M-anticholinergic drugs are fairly well-known drugs. These atropine-like drugs block the activity of the parasympathetic nervous system, its effect on the organs and glands of the body. Further, the article describes the effects of m-anticholinergic blockers, their significance in medicine, the effect and areas of application of these drugs.
Classification
M-anticholinergic drugs are divided into three main groups:
- Means "Atropine" and "Scopolamine", which are natural alkaloids.
- Their semisynthetic derivatives, which differ from the starting substances, consisting in pharmacokinetic properties.
- Synthetic compounds that may have selectivity for other subtypes of m-cholinergic receptors.
The properties
Means "Atropine", as a reference drug, can have a stimulating effect on the activity of the central nervous system. The medication "Scopolamine" also has a sedative property and is used for gait disorders, dizziness and other vestibular disorders. Contained in Aeron tablets as an active substance, this compound is used to prevent seasickness.
The action of m-anticholinergic drugs "Atropine" and "Scopolamine" is different. Most clearly, differences are noted when affecting the central nervous system. Means "Scopolamine", in contrast to the drug "Atropine", has a central effect of a pronounced nature even in small doses. This is due to the different permeability of the blood-brain barrier. This is precisely the reason why m-anticholinergics containing atropine are used much more often.
Of the semi-synthetic derivatives of natural alkaloids, the most important are Gomatropin and Tropicamide, as well as Methylatropin nitrate, Ipratropium bromide and Thiotropium bromide. All these drugs are not able to penetrate the blood-brain barrier. Synthetic compounds of the third group include m-anticholinergics such as Pirenzepine (prescribed for peptic ulcers) and Tolterodine (recommended for urinary incontinence).
Application
M-anticholinergics (the mechanism of action of some of them will be described below) find their application as antispasmodics for various types of colic (renal, hepatic, intestinal), are prescribed for bronchospasm, and a decrease in the frequency of contractions in the heart. Medications are recommended for examination of the fundus, treatment of iritis and iridocyclitis, atrial ventricular conduction disorders.
The action of m-anticholinergics, among other things, is manifested in the relaxation of gastric and intestinal smooth muscles, a decrease in the secretion of the digestive glands. Due to this, the funds can be used in the treatment of ulcers in the stomach and in the duodenum. The drugs are also used as an antidode for intoxication with cholinomimetic and anticholinesterase components.
The effect of Atropine on the central nervous system
In moderate doses, which are 0.5-1 mg, the drug is capable of only a sufficient increase in parasympathetic tone. This occurs as a result of the excitation of centers in the medulla oblongata and its overlying departments. With increasing dosage, the patient has an excited state, which is manifested by anxiety, disorientation, hallucinations. Very large doses give an inhibitory effect, coma and paralysis, cardiovascular failure may develop.
The effect of "Scopolamine" on the central nervous system
This drug is able to exert a inhibitory effect on the activity of the nervous system. It manifests itself in drowsiness, fatigue, a decrease in the proportion of REM sleep, amnesia. Due to the ability to cause euphoria in some patients who abuse the drug, addiction is noted. Because of the sedative effect, the drug "Scopolamine" at one time wanted to be used for general anesthesia. However, it was later revealed that with severe pain it can even cause anxiety, hallucinations and agitation in therapeutic doses. Acting on the cerebral cortex, the drug prevents motion sickness.
The effect of Atropine on the cardiovascular system
The main effect of the drug is a change in the frequency of contractions in the heart. The tool is capable of causing severe tachycardia. However, when using doses not exceeding permissible, a decrease in heart rate occurs temporarily and does not lead to a change in blood pressure. It was previously believed that such an effect occurs due to stimulation of the centers of the vagus nerves. But then it turned out that m-anticholinergic drugs, which do not cross the blood-brain barrier , have a similar property . Atropine is able to prevent bradycardia, which is caused by choline esters and ACE inhibitors, cardiac arrest during electrical stimulation of the vagus nerves.
The effect of the medication "Scopolamine" on the cardiovascular system
In small doses of 0.1-0.2 mg, the drug causes a significant decrease in heart rate. After increasing the dosage, tachycardia is first observed, which passes after half an hour, or bradycardia replaces it. The belladonna alkaloids, as well as other m-anticholinergic drugs, have been prescribed for the treatment of parkinsonism since ancient times. A higher result was achieved when used in combination with the drug "Levodopa". M-anticholinergics are used in extrapyramidal disorders caused by antipsychotics.