A fast and sensitive UHPLC-MS/MS method for the determination of N-butylscopolamine in human plasma: application in a bioequivalence study.

We have developed and validated a fast and sensitive ultra high-performance liquid chromatography with positive ion electrospray ionization tandem mass spectrometry method for determining N-butylscopolamine levels in human plasma using propranolol as an internal standard. The acquisition was set up in the multiple reaction monitoring mode with the transitions m/z 360.3 → 138.0 for N-butylscopolamine and m/z 260.2 → 116.1 for IS. This method uses a liquid-liquid extraction process with dichloromethane. The analyte and IS were chromatographed on a C18 , 50 × 2.1 mm, 1.7 µm column through isocratic elution with acetonitrile-5 mm ammonium acetate (adjusted to pH 3.0 with formic acid). The method was linear in the 1-1000 pg/mL range for N-butylscopolamine and was selective, precise, accurate and robust. The validated method was successfully applied to perform a bioequivalence study of the reference (Buscopan® , from Boehringer Ingelheim) and the test sample coated-tablet formulations (from Foundation for Popular Remedy), both containing 10 mg of N-butylscopolamine bromide administered as a single dose. Using 58 healthy volunteers and accounting for the high intra-individual variability confirmed by statistical calculations (38%), the two formulations were considered bioequivalent because the rate and extent of absorption (within 80-125% interval), satisfying international requirements.

Development and validation of a UPLC-ESI-MS/MS method for the determination of N-butylscopolamine in human plasma: application to a bioequivalence study.

A sensitive and fast ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) method for measurements of N-butylscopolamine in plasma was developed and validated. A single protein precipitation was proposed for the clean up of the plasma and N-methylhomatropine was added as internal standard (IS). The analyses were carried out using a C(18) column and mobile phase of acetonitrile: 5 mM ammonium acetate + 0.1% formic acid (90:10, v/v). The triple quadrupole mass spectrometer equipped with an electrospray source in positive mode, was set up in selective reaction monitoring, to detect precursor → product ion 360.0 → 194.0 m/z and 290.3 → 138.0 m/z transitions, for N-butylscopolamine and IS, respectively. The method was linear in 0.03 (lower limit of quantitation; LLOQ) - 10.00 ng/ml range for N-butylscopolamine. Satisfactory selectivity, linearity, precision, accuracy, and robustness were obtained for the UPLC-ESI-MS/MS method. The proposed method was successfully applied to a pharmacokinetic study of healthy human volunteers; the results showed that the two scopolamine butylbromide formulations tested are not bioequivalent in rate and extent of absorption.