Vitamin B6 antagonists

Isoniazid, also known as isonicotinic acid hydrazide (INH), is an antibiotic used for the treatment of tuberculosis. For active tuberculosis, it is often used together with rifampicin, pyrazinamide, and either streptomycin or ethambutol. It may also be used for atypical types of mycobacteria, such as M. avium, M. kansasii, and M. xenopi. It is usually taken by mouth, but may be used by injection into muscle.

Monomethylhydrazine (MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide () and nitric acid (). As a propellant, it is described in specification MIL-PRF-27404.

Crimidine is a convulsant poison used as a rodenticide. Crimidine was originally known by its product name, Castrix. It was originally produced in the 1940s by the conglomerate, IG Farben. It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities. It is also no longer used in the United States as a rodenticide, but is still used to this day in other coun

Ginkgotoxin (4'-O-methylpyridoxine) is a neurotoxin naturally occurring in Ginkgo biloba. It is an antivitamin structurally related to vitamin B6 (pyridoxine). It has the capacity to induce epileptic seizures.

4-Deoxypyridoxine is a vitamin B6 antagonist. It may be toxic to developing embryos since it can have negative effects on collagen and elastin during development. The presence of this compound can produce vitamin B6 deficiency, which suppresses the immune system. 4-Deoxypyridoxine lowers vitamin B6 concentration by competitively inhibiting some of the enzymes necessary for the regeneration of vitamin B6. The related immunosuppression can be beneficial in animal models of Trichinella spiralis infections. 4-Deoxypyridoxine has also been described as an inhibitor of sphingosine-1-phosphate lyase.