Is the patient experiencing lithium toxicity, given their increased dosage to 750 milligrams (mg) twice daily, resulting in symptoms of lethargy, decreased motivation, and difficulty speaking, despite improved hallucinations and anxiety while taking lithium and previously taking Lurasidone (lurasidone hydrochloride)?

From the Guidelines

The patient should promptly consult their psychiatrist to consider reducing their lithium dosage back to the previous level, as the current dose of 750 mg twice daily is likely causing adverse effects such as fatigue, decreased motivation, and speech difficulties. The recent increase in lithium dosage appears to be associated with these side effects, which are known to occur at higher doses or when blood levels become elevated 1. Although the medication has been effective in stabilizing hallucinations and improving anxiety, the emergence of new symptoms suggests that the current dose may be too high. Lithium has a narrow therapeutic window, meaning the difference between effective and toxic doses is small, and blood level monitoring is essential when adjusting lithium dosage to ensure it remains within the therapeutic range (typically 0.6-1.2 mEq/L) 1. Some key points to consider include:

• The patient should request a lithium level test to determine if they are experiencing toxicity
• Maintaining consistent salt and water intake is crucial, as changes can affect lithium levels
• The improvement in hallucinations and anxiety indicates that lithium is effective for this patient's condition, but finding the optimal dose that balances symptom control with minimal side effects is crucial for long-term treatment success
• Regular monitoring of the patient's clinical state and serum lithium concentrations is necessary, 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 1.

From the FDA Drug Label

ADVERSE REACTIONS Lithium toxicity: The likelihood of toxicity increases with increasing serum lithium levels. Diarrhea, vomiting, drowsiness, muscular weakness and lack of coordination may be early signs of lithium toxicity, and can occur at lithium levels below 2 mEq/l. Fine hand tremor, polyuria and mild thirst may occur during initial therapy for the acute manic phase, and may persist throughout treatment. Transient and mild nausea and general discomfort may also appear during the first few days of lithium administration Neuromuscular: Tremor, muscle hyperirritability (fasciculations, twitching, clonic movements of whole limbs), ataxia, choreo-athetotic movements, hyperactive deep tendon reflexes Central Nervous System: Blackout spells, epileptiform seizures, slurred speech, dizziness, vertigo, incontinence of urine or feces, somnolence, psychomotor retardation, restlessness, confusion, stupor, coma, acute dystonia, downbeat nystagmus Miscellaneous: Fatigue, lethargy, transient scotomata, dehydration, weight loss, tendency to sleep

The patient's symptoms of tiredness, less motivation, difficulty speaking, and hopelessness could be related to lithium toxicity or side effects, as the drug label lists similar symptoms such as drowsiness, muscular weakness, slurred speech, somnolence, psychomotor retardation, fatigue, and lethargy 2. It is essential to monitor the patient's serum lithium levels and adjust the dosage accordingly to avoid toxicity. The patient should be cautioned to watch for early symptoms of lithium toxicity and to discontinue the drug and inform the physician should they occur 2.

From the Research

Side Effects of Lithium

• The patient's increased tiredness and lack of motivation may be related to lithium treatment, as it can cause various side effects, including endocrine disorders 3.
• Lithium can inhibit the secretion of thyroid hormones, leading to hypothyroidism, which may cause fatigue and decreased motivation 3.
• The patient's difficulty speaking could be a side effect of lithium, as it can cause tremors and other motor symptoms 4, 5.

Lithium Dosage and Efficacy

• The patient's current dosage of 750 mg twice daily may be too high, as high doses (over 1.0 mmol/L) can increase side effects and complications associated with long-term use 6.
• Reducing the lithium dosage can decrease morbidity and side effects during prophylaxis, while maintaining its efficacy in treating bipolar disorder 5.
• The patient's improved hallucinations and anxiety may be due to the therapeutic effects of lithium, which can stabilize mood and reduce symptoms of bipolar disorder 6, 4.

Monitoring and Management

• Regular monitoring of serum calcium, sodium, creatinine, TSH, and lithium levels is recommended to minimize the risk of side effects and complications 3.
• The patient's lithium serum levels should be checked to determine if they are within the therapeutic range, and adjustments can be made to minimize side effects 7, 5.
• Managing strategies are available for side effects, and the patient's treatment plan can be adjusted to balance the benefits and risks of lithium therapy 6.