Halofuginone is a low molecular weight quinazolinone alkaloid, and a potent inhibitor of collagen alpha1(I) and matrix metalloproteinase 2 (MMP-2) gene expression. Halofuginone also effectively suppresses tumor progression and metastasis in mice. Halofuginone is a potent inhibitor of collagen a1(I) and matrix metalloproteinase 2 (MMP-2) gene expression. Halofuginone also suppresses extracellular matrix deposition and cell proliferation. Also was shown that halofuginone increased apoptosis in α smooth muscle actin- and prolyl 4-hydroxylase β-expressing cells in mdx diaphragm and in myofibroblasts, the major source of extracellular matrix. The profound antitumoral effect of halofuginone is attributed to its combined inhibition of tumour-stromal support, vascularization, invasiveness, and cell proliferation. HT-100 (delayed-release halofuginone), currently in clinical phase 1b/2a in five U.S. hospitals, is a small molecule drug candidate taken orally for the treatment of Duchenne muscular dystrophy (DMD) patients primarily through its ability to reduce fibrosis and inflammation and promote muscle fiber regeneration. The medicine candidate has been granted orphan drug designation in the U.S. and the EU — meaning it has been commercially undeveloped due to its limited profitability — and fast-track designation in the U.S. — an FDA process that aims to facilitate the development and patients’ reach to novel therapies for unmet medical needs.

Oxazafone was studied as an anticonvulsant and anxiolytic agent. Information about the further development of this compound is not available.

Nifurethazone, a 5-nitrofuran derivative, is an antibacterial agent. It was used for controlling Salmonella choleraesuis in swine. The mode of action of 5-nitrofuran analogues is based on red-ox biotransformation.

Oxapadol (MD 720111), a non-narcotic analgesic that caused a significant increase in the threshold of the reflex whereas no change was noted with placebo. The current use of this drug is unknown.

Nicothiazone (nicotinaldehyde thiosemicarbazone), an antituberculosis drug, was apparently responsible for inducing vacuoles in the corneal epithelium and thus caused discomfort and photophobia from corneal disturbance.

Nictiazem, diltiazem derivative, is a calcium channel blocker. Calcium antagonists and compounds which lower intraocular pressure may be combined in ophthalmic compositions to treat glaucoma.

Saviprazole (also known as HOE 731) is a potent inhibitor of gastric H+/K(+)-ATPase that has been studied in phase I clinical trial for the treatment of gastric ulcer. However, this study was discontinued.

Axitirome (also known as CGS 26214), a thyroid hormone receptor β selective agonist and an LDL receptor function stimulant, has a cholesterol-lowering activity. This drug was in phase I clinical trials for the treatment of hyperlipidemia, but studies were discontinued because of the unexpected side effects.

Naxifylline [CVT 124, BG 9719], a small molecule diuretic, is one of a new class of potent and highly selective adenosine A1 receptor antagonists discovered at University of Florida. Naxifylline is an A1 adenosine receptor antagonist used for the treatment of edema associated with congestive heart failure. Naxifylline appears to be one of the more potent and clearly the most A1-selective antagonist reported to date, with K1 values of 0.67 and 0.45 nM, respectively, at the rat and cloned human A1-receptors and with 1800-fold (rat) and 2400-fold (human) subtype selectivity. Naxifylline protects against the decline in renal function observed with diuretic therapy by promoting urine output.