Parasympatomimeettejä

Parasympatomimeettejä, also known as cholinergic agonists or parasympathomimetic drugs, are a class of pharmacological agents that mimic or enhance the effects of the neurotransmitter acetylcholine (ACh) at parasympathetic nerve endings. The parasympathetic nervous system is a division of the autonomic nervous system responsible for the "rest and digest" functions of the body, including slowing heart rate, increasing gastrointestinal motility, constricting pupils, and promoting glandular secretions.

These drugs work by either directly stimulating muscarinic and/or nicotinic acetylcholine receptors, or indirectly by inhibiting the enzyme acetylcholinesterase, which breaks down acetylcholine. Direct-acting parasympathomimetics bind to and activate these receptors, while indirect-acting ones increase the availability of acetylcholine in the synaptic cleft, thereby prolonging its action.

Parasympatomimeettejä have various clinical applications. For instance, pilocarpine, a direct-acting agent, is used to treat glaucoma by reducing intraocular pressure and to manage dry mouth. Indirect-acting agents like neostigmine and pyridostigmine are used to treat myasthenia gravis, a neuromuscular disorder characterized by muscle weakness, by increasing acetylcholine levels at the neuromuscular junction. Other applications include the treatment of urinary retention and paralytic ileus. However, due to their widespread effects on multiple organ systems, parasympatomimetics can also cause side effects such as salivation, lacrimation, urination, defecation, gastrointestinal cramping, and emesis, collectively known as the "SLUDGE" syndrome, as well as bradycardia and bronchoconstriction.