Cholinolytics are substances that have the ability to block or attenuate the effects of acetylcholine, which is responsible for the appearance of an excited state of the nervous system. Cholinolytic compounds are able to affect various body structures, and therefore they are conditionally divided into atropine-like substances, central, curariform, ganglioblocking.
Description
In clinical practice, these compounds are of great importance due to their ability to influence the reflex regulation of body structures.
The most common anticholinergic drugs are alkaloids, which include platifillin, scopolamine, atropine and preparations based on belladonna, datura, and bleached (can be used in combination and independently). They have a natural origin.
Currently, synthetic substances are widely used. In their composition there are compounds that can significantly enhance the effect of anticholinergics.
Preparations based on these substances are convenient to use in practice, and the number of negative reactions provoked by them is significantly reduced. Most anticholinergics can also have antispasmodic and analgesic effects. The group of such medicines has features that are also inherent in some cholinolytics of local anesthetic and antihistamine effects. These include diphenhydramine, diprazine.
Below is a list of anticholinergic drugs.
All anticholinergic drugs are very diverse in their chemical structure. In addition, given the ability to block different types of effects of acetylcholine, it is customary to subdivide them into M-anticholinergics and H-anticholinergics.
M-anticholinergics
M-anticholinergics are:
- Alkaloids, including scopolamine, platifillin, atropine.
- Herbal anticholinergics. These include: the godson, dope, henbane, belladonna.
- Anticholinergics having a semisynthetic origin, for example, homatropin.
- Cholinolytics of synthetic origin. Among them: chlorosyl, spasmolithin, propantheline, metacin, pirenzepine, ipratropium bromide, aprofen, arpenal.
The action of M-anticholinergics
M-cholinolytics, blocking M-cholinergic receptors, interfere with the interaction of the acetylcholine mediator with them. Reduce or eliminate the effects of irritation of cholinergic (parasympathetic) nerves and the action of substances with M-cholinomimetic activity.
M-anticholinergic drugs are used in the following situations:
- Acute poisoning with cholinomimetic, anticholinesterase poison.
- Parkinsonism, other CNS pathologies.
- Eye injury, iridocyclitis, iritis. In this case, m-anticholinergics are used to relax the eye muscles.
- Spasms of organs having smooth muscle layers (pylorospasm, hepatic, renal colic).
- Peptic ulcer of the duodenum, stomach.
- Vagotonic bradycardia.
- Violation of atrial, atrioventricular conduction.
- Preoperative premedication (for the prevention of laryngospasm, bronchospasm, hypersalivation).
- Bronchospasm.
In addition, M-anticholinergics are used in diagnostic studies, for example, to expand the pupil during examination of the fundus, with an X-ray of the gastrointestinal tract.
Contraindications
The main contraindications that prevent the use of anticholinergic drugs are:
- Hypertrophic changes in the prostate gland, atonic conditions of the bladder.
- Atonic constipation.
- Asthmatic status.
- Glaucoma in any form.
Central anticholinergics, which include scopolamine, antispasmodic, aprofen, arpenal, are contraindicated for persons whose activity requires concentration and speed of reactions and is associated with the management of complex mechanisms and vehicles.
H-anticholinergics
All H-anticholinergics are drugs that are conventionally divided into two main groups: ganglion blocking and curariform.
Ganglion-blocking anticholinergics are able to block n-cholinergic receptors located in the ganglia. These include: fubromegan, temehin, pyrene, pentamine, pachycarpine, quateron, camphonium, imechin, dimecoline, hygronium, benzohexonium.
Ganglioblocking anticholinergics are used, as a rule, as antihypertensive and vasodilator drugs in the following cases:
- Spasms of peripheral vessels (obliterating endarteritis, Raynaud's disease).
- In order to stop crises of a hypertensive nature.
- In order to control hypotensive conditions.
- For the treatment of peptic ulcer of the duodenum, stomach.
- For the purpose of symptomatic therapy of arterial hypertension.
