I feel that doing meditation and breathing exercises consistently can have similar or better effect compared to these drugs, and with no dependency or side effects. However, one has to put lot of work until meditation and breathwork becomes a habit, which most people do not have patience for. I messed around with supplements and drugs to control my stutter, but i stopped because i realized the heavy price i had to pay in terms of the side effects. Ive been doing meditation and breathwork for 2 years now, and im in much better place with my speech and mental health.