Quantitative analysis of a quaternary ammonium drug: ipratropium bromide by LC/ESI-MS(n) in horse plasma and urine.

A quantitative method, using LC/ESI-MS(n) with a quadrupole linear ion trap mass analyzer, has been developed for the analysis of ipratropium cation in horse plasma and urine. The method applies solid-phase extraction with WCX cartridges for plasma and MM2 cartridges for urine, prior to analysis by LC/ESI-MS(n). The efficiency of extraction combined with the sensitivity and the selectivity of MS(n) allows for the quantification of ipratropium cation at picogram per milliliter levels. The analytical capabilities of the method have been successfully checked by the quantitative analysis of ipratropium cation in post-administration samples collected from horses treated by nebulization.

Analyses of quaternary ammonium drugs in horse urine by capillary electrophoresis-mass spectrometry.

A capillary electrophoresis-mass spectrometry (CE-MS) method for the analysis of quaternary ammonium drugs in equine urine was developed. Quaternary ammonium drugs were first extracted from equine urine by ion-pair extraction and then analysed by CE-MS in the positive electrospray ionization (ESI) mode. Within 12 min, eight quaternary ammonium drugs, each at 1 ng/mL in horse urine, could be detected. The confirmation of these drugs in urine samples was achieved by capillary electrophoresis tandem mass spectrometry (CE-MS/MS). A direct comparison of this method was made with existing liquid chromatography/mass spectrometry (LC-MS) methods in the detection and confirmation of glycopyrrolate and ipratropium bromide in horse urine. While the two drugs could be detected within the same CE-MS run at 1 ng/mL in urine, they could only be detected in separate LC-MS runs at 5 ng/mL in urine. In addition, CE-MS consumed a much smaller volume of extract; the analyte peak widths, in some cases, were much narrower; and as the quaternary ammonium ions were well separated electrophoretically from the mainly neutral urine matrix, a much cleaner background in the CE-MS total ion trace was observed.

Pharmacokinetics of ipratropium bromide after single dose inhalation and oral and intravenous administration.

Single doses of ipratropium bromide were administered intravenously, orally and by slow inhalation to ten healthy male volunteers. The plasma level after oral administration followed a low but broad plateau persisting for several hours. After i.v. administration the kinetic parameters were: Vc = 25.9 l, V alpha = 13.1 l, V beta = 3.38 l, t1/2 alpha = 3.85 min, t1/2 beta = 98.4 min, AUC = 15.0 h.ng/ml, kel = 11.8 l/h and total clearance is 2325 ml/min. The bioavailability was 3.3% (range 0.9-6.1%) on comparing the plasma AUCs following i.v. and 20 mg oral administration. The cumulative renal excretion (0-24 h) after i.v. administration was compared with that after oral administration and inhalation. Following oral administration, the apparent systemic availability was around 2%, and after inhalation it was 6.9%. In comparison with oral placebo administration, only after i.v. administration was there a significant change in heart rate (from 63.7 to 90.2 beats/min). The systolic blood pressure rose from 115.1 to 119.6 mm Hg and the diastolic blood pressure from 68.3 to 78.3 mm Hg.