Tetrodotoxin (TTX) is a potent marine neurotoxin that blocks voltage-gated sodium channels (VGSCs). VGSCs play a critical role in neuronal function under both physiological and pathological conditions. TTX has been extensively used to functionally characterize VGSCs, which can be classified as TTX-sensitive or TTX-resistant channels according to their sensitivity to this toxin. Wex Pharmaceuticals is investigating tetrodotoxin for the treatment of chronic and breakthrough pain. The toxin is currently undergoing Phase III clinical trials in Canada as a systemic analgesic for inadequately controlled pain due to advanced cancer, especially where the pain has neuropathic features. In addition, TTX is in Phase II clinical trials to study its ability in moderate to severe neuropathic pain caused by chemotherapy.

Ammonium trichlorotellurate (AS-101) is a synthetic non-toxic tellurium derivative, structurally similar to cisplatin, with immunostimulatory and anti-hair loss properties. Ammonium trichlorotellurate induces production of colony stimulating factor (CSF), interleukin-2 (IL-2), and IL-2 receptors by increasing the calcium ion influx through the cell membrane and subsequently exerts its immunostimulatory effects through the CSF-mediated increase in macrophage/granulocytes. This agent is also a potent inducer of interferon and a spectrum of cytokines such as IL-1, IL-6, and tumor necrosis factor (TNF). In animal studies, ammonium trichlorotellurate exerts its anti-hair loss effect by inducing anagen and obstructing spontaneous catagen via promoting follicular keratinocyte proliferation and interfering with terminal differentiation, respectively. AS-101 suppresses production of HIV-1. It inhibited reverse transcriptase activity and replication of human immunodeficiency virus type 1. RDDP and DDDP activities were impaired by the drug with calculated IC50 value of about 4 uM. Intravenous AS-101 was in trials in patients with HIV infections. AS-101, a small-molecule integrin αvβ3 and VLA-4 inhibitor is being developed by BioMAS in Israel for the treatment of genital warts, age-related macular degeneration and fertility preservation. Phase II clinical trials are ongoing. The drug was also undergoing phase II development in acute myeloid leukaemia, atopic dermatitis, chemotherapy-induced damage, myelodysplastic syndromes, thrombocytopenia, alopecia, psoriasis. However, development for these indications was discontinued.

S-(+)-niguldipine is a more active enantiomer and is a selective antagonist for the and α1A-adrenoceptor. In addition, it can be used for discriminating of alpha 1A- from alpha 1B-adrenoceptors. There were made attempts to investigate the antidepressant action of S-(+)-niguldipine on rats, but that studies were unsuccessful.

IZONSTERIDE, a benzoquinolinone, is a selective inhibitor of the 5-alpha reductase, with antagonistic effect on both the type I (liver, skin, hair follicles) and type II (prostate) isoforms of the enzyme. It is a competitive inhibitor of type I 5-alpha reductase and a non-competitive inhibitor of type II 5-alpha reductase. It was under development for the treatment of prostatic cancer.

MKC-442 (6-benzyl-1-(ethoxymethyl)-5-isopropyl-uracil) is a highly potent and selective inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). Emivirine structurally is a nucleoside analog (NRTI) molecule, but it functions as a non-nucleoside reverse transcriptase inhibitor (NNRTI). Emivirine had reached phase 3 clinical trials for the treatment of HIV-1 infections before its further development was stopped.

Triafungin is the antifungal agent.

Enolicam (CGS 5391B) is a non-steroidal anti-inflammatory drug with combined cyclooxygenase and lipoxygenase inhibitory activity. It is able to trap oxygen radicals. Enolicam was effective in animal models of traumatic shock and osteoarthritis.

LECOZOTAN, a benzodioxanylpiperazine derivative, is a selective serotonin 1A receptor antagonist. It was in development for the symptomatic treatment of cognitive deficits in Alzheimer's disease.

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.