A drug that is only modestly efficacious but has a favourable safety profile may look better than a drug that is more efficacious but produces clinically meaningful adverse events. Therefore, a drug's retention rate is mainly determined by its side effect profile. As a consequence, retention rate was highest for lamotrigine and lowest for topiramate. Intermediate retention rates were seen with levetiracetam use.

For the treatment of patients with chronic refractory epilepsies, information about the long-term efficacy and safety profile of any new antiepileptic drug is crucial. Topiramate has been proven to be effective in patients with refractory chronic partial epilepsies in short-term controlled clinical trials, but the long-term retention, long-term efficacy, and long-term side-effect profile have not been sufficiently investigated. We analyzed all patients who had been treated with topiramate in the Epilepsy Centre Kempenhaeghe from the introduction of the drug in the spring of 1993 up to a final assessment point in mid-2002. In total, 470 patients were identified. The data show that the clinical dose achieved was about 200mg/day, reached after approximately 6 months of treatment. Further dose escalation in the survivors was slow, with a mean dose of about 300 mg/day after 24 months of treatment. Mean titration dose is 25mg/week, but titration strategy is mostly individual and responds to patient complaints. With respect to seizure frequency, 10-15% of the patients were seizure-free at the 6-month evaluation; 4 patients achieved a 2-year remission. Retention rate was 53% after 1 year, 45% after 2 years, 38% after 3 years, and 30% after 4 years. At 4 years, almost 70% of the patients had discontinued topiramate. The main reason was adverse events, which accounted for about 65% of the discontinuations. Behavioral side effects were dominant, with mental slowing (27.6%), dysphasia (16.0%), and mood problems (agitation: 11.9%) being the most frequently reported side effects. In about 10% of the patients side effects led to discontinuation despite the obvious favorable effects on seizure frequency. Comparisons between the patients who discontinued topiramate treatment and those who continued topiramate showed that discontinuation was associated with comedication (vigabatrin and lamotrigine). Our conclusion is that TPM is associated with a high incidence of side effects in clinical practice, affecting long-term retention. Meaningful prognostic factors that may help us in clinical decision making, i.e., to prevent the side effects or to help us identify those at risk, have not been found.

The retention rate for LEV is significantly higher than for TPM. LEV had a more favourable side effect profile than TPM with comparable efficacy. Patients on TPM discontinued treatment mainly because of neurocognitive side effects. In the treatment with LEV, the effects on mood must not be underestimated.

Summary:Purpose: This study aimed at investigating the cognitive and mood effects of lamotrigine (LTG) versus valproate (VPA) and placebo (PBO).Methods: By studying the effects in healthy volunteers, it is possible to separate the genuine effects of LTG from the cognitive improvements, caused by better seizure control. The study used a pretest-posttest comparison of 50 mg LTG, 900 mg VPA, or PBO in a double-blind single-dummy parallelgroup design with 30 healthy volunteers. Study duration was 12 days (with a last control on day 13). Outcome measures included cognitive tests (FePsy neuropsychological test battery), mood scales (ASL; mood-rating scale), and a scale for subjective complaints (ABNAS Neurotoxicity scale). Total sleep time was controlled with actigraphic recordings. The results were analyzed by comparing the change over time (pretest with posttest) for the three treatments with Student's t tests.Results: Cognitive tests: significant differences between the treatments were found for measurements of cognitive activation (i.e., three of the four simple reaction-time measurements showed statistically significant differences in change between PBO and LTG in favor of LTG (p ‫ס‬ 0.03; 0.03; 0.04); two of four tests showed statistically significant differences in change between LTG and VPA, both in favor of LTG (p ‫ס‬ 0.03; 0.05). Subjective complaints: the ABNAS-neurotoxicity scale reveals a significant reduction of drug-related cognitive complaints for the subjects taking LTG, relative to VPA (p ‫ס‬ 0.02). Mood rating: significant changes were found on the scale assessing "tiredness," showing increased tiredness/sedation for VPA relative to PBO (p ‫ס‬ 0.02) and on the "timid scale" for LTG reporting "being more at ease" compared with both PBO and VPA (p ‫ס‬ 0.02; 0.02). The general direction of change for the mood scales was toward "activation" for LTG (five of six scales improved), whereas for VPA, the reverse effect was found (four of six scales showed a change in the direction of "tiredness/sedation").Conclusions: Short-term treatment in normal volunteers with a low dose of LTG resulted in improved cognitive activation on simple reaction-time measurements, a more positive subjective report about the impact of drug treatment relative to VPA, and mood changes concurring with the activating effect demonstrated by the cognitive tests.

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