Influence of uridine diphosphate glucuronosyltransferase inducers and inhibitors on the plasma lamotrigine concentration in pediatric patients with refractory epilepsy

Evaluation of the Safety of Taking Lamotrigine During Lactation Period

Introduction: Evaluation of the safety of taking lamotrigine (LTG) during lactation in breastfed infants varies according to the information sources. As it is possible that prescribers may avoid prescribing LTG despite of it being one of the essential drugs, more information needs to be accumulated to facilitate its use. Materials and Methods: We retrospectively compared the safety of LTG during the lactation period in 20 pairs of mothers and infants with 20 pairs as the control group. Results: The mean dose of LTG in 20 mothers was 161.1 mg/day (range: 50-400 mg/day). None of the infants showed a neonatal withdrawal syndrome score of 2 or more up to 1 month after delivery. Although drowsiness (n = 3), skin rash (n = 11), jaundice (n = 8), heart murmur (n = 1), poor suckling (n = 1), and retractive breathing (n = 1) were observed in infants, none of these adverse events were serious and the infants recovered. Nineteen of 20 pairs could continue lactation until 1 month after delivery. One pair discontinued breastfeeding because of pain in the mother's nipples. All pairs could continue maternal medication. We then compared the results with those of the control group. There were no significant differences in the presence of adverse events between the LTG and control groups. Conclusion: These data suggest that taking low to moderate doses of LTG during the lactation period might be relatively safe, at least for a period of 1 month after delivery.

Influence of genetic variants and antiepileptic drug co-treatment on lamotrigine plasma concentration in Mexican Mestizo patients with epilepsy

Genetic and nongenetic factors may contribute to lamotrigine (LTG) plasma concentration variability among patients. We simultaneously investigated the association of UGT1A1, UGT1A4, UGT2B7, ABCB1, ABCG2, and SLC22A1 variants, as well as antiepileptic drug co-treatment, on LTG plasma concentration in 97 Mexican Mestizo (MM) patients with epilepsy. UGT1A4*1b was associated with lower LTG dose-corrected concentrations. Patients with the UGT2B7-161T allele were treated with 21.22% higher LTG daily dose than those with CC genotype. Two novel UGT1A4 variants (c.526A>T; p.Thr185= and c.496T>C; p.Ser166Leu) were identified in one patient. Patients treated with LTG + valproic acid (VPA) showed higher LTG plasma concentration than patients did on LTG monotherapy or LTG + inducer. Despite the numerous drug-metabolizing enzymes and transporter genetic variants analyzed, our results revealed that co-treatment with VPA was the most significant factor influencing LTG plasma concentration, followed by UGT1A4*1b, and that patients carrying UGT2B7 c.-161T required higher LTG daily doses. These data provide valuable information for the clinical use of LTG in MM patients with epilepsy.

Valproate intoxication in a patient with bipolar I disorder due to SGLT2 inhibitor-induced weight reduction

INTRODUCTION

Sodium glucose cotransporter 2 (SGLT2) inhibitors are hypoglycemic agents characterized by a weight loss effect. This effect is likely to increase blood levels of other drugs. Reason for the report: SGLT2 inhibitor-induced weight reduction could bring unexpected side effects of other drugs whose blood concentrations are affected by body weight. However, this interaction between SGLT2 inhibitor and other drugs via weight loss effect has not been reported so far.

CASE SUMMARY

I describe the case of a 67-year-old male with bipolar I disorder who was treated with valproate. He was diagnosed with type 2 diabetes mellitus, started treatment with empagliflozin, and his body weight decreased gradually. Two months after he started empagliflozin, he developed hand tremor which was one of the symptoms of valproate intoxication, and his tremor was improved by dose reduction of valproate. It seemed that this symptom was brought mainly by weight loss effect of empagliflozin. These observations suggest the existence of a detour where blood concentrations of some drugs are increased by weight loss due to SGLT2 inhibitors. Clinicians need to be aware of the blood levels of drugs in patients with type 2 diabetes mellitus after starting SGLT2 inhibitors. Graphical abstract.

Determination of lamotrigine in human plasma using liquid chromatography-tandem mass spectrometry

Aim

Lamotrigine (LTG) is a widely used anti‐epileptic drug that is administered to avoid seizures and to maintain seizure‐free status. However, several factors reportedly cause individual differences of plasma LTG levels, and the therapeutic target range of LTG varies between individuals. Thus, to optimize effective doses of LTG, we developed a rapid and simple method for determining plasma LTG concentrations.

Methods

Lamotrigine and the internal standard papaverine were extracted from human plasma using solid‐phase extraction. After filtration, 5‐μL aliquots of final samples were injected into the liquid chromatography‐tandem mass spectrometry instrument and LTG and internal standard were separated using a Cadenza CD‐C18 column (100 × 2 mm, 3 μm) with 0.1% formic acid in water/acetonitrile (2/1, v/v).

Results

The calibration curve was linear from 0.2 to 5.0 μg/mL, and assessments of recovery, intra‐ and inter‐day precision and accuracy, matrix effects, freeze and thaw stability, and long‐term stability demonstrated good reproducibility. Retention times of LTG and internal standard were 1.6 and 2.0 minutes, respectively, and the total run time was 3.5 minutes for each sample.

Conclusion

We developed a rapid and simple method for determining plasma LTG concentrations. The present novel system could be used to inform LTG dose adjustments for individual patients.

We developed a rapid and simple method for determining plasma concentrations of LTG showing good validation for a relatively wide range (0.2‐5.0 μg/mL). The present method can inform estimates of plasma concentrations of LTG to clinicians within 1 hour of sample collection.

Time course of reversal of valproate-mediated inhibition of lamotrigine

PURPOSE

Conversion to lamotrigine (LTG) monotherapy from sodium valproate (VPA) is complicated by the robust pharmacokinetic interaction between the two AEDs. This study examined changes in LTG serum concentrations immediately following VPA discontinuation.

METHODS

Ten healthy female and male adult subjects were initiated on LTG (Lamictal) 10 mg orally every morning for 30 days and VPA (Depakote ER) 500 mg orally every morning for 14 days. Morning trough (pre-dose) venous blood samples were obtained for determination of LTG and VPA concentrations on study days 14, 15, 16, 18, 20, 22, 24, 26, 28, and 30. Following the collection of the blood sample on day 15, VPA was discontinued.

RESULTS

Despite stable LTG dosage serum concentrations on study day 20, 22, 24, 26, and 28, all were significantly lower compared to baseline (p < 0.05).

CONCLUSIONS

These observations demonstrate that the pharmacokinetic interaction between LTG and VPA is reversible, and that de-inhibition appears to follow a predictable time course. Complete offset, or reversal of this interaction takes place 10-14 days after VPA discontinuation. Our data also confirms the observation that LTG oral clearance may be inhibited by very low concentrations of VPA. These data support the conversion algorithm suggested by the manufacturer, and provide guidance to the clinician. These data provide clinically useful information in developing a dosing algorithm for converting patients to LTG monotherapy.