Etorphine was the first potent opiate agonist employed primarily for use in non-domestic and wild species. Etorphine was 500 times as potent as morphine, with a very rapid onset and short duration of action. In morphine-dependent subjects, etorphine suppressed abstinence but for a shorter period than morphine. Etorphine is a full opiate agonist and binds to multiple opiate sites in the central nervous system. It is believed to produce its clinical effects through binding the µ-, δ-, and κ- opiate sites. It has a potent effect on depressing the respiratory centers of the CNS thus resulting in apnea being commonly seen in immobilized animals. Etorphine revolutionized the ability of biologists and veterinarians to safely capture and restrain many species that previously could not be handled. Etorphine is not currently commercially available due to lack of production by the manufacturer.

Fedotozine [(1R)-1-phenyl-1-[(3,4,5-trimethoxy) benzyloxymethyl]-N,N- dimethyl-n-propylamine, (2S,3S-tartrate], derived from the arylacetamide series, is an opioid drug which acts as a selective agonist for kappa(1a)-opioid receptor. Pharmacological studies have shown that fedotozine exerts a peripheral antinociceptive action, comparable with that of other kappa-agonists. Results of Phase III trials of fedotozine against irritable bowel syndrome and dyspepsia have ultimately been disappointing and was lack of efficacy in subsequent studies.

Merafloxacin (CI 934) is a quinolone antibacterial. It is an inhibitor of Type II DNA topoisomerase. It demonstrated excellent activity against gram-positive organisms, including Corynebacterium sp. In addition, although the activity of merafloxacin against gram-negative bacilli was less than that reported for similar agents, it was comparable to that of aminoglycosidic aminocyclitol antibiotics. Merafloxacin development has been discontinued.

Atigliflozin (also known as AVE2268), a substituted glycopyranoside, is a selective inhibitor of sodium-dependent glucose transporter 2. This drug reached phase II clinical trials as a new antidiabetic drug for the treatment of type 2 diabetes but further development was discontinued.

Adarotene (ST1926) is a new pro-apoptotic and cytodifferentiating antitumour drug, belongs to the so-called class of atypical retinoids. Adarotene is active on its own or in combination with other chemotherapeutics for the treatment of a vast number of experimental tumors. It was found in preclinical investigations the potential therapeutic use it in chronic myeloid leukemia (CML), against Rhabdomyosarcoma and for treatment of Adult T-cell leukemia/lymphoma (ATL). ST1926 induced an early DNA damage response, which led to increase in apoptosis, in addition to S-phase cell cycle arrest and a reduction in protein levels of the cell cycle kinase CDK1. The presence of the phenolic hydroxyl group on adarotene structure allows a rapid O-glucuronidation as a major mechanism of elimination of the drug, favoring a fast excretion of its glucuronide metabolite in the urines.

Exepanol (KC 2450), a benzoxepine derivative, is a gastrokinetic. It facilitated the peristaltic reflex. Exepanol enhances resting pressure of the lower esophageal sphincter.

Moxipraquine is alkylaminopiperazinyl derivative patented by Wellcome Foundation Ltd. as antiparasitic agent effective against Trypanosoma cruzi. Moxipraquine was effective in suppressing parasitaemia but did not eradicate the infection from mice or guinea-pigs. Moxipraquine was less potent against mouse infections with strain Peru than it was against other strains of T. cruzi. In limited tests, moxipraquine was effective on experimental infections of Leishmania major, L. mexicana mexicana and L. brasiliensis panamensis but not L.b. brasiliensis. Significant foetal toxicity, observed experimentally in rats and rabbits, resulted in the termination of further trials.

British Biotech was developing solimastat [BB 3644], an inhibitor of tumour necrosis factor and matrix metalloproteinase, as a potential treatment for colorectal cancer, inflammatory bowel diseases and rheumatoid arthritis. BB-3644 is an oral, broad-spectrum matrix metalloproteinase inhibitor (MMPI) structurally related to marimastat and BB-94. It is also >10-fold more active than marimastat in inhibiting the processing of cell-bound TNF-alpha. Solimastat development has been discontinued due to significant musculoskeletal toxicity.

Hydromorphinol, an opioid, and is a derivative of morphine and possesses similar properties: sedation, analgesia, and respiratory depression. Hydromorphinol is under the control according to US Single Convention 1961.

Rimacalib (SMP 114) is a prostaglandin E2 antagonist that has been evaluated for use in rheumatoid arthritis. This orally bioavailable compound is a CaMKII inhibitor developed for human use. A phase II clinical trial to compare the effects of rimacalib to placebo in patients with rheumatoid arthritis has been terminated in 2009. Rimacalib also reduces SR Ca2+ leak and was therefore suggested as a candidate drug to treat proarrhythmogenic events in human atrial cardiomyocytes and cardiomyocytes from patients with heart failure.