Ethoxzolamide is a carbonic anhydrase I inhibitor. It is used in the treatment of glaucoma and duodenal ulcers, and as a diuretic. Ethoxzolamide was marketed under trade name Cadrase, but is now discontinued.

Methantheline is a synthetic quarternary ammonium antimuscarinic used to relieve cramps or spasms of the stomach, intestines, and bladder. It is indicated for the treatment of peptic ulcer disease, irritable bowel syndrome, pancreatitis, gastritis, biliary dyskinesia, pylorosplasm, and reflex neurogenic bladder in children. It can be used together with antacids or other medicines, such as H2-receptor antagonists, in the treatment of peptic ulcer. Methantheline bromide (diethyl-methyl [2-(9 xanthenyl carbonyloxy) ethyl] ammonium bromide) is marketed to treat neurogenic bladder instability. In comparison with atropine, it influences the parasympathetic nervous transmission more by ganglionic rather than peripheral muscarinic receptor blockade. Methantheline inhibits the muscarinic actions of acetylcholine on structures innervated by postganglionic cholinergic nerves as well as on smooth muscles that respond to acetylcholine but lack cholinergic innervation. Clinical effects after single therapeutic doses of 50-100 mg last for about 6 hours which is longer than after atropine. The drug relaxes smooth muscles of the gastrointestinal and urogenital tract. Furthermore, it inhibits bronchial, salivary and sweat glands secretion, lowers the production of gastric juice and disturbs accommodation. A recent randomised double-blind placebo-controlled study using a new commercial preparation of methantheline bromide (Vagantin, Germany) demonstrated significant sweat reduction and was evaluated as is an effective and safe treatment of axillary hyperhidrosis.

Sodium gualenate (Azunol ST Tablets) is a water-soluble derivative of azulene, a natural product which is an antiinflammatory component of chamomile of the family of Asteraceae. Sodium gualenate was originally studied as an antiulcer agent, is primary indicated in conditions like Duodenal ulcer, Gastric ulcer, Gastritis, but it is also clinically used as a therapeutic agent in the treatment of inflammation of the mouth and throat, for example, pharyngitis as well as other inflammatory diseases such as tonsillitis, stomatitis and conjunctivitis. Although the mechanism by which sodium azulene sulfonate inhibited the capsaicin-induced pharyngitis is not yet unraveled, antioxidative effect, but not inhibitory effect on cyclooxygenase pathway, might be involved.

Pirenzepine is a M1 muscarinic receptor antagonist, which is prescribed for the treatment of gastric and duodenal ulcer in Europe. The drug preferentially acts on the gastric mucosa to inhibit secretion of both gastric acid and pepsin. Experiment with healthy volunteers demonstrated that pirenzepine passes the blood-brain barrier, but only to a small extent.

METHYLMETHIONINE (S-Methionine methyl sulfonium, SMMS) chloride is a derivative of methionine metabolism in some plants. Methylmethionine has therapeutic effects on gastrointestinal ulceration potentially via its ability to promote dermal fibroblast migration and growth. The natural derivative Methylmethionine is biosynthesized from L-methionine which is first converted to S-adenosylmethionine. The subsequent conversion, involving replacement of the adenosyl group by a methyl group is catalyzed by the enzyme methionine S-methyltransferase. Methylmethionine is particularly abundant in plants, being more abundant than methionine. S-Methylmethionine is sometimes referred to as vitamin U, but it is not considered a true vitamin. The term was coined in 1950 by Garnett Cheney for uncharacterized anti-ulcerogenic factors in raw cabbage juice that may help speed healing of peptic ulcers.

Benzilonium is an antispasmodic and antimuscarinic drug. Benzilonium bromide is a quarternary antimuscarinic agent with minimal passage of the blood-brain barrier.

Osutidine (T-593) is a H2 receptor antagonist which was undergoing development by Toyama Chemical for the treatment of peptic/gastric and duodenal ulcers. It is a beta-hydroxyphenethylamine derivative with both antisecretory and cytoprotective properties. Osutidine inhibited the histamine-induced cAMP generation in a concentration-dependent manner. Osutidine suppressed the maximal response of the histamine-induced positive chronotropic response, indicating that the compound is unsurmountable H2-antagonists. The metabolism of Osutidine in humans may not differ from that of rodents and dogs. No clinically relevant accumulation occurred following repeated dosage. In the single oral and subcutaneous dose toxicity studies in rats, there were no dead animals. The oral LD50 value was greater than 5 g/kg for both sexes, and there was no abnormality in general signs. An oral formulation of the drug was in phase III clinical trials in Japan, however Toyama has dropped it from clinical development.

Dalcotidine is a histamine H2 receptor antagonist that demonstrated potent gastric mucosal protective activity on acute gastric lesions and duodenal ulcers. Dalcotidine was discontinued in phase III of clinical trials in Japan.

Tenatoprazole, also known as TU-199 and STU-Na, is a proton pump inhibitor drug candidate that was undergoing clinical testing. The compound was invented by Mitsubishi Tanabe Pharma and was licensed to Negma Laboratories (part of Wockhardt as of 2007). Mitsubishi reported that tenatoprazole was still in Phase I clinical trials in 2007 and again in 2012. STU-Na will be used for treatment of acid related diseases (gastroduodenal ulcers, erosive or ulcerative esophagitis due to gastroesophageal reflux disease). Tenatoprazole has an imidazopyridine ring in place of the benzimidazole moiety found in other proton pump inhibitors; the binding sites of tenatoprazole were in the TM5/6 region at Cys813 and Cys822 as shown by tryptic and thermolysin digestion of the ATPase labeled by tenatoprazole. It has a half-life about seven times longer than other PPIs.

Arbaprostil (15(R)-15-methylprostaglandin E2) is a prodrug, which is activated by epimerization to form the active S-epimer. It was shown, that arbaprostil markedly accelerated the healing rate of active duodenal ulcers, due to inhibition of acid secretion as well as gastric cytoprotection.