hallucinations, convulsions, etc.).

Fentanyl is metabolized in the liver by an enzyme called cytochrome P450 3A4 (CYP3A4). If other drugs that are broken down by the same enzyme are used, it may be necessary for the treating doctor to increase or decrease the dose of fentanyl.

A dose increase may be necessary, for example, with certain anti-seizure drugs (carbamazepine, phenytoin, valproate). On the other hand, ritonavir (HIV agent) and clonidine (for example for high blood pressure and palpitations) may make it necessary to reduce the dose of fentanyl.

If you are already using fentanyl, talk to your doctor or pharmacist before taking any other medication.

Age restriction

Fentanyl for intravenous use is approved from one year of age. Fentanyl-containing patches may be used in patients aged two years and over.

Lozenges and lozenges with an applicator for use in the oral cavity (fentanyl stick) are only permitted from the age of 16, buccal tablets (to be placed in the cheek, where the active ingredient is absorbed through the mucous membrane) and nasal spray from the age of 18.

In elderly patients and in patients with liver or kidney problems, the breakdown and excretion of fentanyl may be slower. Therefore, in these cases, the dosage must often be reduced.

pregnancy and breast feeding period

Fentanyl should not be used during pregnancy due to lack of data because it crosses the placenta. To date, however, there is no evidence of a teratogenic effect.

If indicated, fentanyl can therefore be used throughout pregnancy. If fentanyl is given shortly before delivery, side effects such as respiratory depression and adjustment disorders in the infant are possible.

Small amounts of fentanyl are excreted in breast milk. So far, however, nothing has been reported about undesirable effects in breastfed infants. Therefore, discontinuation of breastfeeding is no longer recommended if the mother needs to be treated with fentanyl.

How to get fentanyl medication

Fentanyl is only available on prescription in Germany, Austria and Switzerland in every dosage and form of administration. In addition, it is considered a narcotic and is subject to the Narcotics Act (Germany and Switzerland) and the Narcotics Act (Austria).

The doctor must therefore prescribe it on a special prescription.If you want to take Fentanyl with you on trips (especially abroad), you should first have a doctor issue a certificate confirming that you are legally in possession of the narcotic.

How long has fentanyl been known?

Fentanyl was developed by Paul Janssen in 1959 and marketed in the 1960s. In the mid-1990s, a newly developed pain plaster for the treatment of chronic pain (otherwise fentanyl is only effective for a very short time) came onto the market.

Fentanyl sticks ("lollipops"), buccal tablets and an oral and nasal spray with fentanyl were later developed.

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