Fentanyl is an opioid synthetic analgesic. In its chemical structure, such a substance is similar to promedol. With a single use, it has a very strong, but short-term effect.
In surgery using local anesthesia, fentanyl can be used as an additional pain medication (usually in combination with some antipsychotic).
Medicines based on this substance are prescribed to patients with the aim of relieving acute pain during myocardial infarction, pulmonary infarction, angina pectoris, as well as hepatic and renal colic. Typically, in such conditions, fentanyl preparations are administered intravenously or intramuscularly.
However, for certain diseases, drugs with the aforementioned component are used externally. One of these local anesthetics is fentanyl patch. Side effects of this drug, indications for its use, analogues and other information are discussed below.
Form, packaging and composition
Fentanyl patch is a transdermal therapeutic system. What does an analgesic for external use look like? This is a translucent rectangular patch with rounded edges, having a removable transparent protective film (divided into 2 parts by a sinusoidal incision), exceeding the size of the patch itself.
Fentanyl agent is packaged in a heat sealable bag of paper, aluminum and polyacrylonitrile. In a cardboard box are five packages, as well as detailed instructions for use.
The composition of the drug under consideration includes such an active component as fentanyl. As for the protective removable layer, it is a polyester film with a fluorine-containing polymer coating.
How does it work?
Transdermal fentanyl patch is a local preparation that provides systemic delivery of the active substance over a period of 72 hours.
Fentanyl is an opioid analgesic related to the opioid µ receptors of the central nervous system, peripheral tissues, and spinal cord. This substance is able to increase the activity of the antinociceptive system and increase the threshold of pain sensitivity. Thus, the drug under consideration based on fentanyl has a sedative and analgesic effect.
Other properties of the substance
Despite the fact that fentanyl patch is applied externally, it should be borne in mind that the active substance of this drug is able to exert a depressing effect on the respiratory center, slow down the heart rate, stimulate the vomiting center and n.vagus centers, and increase the tone of smooth muscles (mainly bile duct and sphincter muscles ), improve the absorption of water from the digestive tract. Also, this component can reduce blood pressure, renal blood flow and intestinal motility. In blood plasma, fentanyl increases the concentration of lipase and amylase, reduces the concentration of growth hormone, ACTH, catecholamines, cortisol and prolactin.
It can not be said that the substance in question causes euphoria and the onset of sleep (in connection with the elimination of the pain syndrome).
The rate of development of tolerance to analgesic effects and drug dependence has individual differences. Compared to other opioid analgesics, fentanyl is much less likely to provoke histamine reactions.
Pharmacokinetic features
What pharmacokinetic features are inherent in the anesthetic fentanyl patch? The minimum effective analgesic concentration in the blood in people who have not previously used opioid drugs is approximately 0.3-1.5 ng / ml.
After the first use of the medication, the concentration of its active substance in the plasma increases gradually and evens out 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 may vary depending on the place of application. In the course of studies, it was noted that reduced absorption of fentanyl is noted when the patch is placed on the chest (compared to the upper back and arm).
Experts report that fentanyl is able to pass through the placenta, the BBB and into breast milk. This component binds to plasma proteins by 84%. It also has 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 functioning of the kidneys and liver can increase the serum concentration of fentanyl.
In the elderly, as well as debilitated or depleted patients, the use of the drug may cause a decrease in the clearance of fentanyl. In this case, a longer half-life of the active substance is possible.
Prescribing medication
What is fentanyl patch used for? Indications for use of this tool are chronic pain sensations of a strong and moderate degree, requiring analgesics with analgesics (opioid). Usually such an external drug is prescribed for:
- pain caused by cancer;
- pain syndromes of non-oncological origin, requiring multiple analgesic analgesics (for example, with neuropathic pain, arthritis and arthrosis, phantom pain after amputation of the limbs).
Prohibitions to use
Before using fentanyl patch, the indications for use of which were listed above, it is imperative to familiarize yourself with the contraindications. These include the following conditions:
- severe damage to the central nervous system;
- acute respiratory depression;
- toxic dyspepsia;
- irritated, damaged or irradiated skin in the area of the intended application;
- diarrhea with pseudomembranous colitis due to the intake of lincosamides, cephalosporins and penicillins;
- minor age;
- acute postoperative pain;
- parallel intake 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 particular caution, this medication is used for chronic lung diseases, brain tumors, intracranial hypertension, arterial hypotension, traumatic brain injury, gallstone disease, bradyarrhythmias, drug dependence, liver / kidney failure, hypothyroidism, renal / hepatic colic, surgical diseases of the abdominal cavity acute (prior to diagnosis), alcoholism, acute severe condition, BPH, urethral strictures, hyperthermia, suicidal th inclinations, concomitant use of corticosteroids, insulin, antihypertensive agents, as well as in the elderly, the weak and malnourished patients.
