Antispasmodic agents, including both natural and synthetic drugs such as scopolamine and butylscopolamine, act on smooth muscles to alleviate spasms and pain. These medications work by blocking nerve signal transmission or acting directly on smooth muscle cells to reduce muscle contractions. They are primarily targeted at the smooth muscles of the gastrointestinal tract, urinary system, and respiratory system. By influencing acetylcholine receptors or calcium ion channels, they regulate neuromuscular signaling, thus slowing down muscle spasms. Genetic variations may affect the rate of drug metabolism or efficacy, leading to differences in individual sensitivity to antispasmodic drugs.