Silymarin

Silymarin is a dietary supplement that contains silybin as its most active ingredient. It is derived from the seeds of the milk thistle plant (Silybum marianum). Silymarin has been used to treat a variety of liver disorders in animals.

Group

Silymarin is a plant-derived dietary supplement and a mixture of antihepatotoxic flavonolignans obtained from the Silybum plant.

Silymarin consists of three flavonolignan components: silidianin, silychristin, and silybin, with silybin (also known as silibinin) being the major active component.

Mechanism of Action

The mechanism of action of silymarin is thought to involve antioxidant effects, including the inhibition of both lipid membrane peroxidation and glutathione (GSH) oxidation.

Experimental studies also suggest that silymarin has hepatoprotective properties through its antioxidant activity and free radical-scavenging effects.

Dose Rates

• Dogs: 5-15 mg/kg q24hr PO
• Cats: 4-8 mg/kg q24hr PO
• Horses: 5-25 mg/kg q12-24hr PO

Indications

• As supportive treatment for acute and chronic hepatic diseases in animals (especially dogs, cats, birds, rabbits, and horses)
• In hepatotoxic reactions
• For hepatoprotective effects following hepatotoxic injury caused by carbon tetrachloride, toxic mushrooms, arsenic, and acetaminophen (paracetamol)
• Some studies have shown that a combination of silymarin and S-adenosylmethionine (SAMe) reduces liver enzyme elevations associated with chemotherapy in tumor in dogs.
• As a supportive treatment for a variety of liver disorders in animals

Contraindications

• No contraindications to silymarin have been reported in animals.

Interactions

• No interactions between silymarin and other medications have been reported in animals.

Adverse effects

• Silymarin is a natural compound, and no adverse reactions have been reported in animals.

Toxicity

Silymarin has very low toxicity in animals and a high degree of oral safety. However, administration of extremely high doses, far exceeding standard therapeutic levels, may cause adverse effects. There is no specific antidote for silymarin overdose. Treatment is symptomatic and supportive.

Preparations

Silymarin is often administered in combination with S-adenosylmethionine (SAMe), and commercial formulations containing both compounds (e.g., Denamarin, Nutramax, etc.) are available.

More About Silymarin (Milk Thistle) for Animals

Silymarin is considered a dietary supplement and is not regulated as a drug by the U.S. Food and Drug Administration (FDA). It is available over the counter (OTC), and its purity and potency may vary among manufacturers.