Tritoqualine is an inhibitor of histidine decarboxylase, an enzyme that catalyzes the conversion of histidine to histamine. Tritoqualine does not act on histamine receptors. It was marketed since 1960 for the treatment of allergic conditions and is available under tradename Hypostamine.

Tisopurine (or Thiopurinol) was used in the treatment of gout. This drug reduces uric acid concentrations by interfering with the early stages of its synthesis, thus avoiding increased blood concentrations of hypoxanthine and xanthine. In addition, it was discovered, that tisopurine caused acute hepatitis.

Proxyphylline is a xanthine derivative that acts as a cardiac stimulant, vasodilator and bronchodilator. In combination with ephedrine it’s used for relief of acute bronchial asthma and for reversible bronchospasm associated with chronic bronchitis and emphysema. Proxyphylline is readily absorbed from the gastrointestinal tract and it’s not converted to theophylline in the body. The clinical studies are agreed with the property of proxyphylline to inhibit the cyclic nucleotide phosphodiesterases.

Benmoxin is an inhibitor of monoamine oxidase that was used as an antidepressant but now is no longer marketed.

Itopride is a dopamine D2 receptor antagonist and inhibitor of acetylcholinesterase. It is indicated in the for the treatment of gastrointestinal symptoms caused by reduced gastrointestinal motility, such as functional non-ulcer dyspepsia (chronic gastritis), gastric fullness, rapid satiation, pain or discomfort in the upper abdomen, anorexia, heartburn, nausea, and vomiting. The drug is not approved in the USA or UK but is available in Japan and Western European countries.

Candoxatril is the orally-active prodrug of candoxatrilat (UK-73967), a potent neutral endopeptidase (NEP) inhibitor. Neutral endopeptidase inhibitors such as Candoxatril have a dual mechanism of action. They inhibit two metalloprotease enzymes, neutral endopeptidase, and ACE, resulting in an increased availability of natriuretic peptides that exhibit vasodilatory effects and, possibly, tissue protective effects. Candoxatril is the first drug of its kind to be released for clinical trials regarding heart failure. This is because Candoxatril produces favorable hemodynamic effects in patients with chronic heart failure. It has been demonstrated that Candoxatril is associated with a beneficial hemodynamic effect that is useful both for rest and exercise. In several different studies, candoxatril has been shown to improve performance in people with heart failure. In one study, 12 different patients were selected, all with moderately severe heart failure. On day one of this study, the candoxatril had increased plasma ANP levels, suppressed aldosterone and decreased right atrial and pulmonary capillary wedge pressures. After treatment for 10 days, patients health had improved with an increase of basal ANP and a decrease of aldosterone, along with a reduced body weight that could be a reflection of chronic natriuretic, diuretic effects, or both. It was decided that on day 10 of the study, the effects of candoxatril were similar to that on day one.

Gimeracil is a component of an oral fixed combination known under the name Teysuno or S-1 (tegafur, gimeracil and oteracil potassium at a molar ratio of 1:0.4:1). The formulation was approved in Asia and Europe for the treatment of a rare condition of gastric cancer. Given in combination, gimeracil enhances the efficacy of tegafur by inhibiting dihydropyrimidine dehydrogenase, an enzyme involved in metabolism of tegafur and its active metabolite 5-fluorouracil.

Ecabet is an anti-ulcer agent, marketed in Japan as an oral agent for treatment of gastric ulcers and gastritis. Ecabet eradicates Helicobacter pylori infection in gastric ulcer patients. Antibacterial effect of ecabet is demonstrated at low pH, is mediated by inhibition of bacterial urease and accompanied by interference with TLR4 signaling and pepsin inhibition. Ecabet is also investigated for the treatment of dry eye syndrome.

Belotecan is a semisynthetic analogue of camptothecin containing a 2-(N-isopropylamino) ethyl group linkage at position C-7 of the camptothecin ring. It stabilizes the complex formed between topoisomerase I and DNA, thereby preventing the religation of DNA breaks. This leads to an inhibition of DNA replication and triggers apoptotic cell death. Belotecan was approved in Korea under the name Camtobell for the treatment of patients with ovarian and small cell lung cancers.

Remikiren (Ro 42-5892) is a very potent renin inhibitor in vitro and in vivo. Clinical results show that remikiren is a potent orally active renin inhibitor inducing a long lasting blood pressure decrease. Remikiren development has been discontinued.