What is the best antidepressant to augment lithium in a patient with bipolar disorder?

Best Antidepressant to Augment Lithium in Bipolar Disorder

Lamotrigine is the best antidepressant to augment lithium in patients with bipolar disorder, particularly for those experiencing depressive episodes, due to its effectiveness for depressive symptoms and minimal sexual and metabolic side effects. 1

Medication Selection Algorithm

1. First-line augmentation option: Lamotrigine

   • Particularly effective for depressive episodes in bipolar disorder
   • Minimal sexual and metabolic side effects
   • Can be safely combined with lithium

2. Alternative augmentation options (if lamotrigine is contraindicated):

   • For patients with insomnia or weight loss: Mirtazapine (7.5mg at bedtime, max 30mg)

     • Promotes sleep, appetite, and weight gain
     • Well-tolerated when combined with lithium 2

   • For patients with comorbid anxiety: Sertraline (25-50mg daily, max 200mg)

     • Well-tolerated SSRI
     • Less effect on metabolism of other medications compared to other SSRIs
     • Can be taken morning or evening 2

Lithium Dosing Considerations

• Initial lithium dose: 150mg daily
• Target blood levels: 0.2-0.6 mEq/L (generally adequate)
• Usually achieved with 150-300mg daily dosing 1
• Higher serum concentrations (0.8-1.0 mmol/L) may improve prophylactic treatment efficacy 3
• Lower doses recommended for elderly patients due to increased risk of neurotoxicity

Monitoring Parameters

When augmenting lithium with an antidepressant, regular monitoring is essential:

• Serum lithium levels
• Renal function
• Thyroid function
• Electrolytes
• Weight and BMI
• Blood pressure
• Fasting glucose and lipid panel 1

Important Clinical Considerations

• Duration of treatment: Lithium augmentation should be prescribed for at least 3-6 weeks to determine efficacy
• Bipolar patients specifically benefit: Lithium augmentation is particularly beneficial in bipolar patients to obtain full prophylactic effect 4
• Slow-release formulations: Consider using slow-release lithium formulations to minimize side effects and improve tolerability 5
• Caution with SSRIs: When using SSRIs with lithium, be aware of potential side effects including sweating, tremors, nervousness, insomnia/somnolence, dizziness, and gastrointestinal/sexual disturbances 2

Common Pitfalls to Avoid

1. Avoid olanzapine and quetiapine as augmentation agents due to significant weight gain and metabolic side effects 1

2. Avoid bupropion in agitated patients or those with seizure disorders; it can be activating and should not be used in this population 2

3. Avoid rapid discontinuation of either lithium or the antidepressant, as this can precipitate mood episodes. Any medication changes should be done gradually under close supervision 1

4. Don't overlook psychotherapy components: Cognitive Behavioral Therapy, psychoeducation, and Interpersonal and Social Rhythm Therapy should be considered alongside medication management 1