Pruvanserin (EMD 281014, LY-2422347) is a selective serotonin 5-HT2A receptor antagonist. Pruvanserin was originated by Merck KGaA. Eli Lilly had been developing pruvanserin, under a global licence from Merck KGaA, for the treatment of primary insomnia and major depressive disorder. Phase II trials were completed in the US, Hungary and Spain. However, development appears to have been 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.

Benzindopyrine belongs to anticholinergic agents. It was studied as an antipsychotic drug.

Epetirimod (S-30563 or TAK-851) is an immunostimulant. The compound is structurally related to the marketed topical imidazoquinoline drug, imiquimod, an agonist of Toll-like receptor 7. Epetirimod was under development with Takeda Pharmaceutical as a topical treatment for cervical high-risk HPV infection and cervical dysplasia. Takeda has discontinued epetirimod development as it did not meet the predefined efficacy end points in a US Phase II trial.

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.

Prinomide is a carbamoylpyrrolepropionitrile derivative patented by Ciba-Geigy A.-G. as a nonsteroidal anti-inflammatory drug that has disease-modifying activity in rheumatoid arthritis. In clinical trials, Prinomide demonstrate significant improvement in symptom score and laboratory variables.

Enazadrem (CP-70490-09) is an antipsoriatic agent inhibiting arachidonate 5-lipoxygenase.

Sezolamide (previously known as MK-417), a potent carbonic anhydrase inhibitor capable of reducing intraocular pressure after topical application, was under investigation for the treatment of glaucoma. . Sezolamide is the more potent of the two stereo isomers of MK-927 in inhibiting human carbonic anhydrase isoenzyme II, the isoenzyme found in ciliary processes. Sezolamide, the S-enantiomer of MK-927, has demonstrated activity in vitro approximately 80 times that of the R-enantiomer of MK-927 (concentrations of 0.54 nmolll and 44 nM, respectively, inhibiting activity of human carbonic anhydrase isoenzyme II by 50%). Clinically, sezolamide has also demonstrated greater activity than MK-927 both after single-dose and after twice daily administration in patients.

Obatoclax (GX15-070) is a novel BH3 mimetic pan Bcl- 2 inhibitor. The clinically studied formulation is as obatoclax mesylate (Box 1), a salt. It is only under study as an intravenous preparation. It functions to block BH3-mediated binding of Bcl-2, Bcl-XL, Mcl-1 and A1 to Bax and Bak. Bax and Bak thus are unopposed and able to dimerize to allow initiation of intrinsic apoptosis. Preclinically, obatoclax has been shown to reverse inhibition of Bax or Bak by Bcl-2, Bcl-XL, Bcl-w and Mcl-1. Obatoclax was discovered by Gemin X, which was acquired by Cephalon, which has since been acquired by Teva Pharmaceuticals. Obatoclax had been in phase III clinical trials by Gemin X Biotechnologies (subsidiary of Teva) for the treatment of non-small lung cancer (NSCLC). The compound received orphan drug designation in the U.S. in 2004 for the treatment of chronic lymphocytic leukemia (CLL). However, Teva discontinued the development of obatoclax in 2013.