Abstracts

Rationale: Adherence to pharmacologic treatment is inversely related to dosing frequency. Improved adherence increases pharmacologic effectiveness in epilepsy, which in turn may decrease morbidity, mortality, and associated costs. Supernus Pharmaceuticals, Inc. is developing SPN-538, a novel, once-daily, extended-release (ER) formulation of topiramate that may reduce the dose- and peak-related adverse events that occur with twice-daily topiramate and may facilitate adherence to therapy. This study was conducted to evaluate patient preference regarding dosing frequency and how dosing frequency affects adherence. Methods: We conducted a multicenter, open-label conversion study in patients with partial-onset seizures or primary generalized seizures being treated with topiramate immediate-release (IR). The study consisted of a 28-day screening period, followed by 2 weeks of treatment with Topamax twice daily, and then conversion to SPN-538 once daily for the final 2 weeks. Patients were asked their preference regarding the dosing schedule (twice-daily Topamax vs once-daily SPN-538) and their impression of how dosing schedule impacted adherence. We compared our findings with the literature, both in chronic medical illness and specifically in epilepsy, focusing on patient preference between IR and ER products.Results: 61 patients (88.4%) completed the study. Once-daily dosing with SPN-538 was preferred by 57 (93.4%) patients; 4 patients (6.6%) preferred twice-daily dosing with Topamax. Fifty-six patients (91.8%) believed that once-daily dosing improved their adherence to therapy; 5 patients (8.2%) did not hold that view. Our results support a 2009 systematic review by Saini et al, who found that once-daily dosing improved adherence compared with more frequent dosing in patients with chronic medical conditions.¹ Literature searches returned 2 relevant results in epilepsy: 1) a study by Tompson et al of lamotrigine IR vs lamotrigine XR (N=35),² and 2) a study by Pierre-Louis et al focusing on divalproex IR and divalproex ER (N=38).³ In the first study, once-daily lamotrigine XR was preferred in 69% of patients, while 17% expressed no preference of once- vs twice-daily administration. Divalproex ER, given once-daily, was preferred by 71% of patients compared with the twice-daily IR preparation. Conclusions: Once-daily dosing of SPN-538 resulted in a high level of patient satisfaction, as evidenced by reported patient preferences for this once-daily formulation compared with twice-daily Topamax. Moreover, over 90% of patients felt that the once-daily SPN-538 formulation helped them to be more adherent to therapy. As adherence to treatment continues to be a major goal in the management of epilepsy, once-daily formulations such as SPN-538 may result in improved effectiveness of therapy and decrease the morbidity, mortality, and associated costs of epilepsy. References: 1. Saini SD et al. Am J Manag Care 2009;15:e22-e33. 2. Tompson DJ et al. Epilepsia 2008;49:410-417. 3. Pierre-Louis SJ et al. Clin Neurol Neurosurg 2009;111:437-441. This study was funded by Supernus Pharmaceuticals, Inc.