Pharmacoepidemiol Risk Manage.  2023 Mar;15(1):94-99. 10.56142/perm.23.0003.

A Case of Generalized Maculopapular Rash Induced by Letrozole and Anastrozole

• Kim S
• Kim HJ
• Yoon J
• Seo JH
• Lee JY
• Kang HR

• KMID: 2544381
• DOI: http://doi.org/10.56142/perm.23.0003

Abstract

Aromatase inhibitors are widely used as a treatment for postmenopausal women with hormone receptor-positive breast cancer. They are classified as type 1 steroidal or type 2 nonsteroidal agents. Letrozole and anastrozole are the most frequently used type 2 nonsteroidal inhibitors that share common structure and bind reversibly to aromatase. Both are generally well tolerated; while type A adverse reactions such as hot flashes, vaginal dryness, musculoskeletal pain, and headache can occur, drug hypersensitivity reactions are very rare. Here, we present a case of a 55 years old woman who experienced maculopapular rash to letrozole after five days administration. Her symptoms resolved after chlorpheniramine and dexamethasone injection. Then, she took a single dose of letrozole and symptoms were aggravated. Sixteen days after her initial symptom to letrozole, she switched to anastrozole. After taking anastrozole for two days, she developed urticarial rash and stopped anastrozole arbitrarily. Her symptoms resolved after discontinuing anastrozole. Patients and physicians should be aware of potential cross reactivity to both aromatase inhibitors which may be due to the common structure in the aromatase inhibitors. (PeRM 2023;15:94-99)

Keyword

Aromatase inhibitors; Drug hypersensitivity; Drug-related side effects and adverse reactions; Letrozole; Anastrozole