FENETHAZINE was a first-generation phenothiazine-derived antihistamine drug. Promethazine was derived from FENETHAZINE.

Stannsoporfin is a mesoporphyrin derivative patented by Rockefeller University as competitive heme oxygenase (HO) inhibitor for the prevention of hyperbilirubinemia in infants at risk of developing jaundice. Parenteral administration of Stannsoporfin has been shown to suppress or moderate jaundice in a wide variety of experimental and naturally occurring forms of hyperbilirubinemia in animals and man. Stannsoporfin is rapidly cleared from the plasma in animals, in adult humans, and in newborn infants and may inhibit competitive heme oxygenase for prolonged periods. The Stannsoporfin decreases the production of carbon monoxide from heme and increases the biliary excretion of unmetabolized heme but has no effect on the metabolic disposition of preformed bilirubin.

Clazosentan is an endothelin receptor antagonist, developed by the Swiss pharmaceutical company Actelion, and licensed to its spin-off, Idorsia. The drug was designed to inhibit endothelin-mediated cerebral vasospasm and associated delayed ischaemic neurological deficit. The drug has been investigated in a phase III clinical trials in patients with aneurysmal subarachnoid hemorrhage. Clazosentan at 5 mg/h had no significant effect on mortality and vasospasm-related morbidity or functional outcome. Clinical investigation of a higher dose of the drug is underway.

Furaprevir (also known as TG-2349), an NS3/4A protease inhibitor, discovered and developed by TaiGen for the treatment of chronic hepatitis C. Furaprevir blocks the protease enzyme that is essential in hepatitis C virus replication. In April 2019, TaiGen started the Phase III trial of the combination therapy Furaprevir - Yimitasvir for the treatment of chronic hepatitis C patients.

Biclofibrate was investigated as an antilipidemic agent.

Necopidem, a zolpidem derivative, is an anxiolytic and sedative drug.

Clemeprol is an antidepressant drug of the 3,3-diraylpropyl-amine type. It exhibits antireserpine activity in animal tests, inhibits the neuronal uptake of noradrenaline. The drug was used in the clinic for the treatment of depression in the 1980s, but no development was reported since.

Clamidoxic acid is a derivative of phenoxyacetic acid developed in the late 1950s by Smith and Nephew Research Ltd. Clamidoxic acid has been shown to have anti-inflammatory activity and low toxicity in animal tests. The compound was investigated in the clinical trials in patients suffering from rheumatoid arthritis and painful uncomplicated osteoarthritis of the hip, however, no further clinical development was reported.

Bithionol sulfoxide is an effective cestocide, and also used as a fasciolicide, usually in combination with other compounds because of its poor efficiency against immature flukes. It has also demonstrated efficacy in vitro as an antiprotozoal agent effective against species causing amoebic gill disease in fish. It has been used for veterinary applications but has more recently been superseded by modern anthelmintic drugs.