plicamycin

Plicamycin (INN, also known as mithramycin; trade name Mithracin) is an antineoplastic antibiotic produced by Streptomyces plicatus. Plicamycin belongs to the group of medicines known as antineoplastics. It may be used to treat certain types of cancer. It is also used to treat hypercalcemia or hypercalciuria (too much calcium in the blood or urine) that may occur with some types of cancer. Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in product labeling, plicamycin is used in certain patients with the following medical condition:Paget's disease of the bone. The manufacturer discontinued plicamycin in 2000. Several different structures are currently reported in different places all with the same chromomycin core, but with different stereochemistry in the glycoside chain, a 1999 study has re-investigated the compound and proposed a revised structure. Although the exact mechanism by which Mithracin (plicamycin) causes tumor inhibition is not yet known, studies have indicated that this compound forms a complex with deoxyribonucleic acid (DNA) and inhibits cellular ribonucleic acid (RNA) and enzymic RNA synthesis. The binding of Mithracin (plicamycin) to DNA in the presence of Mg + + (or other divalent cations) is responsible for the inhibition of DNA-dependent or DNA-directed RNA synthesis. This action presumably accounts for the biological properties of Mithracin (plicamycin). Plicamycin may also lower calcium serum levels by inhibiting the effect of parathyroid hormone upon osteoclasts or by blocking the hypercalcemic action of pharmacologic doses of vitamin D. — NCATS