PHILADELPHIA – May 22, 2009 – Shire plc (LSE: SHP, NASDAQ: SHPGY), the global specialty biopharmaceutical company, announced results of a study showing that coadministration of the ADHD medication VYVANSE® (lisdexamfetamine dimesylate) CII with the proton pump inhibitor (PPI) Prilosec OTC® 40 mg (20 mg X 2), did not alter the median time it took for maximum plasma concentration of d-amphetamine to be reached in the subjects evaluated. In the same study, coadministration of Prilosec OTC with ADDERALL XR resulted in a nearly 45 percent reduction in the median time to reach maximum plasma concentrations of amphetamine, the active medication. Other pharmacokinetic parameters (maximum plasma concentration and area under curve) of active medication were not altered for either VYVANSE or ADDERALL XR when coadministered with Prilosec OTC. This study, which is the first to evaluate the pharmacokinetics of VYVANSE and ADDERALL XR taken alone and with Prilosec OTC 40 mg, was recently presented at the International Congress on Clinical Pharmacy, co-sponsored by the American College of Clinical Pharmacy (ACCP), in Orlando, FL.
"Since its approval for ADHD in adults in 2008, VYVANSE has been an important treatment option for physicians treating adult patients seeking significant ADHD symptom control during their busy day," said Jeffrey Jonas, Senior Vice President of Research & Development for the Specialty Pharmaceuticals business at Shire. "This study is the first to evaluate the impact of a proton pump inhibitor on the amphetamine pharmacokinetics of VYVANSE and ADDERALL XR and further supports that, as a prodrug, VYVANSE does not rely on pH for its absorption or conversion."
Heartburn is a common problem affecting millions of Americans. Prilosec OTC and other proton pump inhibitors reduce the acidity (increase the pH) in the stomach and are commonly used by millions of adults in the United States who suffer from acid reflux. ADHD is estimated to affect 4.4 percent of US adults aged 18 to 44 based on results from the National Comorbidity Survey Replication. When this percentage is extrapolated to the full US population aged 18 and over, approximately 9.8 million adults are believed to have ADHD."
"These study findings may be of particular significance for adults who are taking an ADHD medication along with a proton pump inhibitor, as proton pump inhibitors tend to decrease the production of acid in the stomach," said Dr. Matthew Brams, a psychiatrist in private practice with Bayou City Research, Ltd. in Houston, TX. "In this study, the conversion of VYVANSE to its active form was not affected when coadministered with Prilosec OTC 40 mg, which relates to the characteristics of VYVANSE as a prodrug stimulant."
As a prodrug, VYVANSE is converted to its active form by the body's natural metabolism. This conversion takes place minimally in the gastrointestinal tract and primarily in the blood. Additional pharmacokinetic studies have demonstrated that the conversion of VYVANSE to active medication is unlikely to be affected by alterations in GI transit times and does not rely on gastric pH. ADDERALL XR has a drug delivery system which utilizes immediate release and pH dependent release beads. This pH-dependent delivery system has one type of bead designed to be released immediately and the other type to be released approximately four hours later in the lower intestine where pH levels are higher.
The drug interactions section of the ADDERALL XR product labeling states that coadministration of ADDERALL XR and proton pump inhibitors should be avoided, as these medications act on proton pumps by blocking acid production thereby reducing gastric acidity.
Source: Porter Novelli