A High Plasma Lamotrigine Concentration at Week 2 as a Risk Factor for Lamotrigine-Related Rash

Time-Course Changes in Lamotrigine Concentration after Addition of Valproate and the Safety and Long-Term Tolerability of Lamotrigine-Valproate Combination Therapy

The aim of this study was to evaluate the time-course changes in lamotrigine (LTG) concentration after addition of valproate (VPA) and the safety and tolerability of the combination therapy. We reviewed our therapeutic drug monitoring (TDM) database and found 345 patients on LTG who received add-on therapy with VPA. VPA had been added at least 12 weeks after patients finished stepwise LTG titration. Also, we retrospectively evaluated the LTG concentration after addition of VPA and the safety and long-term tolerability of LTG-VPA combination therapy. Plasma LTG concentration increased more than 1.5-fold within 15 d of addition of VPA and reached a peak at 30 d. The rate of increase in LTG concentration occurred in a VPA concentration-dependent manner. During the first 120 d after addition of VPA, adverse events were reported by 58 patients (16.8%), but no patient developed cutaneous reactions. Kaplan-Meier analysis showed estimated retention rates for LTG-VPA combination therapy of 74.5% at 5 years. At 5 years, the mean concentration of LTG was 11.1 µg/mL (43.3 µmol/L). Because addition of VPA leads to a marked increase in LTG concentration over a short period, TDM for LTG should be performed at the earliest from 14 d after starting VPA. At 120 d after starting VPA therapy, the higher LTG concentration due to addition of VPA is not associated with an increased risk of cutaneous reactions. Although LTG-VPA combination therapy increases LTG concentration, it is well tolerated and has a high long-term retention rate.

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.

Impact of Selected Initial Titration Schedules on Safety and Long-Term Effectiveness of Lamotrigine for the Treatment of Mood Disorders

PURPOSE

Lamotrigine (LTG) is used for treatment of mood disorders, but it is associated with the risk of rash occurrence in the initial administration phase. Although slow titration reduces this risk, its effectiveness in the treatment of mood disorders has not been verified. The effects of titration method on the safety and effectiveness of LTG for the treatment of mood disorders were examined in this study.

METHODS

This retrospective cohort study included 312 patients with mood disorders who underwent initiation of LTG therapy. Data regarding baseline demographics, titration schedules, concomitant medications, and time to and cause of discontinuation of LTG were collected. A multivariate analysis was used to evaluate the effects of the titration schedules. The 12-month effectiveness was also evaluated.

RESULTS

The 12-month discontinuation rate of LTG was 16.7%. The most frequent cause of discontinuation was development of a rash (47.7%, n = 312). Fast titration (adjusted odds ratio, 8.15) significantly increased the risk of rash development, and slow titration (adjusted odds ratio, 0.29) significantly decreased this risk. The time to all-cause discontinuation was not significantly different between the slow and standard titration groups (n = 303). After 12 months of treatment, the condition of 46.7% patients were rated much or very much improved using CGI-C.

CONCLUSIONS

Although slow titration of LTG reduces the occurrence of a rash, it is not more effective than standard titration in the long term. Optimizing the initial LTG titration schedule for patients with mood disorders is challenging.

Association of Optimal Lamotrigine Serum Levels and Therapeutic Efficacy in Mood Disorders: A Systematic Review

PURPOSE

The aim of the study was to appraise the current evidence on the optimal serum level for lamotrigine (LAM) in the treatment of mood disorders (major depressive disorder, bipolar disorder).

METHODS

Major databases were searched for randomized controlled trials, open-label trials, and observational studies reporting serum LAM levels in adult patients treated with LAM for mood disorders.

RESULTS

A total of 814 abstracts were screened and 24 articles were selected for full-text review. Seven studies (226 bipolar disorder and 17 major depressive disorder patients) including 1 randomized controlled trial (n = 43), 3 prospective (n = 53), and 3 retrospective (n = 147) studies met the study criteria with a study duration range from 6 to 96 weeks. Lamotrigine daily dosage varied from 25 to 425 mg/d among the studies. Studies reported inconsistent findings between LAM concentration and efficacy. Three studies did not identify a relationship between LAM levels and a significant improvement in mood symptoms. Two studies (n = 99) reported higher response rates with LAM serum levels of greater than 3.25 μg/mL and 1 study (n = 25) reported a wide therapeutic window of 5 to 11 μg/mL. Overall, LAM was well tolerated with no major significant adverse effects.

CONCLUSIONS

Most studies showed a minimum LAM threshold level of 3 μg/mL in patients with mood disorders; however, the data are inconsistent regarding the therapeutic range for LAM. Based on the pooled data, there is inconsistent evidence to make conclusive recommendations on therapeutic LAM serum levels for mood improvement. Further studies including larger sample sizes are required to address this relevant clinical question.