Efficacy and safety of topiramate in migraine prophylaxis: an open controlled randomized study comparing Sincronil and topamax formulations

Topiramate is a small molecule widely used for the treatment of epilepsy, migraine, bipolar disorders and alcoholism, and its availability as a generic formulation could significantly reduce the National Health Service expenditure. A generic formulation, available in Italy under the trademark Sincronil, recently showed superimposable blood levels, after oral administration to healthy volunteers, with the reference formulation. In the present study we report the results of an open label, parallel group, randomized, controlled study performed to evaluate the efficacy, tolerability and impact on disability of two different formulations of topiramate (Sincronil and Topamax) in patients with migraine without aura.

Sixty patients aged between 18 and 65 years, suffering from migraine without aura with an attack frequency of 3-15 attacks/month were enrolled and received, after a titration phase lasting 20 days, randomly either Sincronil or Topamax at the dose of 25 mg twice daily for 3 months.

Fifteen out of the 30 patients who were administered Sincronil reported an improvement in the clinical condition, with a decrease in the frequency of attacks at the 3rd month of treatment higher than 50% with respect to the run-in period, 9 reported their clinical condition as being substantially unchanged and 6 reported that they had suspended the treatment within the first 4 weeks of therapy due to side effects. Among the 24 patients who continued treatment up to the 3rd month, the frequency of attacks during the 3rd month of treatment was significantly decreased from 7 ± 3.6 to 3.7 ± 3.7 (P<0.0001), migraine severity was reduced from 2.5 ± 0.5 to 1.7 ± 0.7 (P<0.0005) and the MIDAS score was reduced from 14.3 ± 4.9 to 8.6 ± 5.5 (P<0.0001). Sixteen out of the 30 patients who were administered Topamax reported an improvement in the clinical condition with a reduction in the attack frequency at the 3rd month of treatment higher than 50% with respect to the run-in period, 10 reported a substantially unchanged clinical condition and 4 stopped the treatment within the first weeks due to side effects. Among the 26 patients who continued treatment up to the 3rd month, headache frequency during the 3rd month of treatment was significantly reduced, from 7.3 ± 2.6 to 3.5 ± 2.7 (P<0.0001), migraine severity decreased from 2.4 ± 0.6 to 1.6 ± 0.8 (P<0.0005) and the MIDAS score from 14.1 ± 4.2 to 6.8 ± 4.8 (P<0.0001).

In conclusion, in this study Topamax (reference product) and Sincronil (generic formulation) have proven therapeutically equivalent and both products were well tolerated.