7β-hydroxycholesteryl-3-oleate has been shown to inhibit astrogliosis and intracranial glioblastoma growth. Local administration of 7β-hydroxycholesteryl-3-oleate inhibits growth of experimental rat C6 glioblastoma. These data suggest that 7β-hydroxycholesteryl-3-oleate might be useful for local glioblastoma chemotherapy. 7β-hydroxycholesteryl-3-oleate is a potent inhibitor of the endogenous cholesterol biosynthesis in brain showing a correlation between cholesterogenesis and reactive astrocyte proliferation. 7β-hydroxycholesteryl-3-oleate can reduce the astrocytic reaction following spinal cord injury, promoting the serotonergic reinnervation of a denervated territory. On 17 December 2010, orphan designation (EU/3/10/816) was granted by the European Commission to Intsel Chimos SA, France, for 7-beta-hydroxy cholesteryl-3-beta-oleate for the treatment of glioma. The substance is going to be injected directly into the brain tumour contained within liposomes, which are expected to carry the medicine into the glioma cells.

HPA-23 (ammonium-21-tungsto-9- antimoniate) inhibits retrovirus replication by inhibiting RNA-dependent DNA polymerases and thus could be effective in the treatment of HIV-1 infections and AIDS. HPA-23 inhibits nucleic acid polymerases in vitro and has antiviral activity both in vitro and in vivo. Furthermore, HPA-23 inhibits HIV-1 reverse transcriptase in vitro. Inhibition occurred when treatment with HPA-23 was started 18 to 24 h after infection in the plaque assay but no effect was seen when HPA 23 was added 48 h after virus inoculation. HPA-23 was concentrated in the lysosomes and localized in the macrophages of different tissues (thymus, spleen and bone marrow). By 1986, the National Academy of Science had concluded that no therapeutic benefits for persons infected with HIV could be attributed to HPA-23. It was subsequently abandoned as a treatment option.

L-aminocarnityl-succinyl-leucyl-argininal-diethylacetal (Myodur or C101) is a compound that comprise a carrier residue that is an analog of carnitine, a linker group, and a residue of a protease inhibitor comprising an acetal derivative of the aldehyde group. Myodur is a muscle cell targeted product that inhibits calpain in an effort to preserve muscle tissue. In 2006 CepTor Corporation (OTCBB:CEPO), a development-stage biopharmaceutical company focusing on cell-targeted therapeutic products for neuromuscular and neurodegenerative diseases announced that the Office of Orphan Products Development of the Food and Drug Administration (FDA) granted orphan drug designation for Myodur for both Duchenne and Becker muscular dystrophies. Myodur development has been discontinued.

Ribavirin elaidate (CP-4033; TRX-201), a Lipid Vector Technology derivative of ribavirin. It inhibits elongation factor F4E (elF4E), which stimulates cell growth. Translational Therapeutics Inc. received orphan drug status from the U.S. Food and Drug Administration (FDA) in 2011 for ribavirin elaidate in the treatment of aggressive follicular, medullary and anaplastic thyroid carcinoma.

Carbovir is a nucleoside reverse transcriptase inhibitor analog of guanosine. Carbovir decreases HIV viral loads, retards or prevents the damage to the immune system, and reduces the risk of developing AIDS. Carbovir Triphosphate belongs to the class of organic compounds known as nucleoside and nucleotide analogues. These are analogues of nucleosides and nucleotides. Carbovir interferes with the enzyme HIV uses to manufacture new viral particles within an infected cell, and is primarily metabolized to the 5'-triphosphate of Carbovir (CBV-TP) to concentrations sufficient to inhibit HIV reverse transcriptase.