Pirmagrel is the selective thromboxane synthetase inhibitor. The compound was well tolerated by all subjects without evidence of any adverse reactions. Serum thromboxane B2 levels (the stable metabolic product of thromboxane A2) were significantly reduced after administration of the compound, with the maximal effect of a 99 per cent reduction occurring at 0.5 and 1 hour after administration. Bleeding times showed a slight increase 2 hours after administration of the compound. Pirmagrel was able to completely prevent the increase in serum thromboxane B2 following allergen challenge in asthmatic patients; while it caused a very small reduction in the early response to allergen, there was no effect on the late response or on airway hyperresponsiveness. Pirmagrel was developed for the treatment of ischemic heart disorders and thrombosis. However, this development was discontinued.

Metronidazole phosphate is a water-soluble prodrug of metronidazole.

Sodium arsenate as-74 (As74) has been the principal positron-emitting scanning agent. As74 as a commercial preparation for parenteral adminitration was made available towards the end of 1956. From March 1957 all studies were made with sodium arsenate rather than sodium arsenite. Sodium arsenate as-74 was used in the diagnosis of suvatentorial brain tumours. Traces of the element were found in all body tissues, and assays of injected As74 recovered in brain tumours showed highest values in meningiomas, followed, in order, by gliolastomas, metastatic carcinomas and astrocytomas.

Meteneprost (9-deoxo-16, 16-dimethyl-9-methylene PGE2) is a prostaglandin E2 analog. It exerts uterine-stimulating potency: meteneprost is able to both stimulate uterine contractions and dilate the cervical canal. It was studied as an abortifacient in early pregnancy.

Pipendoxifene (ERA-923) is a selective estrogen receptor modulator with a distinct profile compared with tamoxifen. In particular, unlike tamoxifen, ERA-923 is devoid of uterotropic activity and does not stimulate the growth of endometrial tumors in the EnCa-101 (human endometrial adenocarcinoma that is continuously passaged in animals in the presence of estrogen) experimental mice model. These data may indicate that, in patients, ERA-923 will not increase the incidence of endometrial hyperplasia or cancer. ERA-923 inhibits estrogen-stimulated ER-alpha-dependent tumor growth with equal effects compared with tamoxifen in models sensitive to tamoxifen. ERA-923 partially or completely overcomes tamoxifen resistance. In vivo combination of temsirolimus and ERA-923 at certain doses and schedules completely inhibited breast carcinoma growth, while individual agents were only partially effective. Pipendoxifene had been in phase II clinical trial for the treatment of refractory metastatic breast cancer. However, this research has been discontinued.

GV 150526A (gavestinel) is an investigational drug for a neuroprotective therapy of acute ischemic stroke within 6 hours of symptom onset. It is a potent and selective non-competitive antagonist at the glycine site of the N-methyl-D-aspartate receptor (NMDA) which reduces infarct volume in experimental stroke models. Gavestinel acts at the strychnine-insensitive glycine binding site of the NMDA receptor-channel complex with nanomolar affinity (pKi = 8.5), coupled with high glutamate receptor selectivity. Gavestinel displays higher than 1000-fold selectivity over NMDA, AMPA and kainate binding sites and is orally bioavailable and active in vivo. GV 150526A inhibited convulsions induced by NMDA in mice, when administered by both IV and po routes (ED50 = 0.06 and 6 mg/kg, respectively). The safety and efficacy of GV150526 were studied in two phase III randomized placebo-controlled clinical trials of acute ischemic stroke patients within 6 h from onset [The Glycine Antagonist in Neuroprotection (GAIN) International and GAIN Americas Trials] sponsored by GlaxoSmithKline. The results of these trials suggested that gavestinel was not of substantial benefit or harm to patients with primary intracerebral hemorrhage.

Estrazinol is a synthetic estrogen.

Mifentidine, a histamine H2 receptor antagonist, was studied to treat the duodenal ulcer. This drug was in phase II clinical trials when apparently further researches had been discontinued.

Picartamide had potent antisecretory and antiulcerogenic effects which were, at least, 10 times more pronounced than those of cimetidine. The mechanism of action of picartamide has not yet been determined but it seems that an anticholinergic or an H2 receptor antagonist effect should be excluded. The results show that picartamide is also active on the pure vagus-stimulated gastric acid secretion. The lack of effect upon gastric pepsin and plasma PP suggests that picartamide is not likely to act on the basolateral cholinergic receptor and that it affects further cellular steps involved in hydrogen ion secretion.