What is the starting dose of lithium carbonate for adults?

Starting Dose of Lithium Carbonate for Adults

The starting dose of lithium carbonate for adults is 300 mg two to three times daily (total of 600-900 mg/day), with dosage adjustments based on serum lithium levels and clinical response. 1

Initial Dosing Recommendations

• Standard starting dose: 300 mg 2-3 times daily (600-900 mg/day) 1
• Elderly patients: Lower starting dose of 150 mg per day is recommended due to increased sensitivity 1, 2
• Administration timing:
  • Standard-release formulation: Divided doses (2-3 times daily)
  • Sustained-release formulation: Can be given twice daily or once daily in the evening 2

Dosage Adjustment Protocol

1. Initial monitoring: Measure serum lithium levels twice weekly during acute treatment phase 1
2. Target serum levels:
   • Acute mania: 1.0-1.5 mEq/L 1
   • Maintenance therapy: 0.6-1.2 mEq/L 1
3. Blood sampling: Draw samples 8-12 hours after the last dose (trough level) 1
4. Dose adjustments: Individualize based on serum levels and clinical response

Age-Based Maintenance Dosing

Age Group	Typical Maintenance Dose
<40 years	25-35 mmol (925-1300 mg) daily
40-60 years	20-25 mmol (740-925 mg) daily
>60 years	15-20 mmol (550-740 mg) daily

Important Clinical Considerations

• Narrow therapeutic window: Lithium has a narrow therapeutic index requiring careful monitoring 2
• Renal function: Lithium is primarily excreted by the kidneys; renal insufficiency is a contraindication 2
• Elderly patients: Often require lower doses and may exhibit toxicity at serum levels normally tolerated by younger patients 1
• Formulation differences: Sustained-release formulations result in 30-50% lower peak plasma concentrations compared to standard-release 2

Dosing Schedule Options

• Traditional approach: 2-3 times daily dosing
• Alternative approach: Once-daily dosing (preferably in the evening) may improve tolerability and adherence 3
  • A study found once-daily dosing had similar efficacy to twice-daily dosing but with fewer renal adverse effects 3

Common Pitfalls to Avoid

1. Relying solely on serum levels: Clinical evaluation remains essential alongside laboratory monitoring 1
2. Inadequate monitoring: Failure to check lithium levels regularly can lead to toxicity
3. Ignoring drug interactions: Many medications can decrease lithium clearance, increasing toxicity risk 2
4. Dehydration risk: Patients should maintain adequate fluid intake to prevent lithium toxicity
5. Sodium restriction: Low-sodium diets can increase lithium levels and toxicity risk 2

By following these guidelines for lithium carbonate initiation and careful monitoring of serum levels and clinical response, clinicians can optimize therapeutic outcomes while minimizing adverse effects.