Fenretinide (4-HPR) is an orally-active synthetic phenylretinamide analogue of retinol (vitamin A) with potential antineoplastic and chemopreventive activities. Fenretinide binds to and activates retinoic acid receptors (RARs), thereby inducing cell differentiation and apoptosis in some tumor cell types. This agent also inhibits tumor growth by modulating angiogenesis-associated growth factors and their receptors and exhibits retinoid receptor-independent apoptotic properties. Phase III clinical trial data has suggested that fenretinide reduces breast cancer relapse in pre-menopausal women. Fenretinide is the most studied retinoid in breast cancer chemoprevention clinical trials due to its selective accumulation in breast tissue and its favorable toxicological profile. This agent showed a significative reduction of the incidence of second breast tumors in premenopausal women confirmed after 15-year followups. Fenretinide, a drug being developed by Sirion Therapeutics, slowed the progression of advanced dry age-related macular degeneration (AMD) by 45 percent for people receiving a higher dose of the treatment in a Phase II clinical trial. Sirion has been granted a Fast Track designation for the treatment by the FDA. Fenretinide is in phase II clinical trials for the treatment of B-cell lymphoma, chronic lymphocytic leukemia. It is also in phase I clinical trials for the treatment of cystic fibrosis.

Cyheptamide is anticonvulsant compound, developed by the Canadian company Ayerst Research Laboratories in the 1960s. Oral administration of compound at 14-25 mg/kg protected mice against the tonic phase of pentylenetetrazole convulsion and maximal electroshock seizure. Anticonvulsant activity of cyheptamide was confirmed in initial clinical studies, but the compound was not marketed.

Citenamide is tricyclic drug, an analog of the anticonvulsant cyheptamide.

Ampyrone (4-Aminoantipyrine or AAP) is a metabolite of aminophenazone and is an aromatic substance with analgesic, antipyretic and anti-inflammatory properties. When combined with the antineoplastic agents, ampyrone decreased their genotoxic, mutagenic, apoptotic, and phagocytic effects. However, ampyrone usually produces side effects, such as the risk of agranulocytosis. Although ampyrone is scarcely ever administered as an analgesic because of the potential side effects, as a raw material, it is mostly used to produce ampyrone derivatives, which have better biological activities. In addition, it is used as a reagent for biochemical reactions producing peroxides or phenols and can also be used to detect phenols in the environment. Exposure to ampyrone could induce changes in the enzyme catalase structure and function.