Montelukast is a leukotriene receptor antagonist for treatment of asthma, gliclazide is an oral hypoglycemic antidiabetic agent, and nifedipine is a calcium channel blocker used for treatment of angina pectoris and hypertension. These drugs may be prescribed to patients suffering from these chronic diseases. A survey of the literature reveals that there is no reported method for the simultaneous determination of montelukast, gliclazide, and nifedipine in pharmaceutical preparations or biological fluids.

A simple, sensitive, and rapid method for the simultaneous quantification of montelukast, gliclazide, and nifedipine in human plasma was developed and validated. Montelukast, gliclazide, and nifedipine were resolved using rapid resolution LC/MS/MS Agilent system and SB-C₁₈ (50 × 4.6 mm) 1.8 μm particle size column. The mobile phase consisted of acetonitrile: 0.1% formic acid (84:16). The three drugs were simultaneously extracted from plasma by protein precipitation with acetonitrile using zaferolukast as an internal standard. The method was validated according to FDA guidelines with good reproducibility and linearity of 0.999 and the limits of quantification were 0.11, 0.04, and 0.07 ng/mL for montelukast, gliclazide, and nifedipine, respectively. The accuracies of the three QCs for the three drugs were 99.48% (montelukast), 106.53% (gliclazide), and 108.03% (nifedipine) in human plasma. The validated method was applied to a pharmacokinetic study in human volunteers after oral administration of the three drugs. The applied LC/MS/MS method was shown to be sufficiently sensitive and suitable for pharmacokinetic studies.

The LC/MS/MS method was validated and successfully applied for the determination of montelukast, gliclazide, and nifedipine concentrations in human plasma.