Topiramate in an Experimental Model of Epilepsy - Similarity between Generic, Similar and Reference Drugs.

Background and purpose: The literature is still controversial in relation to therapeutic differences between innovative, generic, and similar anti-seizures medications (ASM). Topiramate (TPM) is an ASM used in the treatment of various seizure types and in different epileptic syndromes, as well as in other groups of morbidities, and it is available in many generic and similar forms, besides the innovator. The aim of this translational work was to compare different brands of TPM by using animal models of seizures induced by pentylenetetrazole (PTZ).

Methods: Five brands of TPM (one reference, two similar and two generics) were tested in mice. Animals were previously treated with TPM (n=6/brand) and latencies from PTZ injection to onset of manifestations, first seizure and death were measured and compared between groups. Experiment was conducted in two settings: acute seizure model (PTZ 80 mg/kg) and kindling model (PTZ 20, 30, and 40 mg/kg in 8 alternate days).

Results: The experiment did not demonstrate significant differences between the TPM brands regarding the protective effect in the acute seizure and kindling models.

Conclusions: In conclusion, results can be explained by true therapeutic equivalence or insufficiency of the PTZ model to reveal differences among brands.