API Monensin

Monensin More Info

Monensin, also known as monensic acid, is an ionophore antibiotic belonging to the polyether monocarboxylic acid chemical family, which is a subclass of polyketides. It was discovered in 1967 by Agtarap and co-workers as a product of fermentation of Streptomyces cinnamonensis bacteria and was first synthesized in 1979 by Kishi.

Chemical Identifiers:

CAS Number: 22373-78-0

Molecular Formula: C₃₆H₆₁NaO₁₁

Molecular Weight: 692.85 g/mol

Synonyms and Brand Names

Common synonyms for Monensin include: Rumensin, Coban, Elancoban, Monensin A sodium salt, Monensin sodium salt, Sodium monensin. Other brand names include Monensin A Sodium Salt and Romensin.

Product Forms and Specifications

Monensin is available in multiple formulations including granular, powder, and premix forms. The commercial specifications include monensin sodium concentrations ranging from 8% to 20% in premix formulations. The product typically appears as white to pale yellow powder. Purity levels commonly range from 90% to 99%.

Primary Applications and Indications

Veterinary Animal Health

Coccidiosis Control in Poultry:

Monensin is primarily used as an anticoccidial agent for the prevention and treatment of coccidiosis in chickens and turkeys. It is effective against multiple Eimeria species including E. tenella, E. acervulina, E. brunetti, E. maxima, E. necatrix, E. mitis, and E. praecox in chickens. For turkeys, it targets E. adenoeides, E. meleagrimitis, E. gallopavonis, E. meleagridis, E. dispersa, E. adenoeides, and E. meleagrimitis.

Livestock Applications:

Beef Cattle: Used for improved feed efficiency in beef cattle (steers and heifers) fed in confinement for slaughter

Dairy Cattle: Helps increase milk yield, control ketosis, and reduce bloat

Goats: Prevents coccidiosis caused by Eimeria crandallis, Eimeria christenseni, and Eimeria ninakohlyakimovae in goats

Laboratory Research Applications

Monensin is widely used in biochemical research as a sodium ionophore. It is used to:

Block Golgi apparatus transport in eukaryotic cells

Disrupt vesicular transport

Induce apoptosis in cancer cell studies

Studies on bacterial, fungal, and parasitic infections

Ion-selective electrodes and analytical chemistry research

Mechanism of Action

Monensin functions as a monovalent ionophore antibiotic that neutralizes acidic intracellular compartments. It forms lipophilic complexes with monovalent cations such as Li+, Na+, K+, and Rb+, facilitating their transport across cell membranes. The drug effect is optimal during the first two days of the coccidia life cycle, inhibiting sporozoites and first-generation schizonts.

Monensin mediates Na+/H+ exchange and induces the expansion of multivesicular bodies (MVBs) while modulating exocytosis. The ionophore effect modifies the normal concentration gradient of Na+/K+, leading to cell death.

Safety and Regulatory Information

Species Toxicity

Horses and Equines: Monensin is highly toxic to horses and other equines. The lethal dose for most horses is 2-3 mg/kg, equivalent to about 1,000 mg (1 gram) for the average horse. Ingestion by horses is fatal and can cause myocardial necrosis, heart failure, and death. There is no specific antidote for monensin or lasalocid toxicity.

Other Animals: Consumption by unapproved species may result in toxic reactions. Dogs and pigs can also be affected by monensin ingestion.

Usage Restrictions

Intended Use: Feed additive only, NOT for human or medicinal use

Veterinary Use Only: Federal law restricts the use of monensin medicated feed to licensed veterinarians

Species Restrictions: Monensin medicated feeds are safe for use in cattle and goats only

Withdrawal Time: Cattle must not be slaughtered within 28 days of the last treatment with certain combinations

Storage and Handling

Monensin sodium salt should be stored at -20°C in a dry environment for up to three years to maintain stability. For laboratory use, the typical storage condition is 4°C, sealed, away from moisture. Commercial feed additives should be stored in a cool and dry place. The product is typically packaged in 25kg drum or equivalent packaging.

Physical and Chemical Characteristics

Appearance: White to pale yellow crystalline powder

Solubility: Soluble in ethanol to 100 mM

EC Number: EINECS 244-941-7

Grade: Available in pharmaceutical grade, veterinary grade, and research grade

Clinical Signs of Monensin Poisoning in Horses

Symptoms include depression, abnormal gaits (incoordination, weakness, and paresis), reduced appetite, colic, diarrhea, intermittent sweating, stiffness, and muscle weakness. Clinical signs may also include increased heart and respiratory rates, low blood pressure, and increased urination. The drug causes oxidative damage to mitochondria, particularly affecting cardiac muscle, which has the highest density of mitochondria.