Methylphenidate patch-test protocol and irritancy threshold determination in healthy adult subjects

Area of Science:

• Dermatology
• Pharmacology

Background:

• Methylphenidate transdermal system (MTS) is effective but can cause skin reactions like redness and itching.
• Understanding the irritancy of methylphenidate (MPH) is crucial for accurate allergy testing.

Purpose of the Study:

• To determine the irritancy threshold of methylphenidate (MPH) in healthy adults.
• To establish appropriate concentrations for subsequent patch testing.

Main Methods:

• An open-label pilot study involving 20 healthy adults.
• Application of MPH at six different concentrations in two vehicles to the upper back.
• Investigator assessment of skin reactions at 48 and 96 hours.

Main Results:

• No definite positive allergic contact dermatitis reactions were observed at any MPH concentration.
• Minimal doubtful reactions (macular erythema) were noted, decreasing over time.
• Lower MPH concentrations showed slightly more doubtful reactions in both aqueous and petrolatum vehicles.

Conclusions:

• Methylphenidate (MPH) demonstrates low irritancy potential in healthy adults.
• Patch testing with MPH at low-to-mid concentrations (0.1%, 1%, 10%) in petrolatum is recommended for diagnosing contact dermatitis.