Strong opioids and chronic pain

Previously, it was said that chronic pathological pain can become an independent disease that has severe consequences for many organs and systems. Pathological pain loses its protective functions, it has a disadaptive and pathological importance for the body. Irresponsible, severe, pathological pain causes mental and emotional disorders, disintegration of the central nervous system, frequent suicidal actions, structural and functional changes and injuries in internal organs and cardiovascular system, dystrophic changes in tissues, violation of autonomic functions and endocrine system, secondary immune deficiency. For the treatment of chronic pain, there is a large arsenal of non-narcotic analgesics. But in situations where their use is limited by the occurrence of side effects (gastro, nephro- and hepatotoxicity) or their analgesic potential is exhausted, the question arises of the possibility of using strong opioid analgesics for the treatment of chronic non-oncological pain. Doctors recognized that from a legal and ethical point of view, patients with chronic pain can not be denied the appointment of opioid analgesics, providing maximum analgesia, opioids have been used to treat pain in rheumatoid arthritis, back pain, neuropathic pain.

The prescription of opioid (narcotic) analgesics for non-oncological pain is possible only when doctors have high theoretical training and a serious clinical experience in the management of chronic pain syndromes. The physician should be able to clearly define the nature and cause of the pain, consider and use the entire arsenal of medical and non-medicinal methods of treatment for a particular patient, including surgical ones.

Opioid analgesics are the main treatment for somatogenic pain syndromes of medium and high intensity in various fields of medicine. On the analgesic effect, they significantly exceed all known non-opioid analgesics. Opioid analgesics have a central mechanism of action, realized by interaction with opioid receptors of different parts of the central nervous system.

The class of modern opioid analgesics includes, with a variety of analgesic activity and a different spectrum of other additional properties, which is of great importance for the correct choice of opioid in specific clinical situations. Differences in the properties of different opioids are due to their different relationships with opioid receptors:

1. affinity for a specific type of receptor (mu-kappa-sigma receptors),
2. the degree of binding to the receptor (strength and duration of the effect),
3. coking ability (antagonism) to a specific type of receptor.

In accordance with this, opioids can be agonists or stagonists of various receptors, which determines the range of properties inherent in each opioid.

Opioids of different groups differ in the degree of expression of such specific characteristics as the ability to cause tolerance and dependence.

Tolerance, i.e. Resistance to opioid analgesia, is associated with the "habituation" of receptors to the applied dose of opioid and a decrease in the analgesic effect in long-term therapy (in morphine tolerance begins to appear after 2-3 weeks), which requires a gradual increase in the analgesic dose of the opioid.

Dependence on the drug (physical and / or psychic) can be formed at different times from the start of therapy. Physical dependence manifests itself when the drug is suddenly stopped taking a characteristic withdrawal syndrome (psychomotor agitation, chills, spastic abdominal pain, nausea, vomiting, salivation, etc.) and requires special therapy. Mental addiction (addiction or addiction) is characterized by an insurmountable psychological need to get a drug (even in the absence of pain) to avoid severe emotional distress and severe discomfort when stopping the use of the drug.

To identify the risk of drug dependence, you can use the CAGE and CAGE-AID questionnaires. The difference is that the first questionnaire was proposed to identify the risk of alcohol dependence, and the second one added questions for the detection of drug dependence.

Question	Yes	No
Did you have a desire (in general or in the last 3 months) to reduce the dose of alcohol or drugs?
Did the people around you comment (in general or in the last 3 months) about the use of alcohol or drugs?
Have you ever felt guilty about drinking alcohol or drugs?
Did you drink or take medication first thing in the morning to calm your nerves or eliminate a hangover (in general or in the last 3 months)?

The ability to induce addiction (so-called narcogenic potential) is differently expressed in opioids of different groups. Some opioids (gramal, butorphanol, nalbuphine), due to the minimal narcogenic potential, are not classified as narcotic drugs and are non-narcotic analgesics. Moureceptor agonists (except tramadol) are more likely to cause dependence. Due to the high social importance of this dangerous property of opioid analgesics in all countries, there is a special system for controlling the use of narcotic drugs to prevent possible abuses. Differences between different opioids for narcotics potential determine the features of their accounting, appointment, leave, use.

To minimize the risk of developing mental dependence when using opioids in patients with chronic pain, preliminary screening and systematic monitoring of the use of recommended doses of narcotic analgesics is required.

Most opioids undergo metabolism in the liver, and their metabolites are excreted by the kidneys, so opioids can be exacerbated in patients with impaired function of these parenchymal organs and manifest as depression of the central nervous system (sedation, respiratory depression).

Contraindications to the appointment of all opioid analgesics are: increased sensitivity (intolerance) of a particular drug, intoxication with alcohol or drugs depressing the central nervous system (hypnotics, narcotic, psychotropic drugs), concomitant use of MAO inhibitors and a period of 2 weeks. After their cancellation, severe hepatic or renal failure, epilepsy, withdrawal syndrome, pregnancy and lactation. Care should be taken when prescribing opioids to elderly and senile patients (a safe analgesic dose may be 1.5-2 times lower than in middle-aged people.

Recently, transdermal therapeutic systems (TTS) have been increasingly introduced into practical medicine for the dosed administration of medications (estrogens, androgens, lidocaine).

TTS allows the patient to independently administer the drug without the services of medical personnel, the procedure is non-invasive, which undoubtedly contributes to the patient's greater adherence to treatment.

All narcotic analgesics should be prescribed only if inefficiency or intolerance of previously conducted ethiopathic therapy and a low risk of dependence, doctor knowledge of all the features of the prescribed drug, drug interactions, complications.

[1], [2], [3], [4], [5]