Furafylline is a methylxanthine derivative that was introduced as a long-acting replacement for theophylline in the treatment of asthma, it was a bronchodilator with extended duration compared to theophylline, but then subsequently reported the adverse side effects the inhibition of the oxidation of caffeine, a reaction catalyzed by CYP1A2. Furafylline is now widely used in biochemical studies as a selective mechanism-based inhibitor of cytochrome p450 1A2.

Inecalcitol is a calcitriol analog with potential antineoplastic activity patented by a global pharmaceutical company Laboratoire Theramex. Inecalcitol is a potent agonist of vitamin D receptor (VDR). Inecalcitol was shown to be more potent than calcitriol in decreasing tumor cell growth and inducing apoptosis in a number of different model systems including models of breast cancer, prostate cancer, and squamous cell cancer. Importantly, at the doses shown to induce tumor regression in the animal models investigated, Inecalcitol had no major effect on blood calcium levels. In this phase I study, Inecalcitol was found to be well tolerated. Currently, Inecalcitol in combination with the cytotoxic drug, decitabine is undergoing a phase II clinical trial in patients with acute myeloid leukemia who are unfit to receive standard chemotherapy.

Cinnofuradione is a cinnoline derivative with analgesic properties. It was patented in 1954 and was claimed to be useful in combatting inflammation and rheumatism.

Siagoside (Sygen, AGF 2) is a naturally occurring substance in the nerve cell’s membrane that is thought to play a role in cell growth, development, and repair. Siagoside completed phase 2 trials for parkinson's disease (PD) treatment. Sygen appears to be beneficial in patients with severe spinal cord injury. Treatment results in a 52% decrease in mortality 48 hours after the induction of ischemia in gerbils by permanent unilateral ligation of the common carotid artery.

Sarafloxacin [A 55620] is a quinolone antibiotic that was under development with Abbott Laboratories in the USA. It was removed from clinical use by its manufacturer Abbott Laboratories from April 30, 2001. It was never approved for use in the US or Canada.

The dihydrochloride salt of nolatrexed, a water-soluble lipophilic quinazoline folate analog with antineoplastic activity. Nolatrexed occupies the folate binding site of thymidylate synthase, resulting in inhibition of thymidylate synthase activity and thymine nucleotide synthesis with subsequent inhibition of DNA replication, DNA damage, S-phase cell cycle arrest, and caspase-dependent apoptosis. This agent also exhibits radiosensitizing activity. Orphan designation of nolatrexed was granted in the Unites States of America for treatment of hepatocellular carcinoma.

Siramesine is a sigma2 opioid agonist under development by H Lundbeck as a potential treatment for anxiety. In March 1998, the compound was licensed to Forest Laboratories under a strategic alliance. In August 2000, siramesine entered phase II trials. Siramesine has been shown to trigger cell death of cancer cells and to exhibit a potent anticancer activity in vivo. Siramesine triggers cell death through destabilisation of mitochondria, but not lysosomes. Siramesine is a lysosomotropic detergent that induces cytoprotective autophagosome accumulation. Siramesine involves lysosomal leakage and oxidative stress.