Opioid analgesics (opioids) are used primarily for the treatment of long-term, extremely severe pain. Although these drugs are able to endure even the strongest pain, some patients are afraid of taking them - in this case, anxiety is most often caused by the possibility of becoming addicted to opioids. Check if opioids really have such a high addictive potential, and find out what the mechanism of action of these drugs is and what distinguishes opioid analgesics.

Opioidsthat isopioid analgesicshave been known to mankind for a long time - it is even assumed that they are one of those drugs that accompany mankind the longest.

The first records of the operation and use of opium date back even 300 years BC.

For centuries they have been used - for various purposes, both to induce euphoria and relieve pain - of the natural origin of opiates (e.g. those derived from poppy seedsPapaverum somniferum , i.e. medical poppy ).

After many years, only at the beginning of the 19th century, scientists managed to isolate morphine. This substance was already used then, but the full knowledge of the effects of opioids became available much later, in the second half of the 20th century.

Opioid analgesics and the analgesic ladder

Pain treatment is a really very important aspect - special emphasis on how to relieve patients' pain is already at the very early stages of the education of future doctors.

In order to standardize the principles of pain treatment, the World He alth Organization (WHO) has developed the so-called analgesic ladder.

There are 3 stages: the first one is first-line drugs, which are initially introduced to patients struggling with pain - mainly non-steroidal anti-inflammatory drugs.

The second and third steps of the analgesic ladder are occupied by opioids. The so-called weak opioid painkillers, while on the third step of the ladder there are definitely more powerful opioids.

Opioid Analgesics: Mechanism of Action

The fact that opioids can endure even the strongest pain is possible thanks to the influence of thesedrugs for specific receptors: μ (mi), δ (delta) and κ (kappa).

These receptors were discovered in the 1970s and are located within the structures of the central and peripheral nervous system.

The effects of stimulating these receptors by opioid analgesics are different: the fact that after a drug molecule attaches to an opioid receptor in a nerve cell, hyperpolarisation will occur, i.e. a state in which its excitability is reduced (in such a situation, various stimuli - including pain stimuli - are simply not conducted).

Some opioids also have other effects, such as reducing the reuptake of certain neurotransmitters (such as serotonin and noradrenaline) in various structures of the nervous system.

However, not all opioid analgesics have the same effect on opioid receptors.

Some of them affect only one specific receptor (e.g. morphine, which binds to the μ receptor), while others may affect all three types of opioid receptors (as is the case with e.g. tramadol).

Some of these preparations are pure agonists of opioid receptors (i.e. they stimulate these structures), while others have mixed agonist-antagonistic activity (some receptors stimulate, others inhibit - such a drug is e.g. buprenorphine).

Still other opioids are pure opioid antagonists (naloxone is one such agent).

Opioid analgesics: uses

The indication for the use of opioid analgesics is primarily pain that cannot be controlled with drugs belonging to other classes.

Opioids are used, inter alia, in in patients with pains caused by cancer or having undergone some extensive surgery.

Opioid analgesics can also be administered to patients with a heart attack, pulmonary edema or patients who have experienced extensive injuries.

Opioids are typically associated with the treatment of pain, but in practice it is not the only possible use of them.

Preparations belonging to this group are also used in premedication before various surgeries, in the treatment of heroin addiction (where methadone is used), and … in controlling diarrhea.

In the latter case, loperamide may be used - it is an opioid drug that does not have a central effect (it does not affect the receptors present in the central nervous system), but it affects the opioid receptors present in thethe walls of the digestive tract and that is why it can inhibit diarrhea.

Opioid painkillers: types

Opioids can be divided in several different ways - the basic one is the division into natural and synthetic opioids.

Natural opioids include: morphine and codeine, but also substances that are naturally present in the human body, which are endorphins (sometimes referred to as endogenous opioids).

Synthetic opioid analgesics include fentanyl, pethidine and methadone, but the breakdown of opioids according to their potency is much better known. The weak opioids are, among others, tramadol, codeine and hydroxycodeine.

Opioid analgesics with a much stronger effect are morphine, fentanyl, buprenorphine and oxycodone.

Opioid analgesics: administration forms

Drugs from the opioid group are available in various forms, such as:

  • tablets
  • solutions for intravenous administration
  • patches to be applied on the skin
  • syrups
  • nasal sprays

Oral tablets are the initially preferred form of administration of opioid analgesics by medical standards.

