Yoshinori Watanabe, Seiji Hongo

We investigated whether the long-term efficacy and safety of lamotrigine (LTG) for bipolar disorder (BP) differs between disease types (BP-I, BP-II, or BP not otherwise specified [BP-NOS]), and the efficacy of the concomitant use of antidepressants (ADs). For >1 year, we observed 445 outpatients with BP (diagnosed by DSM-IV criteria) who initiated LTG treatment between July 1 and October 31, 2011, using the Himorogi Self-rating Depression (HSDS) and Anxiety Scales and the Clinical Global Impression-Improvement scale and also recorded adverse events. Treatment efficacy was observed at week 4, with the improved HSDS scores sustained until week 52 for all types of BP; 50% of the patients with any type of BP could be treated with LTG for 1 year, whereas ~40% could be treated for >1.5 years. However, 25% of the patients were withdrawn within the first 4 weeks. The overall incidence of adverse events was 22.9% (104/455): 34.1% (14/41) for BP-I, 22.7% (15/66) for BP-II, and 22.2% (75/338) for BP-NOS. The most common adverse event was skin rash: 22.0% for BP-I, 16.7% for BP-II, and 12.1% for BP-NOS. There was no control group. Data were collected retrospectively. With careful and adequate titration, long-term treatment with LTG is possible for any type of BP, with BP-NOS patients, the largest population in clinical practice, responding particularly well. Symptoms can improve with or without ADs. Large-scale prospective studies of the efficacy of ADs in bipolar treatment are warranted.