Directly and Indirectly Acting Cholinomimetics

Cholinomimetic drugs can elicit some or all of the effects that acetylcholine (ACh) produces. This class of drugs includes agents that act directly as agonists at cholinoreceptors and agents that act indirectly by inhibiting the enzymatic destruction of endogenous ACh (i.e., cholinesterase inhibitors).The directly acting cholinomimetics can be subdivided into agents that exert their effects primarily through stimulation of muscarinic receptors at parasympathetic neuroeffector junctions (parasympathomimetic drugs) and agents that stimulate nicotinic receptors in autonomic ganglia and at the neuromuscular junction (see Chapter 9). This chapter focuses on the parasympathomimetic drugs and cholinesterase inhibitors. Drugs acting at nicotinic receptors are presented in Chapters 14 and 28. Muscarinic Receptors and Signal Transduction