A double-blind investigation of the potential systemic absorption of isotretinoin, when combined with chemical sunscreens, following topical application to patients with widespread acne of the face and trunk

This study assessed the systemic absorption of isotretinoin and its metabol ites, during a 4-week application of a cream containing 0.1% isotretinoin a nd chemical sunscreens, compared with a 4% benzoyl peroxide cream, in patie nts with acne on the face and trunk, Blood was drawn at weeks 0, 1, 2, 3 an d 4 and at 96 h post-treatment, Plasma levels of isotretinoin (13-cis-retin oic acid) and tretinoin (all-trans-retinoic acid) were quantified by liquid chromatography with tandem mass spectrometry and the presence of their com bined l-oxo metabolites were monitored from the peak area ratios observed, The isotretinoin group showed no statistically or clinically significant in creases in plasma retinoid levels and mean levels did not exceed +/-2 SD of the mean pre-treatment values, indicating that endogenous levels were not being exceeded. No significant differences were detected between the isotre tinoin group and the 4% benzoyl peroxide group. These findings indicated th at retinoid absorption from a cream containing 0.1% isotretinoin and chemic al sunscreens was clinically insignificant, when applied to patients with w idespread acne.