Merck Manual

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Professional Version



Dawn Merton Boothe

, DVM, PhD, Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University

Last full review/revision Nov 2015 | Content last modified Nov 2015

Ionophores are lipid-soluble molecules that transport ions across lipid cell membranes. The subsequent disruption of cell membrane permeability results in antibacterial effects. Monensin is an ionophore antibiotic derived from Streptomyces that forms complexes with monovalent cations, including sodium and potassium. The complexes are transported in a nonpolar manner across the bacterial cell membrane. As such, it acts as an Na+/H+ antiporter. Monensin blocks intracellular protein transport, resulting in antibacterial and antimalarial effects. Monensin is used extensively in the beef and dairy industries in feed to prevent coccidiosis and improve feed efficiency. Monensin also increases the production of propionic acid and thus prevents bloat.

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