Ganglionic Drugs

Ganglionic Agonists

The ganglionic agonists are essential for analyzing the mechanism of ganglionic function, but they have no therapeutic use. Nicotine is the classic ganglionic agonist, and its effects have been well described.^[446]

Parasympathetic drugs stimulate ganglia, but this action is usually masked by the other parasympathomimetic effects. Experimentally, relatively large doses of acetylcholine administered intravenously after blockade of muscarinic receptors by atropine causes ganglionic stimulation and release of epinephrine by the adrenal medulla.^[446]

Ganglionic Antagonists

The ganglionic antagonists were the first effective therapy for the management of hypertension and were used extensively during the 1950s and 1960s. However, because of interference with transmission through sympathetic and parasympathetic ganglia, antihypertensive action was accompanied by numerous undesirable effects. Hexamethonium, the prototypic drug of this class, has minimal neuromuscular and muscarinic activity. Paton^[447] provided a vivid description of the clinical effects of chronic ganglionic blockade with his "hexamethonium man." The systemic effects of ganglionic blockade are determined by the resting tone of a specific body system before the application of ganglionic blockade (see Table 16-2 ). With the disappearance of trimethaphan from clinical use, these drugs are largely of historic value.