The effect of pneumococcal vaccine on the disposition of theophylline

Pneumococcal vaccine is frequently given to chronic obstructive airway disease patients who are maintained on theophylline therapy. Several studies demonstrating the effect of viral and bacterial vaccines on drug metabolism prompted our evaluation of the effect of pneumococcal vaccine on theophylline pharmacokinetics. Six healthy volunteers, acting as their own controls, received 250 mg of theophylline every 8 h for 12 days. Plasma area under the concentration-time curves (AUC) were measured on Days 4, 6, and 12. On Day 5 pneumococcal vaccine (0.5 ml) was given intramuscularly. No significant difference in elimination rate constant, AUC, or apparent oral clearance of theophylline was found at one or seven days after vaccine administration. These results indicate that intramuscular pneumococcal vaccine does not alter the pharmacokinetics of theophylline during chronic oral administration.