Urinary detection of corticosteroid in topical treatment of skin disease by 19F MRS

Abstract

Objective To investigate if it was feasible to quantify the renal excretion of topically applied corticosteroids by 19F MRS. Materials and methods Five participants, one healthy and four with skin diseases, were treated with ointment containing betamethasone 17-valerate. Urine samples were collected for up to 87 h after the initial application. A sample of ointment mixed with urine served as a study control. Organic fractions were obtained after sample freeze drying, and resolved in deuterated chloroform prior to acquisition of 19F MR spectra at 470 MHz for typically 8 h. Results We detected fuorine signals in 40 of the 62 fractions of organic extracts. The corticosteroid was etected in samples from all patients, ranging from 0.1 to 2.8% of the applied steroid. No fuorine signal was obtained in samples from the healthy volunteer. Discussion 19F MRS can be utilized to detect topically applied corticosteroids in urine. However, more work is required to optimize and control for extraction procedures, complete spectral assignments and reliable quantifcation.