drug acting on autonomic nerves system
Based on the division of ANS to which the postganglionic nerve fibres innervate and the type of neurotransmitter released at the nerve endings, the drugs acting on the automatic nervous system are divided into two main groups,
1. cholinergics / Parasympathetic nervous system:
Drugs or chemical which exert either stimulatory or inhibitory effects on parasympathetic nervous system by mediating the actions via acetylcholine are called parasympathetic drugs. These are further classified as,
a. Parasympathomimetics: These are the agents which stimulate the parasympathetic nervous system by mimicking the actions of acetylcholine. These are also referred to as cholinomimetics or cholinergic agents or cholinergic agonists.
• Directly Acting drugs: acetylcholine, methacholine, bethanechol, carbachol, pilocarpine.
• Indirectly Acting/ anticholinesterases:
1. Reversible AChEI: Neostigmine, Physostigmine, Pyridostigmine, Gallantamine, Edrophonium.
2. Irreversible AChEI: Parathion, Malathion, Dyflos, Echothiophate.
b. Parasympatholytics: These agents decrease the parasympathetic activity by blocking the actions of acetylcholine. These are also called as anticholinergic or cholinergic blocking agents or cholinergic antagonists or cholinolytics.
2.Adrenergics / sympathetics nervous system:
Drug or chemicals that cause either stimulation or inhibition of the sympathetic nervous system by mediating actions via norepinephrine or epinephrine are called adrenergic agents. These are further classified as,
a. Sympathomimetics: these are the substances that produce effects similar to those produced when sympathetic nervous system is activated by epinephrine or norepinephrine. They stimulate or mimic sympathetic activity, Hance referred to as sympathomimetics or adrenergic stimulants or adrenergic agonists or adrenomimetics.
b. Sympatholytics: agents which decrease sympathetic activity by blocking the actions of epinephrine or norepinephrine are called sympatholytics or anti-adrenergics or adrenergic blocking agents or adrenergic antagonists or adrenolytics.
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