Lisdexamfetamine dimesylate (NRP104/LDX) is generally well-tolerated.
By Shire plc
Oct 28, 2006, 05:34

Shire plc (LSE: SHP, NASDAQ: SHPGY, TSX: SHQ) and its collaborative partner New River Pharmaceuticals Inc. (NASDAQ: NRPH) announced today that their investigational ADHD treatment, lisdexamfetamine dimesylate (also known as NRP104 or LDX), yielded a 60 percent improvement in the primary rating scale scores for symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD) in children aged 6 to 12 years who received six months of treatment in an open-label phase III study. Results also demonstrated that at 6 months, 95 percent of children taking lisdexamfetamine dimesylate (NRP104/LDX) produced a "much improved" or "very much improved" rating on the Clinical Global Impressions – Improvement score. These results were presented last weekend at a national meeting of child and adolescent psychiatrists.

"This study further demonstrates the potential of lisdexamfetamine dimesylate to be an effective treatment option for children with ADHD," said Ann Childress, M.D., study investigator and president at the Center for Psychiatry and Behavioral Medicine, Inc. in Las Vegas, Nev. "Lisdexamfetamine dimesylate was designed to offer the effectiveness of a stimulant with a novel prodrug formulation that is inactive until metabolized in the body."

New River Pharmaceuticals designed lisdexamfetamine dimesylate as a new ADHD medication in which d-amphetamine is covalently linked to l-lysine, a naturally occurring amino acid. Designed to provide efficacy throughout the day through 6 p.m., lisdexamfetamine dimesylate (NRP104/LDX) remains inactive until converted in the body and the active drug is released. In January 2005, New River signed a collaborative agreement with Shire to develop and commercialize lisdexamfetamine dimesylate (NRP104/LDX). New River received an approvable letter from the U.S. Food and Drug Administration (FDA) for lisdexamfetamine dimesylate (NRP104/LDX) on October 6, 2006. According to the FDA's letter, marketing approval is contingent upon final scheduling by the U.S. Drug Enforcement Administration (DEA). The FDA has not requested any additional studies. Shire and New River are preparing for a product launch in Q2 2007, pending final labeling and scheduling discussions.

Interim Results of Open Label Phase III Study

The subjects in this study had previously participated in either of two blinded clinical trials of lisdexamfetamine dimesylate (NRP104/LDX). All patients in the current trial received lisdexamfetamine dimesylate (NRP104/LDX) 30 mg in the first week. Investigators titrated patients' daily dosage by 20 mg at weekly intervals during subsequent visits to achieve optimal efficacy and tolerability. The maximum daily dose was 70 mg.

In this study of 269 children with ADHD, six months of treatment with lisdexamfetamine dimesylate (NRP104/LDX) resulted in significant reductions in the participants' average total scores on the Attention-Deficit/Hyperactivity Disorder Rating Scale (ADHD-RS-IV). Specifically, the children had an average reduction of 26.9 points which represents an average improvement of more than 60 percent. ADHD-RS-IV, the primary efficacy measurement tool for the study, is a standard test for assessing symptoms of ADHD. The scale, which contains 18 items, is based on the ADHD diagnostic criteria as defined in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision®, a publication of the American Psychiatric Association.

Investigators also measured the efficacy of lisdexamfetamine dimesylate (NRP104/LDX) with the Clinical Global Impressions - Improvement (CGI-I) scale, in which 95 percent of patients' symptoms were rated as "much improved" or "very much improved" after six months of treatment. The CGI is a standard assessment tool used to rate the severity of illness, change of improvement over time and efficacy of medication.

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