Dosage
Fentanyl transdermal patches release their active component within 72 hours. At the same time, its release rate is from 12.5 to 100 μg / h.
The required therapeutic dosage of fentanyl is selected individually and should be evaluated after each use of the patch.
The choice of the initial dose of the drug depends on the level of opioid analgesics in the previous time, taking into account the likely development of tolerance, severity of the disease, concomitant treatment and the general condition of the patient.
In the event that the nature of the patient’s reaction to opioids is not fully understood, the initial dosage should not be higher than 25 μg / h.
How to switch from other opioid analgesics?
Use an anesthetic patch (fentanyl) for oncology after other oral or parenteral opioid analgesics should be used with extreme caution. It should 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 limitation is associated with a gradual increase in the concentration of fentanyl in the blood in the first 24 hours.
Maintenance therapy
According to the instructions for use, the fentanyl patch must be replaced with a new one after 72 hours. The dosage of the drug is selected individually until the desired level of pain relief is achieved. In the event that, after 48-72 hours after application, a noticeable decrease in the analgesic effect is observed, then the patch is replaced after two days.
Discontinuation of treatment
If necessary, discontinue treatment with a transdermal patch, it must be replaced with other opioids gradually (from a low dose with a slow increase). It should be borne in mind that the content of fentanyl in the blood after elimination of the patch decreases linearly (within 17 hours).
Method of application of the patch Fentanyl
The medication in question is used transdermally. The patch is placed on a flat surface of unirradiated 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 placing the patch on the hairline of the body, they should be cut off (but not shaved!).
In the event that the skin area must be washed before applying the drug, then it is better to do this with ordinary water (without using soap, oil, lotions, alcohol or other means that can cause irritation or change the properties of the skin). Before application, the covers should be completely dry.
Due to the fact that the fentanyl patch, the contraindications of which were listed above, has a protective waterproof outer film, it can not be removed before a short shower.
The preparation in question should be applied immediately after removal from the packaging bag. After removing the protective film, the transdermal patch is firmly pressed to the place of application and kept in this state for about 30 seconds. After this, make sure that the patch adheres strongly to the skin, including along the edges. If required, then resort to additional fixation means.
The duration of the fentanyl patch is 72 hours. Therefore, the drug should be worn continuously throughout the specified period, and then replace it with a new one. The second transdermal patch must be applied to another area without capturing the area of the previous application.
The drug based on fentanyl is not recommended to divide and cut.
Side effects
Using a fentanyl patch for back pain and other parts of the body, you should be aware of possible side effects. The mentioned drug can cause such undesirable effects:
- respiratory depression, speech disorders, drowsiness, palpitations, hypersomnia, bradycardia, headache, arrhythmia, dizziness;
- confusion, tachycardia, depression, dyspnea, pharyngitis, anxiety, vomiting, nervousness, rhinitis;
- hallucinations, arterial hypotension, anorexia nervosa, delirium, vasodilation, involuntary muscle contractions, yawning, hypesthesia;
- 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, itching, obstructive pulmonary disease, diarrhea, exudation, painful flatulence, anaphylactic shock, rash, anaphylactic reactions, sweating, urinary retention, anaphylactoid reactions, ureteral spasm, rash;
- changes in the appearance of the skin, microcracks, urinary tract infections, petechial erosion, peeling of the skin, scab, erythema, oliguria, pain in the bladder;
- conjunctivitis, malaise, fatigue, flu-like symptoms, swelling and a feeling of cold.
With prolonged use of fentanyl patch from pain in the back and other parts of the body, mental and physical dependence, tolerance, and short-term muscle stiffness can develop.
Drug interaction
When using the drug in question, parallel intake of barbituric acid derivatives should be excluded, otherwise the latter can increase the likelihood of respiratory depression.
The simultaneous use of other drugs that suppress the central nervous system (opioids, tranquilizers, anxiolytics, general anesthetics, muscle relaxants, phenothiazine derivatives, etc.) can provoke the occurrence of hypoventilation, arterial hypotension, deep sedation or coma.
It's important to know!
Fentanyl-based drugs are prescribed as part of a comprehensive treatment of pain under the condition of an adequate social, medical and psychological assessment of the patient.
With the development of severe side effects, the patient should be under the supervision of specialists for a day after removing the patch.
Unused and used transdermal preparations containing fentanyl must be stored out of the reach of small children.
People with elevated body temperature require careful observation by doctors (if necessary, adjust the dose of fentanyl).
Analogs of fentanyl patch
The analogues of the drug under consideration (Fendivia) are such drugs as Fentanyl M Sandoz, Lunaldin, Fentadol Matrix, Durogezik Matrix, Fentadol Reservoir, Fentanyl, Dolforin. It should be remembered that replacing the main tool with similar ones is permissible only after consulting a doctor.