Simultaneous determination of ipratropium and salbutamol in rat plasma by LC–MS/MS and its application to a pharmacokinetic study

A novel, sensitive and specific LC–MS/MS method with silica-based solid-phase extraction was developed for simultaneous determination of ipratropium (IPR) and salbutamol (SAL) in rat plasma. Chromatographic separation was achieved on a Shiseido Capcell Pak CR column (SCX:C18 = 1:4, 150 mm × 2.0 mm, 5 μm) with a mobile phase consisting of methanol/water (85:15, v/v) containing 20 mmol/L ammonium formate and 0.1% formic acid at a flow rate of 0.3 mL/min. A tandem mass spectrometric detection with an electrospray ionization (ESI) interface was conducted via multiple reaction monitoring (MRM) under positive ionization mode. This method was validated in terms of specificity, linearity, accuracy (within ±115.4%), intra- and inter-day precision (<11.4%) over the concentration range of 8–1612 pg/mL for IPR and 50–10,000 pg/mL for SAL. In addition, stability and matrix effects of IPR and SAL in plasma were evaluated. This method has been successfully applied to the pharmacokinetic study of compound ipratropium bromide aerosol mainly containing ipratropium bromide (IB) and salbutamol sulphate (SS) after inhalation in rats.

► A novel LC–MS/MS method for the simultaneous determination of ipratropium and salbutamol in rat plasma was described.
► The LLOQs for IPR and SAL were 8 pg/mL and 50 pg/mL, respectively.
► SPE was applied to extract analytes with only 200 μL plasma.
► The drug concentration could be detected until 6 h after administration by this method.