As you know, in the nervous system there are many synapses. They are necessary for the transmission of impulses. Several types of mediators are involved in this process. Among them are acetylcholine, norepinephrine, GABA, serotonin, etc. Mediators (transmitters) are necessary for the transmission of signals between neurons. In addition, thanks to them, excitation or inhibition of muscles is carried out. With various pathologies of the nervous system, the work of neurotransmitters can be disrupted. This happens due to atrophic and degenerative processes in the brain. In these cases, drugs necessary to enhance or attenuate signal transmission are used. A similar pharmacological group includes cholinesterase inhibitors. They are used for myasthenia gravis, neuritis, amyotrophic sclerosis, Alzheimer's disease, mental pathologies.
The action of cholinesterase inhibitors
Cholinesterase inhibitors are medications that are widely used in neurology and psychiatry. They are divided into several groups, each of which is used in a particular case. The effect of these medicines is based on blocking cholinesterase. This enzyme is present in both healthy people and those suffering from various diseases. It is necessary for the splitting of the neurotransmitter - acetylcholine. As a result of its action, the transmitter is destroyed to choline and acetic acid. With various pathologies of the brain, a gradual atrophy of the cortex occurs. As a result, some structures can completely collapse, including the cholinergic system. In addition to brain atrophy, degenerative processes of an autoimmune, infectious, and viral nature lead to this. Due to the destruction of the forebrain nuclei, a pronounced lack of a neurotransmitter, acetylcholine, is observed. To avoid a shortage of this substance for as long as possible, it is necessary to act on the enzyme that destroys it. To this end, cholinesterase inhibitors are used. Thanks to them, the activity of the neurotransmitter can persist for several years.
Cholinesterase Inhibitors: Drug Classification
There are several types of anticholinesterase drugs. They are classified by pharmacological effect on the enzyme. Some of them block cholinesterase irreversibly, others temporarily. Allocate 3 groups of medicines. Among them:
- Reversible blockers. These cholinesterase inhibitors act on postsynaptic signaling. Thanks to them, the action of the enzyme is temporarily interrupted. This group includes acridines and piperidines.
- Pseudo-irreversible cholinesterase blockers. The mechanism of their action is to connect with the onion part of the enzyme molecule. In addition, they are able to bind to acetylcholine receptors. A group of carbamates has similar properties.
- Irreversible cholinesterase inhibitors. Preparations of this group are called organophosphorus agents. The representative is the medication "Metrifonate".
The group of acridines includes the drugs Takril and Velnakrin. Representatives of carbamates - medicines "Rivastigmine", "Epistatigmine."
Indications for the use of cholinesterase inhibitors
Cholinesterase inhibitors are used to treat muscle diseases of central origin, atrophic and degenerative brain pathologies. In addition, some medicines are available in the form of drops. They are used with increased intraocular pressure - glaucoma. Drugs that inhibit cholinesterase reversibly are prescribed for the treatment of dementia, Peak's disease and Alzheimer's. Preference should be given to the group of piperidines, since they act selectively and have fewer side effects. Recently, indications for the use of medicines have expanded. This is due to a more detailed study of their properties. Diseases in which anticholinesterase drugs are prescribed include myasthenia gravis, intestinal atony, muscle dystrophy, amyotrophic lateral sclerosis, and paralysis of extremities of a degenerative origin. Irreversible inhibitors are used for poisoning.
Contraindications to the use of anticholinesterase drugs
Medicines belonging to this group are not used for convulsive syndrome, hyperkinesis of any etiology. They are also contraindicated in patients suffering from severe heart failure, bronchial asthma, thyrotoxicosis. It is undesirable to take anticholinesterase drugs with concomitant gastric ulcer, enteritis. Medicines are not indicated for pregnant and lactating women.
Cholinesterase inhibitors: drugs of choice in Alzheimer's disease
Alzheimer's disease is an atrophic lesion of the central nervous system in which amnesia, personality disorder, and dementia are observed. Scientists around the world are trying to find a cure for this pathology. With mild to moderate disease severity, the drug of choice is Donepezil. It belongs to reversible cholinesterase inhibitors, has a selective effect. The medication is used for the purpose of pathogenetic therapy. He is not able to completely cure the patient, but slows down the development of symptoms of Alzheimer's disease.