Lamotrigine and lithium in primary care psychiatric consultation: adoption and adverse effects.

Background: The Collaborative Care Model of psychiatric consultation in primary care has improved outcomes for unipolar depression, but bipolar depressions are challenging for providers and consultants. Although lamotrigine and lithium are both first line medications for bipolar depression, their use in primary care has been declining over the last decade.

Objective: Our project aimed to quantify the frequency of and adoption of recommendations for lamotrigine and lithium, and their adverse effects, in a Collaborative Care program.

Methods: Chart review.

Results: For 620 depressed adult patients (Public Health Questionnaire, 9-item ≥10), lamotrigine and lithium were recommended by psychiatric consultant for 35% and 26% of patients, respectively; and when recommended, were prescribed by primary care providers 50% and 32% of the time, respectively. Eighty-four percent of lithium dosages were 600 mg or less; average serum level 0.32 mEq/l. In follow-up up to 6 months, lithium was associated with no more weight gain than lamotrigine; but 12% of patients receiving lithium had thyroid stimulating hormone increases exceeding the upper limit of normal, occurring in an average of 32 days after the initial prescription.

Conclusions: (i) In a Collaborative Care program of psychiatric consultation, recommendations for lamotrigine and lithium were very frequent. (ii) Adoption of these recommendations is variable, warranting further investigation. (iii) Like higher doses, low doses of lithium induced hypothyroidism (rapidly)-but not weight gain.