Fentanyl is a synthetic opioid analgesic. In its chemical structure, such a substance is similar to promedol. When applied once, it has a very strong, but short-lived effect.
During surgery using local anesthesia, fentanyl can be used as an additional pain reliever (usually in combination with an antipsychotic).
Drugs based on this substance are prescribed to patients to relieve acute pain in myocardial infarction, pulmonary infarction, angina pectoris, as well as hepatic and renal colic. Fentanyl preparations are usually administered intravenously or intramuscularly for these conditions.
However, for certain diseases, drugs with the mentioned component are used externally. One such topical pain reliever is the fentanyl patch. side effects of thisthe drug, indications for its use, analogues and other information are discussed below.
Shape, packaging and composition
Fentanyl patch is a transdermal therapeutic system. What does such an anesthetic for external use look like? This is a semi-transparent, rectangular patch with rounded edges that has a removable transparent protective film (halved by a sinusoidal cut) that is larger than the patch itself.
Fentanyl is packaged in a heat-seal bag made of paper, aluminum and polyacrylonitrile. There are five bags in a cardboard box, as well as detailed instructions for use.
The composition of the drug in question includes such an active ingredient as fentanyl. As for the protective removable layer, it is a polyester film with a fluorine-containing polymer coating.
How does it work?
The fentanyl transdermal patch is a topical formulation that provides a systemic delivery of the active agent for 72 hours.
Fentanyl is an opioid analgesic that is related to opioid μ-receptors in the CNS, peripheral tissues and spinal cord. This substance is able to increase the activity of the antinociceptive system and increase the pain threshold. Thus, the fentanyl-based drug in question has a sedative and analgesic effect.
Other properties of matter
Despite the fact that the fentanyl patch is used externally, it must be taken into account that the active substancethis drug can have a depressant effect on the respiratory center, slow down the heart rate, excite the vomiting center and n.vagus centers, increase the tone of smooth muscles (mainly the muscles of the biliary tract and sphincters), and improve the absorption of water from the digestive tract. Also, this component can reduce blood pressure, renal blood flow and intestinal motility. In plasma, fentanyl increases the concentration of lipase and amylase, reduces the concentration of growth hormone, ACTH, catecholamines, cortisol and prolactin.
It is impossible not to say that the substance in question causes euphoria and the onset of sleep (due to the elimination of pain).
The rate of development of tolerance to analgesic action and drug dependence has individual differences. Compared to other opioid analgesics, fentanyl is much less likely to provoke histamine reactions.
Pharmacokinetic features
What are the pharmacokinetic features of the analgesic fentanyl patch? The minimum effective analgesic blood concentration in opioid-naive people is approximately 0.3-1.5 ng/mL.
After the first use of the drug, the concentration of its active substance in plasma increases gradually and levels off between 12 and 24 hours. The result is stored for the next 72 hours.
According to the instructions, the concentration of fentanyl in the patient's blood is proportional to the size of the patch. The absorption of this substance canvary depending on the place of application. Studies have shown that reduced fentanyl absorption occurs when the patch is placed on the chest (compared to the upper back and arms).
Specialists report that fentanyl is able to cross the placenta, the BBB and into breast milk. This component binds to plasma proteins by 84%. It also has a linear kinetics of biological transformation and is metabolized in the liver by CYP3A4 enzymes.
After removal of the patch in question, its serum concentrations decrease gradually. The half-life of fentanyl after application is 17 hours. This substance is excreted along with urine and bile.
Special clinical cases
Impaired kidney and liver function may increase serum fentanyl levels.
In the elderly, as well as debilitated or malnourished patients, the use of this drug may cause a decrease in the clearance of fentanyl. In this case, a longer half-life of the active substance is possible.
Medication prescription
What is fentanyl patch used for? Indications for the use of this remedy are chronic pain of a strong and moderate degree, requiring pain relief with analgesics (opioid). Typically, such an external drug is prescribed for:
- pain caused by cancer;
- pain syndromes of non-oncological origin requiring repeated anesthesiaanalgesics (for example, for neuropathic pain, arthritis and arthrosis, phantom pain after limb amputation).
Prohibited use
Before using the fentanyl patch, the indications for which were listed above, you should definitely read the contraindications. These include the following states:
- severe CNS lesions;
- acute respiratory depression;
- toxic dyspepsia;
- irritated, damaged or irradiated skin in the intended application area;
- diarrhea in pseudomembranous colitis associated with lincosamides, cephalosporins and penicillins;
- minor age;
- acute postoperative pain;
- concurrent use of MAO inhibitors, as well as the use of the drug within two weeks after their withdrawal;
- high sensitivity to the active substance or auxiliary components of the drug.
With extreme caution, the medication in question is used for chronic lung diseases, brain tumors, intracranial hypertension, arterial hypotension, traumatic brain injury, cholelithiasis, bradyarrhythmias, drug dependence, liver / kidney failure, hypothyroidism, renal / hepatic colic, surgical diseases of the abdominal organs of an acute nature (before diagnosis), alcoholism, acute serious condition, BPH, urethral strictures, hyperthermia, suicidal tendencies, simultaneous use of corticosteroids, insulin, antihypertensivefunds, as well as in the elderly, debilitated and malnourished patients.
