Folitixorin, a thymidylate synthase inhibitor is a substrate used by the enzyme methylenetetrahydrofolate reductase (MTHFR) to generate 5-methyltetrahydrofolate. Folitixorin was studied in clinical trials for the treatment of breast cancer, metastatic colorectal cancer and for the treatment of advanced pancreatic cancer. Folitixorin had been granted orphan drug status for the treatment of pancreatic cancer in both the U.S. and EU. However, further development of this drug was discontinued.

Droxacin is quinolone antibiotic. It is topoisomerase inhibitor.

Indorenate (TR3369, INDO) is a serotonin-like compound with high affinity for 5- HT1A receptors and a lower affinity for 5-HT1C and 5-HT1B receptors. Indorenate possesses antihypertensive and anxiolytic activity in animal behaviour tests. Similar to other serotonin receptor agonists, Indorenate also has anorectic activity; this effect was blocked by the administration of the 5-HT2A/2C receptor antagonists cinanserin, cyproheptadine, metergoline and methysergide. A unpublished clinical trial confirmed its antihypertensive activity in men.

Adaprolol is a beta-adrenergic antagonist that is being developed as a topical agent to treat glaucoma. Adaprolol demonstrated a safer cardiovascular profile, especially in the population over 70 years old. It was in Phase II clinical trials for the treatment of glaucoma. This research has been discontinued.

Morphine-6-glucuronide is a pharmacologically active metabolite of morphine that is being developed by CeNeS Pharmaceuticals as an alternative to morphine for the management of postoperative pain. Compared to morphine, Morphine-6-glucuronide has been reported to have6 and 86 times lower affinity for the human mu and kappa opioid receptors, respectively, and similar affinity for the delta opioid receptor. Morphine-6-glucuronide is was studied in phase III clinical trials for postoperative pain management. Unfortunately, Morphine-6-glucuronide failed to demonstrate superior safety compared to Morphine and further development was discontinued. Morphine-6-glucuronide accumulates after administration of morphine to patients with renal insufficiency, and analgesia can be obtained with lower doses of morphine compared to patients with normal renal function. More importantly, the dose should be reduced to avoid serious side-effects, although the simulations in this review did not account for side-effects.

Eprodisate (1,3-propanedisulfonate) is a negatively charged, sulfonated molecule of low molecular weight that has structural similarities to heparin sulfate; it is a glycosaminoglycan mimetic that binds to the glycosaminoglycan (GAG) binding site on serum A amyloid (AA) to prevent its interaction with glycosaminoglycan and arrest amyloidosis, or inhibit amyloid deposition. In nonclinical toxicity studies in two animal species (i.e., rat and dog), eprodisate was administered orally at doses of up to 2000 mg/kg/day for 39 weeks: eprodisate showed low toxicity potential at doses several fold higher than the anticipated clinical dose, was well tolerated upon chronic exposure and was found to be nonmutagenic and nonclastogenic. Furthermore, a series of safety pharmacology studies showed that eprodisate does not have any clinically significant effect on major organ function.

Carfentanil is a synthetic fentanyl analog. It is a mu-opioid receptor agonist with an estimated analgesic potency approximately 10,000 times that of morphine and 20-30 times that of fentanyl, based on animal studies. Receptor binding studies have shown that carfentanil binds selectively and competitively to the μ subtype of opioid receptors relative to δ and κ opioid receptors. Preclinical studies have demonstrated that the pharmacodynamic effects, such as analgesia and constipation, produced by carfentanil are similar to other μ opioid agonists. Its extreme potency and propensity to produce rapid and profound respiratory depression has prompted recommendations that an opioid antagonist, such as naloxone or naltrexone, be available whenever carfentanil is used or suspected to be present. Carfentanil (Wildnil) has been used in veterinary as a prescription-only general anesthetic for intramuscular injection in large animals. Carfentanil is no longer FDA-approved for use in animals after Wildlife Laboratories withdrew the application for Wildnil. Carfentanyl is increasingly involved in opioid overdose deaths among illicit opioid users.

Esreboxetine (PNU-165442G) is the (S,S)-(+)-enantiomer of antidepressant reboxetine, a selective norepinephrine reuptake inhibitor. The (S,S)-enantiomer is a more potent inhibitor of norepinephrine transporter than (R,R)-enantiomer. Esreboxetine was being developed by Pfizer, primarily for the treatment of fibromyalgia.

Telupidine (GR53992B), a dihydropyridine derivative is a calcium channel blocker. This is an antihypertensive and cardiovascular agent. Information about the current use of this compound is not available.