Anaphylaxis associated with a change in premarin dye formulation

Area of Science:

• Pharmacology
• Allergy and Immunology

Background:

• Coloring agents are common additives in pharmaceuticals, foods, and cosmetics.
• The U.S. Food and Drug Administration (FDA) permits changes to approved additives without physician notification.
• Patients may develop unexpected allergic reactions to medications due to altered inactive ingredients.

Observation:

• A patient experienced severe allergic reactions including angioedema, wheezing, urticaria, and dizziness shortly after taking a new batch of Premarin (conjugated estrogens).
• The patient had a history of tolerating Premarin for seven months without adverse effects.
• The new Premarin tablets had a different shade of maroon, indicating a change in dye formulation (FD&C Red #3 and FD&C Yellow #6 replaced with FD&C Red #40 and D&C #27).

Findings:

• Skin puncture testing with the new Premarin batch was positive for the patient, while testing with a dye-free drug was negative.
• Standard Premarin skin testing in two healthy volunteers yielded negative results.
• The patient tolerated transdermal estrogen therapy without any adverse reactions, suggesting the estrogen itself was not the allergen.

Implications:

• The patient's anaphylaxis was likely caused by a new dye additive in the Premarin tablet, not the active estrogen ingredient.
• This case highlights the potential for sudden, severe allergic reactions to previously tolerated medications due to unannounced changes in inactive ingredients.
• Healthcare providers must be vigilant about potential alterations in drug formulations, including inactive components, and their implications for patient safety and medication tolerance.