An Investigation of the New Breed of ADHD Treatment
9 May 2011
On April 23, 2008, Vyvanse (lisdexamfetamine) received FDA approval for the adult population. The approval of this drug marked a new era in evolution of Attention Deficit Hyperactivity Disorder treatments. After decades of criticism on the rampant abuse and alleged overprescribing of amphetamine ADHD medications New River Pharmaceuticals responded by developing lisdexamfetamine, a compound that is inactive until converted to dextroamphetamine by the gastrointestinal tract. This means that Vyvanse is only effective when taken orally, reducing the potential for abuse. Moreover, that Vyvanse lasts much longer than typical amphetamine ADHD medications. One administration of the drug lasts throughout an entire day. Although this drug removes a few issues pertaining to amphetamine treatment of ADHD, there has been questioning as to its efficacy in treating the full range of symptoms caused by ADHD because it is broken down into dextroamphetamine alone instead of a combination of amphetamines such as Adderall. Nevertheless, Vyvanse has been established as efficacious in the treatment of ADHD symptoms. In order investigate this new breed of ADHD treatment more completely one must understand the neurobiology of ADHD, the pharmacodynamics and pharmacokinetics of lisdexamfetamine, and what the empirical evidence on Vyvanse suggests.
Before one can understand how lisdexamfetamine works to alleviate the symptoms of ADHD, further explanation of the disorder is required. According to the Diagnostic and Statistical Manual of Mental Disorders, Attention Deficit Hyperactivity Disorder can be broken down into three sections: inattention, hyperactivity, and impulsivity. Inattention consists of symptoms such as careless mistakes on schoolwork, trouble with organization, distractibility, inability to listen when spoken to directly, and avoiding tasks that require concentrated mental effort. Fidgeting, running about or climbing inappropriately, trouble enjoying leisurely activities, and excessive talking can indicate hyperactivity. Impulsivity is comprised of trouble waiting one’s turn, blurting out answers before one is finished speaking, and interrupting others. Noting 6 or more of these symptoms can make a diagnosis. With varying combinations of these symptoms, there are 3 types of ADHD that can be identified; Combined type, Predominantly Inattentive type, and Predominantly Hyperactive and Impulsive type. The methods of diagnosis for ADHD have been constantly evolving since its discovery, from merely observation to complicated clinical tests. Clinical procedures are still used to diagnose ADHD, yet the advancement of technology now allows the physical manifestations of ADHD to be made visible with Functional Magnetic Resonance Imaging (fMRI). This technology allows doctors and researchers to gauge the levels of neurotransmitters in the brain in association with the activity or lack of activity in certain brain regions. Dr. Helen Courvoisie completed one of the first studies on ADHD using this technology. Courvoisie states, “Our data show children with ADHD had a two-and-half-fold increased level of glutamate, an excitatory brain chemical that can be toxic to nerve cells… The data also suggest a decreased level of GABA, a neuro-inhibitor. This combination may explain the behavior of children with poor impulse control”. This study measured neurotransmitter metabolites in a specific section of the frontal lobe. Toxic levels of glutamate in the prefrontal cortex and temporal lobes of children with ADHD can lead to neuronal damage, cell death, and resulting inactivity in these regions.
One theory proposes that, for those with ADHD, there is a dysfunction in the dopamine transfer system. A dysfunction in dopamine transfer suggests that while dopamine response to reinforcing stimuli occurs quickly...