Asulacrine, also known as CI-921, an inhibitor of topoisomerase II, participated in clinical trials phase II for the treatment of cancer. In spite of the positive and promising results, this drug showed the toxicity, phlebitis that blocks its implementation in the future.

Milfasartan is an inhibitor of angiotensin II receptor type 1 was used in phase II clinical trial for the treatment of hypertension. However, these studies were discontinued.

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.

Racemethorphan is racemic mixture of Dextromethorphan and Levomethorphan. Racemethorphan is listed under the Single Convention on Narcotic Drugs 1961 and is therefore listed in the United States as a Controlled Substance, specifically as a Narcotic in Schedule II. Dextromethorphan is a non-narcotic morphine derivative widely used as an antitussive. Dextromethorphan is a cough suppressant in many over-the-counter cold and cough medicines. In 2010, the FDA approved the combination product dextromethorphan/quinidine for the treatment of pseudobulbar affect. Dextromethorphan suppresses the cough reflex by a direct action on the cough center in the medulla of the brain. Levomethorphan is an opioid analgesic of the morphinan family that has never been marketed.

Oltipraz is an organosulfur compound belonging to the dithiolethione class. It acts as a schistosomicide and has been shown in rodent models to inhibit the formation of cancers in the bladder, blood, colon, kidney, liver, lung, pancreas, stomach, and trachea, skin, and mammary tissue. Oltipraz and other 1,2-dithiole-3-thiones inactivate protein tyrosine phosphatases under physiologically-relevant conditions. Clinical trials of oltipraz have failed to demonstrate efficacy and have shown significant side effects, including neurotoxicity and gastrointestinal toxicity.

Zolasartan (previously known as GR 117289) is an angiotensin II (AT1) receptor antagonist that was studied for the treatment of hypertension. It was undergoing phase II clinical trials with Glaxo Wellcome in the United Kingdom before the study was discontinued.

Forasartan (also known as SC-52458) was developed as an orally active, competitive angiotensin (Ang) II subtype 1 (AT1)-receptor antagonist for the treatment of hypertension. Forasartan competes with angiotensin II for binding at the AT1 receptor subtype. It is known that angiotensin II is a vasoconstrictor and stimulates the synthesis and release of aldosterone, and blockage of its effects results in a decrease in systemic vascular resistance. Information about the further development of forasartan is not available.

Chlorsulfaquinoxaline is a halogenated derivative of sulfaquixonaline, an immunosuppressive and antifungal agent used in the control of coccidiosis in poultry, rabbit, sheep, and cattle. In vitro, Chlorsulfaquinoxaline acts as a topoisomerases IIα and IIβ poison, thus inhibiting DNA replication. Chlorsulfaquinoxaline shows good activity against human tumor cells in the human tumor colony-forming assay and subsequently has shown activity against murine and human solid tumors. No major objective antitumor responses was observed during Chlorsulfaquinoxaline Phase II clinical evaluation in non-small-cell lung cancer and metastatic colorectal cancer. Chlorsulfaquinoxaline was well tolerated with hypoglycemia being the most clinically significant toxicity.

Mitindomide was studied as an antineoplastic agent that inhibited the activity of the topoisomerase II. The drug underwent preclinical development; however, this study was discontinued.

Embusartan or BAY106734 (6-n-butyl-4-methoxycarbonyl-2-oxo-1[(2'-(1H-tetrazol-5-yl) -3-fluorobiphenyl-4-yl)methyl] 1,2-dihydropyridine) is an angiotensin II receptors antagonist. Embusartan has beneficial effects in different animal hypertension models. Embusartan appears as a potent and specific new inhibitor of angiotensin II-induced growth-related events in vascular smooth muscle cells. It was being developed for the treatment of hypertension.