KINETIC INTERACTION BETWEEN THEOPHYLLINE AND A NEWLY DEVELOPED ANTIALLERGIC DRUG, PEMIROLAST POTASSIUM

The effect of a newly developed anti-allergic drug, pemirolast potassi um (TBX), on the pharmacokinetics and metabolism of theophylline was i nvestigated under steady-state conditions in seven healthy male volunt eers. A sustained-release theophylline formulation (100 mg twice daily at 12 h intervals) was given as monotherapy and coadministered with T BX (10 mg twice daily at 12 h). Plasma concentration-time curves and t he urinary excretion of theophylline and its major metabolites after a dministration of theophylline alone and after coadministration with TB X were compared. No significant adverse effects from this study were o bserved. There were no significant differences in the total body clear ance, renal clearance and maximum concentration of theophylline betwee n the two treatments, although coadministration of TBX significantly d elayed the time to reach maximum concentration of theophylline. In the case of urinary excretion, no significant changes in the fraction of urinary excretion of theophylline and its metabolites were observed. T hese results indicate that TBX has little or no effect on the pharmaco kinetics and metabolism of theophylline and suggest that TBX is safe f or asthma patients receiving theophylline therapy for treatment of chr onic obstructive airway diseases.