Piboserod (SB 207266) is a selective 5-HT(4) receptor, antagonist. The 5-HT4 receptor antagonists are thought to antagonize both the ability of serotonin to sensitize the peristaltic reflex and 5-HT-induced defecation, at least in animal studies. As 5-HT4 receptors are present in human atrial cells and when stimulated may cause atrial arrhythmias, piboserod was under investigation in clinical trials for atrial fibrillation. In addition, GlaxoSmithKline studied the drug for the management of irritable bowel syndrome. Nevertheless, development both indications had been discontinued. Piboserod has successfully passed phase II clinical trials for the treatment of patients with congestive heart failure.

Ciladopa, is a troponylpiperazine derivative and dopamine agonist that has been shown to influence dopaminergic mechanisms in animals. Preclinical pharmacological studies have suggested that it has antiparkinsonian activity similar to that of bromocriptine but without many of the troublesome side effects. Unfortunately in some clinical trials no significant differences was found among the treatment groups and placebo.

Millennium Pharmaceuticals Inc's tandutinib (MLN-518), a piperazinyl derivative of quinazoline, is an orally active inhibitor of FLT3 kinase and family members PDGFR beta and c-Kit. Tandutinib inhibited FLT3 phosphorylation, downstream signaling and malignant growth in vitro and in animal models. The drug exhibited limited activity as a single agent in phase I and II clinical trials in patients with AML and myelodysplastic syndrome, but displayed promising antileukemic activity (90% complete remissions) in a phase I/II trial in patients with newly diagnosed AML when administered in combination with cytarabine and daunorubicin. Phase II clinical trials for tandutinib in patients with Glioblastoma have being discontinued. The use of tandutinib to treat AML has been granted fast-track status by the U.S. Food and Drug Administration. Phase II trials were underway., but later withwrawn.

Denagliptin is a dipeptidyl peptidase IV (DPP-IV) and and tripeptidyl-peptidase inhibitor, which entered phase III clinical trials in 2006 for the treatment of type 2 diabetes mellitus at GlaxoSmithKline. Development of this compound was put on hold due to unfavorable preliminary data from preclinical long-term toxicity trials. Stress testing or forced degradation studies of denagliptin revealed that drug was stable in the solid-state, but degraded in solution, in blends with all excipients, and in capsules predominantly by cyclization to (3S,7S,8aS) amidine, which epimerized to (3S,7S,8aR) amidine.

CS-834 is a beta-lactam antibiotic of a carbapenem class, developed by the Japanese company Sankyo Co. Ltd. CS-834 is an ester-type prodrug of the active metabolite R-95867. The drug showed potent and well balanced antibacterial activity as well as stability against dehydropeptidase-I. The in vivo efficacy of CS-834 was evaluated in murine systemic infections caused by 16 strains of gram-positive and -negative pathogens. The efficacy of CS-834 was in many cases superior to those of cefteram pivoxil, cefpodoxime proxetil, cefdinir, and cefditoren pivoxil, especially against infections caused by S. aureus, penicillin-resistant S. pneumoniae, E. coli, Citrobacter freundii, and Proteus vulgaris. Pharmacokinetics of CS-834 was evaluated in healthy male volunteers, but no further clinical development of the drug was reported.

Pelanserin is an antagonist of the serotonin 5-HT2 receptor and blocks alpha 1-adrenoceptor. Experiments on dogs have revealed that pelanserin showed adequate pharmacokinetic and pharmacodynamics profiles as an antihypertensive agent that is why the drug possessed potential therapeutic usefulness in the treatment of hypertension. Pelanserin was undergoing phase II clinical trials by Cinvestav in Mexico; however, these studied were discontinued.

Valopicitabine is a nucleoside analog and the orally bioavailable prodrug of NM107 that competitively inhibits HCV NS5B polymerase, causing chain termination. Valopicitabine had been in phase II clinical trial for once-daily oral treatment of Hepatitis C virus infection. However, because of the overall risk/benefit profile of subjects undergoing clinical trials, further development of the drug has been temporarily placed on hold by the Swiss drug major Novartis and USA-based Idenix Pharmaceuticals company and the FDA.

Tibenelast is an orally active phosphodiesterase inhibitor that was undergoing phase II clinical trials in the USA as a bronchodilator. In preclinical studies Tibenelast is moderately active against the lung and stomach enzyme while being a very weak inhibitor of the heart enzyme and it does not inhibit enzymes involved in arachidonic acid metabolism. Tibenelast shows potent anti-anaphylactic activity in guinea pigs without cardiovascular effects at the bronchodilatory doses.

Somantadine, an adamantane derivative, is an antiviral agent. Somantadine was synthesized by Pennwalt and has been undergoing tests for the treatment of herpes virus for nearly five years.

Indolapril (CI-907) is a new orally active prodrug of nonsulfhydryl angiotensin-converting enzyme (ACE) inhibitor, developed by Warner-Lambert/Parke-Davis Pharmaceutical Research for treating hypertension. Indolapril is epimer of trandolapril, well-known ACE inhibitor currently in the market for hypertension treatment. Indolapril (Monoester form) and it’s active component (diacid form) produced concentration related ACE inhibition in guinea-pig serum (IC50 for monoester -- 0.1 mkM and for diacid -- 2.6 nM). In isolated rabbit aortic rings and in rat and dog autonomic studies, Indolapril is highly specific in suppressing the contractile or pressor responses to angiotensin I. In two-kidney, one-clip Goldblatt hypertensive rats, single daily doses (0.03-30 mg/kg p.o.) produced dose-dependent decreases in blood pressure; 3 mg/kg lowered blood pressure to normotensive levels. In the spontaneously hypertensive rat, subacute administration of Indolapril produced the same decrease in blood pressure as that obtained in the renal hypertensive rat. In diuretic-pretreated renal hypertensive dogs, 10 mg/kg normalized blood pressure. For equivalent drops in blood pressure, heart rate increases were less in Indolapril than in enalapril-treated renal hypertensive dogs. No side effects were observed with CI-907 in any of the conscious animals. The antihypertensive response to Indolapril (0.03-1.0 mg/kg p.o.) was found to correlate with inhibition of vascular tissue ACE, but not plasma or brain ACE in two-kidney, one-clip renal hypertensive rats.