Case Analysis: US FDA approval of Shire’s Mydayis

Shire has announced that the US Food and Drug Administration (FDA) has approved Mydayis (mixed salts of a single-entity amphetamine product), a once-daily treatment comprised of three different types of drug-releasing beads for patients 13 years and older with Attention Deficit Hyperactivity Disorder (ADHD). Mydayis is not for use in children 12 years and younger. 

Clinical Trials:

The US FDA approval of Mydayis is based on results from 16 clinical studies evaluating Mydayis in more than 1,600 subjects, including adolescents (aged 13 to 17 years) and adults with ADHD. In pivotal, placebo-controlled clinical studies, Mydayis significantly improved symptoms of ADHD, as measured by the ADHD-RS-IV and the Permanent Product Measure of Performance (PERMP), in adults and adolescents. Improvement on the PERMP, an objective, validated, skill-adjusted math test that measures attention in ADHD patients, reached statistical significance beginning at 2 or 4 hours post-dose and lasting up to 16 hours post-dose.

In pivotal phase 3 clinical studies where efficacy was the primary endpoint, a morning dose of Mydayis demonstrated superiority to placebo based on the change from baseline in the ADHD-RS-IV total score for adult and adolescent patients, respectively. The most common adverse reactions associated with Mydayis (incidence =5% and at a rate at least twice placebo) in adults are insomnia, decreased appetite, decreased weight, dry mouth, increased heart rate, and anxiety. For pediatric patients (13 years and older), the most common adverse reactions were insomnia, decreased appetite, decreased weight, irritability, and nausea.

In phase 2 studies (two studies in adults and one in adolescents), patients treated with Mydayis demonstrated improved attention compared to placebo, as assessed by the total PERMP score, with results reaching statistical significance beginning at 2 or 4 hours post-dose, and lasting up to 16 hours post-dose. Across all clinical studies, adverse events were generally mild to moderate in severity and similar to those observed with other amphetamine compounds.

About ADHD:

ADHD is a neurodevelopmental disorder that manifests as a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development. An estimated 4.4% of adults have ADHD in the U.S. When applied to the full U.S. adult population aged 18 and over, approximately 10.5 million adults are estimated to have ADHD in the U.S. Approximately 50 to 66% of children with ADHD may continue to have ADHD symptoms as adults. Medication is not appropriate for all individuals diagnosed with ADHD.

Market Scenario:

The new drug Mydayis, previously known as SHP465, contains the same active ingredient as Shire’s widely used attention deficit hyperactivity disorder (ADHD) treatment Adderall XR but is formulated to last up to 16 hours.

Adderall XR, which is also available in generic forms, manages symptoms for up to 12 hours.

Shire, whose ADHD drugs Adderall XR and Vyvanse generated close to $2.4 billion in sales last year. Shire expects to make Mydayis commercially available in the United States in the third quarter of 2017.

The company has said Mydayis could have annual sales of $500 million by 2020.

Both Mydayis and Adderall XR contain amphetamine, a stimulant that elevates levels of dopamine – a neurotransmitter associated with motivation, attention and movement.

As a stimulant, such drugs carry a risk of abuse, can be poorly tolerated, and even be fatal in rare cases. Non-stimulant ADHD treatments have fewer side-effects but are typically less effective.