DANGERS OF STIMULANT PATCH MISUSE
In “New warning on stimulants for ADHD: Cause for alarm?” (Current Psychiatry, October 2006), Drs. Lenard Adler and Anthony Rostain discuss new FDA warnings on stimulant use in ADHD. However, the development of a transdermal form of methylphenidate raises issues about potential toxicity.
Transdermal methylphenidate is designed to produce safe, sustained levels of medication when used as indicated. However, chewing, sucking, or swallowing the patch can lead to sudden, potentially toxic increases in methylphenidate levels.1 Even repositioning or reattaching a patch that has come off or scratching a patch that itches can disrupt the control membrane and cause increased and unregulated exposure to the highly concentrated drug.2,3
Although the likelihood of such misuse might be remote, this risk depends on the patient’s and his peer group’s knowledge about the dangers of patch misuse. Just telling the patient about the risks of misuse could inspire him or her to intentionally misuse the patch. Yet ethics and the law require full disclosure of these risks to the patient and parents of minor patients. In the case of children, the school should be informed as well.
Physicians need to know when not to prescribe transdermal stimulant medication. Transdermal patch misuse is expected to be higher in those with substance abuse or suicidal impulses and in highly impulsive or oppositional patients. Also be careful when using transdermal medications in inpatient psychiatric units or on residential substance abuse units where unpredictable behaviors might be magnified. At home, small children might find and ingest used patches discarded by another family member.2
Used transdermal patches may retain a large portion of the drug and are a potential source of abuse.3 For example, the amount of residual drug in a clonidine patch varies from 20% to 70% even after 7 days of use.3
When a person swallows a transdermal patch, exposure to the drug reservoir may be maximized and the situation may become more urgent. An ICU technique used in children called whole bowel irrigation might help reduce toxicity by expediting the patch’s movement through the bowel.3
A. Preston West, MD
West Los Angeles Veterans Affairs Health Care Center
1. Harris JM. Clonidine patch toxicity. DICP 1990;24(12):1191-3.
2. Broderick-Cantwell JJ. Case study: accidental clonidine patch overdose in attention deficit/hyperactivity disorder patients. J Am Acad Child Adolesc Psychiatry 1999;38(1):95-8.
3. Horowitz R, Mazor SS, Aks SE, Leikin JB. Accidental clonidine patch ingestion in a child. Am J Ther 2005;12:272-4.