Lithium Carbonate

Psychotropic Agent Mood Stabilizer (Antimanic Agent)

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO Initial: 10-20 mg/kg/day divided q12h; adjust to maintain serum lithium levels 0.6-1.2 mEq/L q12h Duration: Variable; monitor serum levels regularly
Notes: Start at low dose and titrate based on serum levels and clinical response. Monitor for signs of toxicity.
Cat PO Initial: 5-10 mg/kg/day divided q12h; adjust to maintain serum lithium levels 0.6-1.2 mEq/L q12h Duration: Variable; monitor serum levels regularly
Notes: Cats are more sensitive to lithium; use lower doses and monitor closely.
Horse PO Initial: 5-10 mg/kg/day divided q12h; adjust to maintain serum lithium levels 0.6-1.2 mEq/L q12h Duration: Variable; monitor serum levels regularly
Notes: Limited data; use with caution and monitor for toxicity.
Cattle PO Not established; experimental use only Not established Duration: Not established
Notes: Not recommended for routine use.
Small Ruminants PO Not established Not established Duration: Not established
Notes: Not recommended for routine use.
Rabbit PO Not established Not established Duration: Not established
Notes: Not recommended for routine use.
Bird/Poultry PO Not established Not established Duration: Not established
Notes: Not recommended for routine use.
Exotic/Other PO Not established Not established Duration: Not established
Notes: Not recommended for routine use.

Clinical Indications & Species Uses

General Indications
  • Mood stabilization and behavioral modification in various species (off-label)
  • Experimental use for stimulating granulopoiesis in neutropenic patients
Dog (Canine)
  • Treatment of behavioral disorders such as aggression, anxiety, and compulsive behaviors (off-label)
  • Adjunct in the treatment of canine bipolar disorder (rare)
  • Experimental use for neutropenia (e.g., chemotherapy-induced)
Cat (Feline)
  • Treatment of behavioral disorders such as aggression and inappropriate urination (off-label)
  • Experimental use for feline hyperthyroidism (not standard)
Horse (Equine)
  • Treatment of behavioral disorders such as stereotypies (e.g., cribbing) and aggression (off-label)
  • Experimental use for equine polysaccharide storage myopathy (not standard)

Pharmacology & Mechanism of Action

Drug Class: Psychotropic Agent | Pharmacological Group: Mood Stabilizer (Antimanic Agent)

Mechanism of Action: Lithium's exact mechanism of action is not fully understood, but it is known to modulate neurotransmitter systems and intracellular signaling pathways. It inhibits inositol monophosphatase, leading to reduced inositol triphosphate (IP3) and diacylglycerol (DAG) second messenger activity, which affects neuronal signaling. Lithium also influences sodium ion transport across cell membranes, alters neurotransmitter release (e.g., serotonin, norepinephrine, dopamine), and has neuroprotective effects by upregulating brain-derived neurotrophic factor (BDNF) and inhibiting glycogen synthase kinase-3 beta (GSK-3β). These actions contribute to its mood-stabilizing and antimanic properties.

Pharmacodynamics: Lithium exerts its therapeutic effects by stabilizing mood, reducing manic episodes, and preventing relapse in bipolar disorder. It has a narrow therapeutic index, with serum concentrations between 0.6-1.2 mEq/L considered therapeutic for most species. At toxic levels (>1.5 mEq/L), it causes neurological and cardiac toxicity. Lithium also affects thyroid function (can cause hypothyroidism) and renal function (can impair concentrating ability). It has anti-inflammatory and immunomodulatory effects, and in veterinary medicine, it has been used experimentally for its potential to stimulate granulopoiesis and treat neutropenia.

⚡ Pharmacokinetics Summary

Absorption: Lithium is rapidly and completely absorbed from the gastrointestinal tract after oral administration. Peak serum concentrations occur within 1-2 hours for immediate-release formulations and 4-5 hours for sustained-release formulations. Food can affect absorption rate but not extent.
Distribution: Lithium distributes into total body water and initially enters the extracellular fluid, then gradually accumulates in tissues. It crosses the blood-brain barrier and placenta, and is distributed into milk. Volume of distribution is approximately 0.7-0.9 L/kg. It does not bind significantly to plasma proteins.
Metabolism: Lithium is not metabolized; it is excreted unchanged by the kidneys.
Excretion: Lithium is primarily excreted via the kidneys, with about 80% of filtered lithium reabsorbed in the proximal tubules. Clearance is proportional to renal function and sodium balance. Sodium depletion or dehydration can increase lithium reabsorption, leading to toxicity. Elimination half-life varies by species: approximately 20-24 hours in dogs, 24-30 hours in cats, and 8-12 hours in horses.
Half-Life: Dogs: 20-24 hours; Cats: 24-30 hours; Horses: 8-12 hours
Bioavailability: Oral bioavailability is nearly 100%.
Protein Binding: Negligible (<1%)

