Diphemanil methylsulfate (Prantal), a quarternary amine, is a highly specific parasympathetic blocking agent.

Isometheptene (usually as isometheptene mucate) is a sympathomimetic amine sometimes used in the treatment of migraines and tension headaches due to its vasoconstricting properties. Isometheptene's vasoconstricting properties arise through activation of the sympathetic nervous system via epinephrine and norepinephrine. These compounds elicit smooth muscle activation leading to vasoconstriction by interacting with cell surface adrenergic receptors.

Alverine is a smooth muscle relaxant used for the treatment irritable bowel syndrome. Alverine may increase calcium influx during action potentials due to inhibition of the inactivation of L-type calcium channels, but may also suppress evoked activity by inhibiting the sensitivity of contractile proteins to calcium.

Hyoscyamine as a natural plant alkaloid derivative and anticholinergic. Hyoscyamine is used to treat a variety of stomach/intestinal problems such as cramps and irritable bowel syndrome. It is also used to treat other conditions such as bladder and bowel control problems, cramping pain caused by kidney stones and gallstones, and Parkinson's disease. In addition, it is used to decrease side effects of certain medications (drugs used to treat myasthenia gravis) and insecticides. Hyoscyamine inhibits specifically the actions of acetylcholine on structures innervated by postganglionic cholinergic nerves and on smooth muscles that respond to acetylcholine but lack cholinergic innervation. These peripheral cholinergic receptors are present in the autonomic effector cells of the smooth muscle, cardiac muscle, the sinoatrial node, the atrioventricular node, and the exocrine glands. At therapeutic doses, it is completely devoid of any action on autonomic ganglia. Side effects include dry mouth and throat, increased appetite leading to weight gain, eye pain, blurred vision, restlessness, dizziness, arrhythmia, flushing, and faintness. Additive adverse effects resulting from cholinergic blockade may occur when hyoscyamine is administered concomitantly with other antimuscarinics, amantadine, haloperidol, phenothiazines, monoamine oxidase (MAO) inhibitors, tricyclic antidepressants or some antihistamines.

Methylatropine (methylatroponium) is a belladonna derivative. In 1902 the Bayer Company introduced atropine methonitrate, a quaternary ammonium salt of atropine (Eumydrin), as a mydriatic for dilation of the pupil during ophthalmic examination. Due to its highly polar nature it penetrates less readily into the central nervous system than atropine and was therefore introduced for relieving pyloric spasms in infants. Atropine methyl nitrate is a muscarinic acetylcholine receptor antagonist that does not cross the blood-brain barrier. Atropine methyl nitrate has been used for its peripheral muscarinic effects (targeting the bladder, respiratory tract, and to block parasympathetic signaling to the heart, among others) and to separate central from peripheral nervous system effects, or to protect against peripheral side effects when using muscarinics that do cross the blood brain barrier.

Domperidone is a peripherally selective D2 receptor antagonist. It acts as an antiemetic and a prokinetic agent through its effects on the chemoreceptor trigger zone and motor function of the stomach and small intestine. Domperidone was not approved in USA due to risks of cardiac arrhythmias, cardiac arrest, and sudden death, but is available in other countries. However, FDA allows access to Domperidone through an expanded access investigational new drug application (IND) to patients with gastroesophageal reflux disease with upper GI symptoms, gastroparesis, and chronic constipation. As an “off-label” use, domperidone is prescribed to breastfeeding women to enhance their milk production.

An alkaloid found in opium but not closely related to the other opium alkaloids in its structure or pharmacological actions. Papaverine is a vasodilating agent. Papaverine is used for the treating certain conditions that are accompanied by smooth muscle spasms (eg, blood vessel, urinary, gallbladder, or intestinal spasm). Papaverine is a nonxanthine phosphodiesterase inhibitor for the relief of cerebral and peripheral ischemia associated with arterial spasm and myocardial ischemia complicated by arrhythmias. The main actions of Papaverine are exerted on cardiac and smooth muscle. Like qathidine, Papaverine acts directly on the heart muscle to depress conduction and prolong the refractory period. Papaverine relaxes various smooth muscles. This relaxation may be prominent if spasm exists. The muscle cell is not paralyzed by Papaverine and still responds to drugs and other stimuli causing contraction. The antispasmodic effect is a direct one, and unrelated to muscle innervation. Papaverine is practically devoid of effects on the central nervous system. Papaverine relaxes the smooth musculature of the larger blood vessels, especially coronary, systemic peripheral, and pulmonary arteries. Papaverine is a potent, specific inhibitor of PDE10A. Papaverine for treatment of erectile dysfunction (ED) is excluded from coverage.

Cinitapride is an agonist of 5-HT4 and 5-HT1 receptors and antagonist of 5-HT2 receptors. Cinitapride is marketed worldwide for the treatment of gastrointestinal disorders related to motility such as indigestion or functional or non-ulcer dyspepsia, gastroesophageal reflux diseases, delay in gastric emptying and vomiting.

Fenoverine is a potent musculotropic, the anti-spasmodic agent that restores smooth muscle motility and relieves the distressing symptoms associated with irritable bowel syndrome (IBS) and primary dysmenorrhea. Fenoverine is a non-anticholinergic phenothiazine derivative that may also inhibit calcium channel currents. Fenoverine primarily affects the gastrointestinal tract, bile duct, and female genital organs. Fenoverine has been repeatedly implicated in the occurrence of rhabdomyolysis, a potentially fatal adverse effect, in France. Thes drug has been therefore unavailable in France since December 1995 but commonly used in the treatment of gastrointestinal spasmodic disorders in Taiwan.