Lacosamide is an anticonvulsant drug that has been approved by the FDA for the treatment of partial-onset seizures in adults. The drug has been extensively studied in clinical trials to determine its safety and efficacy, including studies on prolonged use.

According to the drug patent watch website [1], the patent for lacosamide was filed in 2002 and was granted in 2008. The patent will expire in 2025. This suggests that the drug has been in use for a significant amount of time, and has been deemed safe and effective enough to warrant a patent.

A recent clinical trial [2] investigated the long-term safety and efficacy of lacosamide in patients with epilepsy. The trial included 138 patients who were treated with lacosamide for up to 5 years. The study found that lacosamide was well-tolerated and effective in reducing seizure frequency over the long-term.

Another study [3] reviewed the safety and efficacy of lacosamide in elderly patients with epilepsy. The study found that lacosamide was safe and effective in reducing seizure frequency in this population, and that there were no significant adverse effects associated with prolonged use.

In conclusion, lacosamide has been extensively studied for its safety and efficacy in the treatment of partial-onset seizures in adults, including studies on prolonged use. These studies suggest that lacosamide is well-tolerated and effective over the long-term, and there are no significant adverse effects associated with prolonged use.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LACOSAMIDE
[2] https://clinicaltrials.gov/ct2/show/NCT04627285
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7334591/