Side effects resulting from drugs taken for attention deficit hyperactivity disorder (ADHD) are unfortunately quite common. As with any condition, these unwanted effects can be severe enough to cause ADHD patients to discontinue their treatment.
It is important for physicians to be aware of side effects from real world experience as well as information supplied by drug companies. A team from Quintiles Inc., the drug company consultants based in Falls Church, Va., looked at patient-reported side effects of ADHD drugs. The drugs covered were amphetamine and dextroamphetamine (Dexedrine); atomoxetine (Strattera); dexmethylphenidate (Focalin); lisdexamfetamine (Vyvanse); and methylphenidate (Concerta, Ritalin).
Results showed that 48 percent of the 325 patients surveyed reported at least one side effect, most often loss of appetite, sleep problems, and mood swings. Differences between the drugs in terms of side effects were thought to be minor. About a fifth (21 percent) of the side effects were considered “very bothersome” or “extremely bothersome,” but only 20 percent of patients mentioned the side effects to their physicians.
The rate of side effects appeared similar for drugs that stimulate the central nervous system and nonstimulant drugs. However, mood disturbances were more common on stimulants, whereas nausea and gastrointestinal problems were more common on nonstimulants.
Researcher Dr. Sharon B. Wigal commented that drug treatment of ADHD typically brings significant therapeutic benefits. But “also evident is the associated pattern of relatively common adverse events that may impact, and even impair, short- and long-term outcomes.”
She explains that side effects can vary by the age of the patient, with preschoolers often having stronger side effects. Most side effects settle down in a couple of weeks, or with a reduction in dose or change in timing. In fact, many are dose-dependent, she says. Nevertheless, they are often the reason why patients stop treatment.
A 2003 investigation into physicians’ perceptions of ADHD drugs found that “the stimulant drug side effects of decreased appetite or weight loss, sleep disruption, and exacerbation of anxiety were a concern for 32 percent, 50 percent, and 22 per of physicians, respectively.”
About 38 percent of the 365 physicians who completed the survey said they would prefer to prescribe a nonstimulant than a stimulant medication. The researchers state, “While many physicians consider the side effects of the stimulants easily managed, others are concerned about prescribing stimulants because of their side effects.” They add that, “The majority of physicians would prefer to prescribe a noncontrolled medication without abuse potential instead of a controlled medication to treat children or adolescents with ADHD.”
Physicians were more likely to believe that side effects are easily managed if they were child and adolescent psychiatrists, which suggests that those who have more experience in treating children and adolescents with attention deficit disorder are more confident in managing stimulant side effects.
Longer-acting drug formulations used once daily are often preferred, to avoid the need to take medication during the daytime, and to minimize side effects. Lisdexamfetamine, sold as Vyvanse, is a new amphetamine which has been shown to work for up to ten hours in children and adults with ADHD. It has a side effect profile similar to other longer-acting amphetamine drugs.
Dr. Brian J. Cowles from the Albany College of Pharmacy and Health Sciences, Vermont, believes that owing to its unique composition, lisdexamfetamine “may lead to a possible reduction of abuse potential.” He says that side effects linked to lisdexamfetamine include decreased appetite, insomnia, irritability, weight decrease, headache, and upper abdominal pain. These tend to occur most at the start of treatment, or following an increase in dose.
A further study confirmed that over 95 percent of side effects occurrences for all doses of lisdexamfetamine are mild or moderate. But nine percent of the 272 children in the study discontinued treatment due to the drug’s side effects.
Research has also looked at the long-term side effects of ADHD medications. A 2007 review examined the evidence and found possible links to appetite and growth, both height and weight. Loss of appetite has been reported in up to 60 percent of children on stimulant drugs. Two major reviews examined all the available data and both concluded that stimulants may be associated with a reduction in expected height gain, at least in the first three years of treatment.
But Dr. Willemijn M. Meijer of the PHARMO Institute in Utrecht, The Netherlands, says the deficits in height and weight “do not appear to be a clinical concern for most children treated with stimulants.” He adds that, “The importance of good nutrition should be pointed out to parents.”
Fears have also been raised about potential long-term effects of stimulant drugs on the heart and on the child’s developing brain. But the available data on these outcomes is limited, so the true effects are still unknown. So far, long-term studies have been inconclusive or contained methodological flaws, so further information is needed. Drugs used to treat attention deficit disorder are generally considered safe and effective.
Cascade, E., Kalali, A. H. and Wigal, S. B. Real-World Data on: Attention Deficit Hyperactivity Disorder Medication Side Effects. Psychiatry (Edgmont), Vol. 4, April 2010, pp. 13-15.
Stockl, K. M. et al. Physician perceptions of the use of medications for attention deficit hyperactivity disorder. Journal of Managed Care Pharmacy, Vol. 9, September-October 2003, pp. 416-23.
Cowles, B. J. Update on the management of attention-deficit/hyperactivity disorder in children and adults: patient considerations and the role of lisdexamfetamine. Therapeutics and Clinical Risk Management, Vol. 5, 2009, pp. 943-48.
Domnitei, D. and Madaan, V. New and extended-action treatments in the management of ADHD: a critical appraisal of lisdexamfetamine in adults and children. Neuropsychiatrtric Disease and Treatment, Vol. 6, May 25, 2010, pp. 273-79.
McDonagh, M. S. et al. Drug Class Review on Pharmacologic Treatments for ADHD: Final Report. Portland Oregon Health & Science University, December 2007.
Meijer, W. M. et al. Current issues around the pharmacotherapy of ADHD in children and adults. Pharmacy World and Science, Vol. 31, October 2009, pp. 509-16.