NOVATO, Calif., Feb. 15, 2011 (GLOBE NEWSWIRE) -- Raptor Pharmaceutical Corp. ("Raptor" or the "Company") (Nasdaq:RPTP), today announced it has reopened enrollment in its Phase 3 clinical trial of its proprietary delayed-release oral formulation of cysteamine bitartrate ("DR Cysteamine") in patients with nephropathic cystinosis ("cystinosis"). The pivotal Phase 3 clinical trial is designed as a study of the safety, tolerability, pharmacokinetics ("PK") and pharmacodynamics ("PD") of DR Cysteamine compared with immediate-release cysteamine bitartrate. The design of the pivotal Phase 3 clinical trial is a result of discussions with the FDA through which the FDA provided significant guidance on trial protocol design, clinical endpoints, and a statistical analysis plan ("SAP"). The primary endpoint of the trial is the steady-state white blood cell ("WBC") cystine levels of patients taking DR Cysteamine, dosed every twelve hours, compared to immediate-release cysteamine bitartrate, which requires dosing every six hours. At defined intervals during the clinical study, WBC cystine measurements are taken from each patient, one per day, over three day periods. The spread of these daily measurements is used to calculate a statistical value called the intra-patient variance and this value, as defined in the SAP, is used to determine the total number of patients required in the study. As defined in the SAP, the total number of patients required to complete the study, is determined by an interim statistical analysis of intra-patient variance of the first 20 patients once they had completed the study. Last month, the Company reported completion of enrollment based upon an intra-patient variance report received by the Company, which determined that a total of 30 patients would be required to complete the study. As of February 7, 2011, a total of 31 patients successfully completed the study. Upon final quality control and quality assurance review of the clinical data set, but prior to database lock, it was reported to the Company that the calculation used to determine the intra-patient variance value contained a mathematical error. A repeat of the 20-patient interim analysis of the intra-patient variance using the corrected data resulted in an increase in the required patient number to 36 patients, rather than 30, as previously reported. Therefore, as required in the SAP, the Company is obligated to enroll at least 36 patients in the trial.