Dosage
Fentanyl transdermal patches release their active ingredient within 72 hours. At the same time, its release rate is from 12.5 to 100 mcg / h.
The required therapeutic dosage of fentanyl is selected on an individual basis and should be evaluated after each use of the patch.
The choice of the initial dose of the drug depends on the level of use of opioid analgesics in the previous time, taking into account the likely development of tolerance, the severity of the disease, concomitant treatment and the general condition of the patient.
In the event that the nature of the reaction of the patient's body to opioids is not fully understood, then the initial dosage of the agent should not be higher than 25 mcg / h.
How to switch from other opioid analgesics?
Using pain relief patch (fentanyl) for oncology after other oral or parenteral opioid analgesics should be used with extreme caution. It must be remembered that the initial dose of drugs with fentanyl is calculated in a special way. For accurate dosing, consult a specialist.
Assessment of the maximum analgesic effect of the drug in question can be carried out only a day after the application. This restriction is associated with a gradual increase in the concentration of fentanyl in the blood in the first 24 hours.
Maintenance care
According to the instructions for use, the fentanyl patch must be replaced with a new oneafter 72 hours. The dosage of the drug is selected individually until the required level of anesthesia is achieved. In the event that after 48-72 hours after the application there is a noticeable decrease in the analgesic effect, then the patch is replaced after two days.
Treatment stop
If treatment with the transdermal patch needs to be discontinued, its replacement with other opioids should be done gradually (from a low dose to a slow increase). It should be borne in mind that the content of fentanyl in the blood after the removal of the patch decreases linearly (within 17 hours).
How to use the Fentanyl patch
The medication in question is used transdermally. The patch is placed on a flat surface of non-irradiated and intact skin (on the trunk or shoulder). For the place of application, it is desirable to choose areas with the least amount of hair. Before applying the patch to the hairy area of the body, they should be cut (but not shaved!).
In the event that the skin area needs to be washed before applying the drug, it is better to do this with ordinary water (without using soap, oils, lotions, alcohol or other products that can cause irritation or change the properties of the skin). Covers must be completely dry before application.
Due to the fact that the fentanyl patch, which is contraindicated above, has a protective waterproof outer film, it can be left on before a short shower.
The drug in question should be appliedimmediately after taking it out of the packaging. After removing the protective film, the transdermal patch is pressed tightly to the application site and kept in this state for about 30 seconds. After that, make sure that the patch adheres strongly to the skin, including at the edges. If required, they resort to additional fixation of the funds.
The duration of the fentanyl patch is 72 hours. Therefore, the drug should be worn continuously throughout the specified period, and then replaced with a new one. The second transdermal patch must be applied to a different area without covering the area of the previous application.
Fentanyl is not recommended for splitting and cutting.
Side effects
When using the fentanyl patch for pain in the back and other parts of the body, one should be aware of the possible side effects. This drug may cause the following side effects:
- respiratory depression, speech disorders, drowsiness, palpitations, hypersomnia, bradycardia, headache, arrhythmia, dizziness;
- confusion, tachycardia, depression, dyspnea, pharyngitis, anxiety, vomiting, nervousness, rhinitis;
- hallucinations, hypotension, anorexia nervosa, delirium, vasodilation, involuntary muscle contractions, yawning, hypoesthesia;
- euphoria, laryngospasm, amnesia, arterial hypertension, insomnia, abdominal pain, agitation, intestinal obstruction, tremor, constipation;
- paresthesia, nausea, amblyopia, xerostomia, asthenia, dyspepsia, sexual dysfunction, ataxia,hypoventilation, myoclonic convulsions, hiccups;
- hemoptysis, pruritus, obstructive pulmonary disease, diarrhea, exudation, painful flatulence, anaphylactic shock, rash, anaphylactic reactions, sweating, urinary retention, anaphylactoid reactions, ureteral spasm, rash;
- Change in skin appearance, microfissures, urinary tract infections, petechial erosion, skin peeling, eschar, erythema, oliguria, bladder pain;
- conjunctivitis, malaise, fatigue, flu-like symptoms, swelling and feeling cold.
Prolonged use of the fentanyl patch for pain in the back and other parts of the body may develop mental and physical dependence, tolerance, and short-term muscle stiffness.
Drug Interactions
When using the agent in question, parallel intake of barbituric acid derivatives should be excluded, otherwise the latter may increase the likelihood of respiratory depression.
Concomitant use of other drugs that depress the central nervous system (opioids, tranquilizers, anxiolytics, general anesthetics, muscle relaxants, phenothiazine derivatives, etc.) may cause hypoventilation, hypotension, deep sedation or coma.
Important to know
Fentanyl-based drugs are prescribed as part of complex pain management, subject to an adequate social, medical and psychological assessment of the patient's condition.
With the development of severe side effects, the patient shouldbe under the supervision of specialists for a day after removing the patch.
Unused and used transdermal products containing fentanyl should be kept out of the reach of small children.
People with fever require careful monitoring by doctors (adjust fentanyl dose if necessary).
Fentanyl patch analogues
Analogues of the drug in question ("Fendivia") are such drugs as "Fentanyl M Sandoz", "Lunaldin", "Fentadol Matrix", "Dyurogesic Matrix", "Fentadol Reservoir", "Fentanyl", "Dolforin". It should be remembered that it is permissible to replace the main tool with similar ones only after consulting a doctor.
