A SEMIAUTOMATED SOLID-PHASE EXTRACTION AND RADIORECEPTOR ASSAY FOR THE ANALYSIS OF SCOPOLAMINE IN URINE AND PLASMA

In a double-blind placebo-controlled cross-over study, we evaluated th e therapeutic efficacy of transdermal scopolamine in ten patients with reversible airways obstruction. They received a patch (Scopoderm(R) T TS) behind the ear for three days and samples of blood and urine were taken. A highly sensitive method was developed and validated to measur e the low levels of free and total scopolamine in urine and plasma. Th e procedure consisted of a semi-automated solid-phase extraction follo wed by the analysis using radioreceptor assays. The mean plasma concen trations, taken every third patch day, of free and total scopolamine w ere 43.6 pg/ml and 229.0 pg/ml, respectively. In 24-h urine, collected every second patch day, 6.3 mu g of free scopolamine and 83.4 mu g to tal scopolamine was excreted. This means that 70% of the delivered dos e (120 mu g in 24 h) is excreted in urine. For urine samples, the limi t of detection (LOD) of the assay is 550 pg/ml and the limit of quanti tation (LOQ) is 610 pg/ml. For plasma samples, the LOD is 16 pg/ml and the LOQ is 38 pg/ml. (C) 1997 Elsevier Science B.V.