Sometimes, however - e.g. due to swallowing disorders - the patient is not able to take them. In such a situation, it is possible to consider the use of opioids in a different form, e.g. in the form of patches stuck on for several dozen hours (usually 72 hours) releasing the painkiller.

Opioid Analgesics: Principles of Pain Management

For the treatment of pain with opioids to be effective, the therapy must follow certain assumptions.

Well, initially, the patient is recommended to take small doses of the drug and only when they do not bring the expected pain reduction, the patient is recommended to take larger amounts of the opioid.

Typically, it is recommended to take the drug at strict times (e.g. every 4 hours), and at the same time the patient is assigned additional, smaller doses of the drug, which he can take in the event of the so-called breakthrough pain.

Opioids: can I take them while pregnant?

During pregnancy, some drugs are safe to take, while others are contraindicated: opioids belong to the latter group.

They are recommended during pregnancy only when the benefits of their use outweigh all risks.

There are, unfortunately, many dangers related to the use of opioids by a pregnant woman - in a child whose mother used opioid analgesics during pregnancy, it may occur afterbirth can be respiratory depression or withdrawal syndrome.

There are also reports according to which the use of opioids during pregnancy could contribute to the development of various malformations in children, including heart defects.

Opioid painkillers: side effects

Opioids are really effective in treating pain, but there are some difficulties with their use: these are the side effects of these drugs.

Patients who take opioid analgesics may experience various types of problems, such as:

  • sleepiness
  • apathy
  • constipation (generally the most difficult problem with opioid use, patients using these drugs tend to complain of gastrointestinal dysfunction the most)
  • concentration disorders
  • nausea and vomiting
  • euphoria
  • insomnia
  • itchy skin
  • loss of appetite
  • dry mouth

The greatest intensity of these disorders usually occurs at the beginning of treatment with opioid analgesics.

Unfortunately, these problems are relatively common and therefore it is very important that the doctor who prescribes opioids to the patient warn him about the possible side effects of the treatment.

It is not uncommon for the initiation of opioid analgesic treatment to implement various interactions aimed at at least reducing the possibility of occurrence, and preferably preventing the occurrence of side effects of opioid use.

For this purpose, patients may be recommended, inter alia, antiemetics, and to prevent constipation, patients are told how they should eat (proper diet and hydration reduce the risk of constipation), and sometimes they are also recommended to stimulate peristalsis or soften the stools.

  • Opioid constipation: treatment of constipation after opioids

Opioid painkillers: addiction risk

Patients can avoid opioids for various reasons, one of the main reasons for fear of using these drugs is the potential risk of addiction - after all, it is quite common to hear about how dangerous these opioid painkillers are and how easy it is to get away with it. make them addicted.

Sometimes even doctors take a long time to think about whether the time is really right to offer the patient an opioid to treat their pain.

Indeed, drugs from this group can lead to addiction - in the process of using them, it may eventually developeven tolerance - however, specialists in the treatment of pain emphasize that in fact the benefits of using these drugs most often far outweigh the potential risk.

Pain is a symptom that can really ruin a patient's life: effectively alleviating it is the duty of every practicing medic.

Yes, the use of opioids to achieve their euphoric effect can ultimately lead to addiction to these drugs.

However, in the case of patients who have severe pain complaints - e.g. people with oncological diseases - the fear of using opioid analgesics is usually simply unfounded.

Opioid analgesics: overdose

Opioids can also be fearful because they can be overdosed, which can even lead to death.

It is possible because drugs from this group can affect the respiratory center, even leading to complete respiratory arrest (respiratory depression).

Symptoms that may suggest an opioid overdose (except respiratory disorders) are:

  • sleepiness (even going into a coma)
  • pin-shaped pupils
  • slow heart rate
  • hypotension
  • severe dizziness
  • nausea and vomiting
  • stopping peristalsis in the digestive tract

A patient who overdoses on opioids must urgently be hospitalized - there it is possible to give him the antidote, which is naloxone.

This substance is also an opioid, however, it exerts an antagonistic activity at opioid receptors. Naloxone is administered intravenously and it counteracts the effects of opioid painkillers previously taken by the patient.

Sources:

  1. Interna Szczeklik 2016/2017, ed. P. Gajewski, publ. Practical Medicine
  2. Woroń J., Opioid analgesics, Post-Diploma surgery, 06 2022
  3. Woroń J., Dobrogowski J., Wordliczek J., Selection of opioids and their dosage in the treatment of pain, Medycyna po Diplie 2011 (20); 4 (181): 77-82
About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

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