Trends and changes in the clinical use of lamotrigine

To investigate long-term trends and changes in the pattern of use of lamotrigine (LTG).

Retrospective survey of a large, routine therapeutic drug monitoring database.

Twelve thousand one hundred and seven samples from 4123 subjects were analysed from October 1999 to May 2007. Within this period, the mean daily dose rose from 183 to 253 mg, whereas the median dose remained unchanged at 200 mg. Females became the majority of LTG users, and they had a higher proportion of psychiatric diagnoses than male patients. The mean patient age increased from 34 to 41 years. The proportion of samples from psychiatric patients became larger than that of neurologic patients. A total of 130 different diagnoses were stated, most of them psychiatric off-label. The mean serum concentration was 3.8 mg/L and it remained quite stable during the whole observation period. Neurologic patients had a higher mean serum concentration than psychiatric patients. 30% of the neurologic and 41% of the psychiatric patients had serum concentrations below the reference range. Sixty-eight per cent of the patients used additional drugs. Females used a higher number of additional medications than males. The 10 most frequent co-medications consisted of seven psychotropic drugs, two anticonvulsants, and thyroxine.

Significant changes in the pattern of use of LTG have taken place during the observation period and some significant trends could be identified.