USL255 extended-release topiramate: Dose-proportional pharmacokinetics and tolerability in healthy volunteers

Annie M. Clark, Mark B. Halvorsen, Tricia L. Braun, Krista M. Johnson, James C. Cloyd

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Objective Evaluate the pharmacokinetics (PK), safety, and tolerability of single doses of once-daily USL255, Qudexy XR (topiramate) extended-release capsules, over a wide dosing range. Methods Two single-dose, phase I studies in healthy adults were used to evaluate the PK profile and maximum tolerated dose (MTD) of USL255 from 25-1,400 mg. Standard PK parameters assessed included area under the plasma concentration-time curve (AUC) and maximum plasma concentration (Cmax). Dose proportionality, linearity, and intersubject and intrasubject variability (coefficient of variation [%CV]) of AUC and C max were evaluated. Investigator-reported adverse events (AEs) were obtained throughout the studies. Results After the initial increase in plasma concentration levels immediately following administration of USL255 25-1,400 mg, plasma topiramate concentration-time profiles were flat up to 24 h after dosing. AUC was dose proportional from 25-1,400 mg, and Cmax was dose proportional from 50-1,400 mg; both AUC and Cmax were linear across the entire dose range. Low intersubject and intrasubject %CV values were observed for AUC0-t, AUC0-∞, and Cmax (intersubject %CV: 20.2, 19.6, and 22.4%, respectively; intrasubject %CV of dose-normalized mean values: 10.8, 8.2, and 13.2%, respectively). USL255 was generally safe and well tolerated with MTD established at 1,200 mg. Significance These results demonstrate that USL255 provides consistent plasma topiramate exposure across an extended-dosing interval and predictable plasma topiramate concentrations over a wide dosing range. Overall, the favorable safety profile and consistency of exposure suggest once-daily USL255 can be a useful treatment option for patients with epilepsy. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.

Original languageEnglish (US)
Pages (from-to)1069-1076
Number of pages8
Issue number7
StatePublished - Jul 2014


  • Antiepileptic
  • Antiepileptic drug
  • Epilepsy
  • Once-daily
  • Seizures


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