Prokinetic agent

A gastroprokinetic agent, gastrokinetic, or prokinetic, is a type of drug which enhances gastrointestinal motility by increasing the frequency of contractions in the small intestine or making them stronger, but without disrupting their rhythm. They are used to relieve gastrointestinal symptoms such as abdominal discomfort, bloating, constipation, heart burn, nausea, and vomiting. They are used to treat a number of gastrointestinal disorders, including irritable bowel syndrome, gastritis, acid reflux disease,^[1] gastroparesis, and functional dyspepsia.

Most of these drugs are grouped under ATC code A03F.

Pharmacodynamics

These drugs may increase acetylcholine concentrations by antagonizing the M₁ receptor which inhibits acetylcholine release, or by inhibiting the enzyme acetylcholinesterase which metabolizes acetylcholine. Higher acetylcholine levels increase gastrointestinal peristalsis and further increase pressure on the lower esophageal sphincter, thereby stimulating gastrointestinal motility, accelerating gastric emptying, and improving gastro-duodenal coordination.

The 5-HT₄ receptor is thought to play a significant role in both the physiology and pathophysiology of GI tract motility.^[2] Therefore, 5-HT₄ receptors have been identified as potential therapeutic targets for diseases related to GI dysmotility such as chronic constipation. Some of these prokinetic agents, such as mosapride and cisapride, classic benzamides, have only moderate affinity for 5HT₄ receptors. In recent years, it has become clear that the selectivity profile is a major determinant of the risk-benefit profile of this class of agent. As such, the relatively poor selectivity profile of cisapride versus other receptors (especially hERG [human ether-a-go-go K⁺] channels) contributes to its potential to cause cardiac arrhythmias. Prucalopride, a first in class benzofuran, is a selective, high affinity serotonin (5-HT₄) receptor agonist that stimulates colonic mass movements, which provide the main propulsive force to defecation.^[3][4]

Other molecules, including macrolides such as mitemcinal and Erythromycin, appear to have high 5-HT₄ affinity as well, although limited data exists as this property was an unexpected outcome of off-label use in the clinic.

Examples

References

Further reading

• Hardman JG, Limbird LE, Gilman AG. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 10th ed. New York: McGraw-Hill, 2001. ISBN 0-07-135469-7.