Available Formulations & Strengths

Oral Tablet 150 mg, 300 mg, 600 mg (PO)
Oral Capsule 150 mg, 300 mg, 600 mg (PO)
Oral Solution 8 mEq/5 mL (as lithium citrate) (PO)
Extended-Release Tablet 300 mg, 450 mg (PO)

Contraindications & Clinical Warnings

Contraindications:
  • Known hypersensitivity to lithium
  • Severe renal impairment
  • Severe cardiovascular disease
  • Dehydration or sodium depletion
  • Pregnancy (especially first trimester) unless benefits outweigh risks
  • Concurrent use with NSAIDs, ACE inhibitors, or diuretics (increases risk of toxicity)
Warnings & Clinical Precautions:
  • Narrow therapeutic index; monitor serum lithium levels regularly (therapeutic range 0.6-1.2 mEq/L)
  • Use with caution in patients with renal insufficiency, thyroid disorders, or seizure disorders
  • Monitor renal function, thyroid function, and electrolyte balance periodically
  • Avoid sudden discontinuation; taper dose gradually
  • Ensure adequate hydration and sodium intake to prevent toxicity
  • Use with caution in geriatric or debilitated animals
  • May cause sedation or ataxia; use caution when driving or operating machinery (for owners handling animals)

Adverse Effects & Reactions

Common:

  • Gastrointestinal upset (vomiting, diarrhea)
  • Polyuria and polydipsia
  • Lethargy
  • Tremors
  • Weight gain

Serious / Severe:

  • Neurotoxicity (ataxia, seizures, coma)
  • Cardiac arrhythmias
  • Renal toxicity (nephrogenic diabetes insipidus, chronic interstitial nephritis)
  • Hypothyroidism
  • Hypercalcemia

Rare:

  • Pseudotumor cerebri
  • Leukocytosis
  • Cutaneous reactions
  • Nephrotic syndrome

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
NSAIDs (e.g., carprofen, meloxicam) Reduced renal clearance of lithium, increasing risk of toxicity High
ACE inhibitors (e.g., enalapril) Decreased lithium excretion, leading to elevated serum levels High
Thiazide diuretics (e.g., hydrochlorothiazide) Increased lithium reabsorption, causing toxicity High
Loop diuretics (e.g., furosemide) May alter lithium excretion; monitor levels Moderate
Metronidazole May increase lithium toxicity Moderate
Tetracyclines May increase lithium levels Moderate
Haloperidol Increased risk of neurotoxicity and encephalopathy High
Fluoxetine and other SSRIs May increase lithium levels and risk of serotonin syndrome Moderate
Theophylline May decrease lithium levels Mild
Sodium bicarbonate Increases lithium excretion, reducing efficacy Mild

Overdose & Toxicity Management

Signs of Toxicity:

  • Vomiting
  • Diarrhea
  • Ataxia
  • Tremors
  • Seizures
  • Coma
  • Cardiac arrhythmias
  • Hypotension
  • Renal failure

Emergency Treatment Protocol: Immediate veterinary emergency. Treatment includes: 1) Discontinue lithium. 2) Administer activated charcoal if recent ingestion. 3) Provide supportive care: IV fluids (normal saline) to enhance renal excretion and correct electrolyte imbalances. 4) In severe cases, consider hemodialysis or peritoneal dialysis. 5) Monitor serum lithium levels, renal function, and cardiac status. 6) Symptomatic treatment for seizures (e.g., diazepam) and arrhythmias.

Food Animal Withdrawal Times

Lithium is not approved for use in food animals. If used off-label, a prolonged withdrawal period (e.g., 30 days for meat and 7 days for milk) is recommended, but due to lack of data, it should not be used in food-producing animals.

Storage, Handling & Regulatory Information

Storage Temperature: Store at room temperature (20-25°C)

Handling & Special Conditions: Keep container tightly closed and protect from moisture.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; approved for human use only.

Extra-Label (Off-Label) Use: In the US, lithium is not FDA-approved for veterinary use; use in animals is extra-label. Must comply with AMDUCA regulations: require a valid VCPR, and for food animals, ensure extended withdrawal times and no residues.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Lithium carbonate is a potent mood stabilizer with a narrow therapeutic index. In veterinary medicine, its use is primarily off-label for behavioral disorders in dogs and cats, and occasionally in horses. Due to the high risk of toxicity, it should only be used when other treatments have failed and under close veterinary supervision. Regular monitoring of serum lithium levels, renal function, thyroid function, and electrolytes is essential. Owners must be educated on signs of toxicity and the importance of consistent dosing and hydration. Lithium is not recommended for food animals due to lack of withdrawal data. Alternative therapies should be considered for behavioral issues, as lithium's efficacy in animals is not well-established.

References & Literature

  • 📚 Plumb's Veterinary Drug Handbook
  • 📚 Papich Veterinary Pharmacology and Therapeutics
  • 📚 Compendium of Veterinary Products (CVP)