Anticholinergics are widely used in medicine because of their effect in the parasympathetic nervous system. However, the side effects should not be underestimated.
What are anticholinergics?
Anticholinergics, for example, cause a decrease in bowel activity. Anticholinergics are substances that inhibit the main neurotransmitter acetylcholine in the parasympathetic nervous system. As a part of the autonomic (unconscious) nervous system and an antagonist of the sympathetic nervous system, the parasympathetic nervous system has the task of putting the body into a state of rest and regenerating itself. The suppression of the messenger substance acetylcholine takes place by interrupting certain nerve stimuli. Such nerve stimuli are responsible for smooth muscle contraction and gland secretion. Acetylcholine thus stimulates the activity of the intestines and digestive glands. In contrast, it decreases heart rate and respiration. Because of their action in the parasympathetic nervous system, anticholinergics are also called parasympatholytics.
Medical application, effect, and use
The effects of anticholinergics on the human organism are a decrease in salivation, dilation of the pupils, and a decrease in intestinal activity. These effects result in various applications in medicine. Anticholinergics are used especially in irritable bladder diseases. Patients with various types of incontinence and frequent urination experience rapid improvement because the anticholinergic substances weaken the contractions of the bladder muscles and thus increase the capacity of the bladder. As a result of the more stable bladder, sufferers no longer have to go to the toilet as often to empty their bladder. Another significant application of anticholinergics is Parkinson’s disease, in which there is an excess of acetylcholine and a simultaneous deficiency of dopamine. Anticholinergic agents are administered to reduce this imbalance. However, because of the numerous side effects, these are used cautiously and mainly to reduce rest tremor in Parkinson’s disease. Furthermore, the drugs are effective in excessive sweating (hyperhidrosis), asthmatic disorders, bronchitis, spasms of the internal organs and smooth muscles, bradycardia (too slow heartbeat), and cardiac arrhythmias. In addition, anticholinergics are used to induce anesthesia before surgery and to facilitate examinations of the back of the eye by dilating the pupils.
Herbal, natural, and pharmaceutical anticholinergics.
The various types of anticholinergics differ only slightly. However, differences exist with regard to tolerability. Therefore, in case of intolerance, switching medications is helpful. There are two major groups of anticholinergics: the first group acts exclusively on the nervous system (neurotropic) and the second group acts on both the nervous system and the muscles (musculotropic). Among the neurotropic substances there are the so-called belladonna alkaloids or relatives. The best-known representative of this group is atropine, whose name is derived from belladonna (Atropa belladonna). Today, atropine is mainly used for induction of anesthesia, in emergency medicine and ophthalmology, and rarely for gastrointestinal spasms or colic of the biliary and urinary tracts. In the last two areas of application, the substance butylscopolamine has increasingly replaced atropine. The alkaloid atropine is also used as an antidote for poisoning with certain pesticides and is stored by the military against poisoning with nerve agents. The active ingredients glycopyrronium bromide, ipratropium bromide and tiotropium bromide help with asthmatic symptoms. Neurotropic-musculotropic anticholinergics include, for example, oxybutynin and propiverine in treatments of the bladder or denaverine in gastroenterology and urology.
Risks and side effects
The side effects of anticholinergics are numerous. Fatigue, nausea, dizziness, poor concentration, circulatory problems, constipation, visual disturbances, dry mouth and skin, urinary retention, or bowel weakness often occur, with dry mouth being the most common side effect of all anticholinergic agents. Due to the influence on the nervous system, states of confusion, disturbances of memory as well as restlessness may occur.Older patients in particular suffer increased impairment of their memory during treatment with anticholinergics. People who already have dementia may experience a deterioration in their cognitive performance as a result of anticholinergic drug administration. In certain diseases, anticholinergics must not be taken or the dosage must be changed by the physician. These include, for example, narrow-angle glaucoma, bladder emptying disorders, accelerated heartbeat (tachycardia), acute pulmonary edema, or constrictions in the gastrointestinal tract. Because of the significant side effects of anticholinergics, a physician should be thoroughly consulted and the cost-benefit factor weighed.
