Intuniv: One Step Closer To FDA Approval for ADHD
Monday, June 16th, 2008
Thirty percent of children with AD/ADHD cannot tolerate taking stimulant medications.
For these individuals, the recent news that Shire is one step closer to gaining FDA approval for its time-released non-stimulant INTUNIV is welcome news.
Intuniv provides a 24-hour evenly released dose of the medication guanfacine. Specifically, guanfacine improves the symptom of the inability to concentrate in children with ADD/ADHD.
When given in conjunction with stimulants, it may also help reduce the aggression and the insomnia normally associated with the use of these drugs.
In fact, some physicians already prescribe it – in an immediate release version and under various brands – to their patients with ADD/ADHD along with other medications. The most common brand used is Tenex. This medication, however, appears not to be very effective at alleviating either the attention deficit or the distractibility seen in children with ADD/ADHD.
Two advantages of INTUNIV
Manufactured and marketed as INTUNIV, though, this form of the medication would hold two distinct advantages over what is currently being used. First, it would be approved specifically for the treatment of ADD/ADHD. And secondly – and most importantly to those whose concentration is low – it would relieve the unevenness produced by the immediate-release version of guanfacine.
Guanfacine works well in improving concentration, but it only lasts several hours, and once the medication wears off attentiveness wanes again.
Recent clinical trials conducted as part of the FDA approval process show that INTUNIV is extremely effective at boosting concentration levels consistently for a 24-hour period
The data the FDA scrutinized included the pooled analysis of results from two double-blind trials. Both of these studies used the teacher based ADHD Rating scale as the criteria for improvement.
One group of children received INTUNIV for the other group received a placebo which contained no medication.
All groups which received the medication scored significantly better in the rating scale than those who received the placebo.
The studies also examined the length of time the medication was effective for these children. Assessments were made at 12, 14 and 24 hour periods following the administration of this drug. Again the data showed significant improvement in the concentration of the children at each of these points in time.
Mild and moderate side effects of INTUNIV
Between 75 and 80 percent of the children, did display mild adverse side effects while taking INTUNIV, most of which appeared within the first two weeks and eventually tapered off. These seemed to be dose-related and included: upper abdominal pain, constipation, dizziness, hypotension, sedation, dry mouth, and drowsiness.
The most common of these side effects were related to sedation.
The medical community has been examining guanfacine for its effectiveness since 2001. That year a study appeared in the American Journal of Psychiatry showing that guanfacine to be a safe and effective treatment for children with ADHD and those who suffer with tic disorders.
The medication, according to the journal article, produced a mean improvement of 37 percent in the total score on teacher-rated ADHD Rating Scale following eight weeks of treatment. This was compared to the eight percent improved for those who received the placebo.
INTUNIV is not a controlled substance — as stimulants are — and does not appear at this time to carry any risk for either potential for abuse or dependence.
The FDA has issued an “approval letter” for INTUNIV, which means that it is prepared to approve the new drug application as soon as certain conditions are met, such as any requests for additional information.
How guanfacine works
Guanfacine works, according to Shire, by acting indirectly on the prefrontal cortex of the brain. Located directly at the very front of the brain and directly below the forehead, the prefrontal cortex controls what are known as the executive functions. This includes the resolution of conflicting thoughts, the choices involved in “right or wrong” and “good and bad” decisions, as well as the prediction of future events.
This section of the brain also governs social control that is it is the area used when we suppress or emotional urges.
Guanfacine is a selective alpha-2A-agonist medication.
Admittedly, the treatment of ADD/ADHD is a highly individualized challenge. Discovering the most effective combination the proper medications and other forms of therapy may mean attempting to use several medications in various combinations as well as varying doses. What is appropriate for one child or adult, may not be either appropriate or effective for another.
Nearly 8 percent of all school-aged children have been diagnosed with ADD/ADHD, according to the U.S. Centers for Disease Control and Prevention. While not normally thought of as a disorder affecting adults, some 4.4 percent of all adults, ages 18 to 44 are affected.
The major characteristic of ADD/ADHD is an inattention or hyperactivity-impulsivity that exceeds those normally observed in most individuals. Official diagnosis of this disorder can not be made until the symptoms have been observed for at least six months.
References:
Pro-drug gets attention,
http://www.sciam.com/article.cfm?id=pro-drug-gets-attention, accessed 11 Jun08
Guanfacine, http://www.depression-guide.com/guanfacine.htm, accessed, 7 Jun 08
Intuniv reduces ADHD symptoms, http://www.realmentalhealth.com/adhd/adhd_toc.asp, accessed 6 Jun 08
Shire Investigational Nonstimulant INTUNIV Showed Significant Efficacy In Reducing ADHD Symptoms, http://www.medicalnewstoday.com/articles/106801.php, accessed 10 Jun 08.
What is prefrontal cortex?, http://www.wisegeek.com/what-is-the-prefrontal-cortex.htm, accessed, 11 June 08
Larry Scahill, M.S.N., Ph.D., Phillip B. Chappell, M.D., Young S. Kim, M.D., Robert T. Schultz, Ph.D., Lily Katsovich, M.S., Elizabeth Shepherd, M.A., Amy F.T. Arnsten, Ph.D., Donald J. Cohen, M.D., and James F. Leckman, M.D. A Placebo-Controlled Study of Guanfacine in the Treatment of Children With Tic Disorders and Attention Deficit Hyperactivity Disorder, http://ajp.psychiatryonline.org/cgi/content/abstract/158/7/1067, accessed 11Jun08
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