Dexfosfoserine (Phosphoserine, L-Serine-O-Phosphate, O-Phosphoserine), the most abundant phosphoamino acid in the eukaryotic phosphoproteome, is not encoded in the genetic code but synthesized posttranslationally. Dexfosfoserine is an agonist of the group III metabotropic glutamate receptors. This endogenous compound inhibits neural stem cells proliferation and promotes survival of nascent neurons thus it has potential therapeutic value in addition to its basic utility as a probe for dissecting molecular mechanisms underlying neurogenesis.

Dimethylthiambutene is the synthetic narcotic analgesic agent. It has analgesic effect similar to those of meperidine. The (+)-enantiomer of dimethylthiambutene is more active than the (-)-isomer. Dimethylthiambutene clinically compared with meperidine (pethidine), but maintains the dependence-producing capability of morphine. It has had illicit use in Japan in the past. Dimethylthiambutene is under international control according to the UN Single Convention 1961 and its amendments, Schedule I.

Phenadoxone hydrochloride is one of some forty amino-ketones and amino-esters related to amidone. The compound is a very potent analgesic for the rat; by the subcutaneous route it is more active than either morphine or amidone. In spite of this its acute toxicity to mice is lower than that of amidone and its therapeutic index is therefore correspondingly higher, giving a wider margin of safety. Side effects in dogs, such as narcosis, sedation, and general depression, were much less with phenadoxone than with amidone or morphine. Nausea and vomiting did not occur after phenadoxone in non-tolerant dogs. Clinical results show that for relieving certain types of pain in human subjects it is a potent analgesic that compares favorably with morphine and amidone. At therapeutic dose levels undesirable pharmacological effects, such as cardiac depression and vasomotor disturbance, are absent, and it is only at extremely high dose levels that untoward effects occur. However, the drug has a strong respiratory depressant action when given in high doses; it should be used with special caution if injected intravenously.

Mitoquidone is pentacyclic pyrroloquinone derivative developed for clinical evaluation as a potential anticancer agent. Mitoquidone demonstrated good activity in a range of experimental solid tumour models, but was weakly active against standard prescreens such as the P388 murine leukaemia. Bone marrow suppression or other significant toxicity was not observed in preclinical studies. In clinical trials patients were treated with Mitoquidone given as a 4-h infusion either once every 21 days, once a week, or as 5 daily doses repeated every 28 days. The major adverse events encountered included nausea and vomiting (in virtually all patients), dyspnoea, tumour-related pain, and thrombocytopenia in several patients with pretreatment bone-marrow impairment. Phase I studies were suspended without a maximum tolerated dose being reached because of formulation difficulties. There were no major responses, although stable disease was observed in a number of patients with gastrointestinal malignancies.

Fosfocreatinine, a cardioprotectant that was used for the treatment of cardiac disorders. Information about the current use of this drug is not available.

Silydianin is a flavonolignan from Silymarin, which is the major constituent of milk thistle extract. Silydianin, an active constituent of Silybium marianum, have inhibitory properties against the P2Y12 receptor and block ADP-induced blood platelet activation. Silydianin has antiinflammatory activity, it regulates caspase-3 activation, affects cell membranes and acts as a free radical scavenger. Silydianin non-competitively inhibits the lipoxygenase from soybeans in vitro. It also inhibits the formation of prostaglandins in vitro.

Renanolone is a synthetic neuroactive C21 5β-H steroid. It was never used in a clinical setting. The thermogenic and inflammatory responses induced by renanolone were reported to be similar to responses induced generally by appropriate administration of neutral steroid pyrogens in humans.

Sagopilone (BAY86-5302; ZK 219477; ZK-EPO) is a synthetic epothilone, an analog of patupilone that was developed by Bayer HealthCare as an anticancer agent. Epothilones are 16-member ring macrolides have demonstrated potent antiproliferative activity in several different multidrug-resistant and paclitaxel-resistant tumor cell lines in vitro and in vivo. Sagopilone binds to tubulin and induces microtubule polymerization, which may result in the induction of G2/M arrest, and apoptosis. Sagopilone is not a substrate for the P-glycoprotein efflux pump and so may exhibit activity in multidrug-resistant tumors. This drug was studied in clinical trials phase II in patients with recurrent ovarian cancer, in metastatic melanoma patients, for the treatment of advanced stage breast cancer and in the treatment of Glioblastoma patients. However, the development of this drug was discontinued, because of its adverse effects, including peripheral neuropathy.

Bristol-Myers Squibb developed BMS-275183 for cancer indications. BMS 275183 is an inhibitor of tubulin polymerization. The drug participated in phase II clinical trials for patients with non-small cell lung cancer and in phase I for patients with advanced cancer. However, further development has been discontinued.

Properidine is an isopropyl analog of pethidine that acts as opioid analgesic.