Photosensitized Decomposition of Contraceptive Steroids: A Possible Explanation for the Observed (Photo)allergy of the Oral Contraceptive Pill

Abstract

Abstract The photo‐sensitized decomposition of the main steroids used in the oral contraceptive pill has been studied. Under the circumstances applied, 1 and 8 decomposed rapidly (t ½ = 11.0±0.2 min for 1 and 5.7±0.4 min for 8 ). The decomposition product of 1 has been identified as 17α‐ethynyl‐10β‐hydroperoxy‐17β‐hydroxyestra‐1,4‐dien‐3‐one ( 2 ). The decomposition products of 1 and 8 were previously found in experiments in which the irreversible binding of these steroids to protein was studied. Photosensitized decomposition of the steroids may be the cause of (photo)allergic side‐effects of “the pill”.