Lamotrigine in mood disorders: Flash survey on prescribing habits and blood tests practices.

Objective: Therapeutic drug monitoring for lamotrigine is poorly documented in bipolar and depressive disorders. In order to evaluate its use among French psychiatrists, we explored prescribing habits, therapeutic monitoring and dosage adjustment of lamotrigine through a flash survey.

Methods: A survey was broadcasted by the network of Expert Centers for Bipolar Disorder and Resistant Depression and by the Collegial of Psychiatry of the Assistance publique des Hôpitaux de Paris. Questions concerned the frequency of prescribing depending on the mood disorder, the frequency of plasma levels, therapeutic monitoring, dosage adjustment and the limitation represented by dermatological risk.

Results: Of the 99 hospital psychiatrists who responded, 66 practiced in a university hospital and 62 for more than 5years. Overall, lamotrigine was more frequently prescribed for type 2 bipolar disorder (often: 51%) than for type 1 bipolar disorder (often: 22%). Dermatotoxicity was a major barrier to prescribing for 15% (n=13) of respondents. Nearly two-thirds of prescribers (61%, n=59) measured lamotrigine, of which 50% (n=29) systematically. However, 40% of them did not have an opinion on the optimal plasma concentration. In total, 22% (n=13) always adjusted the dosage according to the result. The first argument for dosage adjustment was clinical response for 80% (n=47) of prescribers, adverse effects for 17% (n=10) and plasma levels for only 4% (n=2).

Conclusion: While many psychiatrists report using plasma dosage of lamotrigine, few use the plasma level result to adapt dosage and many have no opinion of the target values for plasma concentrations. This illustrates the lack of data and recommendations regarding the use of therapeutic pharmacological monitoring of lamotrigine in bipolar and depressive disorders.