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Lisdexamfetamine approved for treating ADHD.

Lisdexamfetamine dimesylate is a new addition to the armamentarium of extended-release stimulants for treating attention-deficit/hyperactivity disorder in young children.

It was recently approved by the Food and Drug Administration for treatment of attention-deficit/hyperactivity disorder (ADHD) in patients aged 6-12 years.

Lisdexamfetamine (Vyvanse, Shire/ New River Pharmaceuticals) is a pro-drug of d-amphetamine. In this unique formulation, it is covalently linked to 1-lysine, an amino acid, and remains inactive until metabolized by the gastrointestinal tract. This metabolism is a rate-limiting effect that provides sustained release. Unlike other extended-release stimulants for ADHD, the active ingredient is not encapsulated in a matrix or bead formulation.

Data from clinical studies in which children with ADHD took the agent in the morning, showed that they still had control of symptoms at 6:00 p.m. on the same day.

The prodrug is inert outside the body, and because the drug is long-acting, there is no immediate high for someone who tries to abuse lisdexamfetamine. "If you grind it and stick it up your nose or stick it in your veins, it's not active," said Dr. Oscar Bukstein, who is on the psychiatry faculty at the University of Pittsburgh.

"The whole purpose of the prodrug seems to be that it is less addictive," said Dr. Raul Silva, vice chairman of the department of child and adolescent psychiatry at New York University, New York, said in an interview.

The manufacturer conducted two studies in known substance abusers, and participants reported a lower preference for lisdexamfetamine, compared with equivalent doses of d-amphetamine.

The U.S. Drug Enforcement Administration accepted the FDA recommendation for a Schedule II controlled substance designation for lisdexamfetamine. However, a final decision is still pending. Other stimulants for ADHD, including Adderall XR (mixed salts of a single entity amphetamine product, Shire), Concerta (methylphenidate HCl, Johnson & Johnson), and Focalin XR (dexmethylphenidate HCl, Novartis), also have a Schedule II designation.

Clinical trials demonstrated statistically significant improvements in ADHD symptoms, compared with placebo at all once-daily doses (30 mg, 50 mg, and 70 mg). A phase II study showed both Vyvanse and Adderall XR improved classroom behavior ratings, compared with placebo using the Swanson, Kotkin, Agler, M. Flynn and Pelham (SKAMP) deportment rating scale. Also, both drugs significantly improved academic productivity, compared with placebo on the Permanent Product Measure of Performance (PERMP) instrument, an age-adjusted collection of math problems that measures a child's ability to pay attention and stay on task.

In a phase III, randomized, double-blind placebo-controlled study, lisdexamfetamine significantly improved the 18-item ADHD Rating Scale (ADHD-RS-IV) scores, compared with placebo after 4 weeks.

Lisdexamfetamine improved ADHD symptom rating scale scores by 60% among children aged 6-12 years who received 6 months of treatment in an open-label, phase III study. Clinicians reported a "much improved" or "very much improved" rating on the Clinical Global Impressions-Improvement score scale for 95% of children.

The medication was generally well tolerated in these clinical studies. Decreased appetite, difficulty falling asleep, stomach ache, and irritability were the most commonly reported side effects. It should not be prescribed for patients with arteriosclerosis, symptomatic heart disease, moderate to severe hypertension, hyperthyroidism, seizures, glaucoma, agitated states, a history of substance abuse problems, a known allergy or unusual reactions to sympathomimetic amines, or for patients who have taken a monoamine oxidase inhibitor in the previous 14 days.

Parents and patients should watch for development of any symptoms that suggest heart problems, such as chest pain or fainting, and monitor children for blurred vision.

Aggression, new abnormal thoughts/ behaviors, mania, growth suppression, worsening of motion or verbal tics, and Tourette's syndrome has been associated with stimulants, said the manufacturer.

Dr. Silva has no affiliation with Shire/New River Pharmaceuticals. Dr. Bukstein is a consultant and speaker for Shire/New River Pharmaceuticals.

BY DAMIAN McNAMARA

Miami Bureau
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Title Annotation:News; attention deficit/hyperactivity disorder
Author:McNamara, Damian
Publication:Family Practice News
Date:Apr 15, 2007
Words:630
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