Oxetacillin was developed as an antibacterial drug that has never been marketed.

Olmidine (also known as dl-mandelamidine) is an antihypertensive drug that has never been marketed. Information about the current use of this drug is not available.

Ulodesine (BCX4208) is a new, orally active, highly potent inhibitor of purine nucleoside phosphorylase (PNP) for the treatment of hyperuricemia and gout. Inhibition of PNP reduces the substrates available for XO to form uric acid. The drug is currently under development for the management of hyperuricemia in chronic gout. Two Phase II clinical trials have shown promising results regarding urate-lowering effect in both as monotherapy and in combination with allopurinol. Ulodesine shows no interaction with CYP450 isoforms and has no hepatic metabolism; therefore, no drug interactions were expected. Following the successful outcome of the Phase IIb clinical trial, Phase III development of ulodesine is planned. One concern regarding the use of ulodesine is its impact on T cells. Lack of PNP is associated with immunodeficiency and autoimmune disorders.

Phenomorphan is the μ-opioid receptor agonist. Phenomorphan is a synthetic narcotic analgesic structurally related to racemorphan and racemethorphan. It has no accepted medicinal value in the United States.

Pazelliptine (previously known as BD 40 or SR 95225A) was developed as an antitumor drug that binds to the DNA sequence, preferable to G-C rich region and thus produces cellular DNA lesions. This drug was undergoing phase II trials in France for the treatment of cancer. However, this study was discontinued.

Pexantel is an anthelmintic, which was used to treat filariasis.

Penirolol is a beta-adrenergic blocking agent that was studied as an antihypertensive agent. Information about the further development of this drug is not available.

Salirasib or S-trans,trans-Farnesylthiosalicylic acid (FTS) is a salicylic acid derivative with potential antineoplastic activity. It acts as a potent competitive inhibitor of the enzyme prenylated protein methyltransferase (PPMTase), which methylates the carboxyl-terminal S-prenylcysteine in a large number of prenylated proteins including Ras. In such systems, Salirasib inhibits Ras methylation but not Ras farnesylation. Salirasib selectively disrupts the association of chronically active Ras proteins with the plasma membrane. Salirasib competes with Ras for binding to Ras-escort proteins, which possess putative farnesyl-binding domains and interact only with the activated form of Ras proteins, thereby promoting Ras nanoclusterization in the plasma membrane and robust signals. Salirasib was studied in the clinical trials in patients with solid tumors, however its development was discontinued.

Tolboxane is an alpha-adrenergic blocking drug. It is a product of arachidonic acid oxidation. Tolboxane is a tranquilizer. It influences atherosclerosis pathogenesis.