S-Adenosyl-Methionine (SAMe)
**S-Adenosyl-Methionine (SAMe)** is a naturally occurring endogenous molecule and a highly utilized veterinary nutraceutical, primarily serving as a **hepatoprotectant**. Key clinical applications include: * **Liver Disease**: Used as an adjunctive treatment for chronic hepatitis, hepatic lipidosis, cholangiohepatitis, and feline triad disease. * **Toxicity Management**: Crucial in the treatment of acute hepatotoxin-induced liver injury, such as **acetaminophen** or **xylitol** toxicity, by replenishing depleted glutathione stores. * **Additional Uses**: May benefit patients with osteoarthritis, age-related cognitive dysfunction (canine cognitive dysfunction syndrome), and those on long-term hepatotoxic medications (e.g., phenobarbital, lomustine). > **Clinical Pearl**: Because SAMe is highly reactive and unstable, commercial formulations use various salt forms (e.g., tosylate, butanedisulfonate) to improve stability. Bioavailability varies significantly between products, so choosing a reputable, veterinary-specific brand is highly recommended.
Mecanismo: SAMe is synthesized from the amino acid methionine and ATP via the enzyme **SAMe synthetase**. In liver compromise, this enzyme's activity is a rate-limiting step, leading to systemic SAMe deficiency. Exogenous SAMe bypasses this block and participates in three major biochemical pathways: * **Transsulfuration** → Generates sulfur-containing compounds → Precursor to **Glutathione (GSH)**. Glutathione is the liver's master antioxidant, essential for ROS scavenging and cellular detoxification. Exogenous SAMe prevents GSH depletion. * **Transmethylation** → Serves as a methyl donor → Essential for phospholipid synthesis (e.g., phosphatidylcholine) → Maintains cell membrane structure, fluidity, and function. * **Aminopropylation** → Donates aminopropyl groups → Source of polyamines → Promotes anti-inflammatory effects, protein/DNA synthesis, and **hepatocyte replication/regeneration**. Additionally, SAMe inhibits hepatocyte apoptosis secondary to alcohol or bile acid accumulation.
Dosificación por especie
- General dosing / Liver support · 18 mg/kg (or based on weight: <5.5 kg: 90 mg; 5.5-11 kg: 180-225 mg) · PO · q24h · Give on an empty stomach, at least one hour before feeding.
- Liver Disease (necro-inflammatory/cholestatic, feline hepatic lipidosis) · 20 mg/kg · PO · q24h · Give on an empty stomach; use a proven bioavailable product.
- Liver disease, cognitive dysfunction, improve bile flow · 100 mg/cat or 20 mg/kg · PO · q24h · Long-term as needed · Administer on an empty stomach at least 1 hour before food. Tablets should be given whole.
- General dosing / Liver support · 18 mg/kg (or based on weight: <5.5 kg: 90 mg; 5.5-11 kg: 180-225 mg; 11-16 kg: 225 mg; 16-29.5 kg: 450 mg; 29.5-41 kg: 675 mg; >41 kg: 900 mg) · PO · q24h (may divide q12h if giving >1 tablet) · Give on an empty stomach, at least one hour before feeding.
- Liver Disease (necro-inflammatory/cholestatic, vacuolar hepatopathy) · 20 mg/kg · PO · q24h · Give on an empty stomach; use a proven bioavailable product.
- Liver disease, cognitive dysfunction, adjunctive therapy · At least 100 mg for every 10 kg or 20 mg/kg · PO · q24h · Long-term as needed · Administer on an empty stomach at least 1 hour before food. Tablets should be given whole.
Las dosis son una referencia clínica para médicos veterinarios. Confirme siempre con la información vigente del producto y el paciente individual.
Vías de administración
Contraindicaciones
- No absolute contraindications
- Use with caution in pregnant animals (safety not definitively proven)
- No absolute contraindications documented
- Use with caution during pregnancy (safety not established)
Efectos adversos
- Immediate post-dose vomiting
- Anorexia
- Anxiety
- Nausea (reported in humans)
- Diarrhea (reported in humans)
- Flatulence (reported in humans)
- Nausea
- Vomiting
- Diarrhoea
- Paradoxical anxiety
- Dry mouth (reported in humans)
- Headache (reported in humans)
- Sweating (reported in humans)
- Dizziness (reported in humans)
Interacciones farmacológicas
- Tramadol · Theoretical risk of additive serotonergic effects (serotonin syndrome) · major
- Meperidine · Theoretical risk of additive serotonergic effects · major
- Dextromethorphan · Theoretical risk of additive serotonergic effects
- Pentazocine · Theoretical risk of additive serotonergic effects · major
- Monoamine oxidase inhibitors (MAOIs) (e.g., selegiline) · Theoretical risk of additive serotonergic effects
- Selective serotonin reuptake inhibitors (SSRIs) (e.g., fluoxetine) · Theoretical risk of additive serotonergic effects
- Tricyclic antidepressants (TCAs) (e.g., amitriptyline, clomipramine) · Theoretical risk of additive serotonergic effects
- Selegiline · Additive serotonergic effects; potential for serotonin syndrome · major
- Fluoxetine · Additive serotonergic effects; potential for serotonin syndrome · major
- Clomipramine · Additive serotonergic effects; potential for serotonin syndrome · major
- Amitriptyline · Additive serotonergic effects; potential for serotonin syndrome · major
- Paracetamol · SAMe may increase the clearance of drugs undergoing hepatic glucuronidation · moderate
Monitoreo
- Clinical signs (appetite, activity, attitude)
- Liver enzymes (ALT, AST, ALP, GGT)
- Bilirubin
- Bile acids
- Liver biopsies (if indicated)
- Hepatic and erythrocyte glutathione levels (Note: may require 1-4 months before changes in lab values are noted)
- Liver enzyme panel (ALT, AST, ALP, GGT)
- Total bilirubin and bile acids
- Clinical signs of cognitive improvement or behavioral changes
- Signs of serotonin syndrome (agitation, tremors, hyperthermia) if used concurrently with serotonergic drugs
Sobredosis
SAMe appears to be quite safe. The LD50 in rodents exceeds 4.65 grams/kg. Toxicity studies in dogs and cats at usual prescribed dosages demonstrated no deleterious effects. In the event of a massive overdose, mild gastrointestinal effects (nausea, vomiting, diarrhea) may be observed, but it is highly unlikely to require specific medical treatment beyond supportive care.
La referencia de fármacos de VetSheet está destinada a médicos veterinarios como apoyo a la decisión clínica; no sustituye el juicio profesional ni la información vigente del fabricante.