Analgesics are drugs that weaken or relieve the sensation of pain while maintaining consciousness and other types of sensitivity. Physiologically, pain occurs as a result of the excitation of the so-called pain receptors, which are localized on the skin, mucous membranes and serous membranes, as well as in the thickness of various organs and systems. Pain receptors are excited by physical (mechanical, thermal, electrical, etc.) and chemical exogenous (acids, alkalis, salts of heavy metals, phenol derivatives, etc.) and endogenous factors of a protein nature (histamine, serotonin, bradykinin).
Thus, pain is a physiological mechanism of the subjective manifestation of an imbalance in the body, therefore it is protective in nature. But extremely strong and prolonged pain is pathological in nature, since it depletes the body, disrupts the function of vital organs, and can even lead to death from shock. From this point of view, a group of analgesic drugs is of great practical importance, and in historical terms is a significant achievement of mankind.
There are several ways to reduce or stop pain. The most effective and radical is to eliminate the cause, which, unfortunately, is not always possible, since it is not always possible to quickly determine it. Therefore, it is often necessary to temporarily dull the pain with the help of drugs of various pharmacological groups. For this purpose, you can use narcotic, local anesthetics, anticholinergic, antispasmodic, anticonvulsant, astringents, enveloping agents.
By the nature of the action on the central nervous system, the origin and chemical nature of analgesics are divided into two groups: narcotic and non-narcotic.
Narcotic analgesics are opium and drugs that have a similar effect. They are characterized, first of all, by a peculiar effect on the central nervous system. They have an analgesic effect, especially in cases not associated with inflammatory processes (with significant injuries, malignant tumors). When reintroduced, narcotic analgesics cause psychological and physical dependence in patients. Drugs in this group increase the threshold of pain sensitivity. Doctors prescribe such analgesics to eliminate severe pain in the presence of burns, injuries, etc. Also, these drugs are prescribed for patients with inoperable malignant neoplasms. Narcotic analgesics facilitate the psychological state of the patient. These drugs can not be used for more than three to four days, otherwise it becomes addictive, and people become drug addicts.
Narcotic analgesics (opium) contain more than 30 alkaloids and additional substances, which include carbohydrates, proteins, lipids, mucus, mineral salts, etc. Opium contains a lot of morphine (about 12%), narcotine (up to 10%), codeine (up to 3-5%) and papeverine (up to 1%).
Narcotic analgesics: the most popular drugs
Among the narcotic drugs, morphine hydrochloride, codeine phosphate, dry opium extract, ethylmorphine hydrochloride (dionine), tincture of simple opium, promedol, omnopon, etc. are of the greatest importance.
Non-narcotic analgesics are drugs that exhibit analgesic, anti-inflammatory and antipyretic effects. Unlike narcotic drugs, they weaken or relieve pain associated with inflammatory processes in the joints, bone, muscle and other tissues (with neuralgia, joint and muscle pain, rheumatism, dental injuries, etc.). This indicates that the basis of analgesia is an anti-inflammatory effect. In addition, non-narcotic analgesics do not cause hypnotic effect and euphoria, do not suppress respiratory and cough centers.
Of great practical importance is the antipyretic effect of non-narcotic analgesics. As you know, body temperature in diseases rises due to the action of pyrogenic substances (products of hydrolysis of proteins, amino acids, nucleic acids, microbial toxins, etc.) on interoreceptors that transmit excitation to the thermoregulation center. The excited center of thermoregulation, changing the intensity of the processes of heat production and heat transfer, promotes body hyperthermia, has an important protective character. However, in some cases, hyperthermia can reach a level dangerous to the life of the body, and its protective character turns into a pathological one. In such cases, it is advisable to use antipyretic drugs.
Non-narcotic analgesics: classification
Given the chemical structure of the preparations, they are divided into several groups: derivatives of salicylic acid (methyl salicylate, acetylsalicylic acid or aspirin), pyrazolone (analgin, butadione, phenazone), para-aminophenol (paracetamol), indoleacetic acid (indomethacin), propionic acid (naproxen ketoprofen), anthranilic acid (flufenamic and mefenamic acids), pyrrolysine carboxylic acid (ketorolac).
Recently, another group of painkillers began to be isolated - non-steroidal analgesics. The most popular means of this group are: piroxicam, diclofenac, indomethacin. The mechanism of their action is associated with blocking the synthesis of the enzyme - cyclooxygenase. This enzyme promotes the formation of prostaglandins - the main mediators of pain and inflammatory reactions. Also, these drugs block the release of bradykinin, which is involved in the onset and spread of pain and inflammation.