How to recommence lithium (lithium carbonate) therapy in a patient with a subtherapeutic lithium level of 0.57 mEq/L, who missed two doses due to vomiting, while on a regimen of 700mg of lithium (lithium carbonate)?

From the Guidelines

I strongly recommend restarting lithium at the same dose of 700mg daily, as the patient's lithium level of 0.57 mEq/L is close to the therapeutic range, and the risk of toxicity or subtherapeutic levels necessitates prompt action. The patient should resume their regular dosing schedule immediately, ensuring they take the medication with food to minimize gastrointestinal upset, as lithium toxicity is closely related to serum lithium concentrations and can occur at doses close to therapeutic concentrations 1.

Key Considerations

• Adequate hydration should be maintained, aiming for 2-3 liters of fluid daily to prevent lithium toxicity, as dehydration can lead to increased lithium concentration 1.
• If vomiting persists for more than 24 hours, the patient should contact their healthcare provider, as continued fluid loss may affect lithium levels and increase the risk of toxicity.
• A follow-up lithium level should be checked in about 5-7 days to ensure it remains therapeutic, as lithium has a narrow therapeutic window, and ongoing vomiting could potentially lead to dehydration and increased lithium concentration, which may cause toxicity 1.
• The patient's clinical state and serum lithium concentrations should be monitored regularly, with serum concentrations determined twice per week during the acute phase and until the serum concentrations and clinical condition of the patient have been stabilized, to minimize the risk of adverse effects such as tremor, polyuria-polydipsia, diarrhea, and subclinical hypothyroidism 1.

Monitoring and Follow-up

• Regular monitoring of the patient's clinical state and serum lithium concentrations is necessary to ensure the balance between the desirable and undesirable effects is likely in favor of lithium, as determined by the task force based on their clinical expertise 1.
• The balance of risks and harms is likely different for pregnant and breastfeeding women, and the patient's healthcare provider should be consulted to determine the best course of action in these cases 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Acute Mania: Optimal patient response to lithium carbonate usually can be established and maintained with 600 mg t.i.d.. Such doses will normally produce an effective serum lithium level ranging between 1 and 1. 5 mEq/L. Dosage must be individualized according to serum levels and clinical response. Long-term Control: The desirable serum lithium levels are 0. 6 to 1.2 mEq/l. Dosage will vary from one individual to another, but usually 300 mg of lithium carbonate t.i.d. or q.i.d., will maintain this level.

To recommence lithium therapy in a patient with a subtherapeutic lithium level of 0.57 mEq/L, who missed two doses due to vomiting, while on a regimen of 700mg of lithium (lithium carbonate), resume the previous dose of 700mg. The patient's serum level is slightly below the desirable range of 0.6 to 1.2 mEq/L, but since the patient missed two doses, it is likely that the level will increase once the medication is restarted. Monitor the patient's serum lithium level and clinical response closely to determine if any adjustments to the dose are needed 2.

• Key considerations:
  • The patient's current serum level is close to the lower end of the desirable range.
  • The patient missed two doses, which likely contributed to the subtherapeutic level.
  • Close monitoring of the patient's serum level and clinical response is necessary to ensure the patient's safety and the effectiveness of the treatment.

From the Research

Recommencing Lithium Therapy

To recommence lithium therapy in a patient with a subtherapeutic lithium level of 0.57 mEq/L, who missed two doses due to vomiting, while on a regimen of 700mg of lithium (lithium carbonate), consider the following:

• The patient's current lithium level is below the therapeutic range of 0.6-0.8 mmol/L 3
• The patient missed two doses due to vomiting, which may have contributed to the subtherapeutic level
• The usual maintenance daily dose is 25-35 mmol (lithium carbonate 925-1300 mg) for patients aged <40 years; 20-25 mmol (740-925 mg) for those aged 40-60 years; and 15-20 mmol (550-740 mg) for patients aged >60 years 3

Adjusting Lithium Dosage

When adjusting the lithium dosage, consider the following:

• Lithium dosages should be adjusted on the basis of the serum concentration drawn (optimally) 12 hours after the last dose 3
• The efficacy of lithium is clearly dose-dependent and reliably correlates with serum concentrations 3
• It is generally accepted that concentrations should be maintained between 0.6 and 0.8 mmol/L, although some authors still favour 0.8-1.2 mmol/L 3

Monitoring and Management

To ensure safe and effective management of lithium therapy:

• Regular monitoring of serum lithium levels is crucial to prevent toxicity 4, 3, 5, 6, 7
• Patients should be educated on the importance of adhering to their medication regimen and reporting any changes in their condition or side effects 3
• Physicians should have a low threshold to screen for toxicity and be prepared to adjust the dosage or discontinue treatment if necessary 7