Research on the interaction between stiripentol and GABA indicates that stiripentol acts as a GABAA receptor allosteric modulator, enhancing the effect of GABA by facilitating the activity of GABA at its receptor sites [1]. However, fenfluramine, on the other hand, primarily affects GABA through indirect mechanisms, specifically the inhibition of GABA reuptake and the stimulation of GABA release, although the primary action of fenfluramine is associated with the inhibition of norepinephrine and serotonin reputake [2][3]. A study found that when compared with fenfluramine, stiripentol demonstrated more pronounced GABA-mediated effects [4].

A patent from drugpatentwatch.com provides additional insight into the mechanism of action of stiripentol. According to the patent, stiripentol's GABA-enhancing effects are a major contributor to its therapeutic benefits in epilepsy treatment [5].

Sources:

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4451116/
[2] https://en.wikipedia.org/wiki/Fenfluramine
[3] https://www.drugs.com/monograph/fenfluramine.html
[4] https://pubmed.ncbi.nlm.nih.gov/16352874/
[5] https://wwwDrugPatentWatch.com/patent/EP1611610B1/