Folic Acid is a B complex vitamin containing a pteridine moiety linked by a methylene bridge to para-aminobenzoic acid, which is joined by a peptide linkage to glutamic acid. Conjugates of Folic Acid are present in a wide variety of foods, particularly liver, kidneys, yeast and leafy green vegetables. Commercially available Folic Acid is prepared synthetically. Folic Acid occurs as a yellow or yellowish-orange crystalline powder and is very slightly soluble in water and insoluble in alcohol. Aqueous solutions of Folic Acid are heat sensitive and rapidly decompose in the presence of light and/or riboflavin; solutions should be stored in a cool place protected from light. Folic Acid is effective in the treatment of megaloblastic anemias due to a deficiency of Folic Acid (as may be seen in tropical or nontropical sprue) and in anemia of nutritional origin, pregnancy, infancy, or childhood. Folic Acid is relatively nontoxic in man. Rare instances of allergic responses to Folic Acid preparations have been reported and have included erythema, skin rash, itching, general malaise, and respiratory difficulty due to bronchospasm. Endocyte is developing an intravenous (IV) formulation of folic acid, called Neocepri®, which is intended for the diagnosis of positive folate receptor-positive status in patients with ovarian cancer when administered prior to the radioactive medicine, technetium Tc99m Etarfolatide. The benefits of Neocepri® are its ability to reduce the background activity observed on single photon emission computed tomography (SPECT) imaging in most normal, nontarget tissues (e.g. intestines, liver, kidney, spleen), thereby improving the image quality of the scans. The product had been granted orphan drug designation in the EU. Endocyte had filed a conditional marketing authorization application (CMA) with the European Medicines Agency (EMA) for Neocepri®.

Folitixorin, a thymidylate synthase inhibitor is a substrate used by the enzyme methylenetetrahydrofolate reductase (MTHFR) to generate 5-methyltetrahydrofolate. Folitixorin was studied in clinical trials for the treatment of breast cancer, metastatic colorectal cancer and for the treatment of advanced pancreatic cancer. Folitixorin had been granted orphan drug status for the treatment of pancreatic cancer in both the U.S. and EU. However, further development of this drug was discontinued.

Tetrahydrofolic acid is a folic acid derivative. It is produced from dihydrofolic acid by dihydrofolate reductase. It is converted into 5,10-methylenetetrahydrofolate by serine hydroxymethyltransferase. It is a coenzyme in many reactions, especially in the metabolism of amino acids and nucleic acids. It acts as a donor of a group with one carbon atom. It gets this carbon atom by sequestering formaldehyde produced in other processes. Tetrahydrofolate is the main active metabolite of dietary folate. It is vital as a coenzyme in reactions involving transfers of single carbon groups. Tetrahydrofolate has a role in nucleic and amino acid synthesis. As nucleic and amino acid synthesis is affected by a deficiency of tetrahydrofolate, actively dividing and growing cells tend to be the first affected. Tetrahydrofolate is used to treat topical sprue and megaloblastic and macrocytic anemias, hematologic complications resulting from a deficiency in folic acid. Tetrahydrofolic acid is used for nutritional supplementation, also for treating dietary shortage or imbalance.