This study confirms the prophylactic effect of folic acid supplementation on spontaneous abortion. For AED therapy, folic acid supplementation should be part of the therapy of every pregnant epileptic woman, especially for those treated with VPA.

In eight women treated with lamotrigine monotherapy, the lamotrigine dose/plasma concentration (D/C) ratio increased by 295% from baseline outside pregnancy to midgestation, whereas in six women treated with lamotrigine in combination with valproate, the increase was only 60%. No difference in lamotrigine D/C ratio was found between users and nonusers of oral contraceptives comedicated with valproate. Valproate seems to reduce the induction of lamotrigine metabolism associated with pregnancy or use of contraceptives.

To investigate the effects of various progestins in combined oral contraceptives (COCs) on lamotrigine (LTG) serum concentrations and, vice versa, the potential impact of LTG on progestin serum levels during the menstrual cycle. Methods: Twenty women with epilepsy (WWE) undergoing LTG monotherapy and COC (LTG group; mean ± SD [median; range] age 24.2 ± 4.6 [23.0; 18-37] years) as well as fourteen controls on COC (24.9 ± 5.6 [22.5; 20-39] years) were assessed for eligibility and all agreed to participate in the study and remained for data analyses. Results: LTG levels differed significantly between phases of inactive pill and active pill use (p= 0.004), particularly with drospirenon (p= 0.018) and levonorgestrel (p= 0.068) as progestogen component but not with gestoden (p= 0.593). Furthermore, the LTG group showed significantly lower progestin levels during inactive pill when compared to active pill use with respect to levonorgestrel (p= 0.042) and drospirenon (p= 0.018) but not to gestoden (p= 0.109). Progestin concentrations did not differ between patients and controls (p > 0.05). Conclusions: The findings suggest that drospirenon and levonorgestrel but not gestoden seem to reduce LTG serum concentrations when being co-administered in WWE which might be of importance concerning seizure risk. Vice versa, no effect of LTG on several progestins could be demonstrated, arguing against a potential loss of contraception safety with LTG.

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