Pharmacokinetic Interaction Between Lansoprazole and Theophylline

Summary The pharmacokinetic interaction potential of the new proton-pump inhibitor lansoprazole and theophylline was assessed in a double-blind, two-period (13-day duration per period), multiple-dose crossover study in 14 healthy male volunteers. Lansoprazole 60 mg or placebo once daily was coad-ministered with anhydrous theophylline 200 mg four times daily. Plasma the-ophylline concentrations were quantitated via high-performance liquid chromatography. Lansoprazole did not appear to affect substantially the absorption profile or clearance of theophylline. Theophylline area under the plasma concentration-versus-time curve over the 6-h dosing interval decreased slightly (13%) but statistically significantly during lansoprazole coadministration. As the magnitude of this effect was small, this interaction is likely to be clinically insignificant.