Antimuskarinergika

Antimuskarinergika, or antimuscarinic agents, are a class of drugs that act as antagonists at muscarinic acetylcholine receptors (M1–M5). By blocking parasympathetic nerve impulses, they reduce secretions, relax smooth muscle, and produce pupil dilation, dry mouth, and other anticholinergic effects. They can be classified by their ability to cross the blood–brain barrier: tertiary amines such as atropine and scopolamine cross readily, while quaternary ammonium compounds like ipratropium and glycopyrronium have limited CNS penetration.

Mechanistically, antimuskarinergika competitively inhibit acetylcholine at muscarinic receptors, thereby diminishing activities mediated by the parasympathetic system. Receptor subtypes contribute to tissue-specific effects, with M1 largely in the CNS and peripheral ganglia, M2 in the heart, and M3 in smooth muscle and glands. The clinical response depends on the tissue distribution of these receptors and the drug’s pharmacokinetic properties.

Clinical uses are diverse. They treat overactive bladder and related voiding symptoms (eg, oxybutynin, tolterodine, solifenacin, darifenacin, trospium). They alleviate parkinsonian tremor and dystonia or drug-induced extrapyramidal symptoms (eg, benztropine, trihexyphenidyl, biperiden). They prevent motion sickness (scopolamine) and reduce secretions perioperatively; some inhaled forms (ipratropium, tiotropium) are central to COPD and asthma management. Pirenzepine and related agents have been used to reduce gastric acid secretion in peptic ulcer disease, though usage has declined.

Common adverse effects reflect systemic anticholinergic activity: dry mouth, constipation, blurred vision, urinary retention, tachycardia, and cognitive impairment, particularly in the elderly. Caution is advised in glaucoma, urinary retention, intestinal obstruction, and myasthenia gravis. Overdose can be treated with supportive care and, in some cases, physostigmine as an antidote.