Are lamotrigine kinetics altered in menopause? Observations from a drug monitoring database.

To assess possible alterations in the pharmacokinetics of lamotrigine (LTG) in menopause, we reviewed the database of the drug monitoring service at the Karolinska University Hospital. Dose/plasma concentration (D/C) ratios of LTG in different age groups of women under treatment with LTG were compared with ratios for men. For further comparison, D/C ratios were calculated for men and women treated with carbamazepine (CBZ). D/C ratios were available for 752 men and 1115 women on LTG, and for 3464 men and 3088 women on CBZ. The D/C ratios of CBZ were very similar among men and women in all age groups under study. In contrast, LTG D/C ratios seemed to decline in women 51-55 years of age, and were in this age group significantly lower among women than among men (P<0.05). Our data suggest that there may be a transient decline in clearance of LTG in conjunction with presumed menopause.