Negative reactions
Against the background of the use of ganglioblocking anticholinergics, some negative reactions may develop, and therefore their use is limited. When using ganglion blockers, it may develop:
- Orthostatic hypotension.
- Decreased venous pressure.
- Violation of accommodation.
- Dry mouth.
- Dilated pupils.
Among the main contraindications that prevent the use of ganglion blockers, the following should be noted:
- Thrombosis.
- Renal, hepatic lesions.
- Myocardial infarction in acute form.
- Arterial hypotension.
- Glaucoma in a closed-angle form.
Curariform anticholinergics
Curariform anticholinergics are able to block H-cholinergic receptors, which are located in the neuromuscular synapses of skeletal muscles. These include: tubocurarine chloride, pipecuronium, pancuronium, melliktin, ditilin, dioxonium.
Curare-like cholinolytics are used, mainly in the field of anesthesiology with the goal of relaxing skeletal muscles:
- With reposition of bone fragments, reduction of dislocations.
- With endoscopic manipulations.
- With surgical interventions.
In addition, curariform agents are often used as an element of the comprehensive treatment of tetanus. Melliktin-based drugs are often used to reduce muscle tone in neurological pathologies, accompanied by a violation of motor function, increased muscle tone of the skeleton.
Against the background of the use of curariform anticholinergics, the following negative symptoms may develop:
- Depolarizing curariform anticholinergics can provoke skeletal muscle soreness.
- Dithilin preparations are able to increase intraocular pressure and increase blood pressure, which in turn provokes cardiac arrhythmias.
- Under the influence of tubocurarine chloride drugs, a decrease in blood pressure, the development of laryngospasm, bronchospasm can be observed.
When should they not be used?
The main contraindications to the use of curariform substances are the following pathologies and physiological conditions:
- Breast age.
- Glaucoma.
- Violations of the liver, renal functionality.
- Myasthenia gravis
It is important to exercise caution when prescribing curariform anticholinergics to patients suffering from cachexia, anemia, as well as those who are pregnant or elderly.
Why are anticholinergics prescribed?
Currently, this list of anticholinergics (drugs of all groups) is widely used in various medical fields. The classification of their use is as follows:
- Use in therapeutic practice, when there is a need for the treatment of pathologies accompanied by spasms in smooth muscle structures. The most relevant drugs in this area are combining myotropic and neurotropic effects, as well as having selective antispasmodic effects.
- Use for the treatment of ulcerative lesions of the duodenum, stomach. In this area, it will be advisable to use anticholinergic drugs with antispasmodic activity that can inhibit the production of gastric juice.
- Use in functional disorders of the nervous system. Anticholinergics are widely used to treat Parkinson's conditions, Parkinson's disease.
- Use in psychiatric practice as tranquilizers.
- Application in the field of anesthesiology. Cholinolytic substances can enhance the effectiveness of sleeping pills and narcotic drugs.
- Use as a prophylactic for the prevention of marine, airborne disease.
- Use as an antidote if intoxication of the body with poisons.
Cholinolytic overdose
With prolonged use, the degree of exposure to anticholinergics may decrease. Due to such a feature of substances, experts recommend a periodic replacement of drugs.
In some cases, against the background of the use of drugs, a side effect of a toxic nature may develop. This happens most often if the patient has an individual sensitivity to the substance, or exceeds the recommended dosage. Cholinolytic intoxication is manifested by the following symptoms:
- Incorrect accommodation.
- Dry mucous membranes in the mouth.
- Tachycardia.
When using central anticholinergics, an overdose is accompanied by the occurrence of impaired NS functionality:
- Hallucinations.
- Feeling of a stupefied head.
- Dizziness.
- Pain in the head.
When treating with anticholinergics, it is important for the patient to observe the dosages recommended by the specialist and take into account the individual characteristics of his own body. Even a slight overdose of substances leads to the development of tachycardia and severe dry mouth. With the onset of intoxication, proserin should be administered intravenously to the patient. The most serious contraindication to their use is glaucoma.