Intuniv (guanfacine extended-release)

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.

Company: Shire Pharmaceuticals
Approval Status: Approved September 2009
Treatment Area: ADHD in children and adolescents

General Information

Intuniv is a once-daily, extended-release formulation of guanfacine hydrochloride in a tablet formulation. Guanfacine is a selective alpha2A-adrenergic receptor agonist. Guanfacine is not a central nervous system (CNS) stimulant. The mechanism of action of guanfacine in ADHD is not known.

Intuniv is specifically indicated for the treatment of Attention Deficit Hyperactivity Disorder (ADHD) in children and adolescents ages 6 to 17 years.

Intuniv is supplied as an extended release tablet designed for oral administration. The recommended initial dose is a single tablet once daily. If switching from immediate-release guanfacine, discontinue that treatment, and titrate with Intuniv according to the following recommended schedule: Begin at a dose of 1 mg/day, and adjust in increments of no more than 1 mg/week. Maintain the dose within the range of 1-4 mg once daily, depending on clinical response and tolerability.
Maintenance Treatment The effectiveness of Intuniv for longer-term use (more than 9 weeks) has not been systematically evaluated in controlled trials.
Discontinuation The Intuniv dose should generally be tapered in decrements of no more than 1 mg every 3 to 7 days.

Clinical Results

FDA Approval
The FDA approval of Intuniv for ADHD in children and adolescents was based on two placebo controlled clinical trials.

Study One was an 8-week, double-blind, placebo controlled, parallel-group, fixed dose design in 345 children and adolescents ages 6-17. The subjects received 2 mg, 3 mg and 4 mg of Intuniv dosed once daily. Study Two was a 9-week, double-blind, placebo-controlled, parallel-group, fixed-dose design in 324 children and adolescents ages 6-17. The subjects received 1 mg, 2 mg, 3 mg and 4 mg of Intuniv dosed once daily. The lowest dose of 1 mg used in Study 2 was assigned only to patients less than 50 kg (110 lbs).

In both studies, the primary outcome was the change from baseline to endpoint in mean ADHD-RS scores. The mean reductions in ADHD-RS scores at endpoint were statistically significantly greater for all doses of Intuniv compared to placebo in both studies. Dose-responsive efficacy was evident, particularly when data were examined on a weight adjusted (mg/kg) basis. When evaluated over the dose range of 0.01-0.17 mg/kg/day, clinically relevant improvements were observed beginning at doses in the range 0.05-0.08 mg/kg/day. Analyses of the primary outcome did not suggest any differential responsiveness on the basis of gender. Analyses by age subgroup revealed a statistically significant treatment effect only in the 6-12 age subgroup. Due to the relatively small proportion of adolescent patients (ages 13-17) enrolled into these studies (approximately 25%), these data may not be sufficient to demonstrate efficacy in the adolescent subgroup.

Side Effects

Adverse events associated with the use of Intuniv may include, but are not limited to, the following:

somnolence
sedation
abdominal pain
dizziness
hypotension/decreased blood pressure
dry mouth
constipation

Mechanism of Action

Literature References

Sallee FR, Lyne A, Wigal T, McGough JJ Long-term safety and efficacy of guanfacine extended release in children and adolescents with attention-deficit/hyperactivity disorder. Journal of Child and Adolescent Psychopharmacology 2009 Jun;19(3):215-26

Biederman J, Melmed RD, Patel A, McBurnett K, Donahue J, Lyne A Long-term, open-label extension study of guanfacine extended release in children and adolescents with ADHD. CNS Spectrums 2008 Dec;13(12):1047-55

Sallee F, McGough J, Wigal T, Donahue J, Lyne A, Biederman J; FOR THE SPD503 STUDY GROUP Guanfacine Extended Release in Children and Adolescents With Attention-Deficit/Hyperactivity Disorder: A Placebo-Controlled Trial. Journal of the American Academy of Child and Adolescent Psychiatry 2008 Dec 20

Biederman J, Melmed RD, Patel A, McBurnett K, Konow J, Lyne A, Scherer N; SPD503 Study Group A randomized, double-blind, placebo-controlled study of guanfacine extended release in children and adolescents with attention-deficit/hyperactivity disorder. Pediatrics 2008 Jan;121(1):e73-84

Boellner SW, Pennick M, Fiske K, Lyne A, Shojaei A Pharmacokinetics of a guanfacine extended-release formulation in children and adolescents with attention-deficit-hyperactivity disorder. Pharmacotherapy 2007 Sep;27(9):1253-62

Cohn LM, Caliendo GC Guanfacine use in children with attention deficit hyperactivity disorder. The Annals of Pharmacotherapy 1997 Jul-Aug;31(7-8):918-9

Additional Information

For additional information regarding Intuniv or ADHD, please visit the Intuniv web page.

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