Skin prick test responses to codeine, histamine, and ragweed utilizing the Multitest device

Area of Science:

• Immunology
• Dermatology
• Allergy Diagnostics

Background:

• Epicutaneous skin testing is a key diagnostic method for allergic conditions.
• Positive controls are essential for standardizing and interpreting skin prick test results.

Purpose of the Study:

• To evaluate codeine phosphate as a positive control in skin prick testing.
• To compare the reliability of codeine phosphate and histamine phosphate as positive controls.
• To assess their utility in grading reactions to allergens such as ragweed.

Main Methods:

• Utilized the Multitest device for skin prick testing in 56 human subjects.
• Administered codeine phosphate (30 and 3 mg/mL) and histamine phosphate (2.75 mg/mL) as positive controls.
• Assessed wheal responses and sizes, and calculated relationships and variability.

Main Results:

• Histamine phosphate induced wheals in 52/56 subjects; codeine phosphate induced wheals in 39/56 and 30/56 subjects.
• Wheal sizes for codeine and histamine showed significant concordance.
• Histamine controls exhibited lower intersubject variability (44%) compared to codeine (64-65%).
• Grading ragweed reactions using allergen-to-control ratios differed between codeine and histamine.

Conclusions:

• Codeine phosphate demonstrates a concordant relationship with histamine in skin prick testing.
• Histamine phosphate provides a more consistent and reliable positive control due to lower variability.
• Findings suggest implications for the use of codeine phosphate as a positive control in allergy testing.